GEK-75889J

MOTORIZED WHEEL DRIVE

SYSTEMS

E–37798
GEK-75889J, PLANNED MAINTENANCE

CONTENTS tems in establishing effective preventative maintenance

programs. With proper planned maintenance inspec-

 tions, maintenance personnel will be able to observe
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 any problem signs developing and then take corrective
ROTATING EQUIPMENT . . . . . . . . . . . . . . . . . . . . . . 3 action, thus preventing failures and reducing downtime
MOTORIZED WHEEL . . . . . . . . . . . . . . . . . . . . . . . . 3 to a minimum.
MOTORIZED WHEEL MAINTENANCE
SCHEDULE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 An effective preventive maintenance program will
CONTROL MAINTENANCE SCHEDULE . . . . . . . . 6 enable the user to obtain:
MOTORIZED WHEEL LUBE-OIL ANALYSIS . . . 12 – maximum component life
COMMUTATORS – optimum performance
(ALL ROTATING EQUIPMENT) . . . . . . . . . . . . . 16 – maximum availability through
COLLECTOR RINGS . . . . . . . . . . . . . . . . . . . . . . . 21 reduced, unscheduled downtime
BRUSHHOLDERS AND BRUSHES . . . . . . . . . . 22
GENERATOR/ALTERNATOR CAUTION: When steam cleaning or spraying
DRIVE BELTS . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 prior to overhaul, do not use a fluid containing
CONTROL EQUIPMENT any amount of caustic agent. It will have a det-
GENERAL INFORMATION . . . . . . . . . . . . . . . . . . 28 rimental effect on the coil insulation and wir-
CONTACTORS/REVERSERS . . . . . . . . . . . . . . . 29 ing system.
INTERLOCKS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
RELAYS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
1000 HOUR CHECKS, AUXILIARY EQUIPMENT CAUTION: When performing regular mainte-
AND AIR VENTILATION SYSTEM nance, do not use a high pressure hose for
RETARDING GRIDS . . . . . . . . . . . . . . . . . . . . . . . 33 cleaning the Motorized Wheel. This causes
RECTIFIER PANELS . . . . . . . . . . . . . . . . . . . . . . . 34 water to enter the outboard hub bearing which
BLOWER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 erodes lubricant and damages the bearing.
1000 HOUR VEHICLE OPERATION TESTS
BATTERY VOLTAGE . . . . . . . . . . . . . . . . . . . . . . . 34 Inspections should be made at the time periods spe-
SPEED EVENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 cified. However, optimum time intervals may vary ac-
AIRFLOW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 cording to geographical operating environments.
GROUND RELAY . . . . . . . . . . . . . . . . . . . . . . . . . . 34
ENGINE CHECKS . . . . . . . . . . . . . . . . . . . . . . . . . 35 Failure to implement a preventive maintenance pro-
RETARDING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 gram may result in accelerated wear and premature fail-
HORSEPOWER CHECK . . . . . . . . . . . . . . . . . . . . 36
1000 HOUR CHECKS, ROTATING EQUIPMENT ure of drive system components.
GENERATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
TIRE CHANGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 The following preventive maintenance inspection
AS-REQUIRED CHECKS AND CLEANING recommendations are based on extensive experience
INSULATION RESISTANCE . . . . . . . . . . . . . . . . . 37 under various operating conditions.
CLEANING PLUG-IN CARDS . . . . . . . . . . . . . . . . 37
BOLT TORQUE INSTRUCTIONS . . . . . . . . . . . . . 39 This information is offered as a general inspection
PLANNED MAINTENANCE guide which calls attention to what should be inspected
OUTLINE SHEETS . . . . . . . . . . . . . . . . . . . . . . . . . 42
_________________________________________ and what to look for.
INTRODUCTION
When certain conditions develop (e.g., excessive
The Planned Maintenance publication is to assist gear end-play or excessive oil consumption of a
mine personnel using GE Motorized Wheel Drive Sys- Motorized Wheel), the components should be removed

These instructions do not purport to cover all details or variations in equipment nor to provide for every possible contingency to be met in connection with installation, operation, or mainte-
nance. Should further information be desired or should particular problems arise which are not covered sufficiently for the user’s purposes, the matter should be referred to the General
Electric Company. Any applicable Federal, State or local regulations or company safety or operating rules must take precedence over any instructions given in this material. GE has no
obligation to keep the material up to date after the original publication.
THERE ARE NO WARRANTIES OF ACCURACY, MERCHANTABILITY OR FITNESS FOR PARTICULAR PURPOSE.
Verify numbers for parts, tools, or material by using the Renewal Parts or Tool Catalogs, or contact your General Electric repre-
sentative for assistance.
Do not order from this publication.

2
 PLANNED MAINTENANCE, GEK–75889J

from service and sent to a General Electric authorized

repair facility. CHECK TO
SEE THAT
DIPSTICK
Whenever there is uncertainty as to what action GASKET IS
should be taken, contact your local General Electric ser- INTACT AND
SEALING
vice representative for assistance. PROPERLY.

CAUTION: When performing any of the inspec-

tions, always protect the gearcase and its con-
tents from contaminants.

CAUTION: When welding on the truck:

1. Connect the welding ground as close as pos-
sible to area being welded, i.e. directly to the
part being welded. FIG. 1. DIPSTICK. E-24069
2. Never connect the welding ground so that cur-
2. Check to see that the filler cap gasket is sealing
rent will pass through bearings of any rotating
equipment. properly, Fig. 1. If necessary, replace the gasket .
3. DO NOT pull any control cards or remove pan Always lubricate the gasket with oil before re-
el connectors. This practice puts unneces – placing the filler cap to ease future cap removal.
sary cycles on connector pins and may cause
loose or dirty pins which could cause a con
trol system failure. Check for oil or grease leakage. Take corrective
action if two quarts of make-up oil per 24 hours on
CAUTION: Never release torque on the Motorized GE772, GE776 and GE791 (five quarts of make-up oil
Wheel thrust ring or adapter ring bolts while the per week on GE787 and GE788) are required. Some
wheel is in a horizontal position. leaks are normal and are to be expected, others may be
WARNING: All checks and inspections should be symptoms of trouble. Look for:
made with wheels chocked and engine and bat- 1. Grease squeezing out between the thrust
tery power off except where indicated. ring and wheel-hub bearing cap. On new or
recently overhauled wheels, this may be a nor-
CAUTION: Use no floor dry or de-icer type clean-
ing agents in the axle box. Use of these may dam- mal purging of excess grease in the bearing and
age the commutator film. no cause for alarm. If there is a large quantity of
grease and/or if the grease is liquefied by oil, it
ROTATING EQUIPMENT may indicate dilution of the bearing grease by
MOTORIZED WHEEL gearcase oil, maybe due to overfilling or pressur-
ization of the gearcase, Fig. 2.
Check Motorized Wheel gearcase oil level. To
perform an accurate check, the truck should first be
parked on a level surface and allowed to stand for 15
minutes if the oil is warm. If the oil is cold and the truck CHECK FOR LARGE QUANTITY
OF GREASE BETWEEN
has been recently run, allow more than 15 minutes. This BEARING CAP AND THRUST
RING. NOTE IF GREASE IS
is necessary to allow the oil to drain into the sump. LIQUEFIED BY OIL.

1. Remove the filler cap from the gearcase sump

and check the oil level. If oil is low, fill to the cor-
rect level:
On units with dipstick, fill to the full mark

On units without dipstick, fill completely (top off).

NOTE: Do not overfill gearcase oil sumps. Over- FIG. 2. THRUST RING AREA OF DISC BRAKE
filling can cause oil to leak from oil seals. MODELS. E-24070

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GEK-75889J, PLANNED MAINTENANCE

  


 

HOURS
WORK TO BE DONE Page GE772 GE776 & GE787 GE788
(SEE NOTE 1) No. GE791
AXLE BOX
1. Check oil level and dipstick (or oil-fill cap) gasket. 3 Daily Daily Weekly Weekly
2. Add 0.5 ounce grease to each dirt seal grease fitting 8 Daily Daily — —
(all models except those with FUF seals).
3. Add 1.0 ounce grease to each dirt seal grease fitting 8 250 250 — —
(all models except those with FUF seals).
4. Clean sun pinion cover magnetic plugs. 9 250 250 250 250
5. Clean or replace gearcase filters. 9 250 250 250 250
6. Check vent pipes for obstruction. 9 250 250 250 250
7. Check current shunts for tightness and discolor 30 250 250 250 250
ation.
8. Check cable connections for tightness and discolor- 30 250 250 250 250
ation.
9. Check axle box door seal. 10 250 250 250 250
10. Inspect for oil and grease leaks. 3 250 250 250 250
11. Take oil sample 12 250 250 250 250
12. Clean axle box. 8 250 250 250 250
13. Change oil (see Note 2). 9 500 500 1500 1500
14. Clean sump magnetic plugs. 10 500 500 1500 1500
15. Check drive ring internal spline wear. 11 500 500 2500 2500
16. Remove and inspect the sun pinion: 10 500 500 2500 2500
a. Check gear condition (visually)
b. Check spline wear (visually)
c. Check oil baffle and snap rings for damage
d. Check for sufficient clearance from cover.
17. Check end play of gears. 11 1000 1000 2500 2500
A.
B.
C.
ARMATURE AREA
1. Check brush length, condition, freedom of move- 23 500 500 500 500
ment.

*Product of E.I. duPont de Nemours Co.

Revisions are indicated by marginal bars.

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 PLANNED MAINTENANCE, GEK–75889J

MOTORIZED WHEEL MAINTENANCE SCHEDULE (Cont'd)

HOURS
WORK TO BE DONE Page GE772 GE776 & GE787 GE788
(SEE NOTE 1) No. GE791
ARMATURE AREA (Cont’d)
2. Check brushholder condition, clearance, brush ten- 22 500 500 500 500
sion.
3. Check commutator condition, film, etc. 17 500 500 500 500
4. Clean Teflon*band. 23 500 500 500 500
5. Check coil insulation (visually). 24 500 500 500 500
6. Check hydraulic line connections for leakage. 10 500 500 500 500
Clean up any fluid found in the frame.
7. Blow out brushholder and commutator area. 11 500 500 500 500
MISCELLANEOUS
1. Remove dirt and grease buildup from dirt seal area. 37
2. Inspect dirt seal grease fittings (only GE772, GE776 37
& GE791 with Triple Lip Dirt seals).
3. Lubricate dirt seal area until purge (only GE772, 8
GE776 & GE791 with Triple Lip Dirt seals).
4. Check wear of torque tube wear band 37
(GE772, GE776 and GE791 only).
5. Visually inspect for broken grease lines, damage 37 At
to hub caps etc. Tire Change
6. Check condition of grease line guards (if used). 37
7. Check tightness of exposed bolts. 37
8. Retorque brake adapter bolts on models equipped 37
with disc brakes.
9. Lubricate Wheel Hub Bearings (GE787 & GE788
only):
a. Remove six grease plugs in wheel hub.
b. Insert zerk grease fittings.
c. Add 4 oz. of grease to each fitting.
d. Replace grease plugs in wheel hub.

NOTE 1: The numbers in the columns under each motor type represent operating hours, except as
specified.

NOTE 2: On GE787 and GE788 Motorized Wheels, change the oil after the first 500 hours; thereafter,
at the indicated 1500 hour interval. 1500 hours is maximum. More frequent oil change inter-
vals may be required, depending on individual mine conditions.

5
GEK-75889J, PLANNED MAINTENANCE


 


 

Work To Be Done Page No. Hours

GENERATOR/ALTERNATOR
1. Check brush length, condition, freedom of movement. 23 250
2. Check brushholder condition, spacing, tension. 22 250
3. Check commutator/slip ring condition, film, etc. 22 250
4. Clean string/Teflon band. 23 250
5. Blow out commutator area with clean dry air (70 psi max.). 24 250
6. Check blower/exciter belt tension. 24 250
7. Blow out air holes (GT603). 37 1000
EXCITER
1. Check brush length, condition, freedom of movement. 23 250
2. Check brushholder condition, spacing, tension. 22 250
3. Check commutator condition, film, etc. 17 250
4. Clean string/Teflon band. 23 250
5. Blow out commutator area with clean dry air (70 psi max.). 24 250
GRID BLOWER MOTOR
1. Check brush length, condition, freedom of movement. 23 500
2. Check brushholder condition, spacing, tension. 22 500
3. Check commutator condition, film, etc. 17 500
4. Clean string/Teflon band. 23 500
5. Check cables for abrasion and burning 34 500
6. Blow out commutator area with clean dry air (70 psi max.). 24 500
CONTROL EQUIPMENT CHECKS
1. Vacuum the control cabinet. 29 250
2. Check all electrical connections for tightness. 29 250
3. Check current shunts for tightness, discoloration. 29 250
4. Check insulators, terminal strips, springs, etc. for breaks or cracks. 29 250
5. Check reverser, contactors, interlocks and relays for tip wear, burning, tip 30 250
break, overtravel, tip pressure and frayed, broken or discolored shunts.
6. Check condition of arc chutes 31 250
7. Check magnet valves for leaks 32 250
8. Check door seal and latch. 34 250

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 PLANNED MAINTENANCE, GEK–75889J

CONTROL MAINTENANCE SCHEDULE (Cont'd)

Work To Be Done Page No. Hours

AUXILIARY EQUIPMENT AND AIR VENTILATION SYSTEM
1. Inspect retarding grids; check for damaged parts, foreign objects. 34 1000
2. Check rectifier panel air passages. 35 1000
3. Check all connections for tightness, damaged clamps. 35 1000
4. Clean blower inlet filter or screen. Make sure it is free from obstructions and 35 1000
foreign objects. Lubricate pillow blocks.
5. Check flexible air ducts for damage. Measure static air pressure (axle box). 35 250
VEHICLE OPERATION TESTS
1. Check battery voltage. Adjust as required. 35 1000
2. Check speedometer calibrations. 35 1000
3. Check all speed event calibrations. 35 1000
4. Test ground relay operation. 35 1000
5. Engine Checks*. 36 —
6. Check tach calibration, adjust as required. 36 1000
7. Check low idle, retarding rpm, top end rpm. Adjust as required. 36 1000
8. Check for proper operation of blower loss warning device. 35 1000
9. Check high idle and throttle cut-off solenoid operation. 36 1000
10. Measure motor field retarding current noting generator/armature voltage. Ad- 36 1000
just as required
11. Check horsepower vs. rpm in road test or statically. 37 1000
12. Check operation of grid blower in road test. 36 1000
13. Measure retarding motor armature current as a function of speed. Adjust as 36 1000
required in road test or statically.
AS-REQUIRED CHECKS AND CLEANING
1. Measure armature, comm. field, and exciting field resistance to ground. Re- 38 As Required
cord to detect degrading insulation
2. Clean plug-in cards 38 As Required
2. Oil accumulation on the inside diameter of 3. Excessive chassis grease accumulation on
the brake drum or on the inside diameter of the inboard tire: Accumulation of grease and
the tire rim of the outboard tire: This may indi- dirt at the dirt seal is not desirable.
cate (1) that oil has leaked past the oil seals or (2)
that oil is leaking into the inside of the motor. 4. Oil draining from the bottom of the seal
Check inside of the motor armature cavity, Fig. 3. housing support at either the dirt seal end or

*These checks and necessary adjustment must be made before proceeding.

7
GEK-75889J, PLANNED MAINTENANCE

CHECK INSIDE OF
MOTORIZED WHEEL FOR
OIL AND HYDRAULIC
FLUID LEAKS.

FIG. 5. GREASE FITTINGS, GE772, GE776

AND GE791. E–24073B.
FIG. 3. MOTORIZED WHEEL, COMMUTATOR
END. E-24071 2. Pump grease into each grease line again until
the mounting flange end. This may be due to grease purges from the entire dirt seal area. This
loose bolts or inadequate sealant, Fig. 4. also must be done whenever tires are removed.
If any of the above conditions are observed, contact 3. During regular service, add grease according to
your General Electric service representative for assis- the Maintenance Schedule, Page 4.
tance. Daily
Lubricate Triple Lip Dirt Seals (GE772, GE776 Add 0.5 oz. of grease to each zerk fitting to
and GE791 Models Only) those wheels with eight–pipe grease sys-
NOTE: GE772, GE776 and GE791 Motorized tems.
Wheels with FUF seals, and all GE787 and
Add 1.0 oz. of grease to each zerk fitting to
GE788 Motorized Wheels do NOT require peri-
those wheels with four–pipe grease systems.
odic lubrication.
250 Hours
After the Motorized Wheel is mounted to the axle
Add 1.0 oz. of grease to each zerk fitting to
box, perform the following:
those wheels with eight–pipe grease sys-
1. Before grease lines are connected to the wheel, tems.
pump grease into each one until grease purges Add 2.0 oz. of grease to each zerk fitting to
from the line. Then connect grease lines to the those wheels with four–pipe grease systems.
wheel.
NOTE: General Electric Co. does not recom-
mend using auto-lube systems in the triple-lip
dirt seal area. The auto-lube grease and greas-
ing intervals do not provide proper lubrication
of the dirt seals.

NOTE: Clean axle box before proceeding with

CHECK FOR OIL following maintenance inspections.
LEAKING FROM
EITHER END OF
SEAL HOUSING Examine Motorized Wheels, generator/alterna-
SUPPORT.
tor, exciter and blower motor for:
1. Damaged cables or loose cable cleats
2. Loose mounting bolts or nuts
FIG. 4. SEAL HOUSING SUPPORT. E–24072. 3. Clogged or restricted air inlets or outlets

8
 PLANNED MAINTENANCE, GEK–75889J

TABLE 1, MOTORIZED WHEEL LUBRICANTS

Location GE Spec. Company Brand Name

1. Armature Bearing (Comm End) D6A2C10 Shell Oil Co. Cyprina RA
Sealing Grease
Lubricating Grease
2. Armature Bearing (Pinion End)
3. Armature Bearing Cap Cavity
4. Armature Bearing Cap Dirt Seal
5. Speed Sensor Cavity
6. Torque Tube Dirt Seal (All GE772,
GE776 & GE791 Motorized Wheels
With FUF Seals And All GE787 And
GE788 Motorized Wheels.
7. Torque Tube Dirt Seal (All GE772, D50E16 Shell Oil Co. Retinax AM
GE776 And GE791 Motorized Wheels Texaco Molytex No. 2
With Triple Lip Dirt Seals) Pennzoil Molysulfide No. 704
8. Wheel Hub Bearings D50E21 *Gulf OIl Corp. Gulfcrown EP2
(USA) Mobilux EP2
Mobil OIl Co.
9. Gearcase Oil All Seasons MIL-L2105C 85W-140 Grade Oil
To -12
C (10.4
F)
An Anti-Foaming
Agent Is Summer MIL-L2105B SAE-140 Grade Oil
Required
Winter MIL-L2105C
To -26
C (-14.8
F) 80W-90 Grade OIl
  

   
 To -40
C (-40
F) 75W-90 Grade Oil
*Use only grease made in the USA.

4. Loose or worn drive belts (adjust as required) Fig. 7. Check for metal particles. If magnetic plugs have
5. Excessive dirt build-up on equipment
6. Condition of hubcaps.
REMOVE AND CLEAN
FILTER. CHECK PIPE
Remove and clean or replace the Motorized OR HOSE INSIDE AXLE
Wheel gearcase vent filter(s), Fig. 6. (Always replace BOX FOR TRAPS.
paper filters.) Check that vent pipes or hoses do not
droop or form a “U” where oil can be trapped, preventing
gearcase depressurization.

Drain the gearcase oil sump and refill with prop-

er grade of oil. Successive oil change intervals should
be determined by magnetic plug accumulation, spectro-
graphic analysis of the oil and general operating experi-
ence.

Remove and clean the Motorized Wheel magnet-

ic plugs located on the sun pinion gearcase cover, FIG. 6. GEARCASE VENT FILTER. E-24074

9
GEK-75889J, PLANNED MAINTENANCE

excessive accumulation of metal particles, it may

indicate gear or bearing distress and the need to change
oil more frequently, Fig. 8.

Check hydraulic line connections for leakage.

Clean any accumulated fluid from the 6 o’clock area in-
side of frame.

Check axle box door gasket. If gasket is not intact

and sealing properly, it will result in cooling air loss.

Remove and clean oil-sump magnetic plugs.

Check for unusual amount of contamination. Refill gear-
case oil sump with SAE 85-140 oil (MIL-L-2105C).

Check Motorized Wheel gearcase oil overfill FIG. 8. MAGNETIC PLUG ACCUMULATIONS.
E-24076
drain out of axle box (if present). Unplug if necessary,
Fig. 10.
CAUTION: Do not damage the oil baffle when
removing the sun pinion.
Remove sun pinion; check wear as follows, Fig.
11: An easy check for spline wear is to measure the
width of the flat at the top of the spline tooth. The follow-
CAUTION: Keep sun pinion clean and pro-
tected when removed from gearcase; i.e., do ing chart indicates tooth dimensions when new and
not lay down on dirty surface or where dirt or tooth condemning limits which indicate that the sun pin-
objects may fall on it. ion must be replaced. See Fig. 9.

9/64 IN. NEW

3/64 IN. MINIMUM

3/64 IN. MIN.

REMOVE AND CLEAN

SUN PINION COVER
MAGNETIC PLUGS. 9/64 IN. NEW
3/64 IN. MINIMUM

NOTE: SOME SPLINE TEETH

MANUFACTURED WITH CHAMFER,
CONDEMNING LIMITS MEASURED
AT BASE OF CHAMFER.

FIG. 7. SUN PINION COVER MAGNETIC PLUGS. FIG. 9. GE772, GE776 AND GE791 SUN PINION.
E-24075A E-18255

10
 PLANNED MAINTENANCE, GEK–75889J

tween the spline teeth, then the armature should be re-

moved and the coupling replaced, Fig. 12.
CHECK GEAR CASE OVERFILL
DRAIN OUT OF AXLE BOX,
UNPLUG IF NECESSARY. Check planet gear assembly for end-play in ex-
cess of 0.030 in. on GE772, 0.020 in. on GE776 and
GE791 and 0.040 in. on 787 and 788. Check manually
or by using a small pinch bar. (See Figs. 13 and 14.) Do
so for all three gears.

This is a valuable test for either GE772, GE776 or

GE791 Motorized Wheels because it gives an indication
of excessive wear on the planet gear bearings.
FIG. 10. GEARCASE OVERFILL DRAIN. E-24090
NOTE: When the manual check reveals exces-
772/776/791 787/788
sive gear end-play, the Motorized Wheel should
New 7/64 in. 1/8 in. be removed from service and sent to a GE au-
Condemning Limit 3/64 in. 3/64 in. thorized repair facility.

Visually inspect gear end of sun pinion for signs of Check to see that sun pinion oil baffle, retaining
rubbing on cover and for abnormal wear or spalling of plate, snap rings and bolt and washer are intact be-
the teeth. fore reinstalling sun pinion. Torque bolt to 185-210 ft.-lb.
(GE772, GE776 and GE791) or 55-60 ft.-lb. (787 or
When the sun pinion removed, manually check 788). When torquing bolt be careful not to distort the sun
drive coupling tightness on armature shaft. If drive pinion oil baffle. Damage to the baffle will result in a loss
ring is loose, the armature shaft and/or drive ring must of lubrication to the drive coupling/pinion spline mesh.
be replaced. Upon reinstalling sun pinion in the wheel, check it for ex-
cessive end-play (over 1/4 in.).
Using gage 41A237848 for GE772, GE776 and
GE791 (41A239826 for GE787 and GE788), check If end-play is excessive, check:
drive coupling spline at sun pinion fit. Insert the pie-
shaped gage with the large radius on top of the drive ring 1. That the retaining bolt is the proper length.
spline teeth. Attempt to tip the small radius into the cou- 2. That the tapped hole in the armature is not ob-
pling. If the small radius cannot be passed through the structed.
area between two of the spline teeth, then the coupling
should be continued in service. If it is possible to tip or Clean the Motorized Wheel as follows:
rock the small radius over center through the area be-
1. Vacuum inside the axle box to remove accumu-
lated dirt.

2. Remove hubcaps and blow the motor with dry,

clean compressed air (70 psi) from the pressur-
ized box out.

3. With the axle box closed, truck in NEUTRAL, en-

gine at IDLE, blow the commutator and brush
area with compressed air.

Check for damaged Motorized Wheel hubcaps.

FIG. 11. REMOVING SUN PINION. E-24091 Replace if air outlet passages are restricted or if extra air
outlets have been created.

11
GEK-75889J, PLANNED MAINTENANCE

GAGE SHOULD NOT BE

ABLE TO REACH A
PERPENDICULAR
POSITION IN THE
DRIVE COUPLING.

USING “PIE GAUGE”

CHECKS PITCH USE USE

DIAMETER
OF SPLINE REJECT

CHECKS I.D. – GE 772, 776, 791 GAUGE

– # 41A237848
OF RING – GE 787,788 –GAUGE # 41A239826

FIG. 12. USING DRIVE RING “PIE GAUGES”. E-24092A.

mium and silicon content. Samples should also be ana-

CAUTION: If using any type of lever for check- lyzed to determine viscosity and the amount of insoluble
ing gear end-play, use only enough pressure
to obtain an accurate indicator reading. Do not particles present.
try to force the gear beyond its free travel.
The condition of internal components can be eva-
Refer to Fig. 15 for the speed sensor cavity grease luated through trends recorded during successive tests.
fitting location. Moving contact between the metallic parts causes fric-
MOTORIZED WHEEL LUBE-OIL ANALYSIS tion and is accompanied by the wearing away of the
metal parts. This results in metal particles becoming
An oil sample should be taken from each Motorized suspended in the oil. Thus, we have a potential source
Wheel and spectrographically analyzed for iron, chro- of information concerning the condition of the Motorized

12
 PLANNED MAINTENANCE, GEK–75889J

WARNING: Personal injury may result if prop-

BAR GEAR IN AND er eye protection is not worn when cleaning
SET INDICATOR with compressed air.
TO ”0”
spectrometric analysis will accurately show even the
presence of wearing metal. Most metals can be mea-
sured down to two or three parts per million (ppm). This
is possible because metallic atoms and ions will emit
characteristic light spectra when vaporized by an elec-
tric arc. So we can identify each metal by its light spectra
and we can tell how much of that particular metal is pres-
ent by the intensity of the spectra line relative to a set
standard.
A sudden increase of iron content will indicate exces-
sive wear of one or more of the drive train components.
A sudden increase in chromium would indicate unusual
wear of the bearing. See examples, Tables II and III.
FIG. 13. CHECKING GEAR END-PLAY. E-24093 Samples must be promptly sent to the analyzing
agent. Analysis and reporting must likewise be equally
Wheel because the chemical characteristics of the par- prompt. Any delay could negate the application of the
ticles will not change; therefore, we know where they analysis report. All samples must be analyzed under the
come from. A normal amount of wear can be determined identical conditions or the results will not be useable.
so that when an abnormal amount of a certain particle- NOTE: The oil analysis program is only a sup-
shows up in the oil analysis, we will know that something plement to Motorized Wheel maintenance pro-
is wearing at a higher-than-average rate, Fig. 8. cedures already in effect. Used conscientiously
and correctly, it has proven itself an effective
tool and not intended to change established
Before being used, gearcase oil will not have any maintenance procedures.
metal particles. As the oil is used in a closed system, NOTE: Lead content of 15-35 ppm in the oil is
normal. When 100-200 ppm is reached, dirt seal
leakage is indicated. Dirt seal must be ade-
quately lubricated to correct leakage.
BAR GEAR OUT, RELEASE
PRESSURE, AND READ
END–PLAY. REPEAT FOR
ALL THREE GEARS.

ADD TWO OZ. OF

GREASE TO FITTING
ON BOTTOM OF
BEARING CAP.

FIG. 15. SPEED SENSOR CAVITY GREASE

FIG. 14. CHECKING GEAR END-PLAY. E-24094 FITTING LOCATION. E-24095

13
GEK-75889J, PLANNED MAINTENANCE

TABLE II, GE772, GE776 AND Procedure for Taking Sample

GE791 - EXAMPLES OF 1. Operate truck for an extended period (at least one
SPECTROGRAPHIC RESULTS hour).
2. Let stand for ten minutes.
Exam- Hours Fe (ppm) Cr Si (ppm) 3. Take sample.
ple Since (ppm)
Last Oil a. Equipment needed.
Change TABLE III, GE787 AND GE788
1 250 57 0 50 EXAMPLES OF
500 68 2 58 SPECTROGRAPHIC RESULTS
250 93 3 58
Exam- Hours Fe (ppm) Cr Si (ppm)
500 589 8 75 ple Since (ppm)
2 250 104 2 180 Last Oil
Change
500 136 2 186
1 1250 57 0 50
250 198 8 190
2500 68 2 58
3 250 420 2 183
1250 93 3 58
500 480 3 196
2500 589 8 75
250 430 3 186
2 1250 104 2 180
500 520 5 210
2500 136 2 186
250 560 4 205
1250 198 8 190
500 930 13 230
3 1250 420 2 183
4 250 106 2 186
2500 480 3 196
500 128 2 210
1250 430 3 186
250 180 3 205
2500 520 5 210
500 240 4 500
1250 560 4 205
EXAMPLES OF VISCOSITY AND 2500 930 13 230
INSOLUBLE PARTICLE TESTS 4 1250 106 2 186
Exam- Hours Viscosity Viscosity Pentane 2500 128 2 210
ple Since (SSU) (SSU) Insoluble 1250 180 3 205
Last Oil 100
F 200
F (%)
Change by 2500 240 4 500
Weight
EXAMPLES OF VISCOSITY AND
5 New Oil 782 79.9 0.05
INSOLUBLE PARTICLE TESTS
250 890 84.6 0.09
500 1130 98.6 1.01 Exam- Hours Viscosity Viscosity Pentane
ple Since (SSU) (SSU) Insoluble
General Recommendations Last Oil 100
F 200
F (%)
Change by
Weight
Frequency of Sampling
5 New Oil 782 79.9 0.05
1. At regular 250 hour inspection
1250 890 84.6 0.09
2. Again prior to oil change
3. More often if suspicious of operation. 2500 1130 98.6 1.01

14
 PLANNED MAINTENANCE, GEK–75889J

1) Heat resistant, unbreakable 1.5 oz. ca- 2) Repeat Steps c), d) and e).
pacity (min.) “turkey” baster, Fig. 16.
3) When all samples have been taken,
2) Clean sample bottles (3–5 oz.). clean the extractor thoroughly.

3) Gage extractor, Fig. 16. Tests to be Done

b. Procedure 1. Spectrographic analysis

2. Viscosity tests
1) Clamp two or more rigid supports ex- 3. Test for amount of insoluble material.
tending 2 in. from the opening of the ex-
tractor. What to Look For

2) Take samples. 1. Spectrographic analysis:

a) Label sample jars to keep track of Check iron, chromium, nickel and silicon con-
samples. tent. Compare amounts, in ppm, to previous
sample. If a significant increase in any of the ele-
b) Insert extractor into sump until the ments above appears, perform a gearcase in-
rigid supports contact the bottom of spection as outlined on page 9. If silicon con-
the sump. tent only shows a large step change, the oil
should be changed. For GE772, GE776 and
NOTE: For accurate oil analysis it is desirable to
GE791 wheels, see Table II, Examples 1
take oil samples approximately 2 in. from the
through 4. For 787 and 788 wheels, see Table
sump bottom.
III, Examples 1 through 4.
c) Fill extractor by squeezing and re-
NOTE: It is important to emphasize that you are
leasing bulb.
looking for a large increase in iron or chromium
d) Empty extractor into sample jar the content between two consecutive tests.
same way.
2. Viscosity test:
e) Repeat Steps c) and d) until sample
jar is full (approx. 3-5 oz.) If viscosity shows a large increase or decrease,
then change the oil. The oil also should be
c. Cleaning changed if viscosity increases over 30 percent of
original. See Example 5, Tables II and III.
1) To take next sample, insert extractor,
Fig. 16, into next sump until the rigid sup- 3. Insoluble material:
ports touch the bottom of the sump.
If the amount of insoluble material test shows a
Squeeze and release bulb several (5-7)
large increase, the oil should be changed. Check
times to flush out oil from the previous
for proper lubing of the dirt seal. See Example 5,
sample.
Tables II and III.

In Examples 1, 2 and 3, the gears should be in-

spected or the wheels should be taken out of service
and checked as soon as possible after the underlined
value, or values are discovered. Note that the magni-
tude of the value is not as important as the sudden In-
crease (compare Examples 1 and 3). This is due to the
fact that this value can vary depending upon the type of
FIG. 16. “BASTER” TYPE EXTRACTOR. E–24102.
spectrographic test conducted.

15
GEK-75889J, PLANNED MAINTENANCE

PLANET GEAR AND PINION BEARINGS

(TYPICALLY 52100 STEEL, 1.5% CHROMIUM).

SUN PINION GEAR ARMATURE SHAFT SPLINE

PLANET PINION SHAFT, DRIVE COUPLING
(TYPICALLY 4620 STEEL, 0.5% CHROMIUM,
3.5% NICKEL, MAY BE MANUFACTURED OF
4320 STEEL, 0.5% CHROMIUM, 19% NICKEL).

PLANET GEARS,
RING GEAR
(TYPICALLY
4142 STEEL, 1.0%
CHROMIUM).

FIG. 17. METAL ALLOYS OF MOTORIZED WHEEL. E-24103

In Example 4, the oil should be changed immediately In a spectrographic analysis of the gear oil, if chro-
upon discovering the sudden change in silicon content. mium is indicated, it should include a nickel determina-
tion. As is noted above, two alloys 4820 and 4320 have
In Example 5, the oil should be changed if either the nickel contents greater than the chromium. A high chro-
sudden change in viscosity or insoluble material is pres- mium content, and very little nickel, might indicate the
ent, or if the 500 hour limit has been reached. principle parts that are wearing. A high nickel content
with some chromium would indicate other parts that are
The above instructions for oil sample analysis are wearing, Fig. 17.
also applicable to the GE787 and GE788 Motorized
Wheels. However, for the increased oil change inter- For every gram of metal worn from these alloys, it
vals, refer to Table III. would produce 1 ppm maximum chromium in 4.5 gal-
lons of gear oil by spectrographic analysis.
Additional Guides
The system is designed to detect only that type of
Along with oil sampling, magnetic plugs should still failure which characteristically begins with an increase
be checked and cleaned regularly. Record appearance in metal wear; that is, worn bearings, worn gears and
of material accumulated. In the event of the appearance slowly progressing fatigue failures. Those Motorized
of a large increase in the amount of metallic particles or Wheel failures which are catastrophic and instanta-
chips, the sun pinion should be checked. If no damage is neous in nature are not caught by this system.
evident here, then the wheel should be removed from
service as soon as possible and checked. Any oil sample taken has to be representative of the
condition of the gearcase components. For that reason,
The chromium content of the alloy steels can be a the oil must have circulated long enough in the Motor-
contributor to the chromium content in the gear oil analy- ized Wheel to accumulate metal particles that show a
sis. The levels should be low (<10 ppm). true picture of the gearcase components wear, Fig. 19.

16
 PLANNED MAINTENANCE, GEK–75889J

Newly changed oil or oil recently added to a system

will not give a true picture when it is analyzed. Also, devi-
ation from accepted procedures in taking the sample
can invalidate the analysis results. Any of these condi-
tions could have dangerous or misleading conse- MAKE SURE FLEXIBLE
quences because the sample analysis would be incor- AIR DUCT IS
CONNECTED AND
rect and not indicate the true condition of the Motorized PROPERLY SECURED
IN PLACE.
Wheel.
The ultimate success of the program rests with
the user. If they take good samples, forward them
promptly, and then use the feedback wisely, the
program will be effective. But if the users only go
through the motions, nothing is accomplished.
FIG. 18. COMMUTATOR COVERS. E-24078
Documentation
surface is smooth and has a polished glossy appear-
1. Date of sample ance, Fig. 20.
2. Serial number of wheel
Temperature, atmosphere and grade of brush used
3. Total hours of wheel life all affect this film. If the film is damaged electrically or
4. Hours of operation since last oil change mechanically, both brush and commutator wear is ac-
5. Complete results of all tests conducted celerated.
6. Any other applicable comments about the wheel’s Chemical contamination probably causes the great-
operation est disturbance, since formation of materials other than
7. Truck serial number and position (left or right) copper oxide is usually harmful. Abrasive dust wears
8. Appearance of magnetic plug accumulation. away the film, while other types of suspended particles
COMMUTATORS (ALL ROTATING EQUIPMENT) react with the vaporized copper to form nonconductive
films. Many organic materials are just as harmful as
CAUTION: Clean all dirt from around genera- chemical contaminants.
tor, Motorized Wheel, exciter and blower mo-
Oil vapors have a decided effect on film condition.
tor commutator covers before removing the
covers. Not only does the oil introduce an insulating surface, it
also prevents bonding of film on the commutator and
Armature Areas of All Rotating Components
DEPOSITS ACCUMULATED
With commutator covers, Fig. 18, and the hubcaps IN DRIVE RING FROM
removed, inspect all commutator surfaces. CONTAMINATED OIL.

A knowledge of various surface conditions and how

they affect commutation and current collection will be
helpful. It is the maintainer’s job to spot a commutator
surface headed for trouble and correct it before a failure
occurs.

The importance of maintaining a proper commutator

surface film cannot be overemphasized. With this film
established and properly maintained, good brush per-
formance (reduced brush and commutator wear) and
satisfactory commutation (no destructive sparking) is
assured. Changes in color from copper to deep brown or FIG. 19. DRIVE RING. E-24077
chocolate should give no cause for worry, as long as the

17
GEKĆ75889J, PLANNED MAINTENANCE

causes a torn or mottled film surface. It will also promote

rapid metal transfer and eventually, threading.

Color Pattern

This term indicates only that the color of the commu-

tator bars is not uniform and a definite pattern exists.
The pattern is almost always related to the arrangement
of coils in the armature slots. In itself, this condition is not
a sign of damage. The color pattern may show up in sev-
eral sequences, Figs. 21 and 22. As long as there is a
definite pattern around the whole commutator, do not be
concerned.

Marking, Etching and Flat Spots

The following conditions indicate discoloration and/

or etching of commutator bars – but in varying degrees.
Possible causes of etching and discoloration include:
FIG. 21. ONE LIGHT – TWO DARK THREE COIL
1. Excessive load on the machine. PER SLOT COLOR PATTERN. E-8762A

2. Electrical adjustment off; such as, wrong shims

behind commutating poles or wrong interpole
gap.
The best way to overcome these conditions is to de-
3. Wrong brush grade. termine the cause and make the necessary corrections.
If damage has not progressed too far, it may clear itself
4. Uneven or rough commutator surface. once the cause has been eliminated. If it is determined
that some resurfacing of the commutator is necessary, it
5. Contaminated atmosphere. should be done sparingly.

FIG. 20. GOOD COMMUTATOR FILM. E-8761A

FIG. 22. ONE DARK – TWO LIGHT THREE COIL
PER SLOT COLOR PATTERN. E-8763

18
 PLANNED MAINTENANCE, GEK–75889J

FIG. 24. HEAVY ETCHING ON A TWO COIL PER

SLOT COMMUTATOR. E-8765A

Threading
Threading is a commutator-surface condition that
shows as circumferential grooves on the commutator.
FIG. 23. COMMUTATOR FILM REMOVED WITH A Threading is the result of abrasive or electro-chemical
PENCIL ERASER. E-8764
action of the brushes.

Marking In light threading, grooves may just barely be appar-

ent where the surface film or color is disturbed or differ-
This condition appears as an opaque darkened sur- ent. In heavy threading, a rippled surface can be felt if
face or black deposit on the bars, usually at their trailing you rub a fingernail along the surface of a bar, Fig. 27.
edge, with no etching or corrosion of copper under-
neath. The brush faces wear to fit these grooves. When the
commutator shifts due to armature end-play, the
Check for this condition quickly by using a common brushes are lifted out of the grooves. Then contact be-
pencil eraser to remove the deposit; then examine the
copper surface for roughness or pitting. If none is seen,
the condition is marking, which can readily be removed
with a canvas cloth, Fig. 23.

Bar Surface Etching

This condition gives the appearance of severe mark-

ing, and a pencil eraser will uncover pitting, eroded or
burned bar surfaces. Such a condition results from arc-
ing between the brush and the copper commutator bars
and the etching is usually visible with the naked eye
when the marking is removed, Figs. 24 and 25.

The term “burned bars” is sometimes used to indi-

cate bar surface etching. This merely represents an ad-
vanced state of etching.

If etching is not corrected and progresses too far, flat

spots will develop. Flat spots may also develop from a
mechanical disturbance; such as, the vibration from a FIG. 25. IRREGULAR FILM AND ETCHING.
defective bearing, Fig. 26. E-8766

19
GEKĆ75889J, PLANNED MAINTENANCE

4. Wrong brush grade.

Determine the cause of the threading and resurface
by grinding (with a rigidly mounted grinding fixture as
listed in the respective maintenance manual or by turn-
ing on a lathe.

Copper Drag
Under certain conditions copper is dragged over the
trailing edges of the commutator bars and has the ap-
pearance of small metal flakes or feathers. Copper drag
is caused by particles of copper, copper oxide and con-
taminates that do not bond firmly to the surface of the
commutator. As the commutator rotates, the brushes
shove small flakes of this material toward or into the
commutator slots. This decreases the distance be-
tween the bars. An arc formed at any brush can then be
more easily carried over to an adjacent brush resulting
in a flashover.
Copper drag should not be confused with bar-corner
FIG. 26. FLAT SPOT ON A COMMUTATOR.
E-8767 etching, Fig. 28.

tween the brush and the commutator is disturbed, Possible causes of copper drag include:
sparking occurs, and commutation is disrupted. 1. Contaminated atmosphere
2. Copper imbedded in brush face
Possible causes of threading include:
3. Hard spot in brush
1. Low current-density in the brush (machine is not
4. Wrong brush grade
heavily loaded).
5. Excessive vibration
2. Abrasive dirt or other foreign material imbedded in
the face of the brush. 6. Low current density.
3. Mica flakes or copper imbedded in the brush face. A temporary solution to copper drag is to clean the
commutator occasionally with a light brush-seater

FIG. 27. HEAVY THREADING OF A

COMMUTATOR. E-8768A FIG. 28. COPPER DRAG ON TRAILING EDGE.
E-8769A

20
 PLANNED MAINTENANCE, GEK–75889J

FIG. 29. EXAMPLE OF BANDING. E-8771

stone. If drag has progressed too far, the slots must be

raked and cleaned.

Banding FIG. 30. EXAMPLE OF A SOFT COMMUTATOR

BAR. E-5022
Banding is a surface defect in the form of bands
around the commutator in which the surface film has Flashover Damage
been partially or completely removed. These bands
may be quite narrow (not to be confused with threading) A commutator does not fail suddenly, it gives indica-
or they may extend over a sizeable percentage of the tions of future trouble in time for most trouble to be pre-
brush path. See Fig. 29 for example of banding. vented. The commutator surface defects previously
mentioned must not be allowed to cause the machine to
Possible causes of banding include: fail.
1. Brush film too heavy (film tears from surface)
Any condition or defect which causes arcing on the
2. One brush is the wrong grade
surface of the commutator must be regarded as a poten-
3. Hard spot in a brush. tial cause of a flashover. When arcing becomes severe
Banding can be corrected by hand-stoning after the enough, the surrounding air changes into a conductive
cause has been eliminated. gas and allows power to spill-over between the brushes
in a flashover. A flashover is the commutator’s final pro-
High Bars test against neglect and abuse. Evidence that a ma-
chine has flashed over will be found in the form of copper
If a motor armature does not rotate while power is splatter on the surface and ends of the commutator
applied, the commutator bars under the brushes will bars, on the brushholders and nearby insulation and on
overheat and expand. Expansion will cause these bars the frame as shown on Fig. 31.
to rise above the adjacent bars. When the armature ro-
tates, the high bars “kick” the brushes which, in turn, arc If a flashover occurs, clean the commutator, the Te-
and burn the commutator surface. If this condition is not flon creepage band and the brushholders. Examine
corrected, the brushes may shatter and a flashover these parts for damage and check the condition of the
could occur, Fig. 30. Refer to the respective instruction brush faces. Repair or replace damaged parts as neces-
book for tolerances and corrective action. sary.

21
GEKĆ75889J, PLANNED MAINTENANCE

BRUSHHOLDERS AND BRUSHES

Inspect brushholders for flashover damage, loose

pigtail terminal connections, cracks or thin spots in the
Teflon sleeve, tightness of cable connections and cor-
rect clearance from the commutator. See Fig. 32 and
Table IV .

TABLE IV, BRUSHHOLDER

CLEARANCES

Apparatus Clearance (in.)

Motorized Wheel 1/16 to 3/32
Alternator 3/32 to 1/8
Generator 3/32
Exciter 1/16
Grid Blower 1/16 to 3/32

Check brushholder spring tension by feel. Do not try

to measure in place. Verify that all springs are of equal
FIG. 31. EQUIPMENT BADLY DAMAGED BY and correct tension. (See Table VI.)
FLASHOVER. E-18333
Check that brush pressure levers are operating cor-
rectly by opening and closing completely at brush in-
Motor flashover usually results in some burning or spection, Fig. 33.
melting of metal on the corners of brushholders. When
repairing such damage, be sure the carbonway is
properly resized before returning the brushholder
to service. Check carbonways for size by insuring
CHECK CABLE CHECK FOR CRACKS
brushes move freely. CONNECTION IN TEFLON SLEEVE
FOR TIGHTNESS

COLLECTOR RINGS

1. Wipe off insulation between collector rings with a

clean, dry cloth and inspect for evidence of phys-
ical damage.

2. Check the surface of the collector rings for evi-

dence of discoloration, etching, grooving,
threading or other signs of distress that may re- KEEP
CHECK SHUNTS
quire corrective action. SHUNT LOOPED
TERMINALS AWAY
FOR FROM
NOTE: Brushes must ride in the center of the TIGHTNESS BRUSH
LEVERS
collector rings. If new brushholders are in-
stalled, adjust the brushholders to center the
brushes on the collector rings. FIG. 32. BRUSHHOLDER. E-24079

22
 PLANNED MAINTENANCE, GEK–75889J

  


 
BRUSH PRESSURE SPRING
THUMB LOOP

PRESSURE ARM
TERMINAL Apparatus Minimum
SCREW BRUSH
Length* (in.)
Motorized Wheel 1
PIGTAIL Generator 1Ć3/8
TERMINAL
Alternator 1Ć1/2
BRUSH PIGTAIL Exciter 1
KEY
Grid Blower 1
BRUSHHOLDER
STUD BRUSH BOX Inspect the Teflon creepage band for possible
flashover damage, including thin spots (gray in col-
FIG. 33. BRUSHHOLDER ASSEMBLY. E–14238. or), Fig. 36. Tap the band lightly and check for move-
ment of the band. If the band is loose or has deep burns,
replace it. Refer to the respective maintenance manual
Examine brushes for chips, burns, frayed or loose for replacement information. Do not paint Teflon
shunts. Be sure that the shunts are looped away from band.
the brush support levers so the shunts will not wear and
fray open. CAUTION: When replacing brushes, use the
GE recommended grade. Mixing of brush
Check to see that brushes move freely in the grades in the same motor or changing to
brushholder carbonways. Move brushes up and another grade brush is not recommended as
this could seriously affect commutation, sur-
down in carbonways several times to release carbon face film, commutator and brush life. Check
dust or foreign matter between brush and holder. Main- with GE Service Representative for approved
tain all brushes at approximately the same length. Never brush grades.
allow brushes to wear below minimum recommended
length.
Clean creepage bands by wiping with a cloth
dipped in a cleaner such as Texize 826**, or equiva-
CAUTION: To prevent the risk of damage to lent.
the commutator by short brushes, always re-
place the complete set of brushes (not just NOTE: Do not use cleaners with an oil base.
those worn to the minimum length) with new
brushes. NOTE: General Electric Co. recommends re-
placement of string creepage bands with Teflon
bands. However, some string bands are still in
service.
NOTE: Condemn brushes at 1/4 in. over mini-
mum length if necessary so they will not be be-
low minimum length at next scheduled inspec-
tion. Refer to Table V for minimum lengths and
Table VII for Brush part numbers.

NOTE: On Motorized Wheels, connect pigtail *All measurements refer to the longest side of
terminals to brushholders alternately as shown the brush.
in Fig. 34. **Product of Texize Chemicals, Inc.

23
GEKĆ75889J, PLANNED MAINTENANCE

TABLE VI, BRUSHHOLDER

TENSION
WARNING: Personal injury may result if prop-
Apparatus Description Tension er eye protection is not worn when cleaning
with compressed air.
5GE772X Motorized Wheel 112 to 128 oz.
S
Using clean, dry air, blow out commutator cham-
5GE772Y Motorized Wheel 160 to 192 oz.
S bers of all rotating equipment except Motorized
Wheel before replacing commutator covers. Check all
5GE776 Motorized Wheel 160 to 192 oz. covers for tightness when reassembling after preceding
5GE787 Motorized Wheel 160 to 192 oz. inspections.
5GE788 Motorized Wheel 160 to 192 oz.
5GE791 Motorized Wheel 160 to 192 oz. NOTE: Motorized Wheels are blown out at 500
hour maintenance. See page 11.
5GTA15 Traction Alterna- 4-1/4 to 4-3/4 lb.
tor
5GTA18 Traction Alterna- 4-1/4 to 4-3/4 lb. Examine field coils for flashover damage, loose
tor connections and any physical damage to the insu-
5GTA22 Traction Alterna- 4-1/4 to 4-3/4 lb. lation and wrappings.
tor
5GTA23 Traction Alterna- 4-1/4 to 4-3/4 lb. GENERATOR/ALTERNATOR DRIVE BELTS
tor
5GTA25 Traction Alterna- 4-1/4 to 4-3/4 lb.
tor Check the belt tension of the generator/alterna-
tor, exciter, and blower assembly. Adjust or replace
5GTA26 Traction Alterna- 4-1/4 to 4-3/4 lb.
tor as needed.

5GT603 Traction Genera- 50 to 60 oz.

tor NOTE: Alternator or generator, exciter, blower
5GY19 Blower Motor 43 to 60 oz. and idler pulleys are to be aligned coplaner
5GY24 Exciter 43 to 53 oz. within 0.08 in., Fig. 38.
5GY48 Exciter 43 to 53 oz.
Belt breakage and short bearing life can be the result
5GY53 Exciter 34 to 42 oz. of a belt being too tight, while belt slippage, cooling air
5GY55 Exciter A1, A2, 28 to 36 oz. loss and power loss may be caused by a belt being too
A3, loose.
B1, B2
5GY55 Exciter A4, A5, 56 to 65 oz. Belt tension may be measured by using a spring
A6, A7, B3, B4, scale and reading the pounds of pull needed to produce
B5, B6
a given amount of belt deflection. Or, use a tensiometer
5GY57 Exciter Blower 3 to 3-3/4 oz. as shown in Fig. 37.

NOTE: When necessary, paint string bands NOTE: All belt tension values are to be mea-
with a coat of electrical varnish. DO NOT PAINT sured in the center of the respective span and
OVER DIRT. perpendicular to the belt.

24
 PLANNED MAINTENANCE, GEK-75889J

TABLE VII, ROTATING EQUIPMENT CARBON BRUSHES

Apparatus Description Approved Carbon Grade

Brush Part Number
5GE772XS Motorized Wheel Recommended – 41A235048P4 T–900
Alternate – 41A235048P1 Speer E–49
5GE772YS Motorized Wheel Recommended – 41A235048P4 T–900
Alternate – 41A235048P1 Speer E–49
5GE776 Motorized Wheel Recommended – 41B537963P1 T–900
(Models D, F, K, HS, KS) Alternate – 41B537963P2 T–959
5GE776 Motorized Wheel Recommended – 41B537963P1 T–900
(All Other Models) Alternate – 41B535453P7 Speer E–49
5GE791 Motorized Wheel Recommended – 41B537963P1 T–900
Alternate – 41B537963P2 T–959
5GE787 Motorized Wheel Recommended – 41B537963P1 T–900
Alternate – 41B537963P2 T–959
Alternate–41B537963P5 T–508
5GE788 Motorized Wheel Recommended – 41B537963P1 T–900
Alternate – 41B537963P2 T–959
Alternate–41B537963P5 T–508
5GTA15 Traction Alternator Recommended – 41A330412P2 R–320
Alternate–41A330412P1 R–318
5GTA18 Traction Alternator Recommended – 41A330412P2 R–320
Alternate–41A330412P1 R–318
5GTA22 Traction Alternator Recommended – 41A330412P2 R–320
Alternate–41A330412P1 R–318
Alternate–41A235676P6 Speer S–700
5GTA23 Traction Alternator Recommended – 41A330412P2 R–320
Alternate–41A330412P1 R–318
Alternate–41A235676P6 Speer S–700
5GTA25 Traction Alternator Recommended – 41A330412P2 R–320
Alternate–41A330412P1 R–318
Alternate–41A235676P6 Speer S–700
5GTA26 Traction Alternator Recommended – 41A330412P2 R–320
Alternate–41A330412P1 R–318
Alternate–41A235676P6 Speer S–700
5GT603 Traction Generator 41A232456P4 5410
5GY19 Blower Motor 8828400P1 T–583
5GY24 Exciter 8828400P1 T–583
5GY24 Exciter 41A238773P1 T–583
5GY55 Exciter 6727518P1 5410
5GY55 Exciter 8828400P1 T–583
5GY57 Exciter Blower 8828400P1 T–583

25
GEKĆ75889J, PLANNED MAINTENANCE

GTA15 Single Belt Path Arrangement TABLE X

Using a spring scale, it should require 4-6 lb. of de- GTA22 SINGLE BELT PATH
flection force on a used belt to produce 0.50 in. of deflec- ARRANGEMENT
tion midway between the exciter and alternator pulleys,
opposite the idler side. New belts should require 7-9 lb.
Apparatus Type Tension Force For
of deflection force. See Table VIII for data for dual belt Per Belt 0.62 in.
path arrangement. (lb.) Deflection
TABLE VIII – GTA15 Dual Belt (lb.)
Path Arrangement Blower Belts New 203 13.3
Used 135 9.1
Apparatus Type Tension Force For Force For
Per 0.62 in. 0.50 in. GT603
Belt Deflection Deflection
(lb.) (lb.) (lb.)
Using a spring scale, it should require 24-35 lb. of de-
Blower New 203 13.3 flection force evenly applied across a used belt band to
Belts produce 0.66 in. of deflection when measuring between
Used 135 9.1 the blower and exciter pulleys. New belts should require
Exciter New 203 13.3 24-36 lb. of deflection force to deflect the belt band 0.44
Belts in.
Used 135 9.1
Replacing Belts
GTA18 Single Belt Path Arrangement
On multiple-belt systems used for the exciter and
Using a spring scale, it should require 9-10.5 lb. of blower drives, satisfactory belt life depends on main-
deflection force on a used belt to produce 0.44 in. of de- taining close belt match and load sharing. It is recom-
flection midway between the exciter and the blower pul- mended that new belts not be mixed with old, because
leys. New belts should require 13.5-16 lb. of deflection the latter probably will have stretched. The various
force. suppliers of belts use the same matching systems and
markings, but the composition of different vendors’ belts
See Table IX for data for dual belt path arrangement. may vary enough to cause unequally distributed loading
during operation. Therefore, belts from different man-
TABLE IX
ufacturers also should not be mixed.
GTA18 Dual Belt Path
Arrangement The belts listed in Table XI are stocked and shipped
in matched sets and each should be replaced as a
Apparatus Type Tension Force For Force For
set.
Per 0.62 in. 0.50 in.
Belt Deflection Deflection CAUTION: Use of belts other than listed may
(lb.) (lb.) (lb.) cause damage to the equipment.
Blower New 203 13.3
Belts
Belts must be matched for multiple-belt drives. All
Used 135 9.1
belts are measured after manufacture and are marked
Exciter New 180 12.7 with a match number – 47, 48, 49, 50, 51, 52 or 53 –
Belts
which is painted or embossed on the belt near the identi-
Used 120 8.7 fication markings. New belts must be matched per the
following belt length criteria: up to 100 in. long, use the
GTA22 Single Belt Path Arrangement
same match number only; 100 to 200 in., use the same
See Table X for GTA22 single belt path arrangement. or two consecutive match numbers only.

26
 PLANNED MAINTENANCE, GEK-75889J

COMMUTATOR CHECK CHART E–37779

FOR COMPARING COMMUTATOR SURFACE MARKINGS
How to Get the Most Value from This Chart
The purpose of the Commutator Check Chart is to help The box chart at the left indicates the importance of se- For additional information or help with carbon brush
you spot undesirable commutator conditions as they lecting the correct brush and having the right operating application or commutation problems, contact your near-
develop so you can take corrective action before the conditions for optimum brush life and commutator wear. est General Electric Sales Office or Distributor.
condition becomes serious. This chart will also serve as General Electric offers a complete line of carbon brushes
an aid in recognizing satisfactory surfaces. designed to meet all operating conditions and require-
ments of integral horsepower machines.

SATISFACTORY COMMUTATOR SURFACES

LIGHT TAN FILM over entire commuta- MOTTLED SURFACE with random film SLOT BAR–MARKING, a slightly darker HEAVY FILM can appear over entire
tor surface is one of many normal con- pattern is probably most frequently ob- film, appears on bars in a definite pat- area of efficient and normal commutator
ditions often seen on a well–functioning served condition of commutators in in- tern related to number of conductors per and, if uniform, is quite acceptable.
machine. dustry. slot.

WATCH FOR THESE DANGER SIGNS

STREAKING on the commutator surface signals the THREADING of commutator with fine lines results when GROOVING is a mechanical condition caused by abra-
beginning of serious metal transfer to the carbon brush. excessive metal transfer occurs. It usually leads to resur- sive material in the brush or atmosphere. If grooves
Check the chart below for possible causes. facing of commutator and rapid brush wear. form, start corrective action.

COPPER DRAG, an abnormal build–up of commutator PITCH BAR–MARKING produced low or burned spots on HEAVY SLOT BAR–MARKING can involve etching of
material, forms most often at trailing edge of bar. Condi- the commutator surface. The number of these markings trailing edge of commutator bar. Pattern is related to
tion is rare but can cause flashover if not checked. equals half or all the number of poles on the motor. number of conductors per slot.

CAUSES OF POOR COMMUTATOR CONDITION

Frequent visual inspection of commutator surfaces can warn you when any of the above conditions are developing so that you can take early corrective action. The chart
below may indicate some possible causes of these conditions, suggesting the proper productive maintenance.

Electrical Electrical Light Armature Unbalanced Brush Vibration Type of Brush Contamination
Adjustment Overload Electrical Connection Shunt Pressure In Use
Load Field (light) Abrasive Porous Gas Abrasive
Brush Brush Dust
Streaking
Threading
Grooving
Copper Drag
Pitch bar–marking
Slot bar–marking

27
GEKĆ75889J, PLANNED MAINTENANCE

TABLE XI
BELT APPLICATION

Belt Part No. Number Of Application

Belts
41A235035P1 1 GT603 Generator
Assembly (Multiple
V-Belt)
41A200514P5 4 GTA18 Alternator
Assembly
41A200514P6 2 GTA18 Alternator
Assembly
41A200514P7 3 GTA18 Alternator
Assembly
41A237021P1 6 GTA15 Alternator
Assembly
41A237021P2 6 GTA15 Alternator
Assembly
41A200514P6 2 GTA22 Alternator
Assembly

The GT603 generator belt listed in Table XI is a multi-

ple V-belt having all three belts secured on one back.

Common Backed Belts for Off-Highway

Systems with Dual Belt Paths

The General Electric Company is now offering com-

mon backed belts as an optional replacement for single
strand belts. Single strand belts will continue to be
supplied as renewal parts.

Tables XII and XII-A explain the application of the

new belts and what single strand belts they replace.

Tightening Procedure

Proper belt tension can be obtained by laying a nar-

row steel bar or wooden block across the band at mid-
FIG. 34. ALTERNATE MOTORIZED WHEEL
span. The force applied to the bar (for the required de- BRUSH TERMINAL CONNECTIONS. E-24106A
flection) must be divided by the number of belts in the
band to determine the deflection force per belt. Refer to
the appropriate generator/alternator, Tables VIII, IX, or and that it is properly secured in place. Also check to in-
X for belt tensioning data. sure that it has not been flattened to restrict air flow, Fig.
39.
When finished adjusting or installing belts, make
sure that the exciter flexible air duct is connected to the Install the belt guard, then check belts and pulleys to
blower discharge duct and exciter commutator cover, see that they have clearance.

28
 PLANNED MAINTENANCE, GEK-75889J

BRUSH PIGTAIL
DAMAGED TEFLON
BAND. REPLACE BAND
WHEN THIN SPOTS ARE
FIRST OBSERVED.

PIGTAIL TERMINAL

FIG. 35. CORRECT POSITION OF BRUSH FIG. 36. DAMAGED TEFLON BAND. E-24080
PIGTAIL AND TERMINAL. E-14237

Visually inspect all current shunt connections for

CONTROL EQUIPMENT tightness and signs of discoloration from overheating.

GENERAL INFORMATION Check all electrical connections for tightness.

Apply a slight pressure on each cable or wire near a
bolted or screwed connection to see if they are tight, Fig.
WARNING: All checks are to be made with 41.
Master switch OFF and engine not running.
Look for signs of overheating.

Inspect all control equipment and the control cabi- Check for broken or cracked insulators, terminal
net, Fig. 40. Vacuum the control box; when dirt is al- strips, resistors, capacitors, springs, etc.
lowed to accumulate, it will absorb enough moisture to
form a conducting path across a surface.
POCKET CLIP SLIDING
O–RING
If necessary, wipe insulated surfaces with a dry,
clean, lintless cloth.

NOTE: Control devices located in the control DEFLECTION

cabinet should be cleaned with a vacuum DISTANCE
SCALE DEFLECTION FORCE
cleaner. Do not use compressed air because SCALE
dirt particles blown into the contacts of a device
A PRODUCT OF EATON, YALE AND TOWNE
could cause it to malfunction. INC., KENOSHA, WISCONSIN

WARNING: To avoid possible electrical shock,

make sure the cleaning device is equipped FIG. 37. TENSIOMETER USED FOR
with a plastic nozzle. MEASURING BELT TENSION.
E-28521

29
GEKĆ75889J, PLANNED MAINTENANCE

TABLE XII
GTA22 SINGLE BELT PATH ARRANGEMENT

Item No. New Common Backed Quantity Per Replaces Single Strand Quantity Per
Belt Assembly Belt Set Assembly
1 41A235035P4 1 41A200514P6 2
2 41A235035P5 1 41A200514P7 3
3 41A235035P6 1 41A200514P8 3

TABLE XII–A
WHERE USED

1 Blower Belts On All Dual Path Systems:

GT603 Asm. Of Accessories 41D731876G7, 8, 9 and 10
GTA15E Asm. of accessories 41D731903G1, 2 and 3
GTA18D and E Asm. of accessories 41D731890G1 and 2
GTA22A and B Asm. of accessories 41D732114G1 and 2
2 Exciter Belts On All Dual Path Systems:
GTA15E Asm. Of accessories 41D731903G1 and 2
GTA18D and E Asm. of accessories 41D731890G1 and 2
3 Exciter Belts On The Following Dual Path Systems:
GT603 Asm. of accessories 41D731876G7, 8, 9 and 10
GTA15E Asm. of accessories 41D731903G3
Check current shunts in the axle box for loose- Check cable connections for tightness, signs of burr-
ness, tight connections or signs of discoloration ing, etc.
from overheating.
Replace the damaged components.
NOTE: Maximum torque value is 15-20 for small CONTACTORS/REVERSERS
(0.375 in.) shunt insulators and 35-45 for large
(0.50 in.) shunt insulators. Make a visual inspection for any obviously
worn, broken or damaged parts, Fig. 42. Repair or re-
place as necessary.

CHECK TENSION OF BELTS

OR BELT BANDS. CHECK
PULLEY ALIGNMENT,
COPLANER WITHIN 0.08 IN. CLEAN DIRT FROM
AROUND COMMUTATOR
COVERS BEFORE
REMOVING.

FIG. 38. DRIVE BELTS. E-24081 FIG. 39. FLEXIBLE AIR DUCT. E-24082

30
 PLANNED MAINTENANCE, GEK-75889J

BURNED ARC CHUTES

BROKEN
TERMINAL
STRIPS

DO NOT USE COMPRESSED

AIR FOR CLEANING INSIDE
OF CONTROL CABINET. CRACKED
CAPACITOR
CASE

BROKEN SPRINGS
FIG. 40. CONTROLS IN CONTROL CABINET.
E-24084
For example: Check for frayed or broken braided
shunts. Normally, they will last for thousands of opera- BROKEN OR
FRAYED SHUNTS CRACKED
tions. But, since the copper strands are very fine, the RESISTOR
TUBES
shunt can be damaged easily. Slightly frayed shunts
may last until the next inspection, but it is a good idea to FIG. 42. WORN, BROKEN OR DAMAGED PART.
repair or replace them as soon as possible. E-23471

Remember, shunts must be flexible. If a misdirected Check the condition of arc chutes. If arc chute
arc strikes the shunt, a number of strands of the shunt side plates are deeply burned or broken, they must be
may become welded together and the shunt becomes replaced.
less flexible. Such shunts should be replaced.
Check Contact Tips for Excessive Roughness,
Discolored flexible shunts indicate heating, possibly Wear or Burning.
due to loose connections or heavy arcing at the contact
tips or excessive current due to overloading. Contact tips must make good contact across their
mating surfaces. Also, the proper tip pressure must be
applied to them when closed. Good contact at the prop-
er pressure assures that contact tips will carry their
rated current.

As tips wear and burn away, the contact tip mating

surfaces may no longer fully match and final tip pressure
may be reduced. Therefore, it is important that the con-
dition of contact tips be checked regularly.
It is normal for some contact tip wear and discolor-
CHECK ALL ELECTRICAL
ation to occur and for a slightly beaded surface to devel-
CONNECTIONS FOR op due to normal current interruption duty. If contact tips
TIGHTNESS
are not worn more than half-way through and if tip sur-
faces are no rougher than coarse sandpaper, then they
are considered serviceable.
Beaded or blistered contact tips can be repaired by
FIG. 41. ELECTRICAL CONNECTIONS. E-24085 smoothing with a fine mill file if sufficient contact tip ma-
terial remains. See Fig. 43.

31
GEKĆ75889J, PLANNED MAINTENANCE

CAUTION: Do not use sandpaper or emery

cloth for repairing contact tips, because they
leave grains imbedded in the silver that insu-
late the tips.

Do not attempt to remove craters. After filing, be sure

good contact is obtained between contact tip pairs.

Contact tips that are worn more than half-way

through must be replaced. Some contact tips have in-
dented wear marks to assist maintenance personnel in
determining when replacement is necessary. BEADING
On silver-faced contact tips, replacement is required
when silver begins to wear through.
Clean contact tip surfaces with a lintless cloth moist-
ened with a safe solvent.
If serrated contactor interlock contact tip surfaces
are worn, resharpen them with a small triangular file. Be
careful not to bend contacts when filing or cleaning.
If oil gets on the surface of contact tips, it forms a film
which collects dirt. When the contactor operates, this
oily dirt is pressed into a thin coating on the tip surfaces.
If this coating builds up, it will form a high resistance con-
nection. The tips will overheat and may even weld to-
gether. So, if oil gets on the tips, wipe it off with solvent DISCOLORATION
and file the tip surface very lightly.

Check Contact Tip Gap on All Circuit-Opening

Devices.

Manually operate devices to verify that they are not

sticking.
Check Contact Tip Overtravel
Contact tip overtravel is the distance a moving con-
tact travels from the position where it first touches the
fixed contact to its final position of extreme travel. Over-
travel has also been referred to as wear allowance and
wipe. The method of measuring overtravel varies with
the different types of contact-carrying devices. Refer to
the appropriate contactor maintenance instructions fur- HEAVY ARCING
nished with the equipment.
Check Contact Tip Pressure
Low initial pressure indicates defective contact pres- FIG. 43. EXAMPLES OF BAD CONTACT TIPS.
sure spring, worn spring seat or washers. E-13717
Inspect contact spring.
Air-Operated Contactors/Reversers (Fig. 44) tional lubrication. Adding more lubricant will
NOTE: Do not lubricate the air cylinder. The cause sticking problems during cold weather
packing is designed to operate without addi- operation.

32
 PLANNED MAINTENANCE, GEK-75889J

BASE ARC
CHUTE

ARC STATIONARY
CHUTE CONTACT TIP
BLOW–
OUT MOVABLE
COIL CONTACT TIP
SHUNT AND
CONTACT CONTACT
ASSEMBLIES LEVER

SHUNT

ARMATURE
STOP

INTERLOCK ARMATURE
AIR
CYLINDER
MAGNET
VALVE CALIBRATING
SCREW OPERATING
COIL

FIG. 44. AIR-OPERATED CONTACTOR. E-9172A

FIG. 45. MAGNETIC CONTACTOR. E-10780B

Faulty operation can be caused by:

1. A leaky magnet valve (detected by a hissing Keep the tips clean by wiping with a clean, lintless
sound). Repair or replace as necessary. cloth.
2. An open–circuited magnet valve coil. Check with
an ohmmeter. Replace as necessary. CAUTION: Do not use sandpaper or emery
cloth, as they leave grains imbedded in the sil-
3. An Overheated (roasted out) coil which has a ver that insulate the contacts.
burned smell. Check with an ohmmeter. Replace
as necessary.
Magnetic Contactor (Fig. 45) Remember that interlocks are small and easily dam-
The knife edge on the armature pivot point may be- aged. Take a look at these interlocks any time work is
come worn. This can cause faulty operation. Don’t try to done on a contactor to see that they haven’t been bent.
repair such an armature - replace it. If a contactor oper-
ates improperly or fails to pick up, refer to the respective A loose connection will cause trouble on interlocks
instruction book for adjustment. too. It won’t cause an overheated connection, but it will
INTERLOCKS (Fig. 46) cause a variety of unusual control operations. Check the
Observe motion when manually operating the con- connections and make sure they are tight.
tactor by pushing on the armature. Being in low-voltage
circuits, they usually have silver contact tips to reduce On most contactors, the interlock tip break can be
electrical resistance. Oil on these tips will collect dirt. Al- adjusted. Once set, it is seldom necessary to readjust.
though they may not overheat as high voltage copper However, it’s wise to look at these gaps – you may be
contacts do, they may fail to make contact. able to prevent a failure before it happens.

33
GEKĆ75889J, PLANNED MAINTENANCE

RELAYS
MOVABLE
CONTACT Manually operate and check.
ASSEMBLY

FINGER A simple relay, Fig. 47, looks like a small magnetic

TIP BREAK
BLOCK contactor and is usually inspected and maintained like a
INTERLOCK CONTACT MOUNTING magnetic contactor. Contact tips should be treated like
FINGERS BAR PLATE contactor interlocks. There are numerous connections
which should be tight and several springs that should be
in good condition. Keep dirt off all surfaces.

Visually inspect the suppression devices located un-

der the contactors and relays.
FINGER
BLOCK Make sure the control cabinet door seal is intact and
SPRING SCREW
securely fastened. Refer to Fig. 48.

CONTACT 1000 HOUR CHECKS, AUXILIARY

SPRING TIP
POST AND
TERMINAL CONTACTOR EQUIPMENT AND AIR
STUD CALIBRATING
SPRING VENTILATION SYSTEMS
RETARDING GRIDS
FIG. 46. INTERLOCKS. E-23472
Check for damaged parts and replace as re-
quired.

Remove dirt build-up from insulators and replace

FIXED CONTACT BLOCK any found to be severely chipped or broken.
MOVABLE
CONTACT FIXED N.C.
BLOCK Visually inspect the blower intake for foreign objects
CONTACT
and mud.

Check blower motor cables for abrasion or burning.

CHECK THAT DOOR

SEAL IS INTACT
WHEN WORK IS
COMPLETED AND
THAT THE LATCH
CONTACT OPERATES
FINGER PROPERLY.

SPRING

MAGNET OPERATING
FRAME COIL

FIG. 47. RELAY. E-23473 FIG. 48. CONTROL CABINET DOOR SEAL.
E-24088

34
 PLANNED MAINTENANCE, GEK-75889J

FIG. 50. FL183 CONTROL PANEL (SEPEX).

E-24086
FIG. 49. CONNECTIONS. E-24083

CAUTION: Do not make adjustments to con-

trol equipment unless definite instructions
RECTIFIER PANELS and the right tools and test equipment are
available. Serious damage to the equipment
1. Check that air passages are free of obstruction. could result from improper adjustment.
If necessary, blow out with dry, compressed air.
Some systems have flexible air ducts. Check for
NOTE: The sequence of steps for making tests
holes in ducts, loose fittings, etc.
will vary with different control systems. Refer to
the respective Instruction Book.
2. Check all connections for loose cable clamps
BATTERY VOLTAGE
and damaged cables, Fig. 49.
1. Proper operation of the control system depends
BLOWER on the battery voltage being between 24 and 28
volts. Check and adjust as necessary.
Clean the blower inlet filter (if installed) or screen. Lu-
2. Check battery voltage at low idle and top end
bricate blower pillow blocks with a hand gun untill purge
rpm. Adjust as required. Check belt tightness
using D6A2C10 grease.
and condition of battery charging alternator.

NOTE: The 7A13F and H model blowers are eq- SPEED EVENTS
uipped with adjustable dirt skimmers. These
should be set at 1/2 in. opening for trucks not 1. Check speedometer calibration.
equipped with air filtration. For a truck with air
filtration, they should be closed. 2. Check the calibration of all speed events.

AIRFLOW
1000 HOUR VEHICLE OPERATION
TESTS Check for proper operation of the blower loss warn-
ing device.

The following tests are to be performed at 1000 GROUND RELAY

hours to insure continued correct performance of the
electric transmission system. Refer to the respective Test ground relay operations as described in the re-
Vehicle Test Instructions to perform control tests. spective Vehicle Test Instructions.

35
GEKĆ75889J, PLANNED MAINTENANCE

FIG. 51. FL191 CONTROL PANEL (STATEX). E-28632

ENGINE CHECKS RETARDING

NOTE: These engine parameters affect the 1. Measure motor field current at full pedal at stand-
proper operation of the General Electric Propul- still. Note generator/armature voltage. If adjust-
sion system. ment is required. Refer to the respective Vehicle
Test Instructions.
1. Check the dashboard tachometer calibration.
2. Check the operation of the grid blower in road
2. Check low idle, retarding rpm, and top end rpm. test.
Adjust as required.
3. Measure peak motor retarding current as a func-
3. Check the operation of the high idle and throttle tion of speed. Adjust for peak and taper as re-
cut-off solenoids. quired in road test.

FIG. 52. FL236 STATEX CONTROL LOGIC PANEL (SSL). E-28633

36
 PLANNED MAINTENANCE, GEK-75889J

HORSEPOWER CHECK

Make a static horsepower demand test as described

in the respective Vehicle Test Instructions* using blown
grids as a load box or an external load box. Adjust as
required.

NOTE: Always check for proper seal of cabinet

doors when completing work inside of cabinet,
Fig. 48.

1000 HOUR CHECKS, ROTATING

EQUIPMENT FIG. 53. DIAGRAM FOR CLEANING GT603
ARMATURE COOLING PASSAGES.
GENERATOR E-24096

Blow dirt out of the area behind the commutator and

the armature cooling air holes of the generator. In dusty
8. Install the bolt that was removed in Step 2.
environments, generator unbalance due to uneven dirt
build-up can occur.**
TIRE CHANGE
1. Make an adapter by drilling a 1/4-in. hole length-
wise through a 1/2-13 x 3 in. bolt. Secure an air Clean dirt and grease build-up from the dirt seal
hose quick-disconnect fitting to the adapter. housing area, Fig. 54.

2. Remove one of the 1/2-13 x 1-1/4 in. bolts secur- CAUTION: On 787 and 788, do not use high
ing the bearing cap to the bearing housing. Fig. pressure water for cleaning the dirt seal area.
53.
Inspect dirt seal grease hoses for breakage or cuts,
3. Screw the adapter into the hole from which the or damaged fittings. If equipped, check grease hose
bolt was removed. guards for damage.
4. Attach an air hose to the quick-disconnect fitting
Using a thin piece of metal or a bent paper clip to
and apply 80 to 120 lb. air pressure.
slide under the rubber seal, feel the extent of wear on the
5. When dust stops coming out, bar the generator wear band, Fig. 55. If the wear band is worn through, re-
over slightly until dust appears again. placement should be considered.

6. Continue barring the generator over, step by NOTE: Excessive seal wear may indicate im-
step, until a complete revolution is made with no proper greasing procedures or grease type.
dust being evident.
Check all bolts of the seal housing and seal housing
7. Turn off the air and remove the adapter.
support for tightness.

On Motorized Wheels equipped with disc brakes, re-

torque all thrust ring bolts. Check the respective service
* If a problem is found, road test noting horsepowĆ manual for the correct torque value.
er vs. rpm over varying grades.
Check the bolts holding the torque tube to the wheel
**If generator problems continue, refer to InstrucĆ hub for tightness. Check the respective service manual
tion Book for additional procedures. for the correct torque value.

37
GEKĆ75889J, PLANNED MAINTENANCE

CHECK FOR GROOVES WORN

THROUGH WEAR BAND

CLEAN DIRT AND

GREASE BUILD–UP
FROM THIS AREA
AT TIRE CHANGE.

FIG. 54. DIRT SEAL AREA. E-24097

BREATHER VENT SHOULD
AS-REQUIRED CHECKS AND BE REPLACED WITH 1/2 IN.
NPT PIPE PLUG IF NOT
CLEANING DONE SO PREVIOUSLY.

INSULATION RESISTANCE
FIG. 55. TORQUE TUBE. E-24098
NOTE: Isolate diodes, capacitors and control ings of dirt will also cause heat sinks for transistors and
panel connections from the power loop. diodes to run at higher temperatures, because the dirt
acts as an insulation blanket, Fig. 56.
With the ground relay coil disconnected, and all
cards pulled, measure armature loop resistance to NOTE: The following cleaning process does
ground at 1000 vdc. Record to detect degrading insula- not apply to printed circuit boards that are se-
tion. Minimum recommended is 500,000 ohms. cured to a panel by mounting hardware such as
If the obtained reading is below the minimum recom- nuts and bolts.
mended resistance, then that portion of the armature
loop circuit should be isolated further. If moisture is WARNING: Personal injury may result if proper
found to be the cause, space heaters can be used to dry eye protection is not worn when cleaning with
compressed air.
it out. If cable insulation is low, replace the cable.

CLEANING PLUG-IN CARDS CAUTION: Do not spray or submerge a plugĆin

card in any type of cleaning fluid, since this
The control system cards should not have to be may damage certain electronic components.
cleaned unless they are suspected of faulty operation.
In such cases troubleshooting and corrections are often
CAUTION: Do not use ultrasonic cleaning proĆ
simplified by cleaning dirty components first.
cesses on plugĆin cards. HighĆfrequency vibraĆ
tions may damage or weaken some electronic
The following describes the proper cleaning proce- components internally and could also cause
dures.These procedures are applicable only to printed their external leads to break.
circuit boards (or cards) that are “plug-in” types, Figs.
50, 51 and 52. Plug-in cards are commonly referred to CAUTION: Do not use Freons such as Freon F*
as “blue-face” cards, modular cards, control cards and or TMC. They have a detrimental effect on the
Lexan** plastic pin connectors.
FD cards.

Clean cards are not only easier to work on and trou- *Miller-Stephenson Chem.
bleshoot, but may also perform better due to removal of Co.
conduction dirt from very sensitive circuits. Thick coat- **Product Of GE Co.

38
 PLANNED MAINTENANCE, GEK-75889J

CAUTION: Do not perform Steps 3 and 4 unĆ

less facilities are available to dry the plugĆin
card at 80
C for two hours. Otherwise, lingerĆ
ing moisture may cause component damage.
3. If an 80
C drying facility is available, this step
may be used as an alternate to Steps 1 and 2.
The more stubborn dirt deposits may be cleaned
with a 10 percent solution of LUX liquid detergent
and water. The dirt deposits may also require
brushing with a stiff-bristled toothbrush or other
plastic soft-bristled brush. When this method is
utilized, the cleaning solution should be rinsed by
spraying warm water over the cleaned surface.
Do not hold the card under a running faucet.
4 After removing the card from the water spray,
shake the card (or blow with dry, compressed,
shop air at 29 psi maximum) to remove any ex-
cess water that may remain on the card or in
open potentiometers. Dry the card for two hours
at 80
C.

CAUTION: Avoid using substitutes for LUX,

such as dishwashing compounds that may
contain builders such as silicates, phosphates
or carbonate salts which can leave electrically
conductive deposits on the surfaces of the
plugĆin cards and damage components.

CAUTION: To avoid the possibility of filling an

open potentiometer with water, do not subĆ
merge the plugĆin card. Use a water spray only.

FIG. 56. EXAMPLES OF DIRTY CARDS.

E-23475 DO NOT OPERATE
WITHOUT LOCK BAR
IN PLACE IF
FURNISHED.

1. Brush deposits with a stiff-bristled toothbrush or

other plastic soft-bristled brush to remove dirt.
Use extreme care on and around delicate com-
ponents. Keep dirt out of open potentiometers.

2. Blow off loosened dirt with dry, compressed shop

air at 29 psi maximum. ”BLUE FACE” OF CARD
NEEDS REPLACED,
CREATES DIRT
WARNING: Personal injury may result if proper ENTRANCE.
eye protection is not worn when cleaning with
compressed air. FIG. 57. CONTROL PANEL. E-24089

39
GEKĆ75889J, PLANNED MAINTENANCE

5. If it has been necessary to replace a component, instruction. It is recommended, but not neces-
any residue from the soldering flux should be re- sary, to lubricate non-critical bolted joints.
moved with isopropyl alcohol. (Most rubbing
alcohol found in a drug store is isopropyl; check LUBRICATION:
the label.)
Torque values are based on lubricated bolts. Bolts
6. To reseal the replaced component onto the must be lubricated with a suitable high-pressure lubri-
printed circuit board, brush Hysol PC-18* or cant, such as automotive motor oil. Lubricate both the
equivalent, around the replaced component. It threads and washer face of the bolt.
protects the possibility of lead breakage, and
also insulates effectively against creepage paths All bolts should be lubricated per this instruction ex-
caused by conductive dirt. cept commutator bolts.

7. Visually inspect the plug-in cards for the follow- Bold Identification:
ing:
1. Medium Carbon Steel –
a. Dirty, corroded or pushedĆout connector
Three radial dashes on head
pins
2. Alloy Steel –
b. Broken or discolored components
“X” stamped on head
c. Broken wires or printed circuit streets
OR:
d. Loose screws and nuts.
Six radial dashes
Repair and tighten as necessary.
3. Non-magnetic bolts –
BOLT TORQUE INSTRUCTIONS
Stamped “NM” or “AL” on head
GENERAL
Table XIII provides maximum and minimum values
There are two basic classifications of bolted joints: of torque that should be applied to the bolts of the size
1. Critical – applications for which the tightening and material indicated. Torque wrenches should be
torque value is specified on the drawing. checked periodically and adjusted if out of calibration
Threads should be lubricated as described be- more than  10 percent.
low and the tightening torque controlled through
These values take only bolt strength into consider-
the use of a torque wrench.
ation and are applicable for steel-to-steel joints. When
2. Non-Critical – applications for which tightening material is softer than steel (brass, plastic, aluminum,
torque is not specified on the drawing. The rec- etc.), thread stripping is a possibility if the table values of
ommended torques are listed in Table XIII in this torque are used. These values may also be excessive
for many gasketed joints since extrusion of the gasket
* Product of Hysol Corp. may result.

40
 PLANNED MAINTENANCE, GEK-75889J

TABLE XIII
RECOMMENDED TORQUE VALUES
(FT.–LB.)

Bolt Threads Medium Carbon Alloy C1A Grade 8 Stainless B7Y7A3

Diameter Per Inch C1C1 SAE Grade 5 Approximate Aluminum B12H56J
(In.) Approximate Stress = 90,000 psi Approximate
Stress = 60,000 psi Stress = 25,000 psi
1/4 20 6-8 10-12
28 6-8 10-12
5/16 18 12-14 18-21
24 12-14 20-23
3/8 16 21-24 30-36
24 25-28 34-40
7/16 14 34-38 50–56
20 40-45 59-66
1/2 13 55–60 80–90
20 65-70 95-105
9/16 12 73-81 110-123
18 86-96 130-145
5/8 11 110-120 160-180 45-50
18 125-139 185-208 56-62
3/4 10 185-210 285-315 78-87
16 220-245 340-370 90-100
7/8 9 293-326 440-490 122-136
14 341-379 510-567 142-158
1 8 440-495 685-745 186-206
12 530-575 790-863 216-240
1–1/8 7 624-694 936-1040 260-290
12 744-827 1116-1240 310-345
1–1/4 7 900-995 1250-1400 374-415
12 1040-1160 1600-1750 435-483
1-3/8 6 1160-1290 1746-1940
12 1422-1580 2124-2360
1–1/2 6 1570-1740 2300-2600
12 1800-2010 2600-3020

NOTE: GE772, GE776 and GE791 Commutating Pole Bolts (special) 110-120 lb.-ft.

NOTE: Shunt mounting insulators: Small (0.375 in.) 15-20 lb.-ft., Large (0.50 in.) 35-45 lb.-ft.

41
GEKĆ75889J, PLANNED MAINTENANCE

PLANNED MAINTENANCE OUTLINE SHEET

Work To Be Done OK Hours, Miles, Date

Remarks Work Performed By
AXLE BOX
1. Check oil level and dipstick (or oil-fill cap) gasket.
2. Add 0.5 ounce grease to each dirt seal grease
fitting (all GE772, 776, 791 models except those
with FUF seals).
3. Add 1.0 ounce grease to each dirt seal grease
fitting (all GE772, 776, 791 models except those
with FUF seals).
4. Clean sun pinion cover magnetic plugs.
5. Clean or replace gearcase filters.
6. Check vent pipes for obstruction.
7. Check current shunts for tightness and discolor-
ation.
8. Check cable connections for tightness and discol-
oration.
9. Check axle box door seal.
10. Inspect for oil and grease leaks.
11. Take oil sample.
12. Clean axle box.
13. Change oil (see Note 2).
14. Clean sump magnetic plugs.
15. Check drive ring internal spline wear.
16. Remove and inspect the sun pinion:
a. Check gear condition (visually)
b. Check spline wear (visually)
c. Check oil baffle and snap rings for
damage
d. Check for sufficient clearance from cover.
17. Check end play of gears.
A.
B.
C.
ARMATURE AREA
1. Check brush length, condition, freedom of move-
ment.
2. Check brushholder condition, clearance, brush
tension.
3. Check commutator condition, film, etc.

42
 PLANNED MAINTENANCE, GEK-75889J

PLANNED MAINTENANCE OUTLINE SHEET (Cont'd)

Work To Be Done OK Hours, Miles, Date

Remarks Work Performed By
ARMATURE AREA (Cont’d)
4. Clean Teflon*band.
5. Check coil insulation (visually).
6. Check hydraulic line connections for leakage.
Clean up any fluid found in the frame.
7. Blow out brushholder and commutator area.
MISCELLANEOUS
1. Remove dirt and grease buildup from dirt seal
area.
2. Inspect dirt seal grease fittings. (GE772, GE776
with Triple Lip Dirt seal).
3. Lubricate dirt seal area until purge. (GE772,
GE776 with Triple Lip Dirt seal).
4. Check wear of torque tube wear band
(GE772, GE776 and GE791 only).
5. Visually inspect for broken grease lines, damage
to hub caps etc.
6. Check condition of grease line guards (if used).
7. Check tightness of exposed bolts.
8. Retorque brake adapter bolts on models equipped
with disc brakes.
9. Lubricate Wheel Hub Bearings (GE787 & GE788
only):
a. Remove grease plugs in wheel hub (6).
b. Insert zerk grease fittings.
c. Add 4 oz. of grease to each fitting.
d. Replace grease plugs in wheel hub.
GENERATOR/ALTERNATOR
1. Check brush length, condition, freedom of move-
ment.
2. Check brushholder condition, spacing, tension.
3. Check commutator/slip ring condition, film, etc.
4. Clean string/Teflon band.
5. Blow out commutator area with clean dry air (70
psi max.).
6. Check blower/exciter belt tension.
7. Blow out air holes (GT603).

43
GEKĆ75889J, PLANNED MAINTENANCE

PLANNED MAINTENANCE OUTLINE SHEET

Work To Be Done OK Hours, Miles Date

Remarks Work Performed By
EXCITER
1. Check brush length, condition, freedom of move-
ment.
2. Check brushholder condition, spacing, tension.
3. Check commutator condition, film, etc.
4. Clean string/Teflon band.
5. Blow out commutator area with clean dry air (70
psi max.).
GRID BLOWER MOTOR
1. Check brush length, condition, freedom of move-
ment.
2. Check brushholder condition, spacing, tension.
3. Check commutator condition, film, etc.
4. Clean string/Teflon band.
5. Check cables for abrasion and burning
6. Blow out commutator area with clean dry air (70
psi max.).
CONTROL EQUIPMENT CHECKS
1. Vacuum the control cabinet.
2. Check all electrical connections for tightness.
3. Check current shunts for tightness, discoloration.
4. Check insulators, terminal strips, springs, etc. for
breaks or cracks.
5. Check reverser, contactors, interlocks and relays
for tip wear, burning, tip break, overtravel, tip
pressure and frayed, broken or discolored shunts.
6. Check magnet valves for leaks
7. Check condition of arc chutes
8. Check door seal and latch.
AUXILIARY EQUIPMENT AND AIR VENTILATION
SYSTEM
1. Inspect retarding grids; check for damaged parts,
foreign objects.
2. Check rectifier panel air passages.
3. Check all connections for tightness, damaged
clamps.

44
 PLANNED MAINTENANCE, GEK-75889J

PLANNED MAINTENANCE OUTLINE SHEET (Cont'd)

Work To Be Done OK Hours, Miles Date

Remarks Work Performed By
AUXILIARY EQUIPMENT AND AIR VENTILATION
SYSTEM (Cont’d)
4. Clean blower inlet filter or screen. Make sure it is
free from obstructions and foreign objects. Lubri-
cate pillow blocks.
5. Check flexible air ducts for damage. Measure
static air pressure (axle box).
VEHICLE OPERATION TESTS
1. Check battery voltage. Adjust as required.
2. Check speedometer calibrations.
3. Check all speed event calibrations.
4. Test ground relay operation.
5. Engine Checks*.
6. Check tach calibration, adjust as required.
7. Check low idle, retarding rpm, top end rpm. Ad-
just as required.
8. Check for proper operation of blower loss warning
device.
9. Check high idle and throttle cut-off solenoid oper-
ation.
10. Measure motor field retarding current noting gen-
erator/armature voltage. Adjust as required
11. Check horsepower vs. rpm in road test or statically.
12. Check operation of grid blower in road test.
13. Measure retarding motor armature current as a
function of speed. Adjust as required in road test
or statically.
AS-REQUIRED CHECKS AND CLEANING
1. Measure armature, comm. field, and exciting field
resistance to ground. Record to detect degrading
insulation
2. Clean plug-in cards

45
GEKĆ75889J, PLANNED MAINTENANCE

GE Transportation
Systems

2901 East Lake Road

Erie, Pennsylvania 16531
REVISED 10–90, WLF PRINTED
REVISED 3–92, WLF IN U.S.A.
E
REVISED 7–92, WLF

46