R

QESV1336-01
August 2008

TECHNICAL PRESENTATION

CS76 AND CP76 VIBRATORY SOIL

COMPACTORS
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IMG_5026

SLIDE 1

CS76 and CP76 Vibratory Soil

Compactors

INTRODUCTION

The CS76 and the CP76 are single-drum soil compactors used in • Machine view
medium and large construction applications. The CS-machines have
a smooth drum and optional padded drum shell. The CP-machines
have a padded drum.

The typical applications for the smooth-drum machines are sites • Machine general
with granular soil. The smooth-drum machines are used when a information
smooth surface is desired. The typical applications for the padded-
drum machines are sites with cohesive or semi-cohesive soils. These
machines are well suited for highway construction projects with
high compaction requirements or thick lifts.

Each machine model is powered by a Caterpillar C6.6 engine which

produces a gross power of 130 kW (174 hp) at 2200 rpm.

This presentation gives a general overview of the machine and then

covers each machine system in detail. After observing this
presentation, service personnel will be able to:

1. Locate and identify major components on the machine.

2. Explain the function of and properly use all machine controls.

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3. Explain operation of the machine’s hydraulic systems by tracing

oil flow through each of the systems.
4. Explain operation of the machine’s electrical system by tracing
current flow through the system.

IMG_5028_1

SLIDE 2

• Machine view A roll-over protection structure, falling object protection structure

(ROPS/FOPS) is standard on the machines. The machine can be
equipped with an optional cab (as shown).

• General specifications The drum and axle on these machines are hydrostatically driven.
The hydrostatic propel system has two speed ranges: high and low.
Drum width is 2134 mm (84 in). The drum diameter on the smooth-
drum machines is 1534 mm (60 in).

Standard operating weights are as follows:

• CS76 — 16 758 kg (36 945 lb)

• CP76 — 16 896 kg (37 249 lb).

• CS76XT — 18 611 kg (41 030 lb)

NOTE: An optional pad-foot shell kit is available for the smooth

drum machine. A new bumper must be installed when a smooth
drum machine is retrofitted with a shell kit.

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IMG_4788_1_3

SLIDE 3

The engine compartment cover (1) can be raised to provide access to • Rear of machine
the engine. Nitrogen-charged gas springs (not shown) provide
assistance to lift the cover.

The prop rod (2) must be raised and locked in place to prevent the • Component location
engine compartment cover from falling. 1. Engine compartment
cover
2. Prop rod

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4 7

5 6

IMG_3113_1_3

SLIDE 5

The operator’s platform can be tilted forward to provide access to • Right side of machine
components which are located below the platform. If the machine is
equipped with an optional tilt cylinder and pump mechanism, a
hydraulic pump (4) is provided to raise and lower the operator’s
platform.

The lift valve (5) is rotated in order to lift or lower the operator’s • Component location
platform. The jack handle (6) is used to manually pump hydraulic 4. Hydraulic pump
oil into or out of the lift cylinder (7). 5. Lift valve
6. Jack handle
NOTE: The four cab mounting bolts must be removed and the 7. Lift cylinder
pivot pins must be installed in the pivot joint before the pump is
used. Refer to the machine service manual for the cab-tilt procedure.

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8 9

IMG_4947_1_3

SLIDE 6

• Right side of engine The fuel pressure sensor (8) is mounted on the right side of the
engine. The fuel pressure sensor monitors pressure in the engine fuel
system. The fuel pressure sensor sends a signal to terminal “J2-51”
of the engine ECM.

• Component location The glow plug terminal (9) receives power from the batteries
8. Fuel pressure through the glow plug breaker when the glow plug relay is
sensor energized. The glow plug terminal distributes power to the glow
9. Glow plug terminal plugs. The glow plugs provide a small hot spot in each combustion
chamber in order to help ignition of the fuel and air mixture.

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IMG_3078_1_3

SLIDE 7

The primary position sensor (10) is mounted on the right side of the • Right side of engine
engine.

The primary position sensor (10) detects when a tooth of the • Component location
crankshaft timing ring passes the sensor. The engine ECM monitors 10. Primary position
this sensor at terminal “J2-10” and terminal “J2-52.” The engine sensor
ECM uses this signal to monitor engine speed and engine timing.

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11 12

IMG_4950_1_3

SLIDE 8

• Right side of engine The inlet air pressure sensor (11) and inlet air temperature sensor
(12) are mounted on the right side of the engine.

• Component location The inlet air pressure sensor (11) detects air pressure at the intake
11. Inlet air pressure manifold. The inlet air pressure signal is sent to terminal “J2-55” of
sensor the engine ECM.
12. Inlet air temperature
sensor The inlet air temperature sensor (12) detects air temperature at the
intake manifold. The inlet air temperature signal is sent to terminal
“J2-42” of the engine ECM.

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13

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SLIDE 9

The engine oil pressure sensor (13) and the engine oil filter (14) are • Right side of engine
mounted on the right side of the engine. The base of the engine oil
filter contains the S•O•S tap (not shown) for the engine lubrication
system.

The engine oil pressure sensor (13) monitors oil pressure. This • Component location
sensor sends a signal to terminal “J2-56” of the engine ECM. 13. Engine oil pressure
During abnormal operating conditions, the engine ECM sends a sensor
signal to the engine oil pressure indicator on the indicator cluster in 14. Engine oil filter
the operator’s compartment.

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ENGINE OIL PRESSURE WARNING LEVELS

CATERPILLAR C6.6 ENGINE
250
ENGINE OIL PRESSURE (kPa)

200

175

150
LEVEL 1
100

0
0 700 900 1000 1200 1400 2500

ENGINE SPEED (RPM)

ENGINE OIL PRESSURE (kPa)

ENGINE OIL PRESSURE (kPa)

220

170

145

120
100
LEVEL 2
70 70
LEVEL 3

0 0
0 700 900 1000 1200 1400 2500 0 700 900 1000 1200 1400 2500

ENGINE SPEED (RPM) ENGINE SPEED (RPM)

0713070840_2

SLIDE 10

• Engine oil pressure maps The engine ECM will generate three different levels of warning for
engine oil pressure faults. The engine ECM begins to evaluate the oil
pressure after the engine has been operating for 10 seconds. The
engine ECM evaluates oil pressure and engine speed in order to
determine if the system is operating within the specified range.

• Level-one warning The engine ECM will generate a level-one fault if the engine oil
pressure is in the “LEVEL 1” area in the above illustration for eight
seconds. The engine ECM will cancel the level-one warning if the oil
pressure increases to 21 kPa (3 psi) above the set point for 20
seconds. During the level-one warning, the engine oil pressure lamp
flashes, but the engine operation is not affected.

• Level-two warning The engine ECM will generate a level-two fault if the engine oil
pressure is in the “LEVEL 2” area in the above illustration for eight
seconds. The engine ECM will cancel the level-two warning if the oil
pressure increases to 21 kPa (3 psi) above the set point for 20
seconds. During the level-two warning, the engine oil pressure lamp
flashes, but the engine operation is not affected.

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The engine ECM will generate a level-three fault if the engine oil • Level-three warning
pressure is in the “LEVEL 3” area in the above illustration for four
seconds. During the level-three warning, the engine oil pressure
lamp flashes, and a warning horn sounds. Under these conditions,
the machine should be stopped as soon as safely possible and
repaired before it is returned to service.

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IMG_4956_1_3

SLIDE 11

The secondary position sensor (15) is mounted on the right side of • Right side of engine
the engine.

The secondary position sensor (15) monitors engine timing. The • Component location
engine ECM monitors this sensor at terminal “J2-10” and terminal 15. Secondary position
“J2-53.” sensor

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16

IMG_4945_1_3

SLIDE 12

• Right side of engine The engine coolant temperature sensor (16) is mounted on the right
side of the engine.

• Component location The engine coolant temperature sensor (16) measures the
16. Engine coolant temperature of the engine coolant. This sensor sends a signal to
temperature sensor terminal “J2-43” of the engine ECM. During abnormal operating
conditions, the engine ECM sends a signal to the high engine
temperature indicator on the indicator cluster in the operator’s
compartment.

• Warning levels The engine ECM will generate three different levels of warning for
engine coolant temperature faults. The engine ECM begins to
evaluate the coolant temperature after the engine has been operating
for 185 seconds.

• Level-one warning The engine ECM will generate a level-one fault if the engine coolant
temperature is 113 °C (233 °F) for 10 seconds. The engine ECM will
cancel the level-one warning if the coolant temperature falls below
the set point for 4 seconds. During the level-one warning, the engine
coolant temperature indicator illuminates, but the engine operation
is not affected.

• Level-two warning The engine ECM will generate a level-two fault if the engine coolant
temperature is 114 °C (237 °F) for 10 seconds. The engine ECM will
cancel the level-two warning if the coolant temperature falls below
the set point for 20 seconds. During the level-two warning, the
engine coolant temperature indicator illuminates, and the engine
ECM derates the engine at the rate given in Table 1.

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Table 1

Temperature Deration Ramp Maximum Deration

115 °C (239 °F) 1 percent per second 35 percent
116 °C (241 °F) 1 percent per second 45 percent
117 °C (243 °F) 1 percent per second 60 percent

The engine ECM will generate a level-three fault if the engine • Level-three warning
coolant temperature is 118 °C (244 °F) for two seconds. During the
level-three warning, the engine coolant temperature indicator
illuminates, and a warning horn sounds. A level-three warning
prompts the engine ECM to derate the engine at the rate given in
Table 2.

Table 2

Temperature Deration Ramp Maximum Deration

118 °C (244 °F) 1 percent per second 80 percent
119 °C (246 °F) 1 percent per second 100 percent(1)
(1) The ECM will not stop the engine.

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21
18

19 22

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SLIDE 13

The primary fuel filter (19) is mounted on the right side of the • Right side of machine
engine. The secondary fuel filter (21) is located to the front of the
primary fuel filter. The head of the primary fuel filter contains the
fuel priming pump (17). A water separator with a drain valve is
located at the bottom of the primary fuel filter.

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• Component location The fuel priming pump (17) is used to fill the fuel system when the
17. Fuel priming pump fuel filters are serviced. The fuel priming pump is controlled by the
18. Priming switch priming switch (18). The priming switch is a toggle switch with two
19. Primary fuel filter positions. The bottom position of the switch is the OFF position,
20. Engine oil dipstick and the top position of the switch is the ON position. The switch
21. Secondary fuel filter provides a ground path for the electric motor that drives the fuel
22. Engine oil fill port priming pump. This switch is only operational when the engine start
switch is in the OFF position. The fuel priming pump must be
operated for approximately 60 seconds in order to fill both fuel
filters.

NOTICE
A new fuel filter should never be filled with unfiltered fuel. Doing so
can cause damage to the components in the fuel system. The fuel
priming pump should be used to fill the fuel filter after the filter has
been installed on the machine.

The water separator, at the bottom of the primary fuel filter (19), is a
clear plastic bowl with a drain valve. The bowl allows the operator
to easily determine if the fuel system contains water. The operator
should check for water in the fuel before the machine is started every
morning. If water is present in the fuel system, the operator should
remove the water through the drain valve at the bottom of the water
separator before the engine is started. The water and fuel mixture
from the drain valve should be collected in a suitable container and
the liquid should be disposed of according to all local mandates.

The engine oil dipstick (20) is used to check the engine oil level.
When necessary, oil can be added to the crankcase through the
engine oil fill port (22).

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IMG_4959_1_3

SLIDE 14

The fuel level sensor (23) is mounted on top of the fuel tank and • Rear of engine
behind the engine.

The fuel level sensor (23) is a resistance-type device. The fuel level • Component location
sensor provides the input signal to operate the fuel gauge, which is 23. Fuel level sensor
located on the indicator cluster in the operator’s compartment.

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25

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IMG_4938_1_3

SLIDE 15

• Right side of engine The air filter (25) is located on top of the engine and can be accessed
from the right side of the machine when the engine compartment is
open.

• Component location The air filter indicator (24) is located behind the air filter (25) and
24. Air filter on the right side of the cooling package. The air filter indicator
25. Air filter indicator records the highest intake air restriction the engine encounters
during operation. The indicator holds the highest value until the
reset button at the bottom of the air filter indicator is depressed. The
air filter indicator allows the operator to check the condition of the
air filter while the engine is not operating. The air filter must be
serviced if the yellow piston in the air filter indicator moves into the
red zone.

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IMG_4923_1_3

SLIDE 16

The engine cooling package (26) includes the hydraulically driven • Rear of machine
fan and the radiator.

The fan motor is driven by hydraulic oil from the fan pump (not • Component location
shown). The fan pump is the second section of a two-stage pump. 26. Cooling package
The other section of this pump group supplies oil to the steering 27. Coolant expansion
system. This pump group is driven by the engine timing gears. The reservoir
pump group operates at a 1.03-to-1 ratio over engine crankshaft 28. Fuel fill port
speed.

The radiator circulates coolant through coils (not shown) in front of

the fan, in order to provide cooling to the engine. The coolant
expansion reservoir (27) allows coolant in the radiator to flow into
the reservoir when the coolant is hot. Coolant is drawn back into
the radiator as the engine cools.

NOTICE
In order for the cooling system to operate properly, the radiator
must be filled while the engine is cold. The radiator is full when
coolant runs into the expansion tank through the outlet tube. This
procedure removes the air from the radiator. Air in the top of the
radiator can cause the cooling system to malfunction.

The fuel fill port (28) allows the operator to add fuel to the fuel
tank.

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IMG_5004_1_3

SLIDE 19

• Center of instrument The alternator indicator (2) is located in the cluster of indicators in
panel the center of the instrument panel.

• Component location The alternator indicator (2) is illuminated when the alternator is not
2. Alternator indicator producing sufficient voltage. The indicator should be illuminated
3. Start-aid indicator when the engine start switch (1) is in the ON position, but the
engine is not running. If the indicator is not illuminated under these
conditions, the lamp may be faulty. If this is the case, the lamp
assembly should be replaced immediately. When the alternator
indicator is illuminated while the engine is operating, the machine
should be stopped as soon as safely possible and repaired before it is
returned to service.

System voltage from the “KEY SW” fuse is available at one side of
the alternator resistor through a blocking diode. Voltage from
terminal “D+” of the alternator is available at the other side of the
alternator resistor. A voltage difference between the sides of the
resistor will result in current being conducted through the resistor. In
this case the alternator indicator (2) will illuminate.

The start-aid indicator (3) is controlled by the engine ECM. The

engine ECM monitors engine air temperature and engine coolant
temperature. The engine ECM provides a signal to the start-aid
relay, in order to energize the glow-plug relay.

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IMG_4974_1_3

SLIDE 21

• Left side of machine The ground-level shutdown switch (5) is located on the left side of
the machine. This switch allows an operator on the ground to stop
the engine.

• Component location The ground-level shutdown switch (5) is a toggle switch with two
5. Shutdown switch positions. The bottom position of the switch is the OPERATE
position, and the top position is the STOP position.

The ground-level shutdown switch (5) provides input signals to the

engine ECM. The switch must be in the OPERATE position in order
to start the engine. When the switch is in the STOP position, the
engine ECM disables fuel injection. In this case, the fault indicator
on the instrument panel flashes. Once fuel injection has been
disabled, the ground-level shutdown switch must be returned to the
OPERATE position, and the engine start switch must be moved to
the OFF position in order to reset the system.

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IMG_4937_1_3

SLIDE 22

The electrical disconnect switch (6) is located at the rear of the • Right side of machine
machine, on the right side. The engine compartment cover provides
access to this component.

The electrical disconnect switch (6) is a keyed switch with two • Component location
positions. The electrical system turns on when the electrical 6. Electrical disconnect
disconnect switch is moved clockwise. The switch must be in the switch
ON position before the engine will start. The entire machine
electrical system shuts off when the switch is moved
counterclockwise.

NOTICE
The electrical disconnect switch must not be used to shut off the
engine. Doing so can damage electrical components on the machine.

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3

IMG_5005_1_3

SLIDE 23

FUSES, DIODES, AND RELAYS

• Right side of operator’s The main electrical panel is located on the right side of the
compartment operator’s station. A cover plate (5) provides access to the
components in the electrical panel.

• Component location A decal on the inside of the cover plate (5) identifies each fuse in the
1. Fuse panel fuse panel (1) and each relay in the relay bank (2).
2. Relay bank
3. Start-aid relay The start-aid relay (3) transfers power from the “START-AID
4. Arc suppressor RELAY” fuse to the coil of the glow-plug relay. The coil of the start-
5. Cover plate aid relay (3) is controlled by the engine ECM.

The arc suppressor (4) provides a current path for the inductive
energy in the coil of the start-aid relay. This path prevents voltage
spikes from forming at contact “40” and contact “57” of the
machine ECM when the relay is de-energized.

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5

IMG_4936_1_3

SLIDE 25

SYSTEM COMPONENTS

• Rear of machine The glow plug circuit breaker (1), the alternator circuit breaker (2),
the main circuit breaker (3), and the ECM circuit breaker (4) are
mounted on the power panel, located at the rear of the machine. The
batteries (5) are also located at the rear of the machine.

• Component location The glow plug circuit breaker (1) transfers power from the batteries
1. Glow plug circuit to the glow plug relay.
breaker
2. Alternator circuit The alternator circuit breaker (2) transfers power from the “B+”
breaker terminal of the alternator to the batteries.
3. Main circuit breaker
4. ECM circuit breaker The main circuit breaker (3) transfers power from the batteries to
5. Batteries the gate of the start relay and the gate of the main relay.

The ECM circuit breaker (4) transfers power from the batteries to
the “BATTERY” contacts of the ECM.

The batteries (5) are connected in series and provide a 24-volt

electrical system.

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IMG_4926_1_3

SLIDE 26

The glow plug relay (6) and the start relay (7) are located on the • Rear of machine
front side of the power panel.

The coil of the glow plug relay (6) is energized by the start-aid relay • Component location
when the start-aid relay is energized. The glow plug relay (6) 6. Glow plug relay
transfers power to the glow plugs. 7. Start relay

The coil of the start relay (7) is energized by neutral start relay “P3”
when the neutral start switch is closed and the engine start switch is
in the START position.

The machine is equipped with a diode block (not shown). This block
is mounted to the cable clamps on the fuel tank. The diode block is
an arc suppressor. The arc suppressor provides a current path for the
inductive energy in the coil of the start relay (7). This prevents an arc
from forming across the gate of the neutral start relay “P3” when
the relay is de-energized.

The arc suppressor also provides a current path for the inductive
energy in the coil of the glow plug relay (6). This path prevents an
arc from forming across the gate of the start aid relay when the relay
is de-energized.

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IMG_4960_1_3

SLIDE 27

• Left side of machine The alternator (8) is located on the left side of the engine. The engine
compartment cover provides access to this component.

• Component location After the engine has been started, the alternator (8) provides power
8. Alternator to the machine electrical system. During machine operation, the
alternator charges the batteries.

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11

IMG_4944_1_3

SLIDE 30

The engine ECM (11) is located on the right side of the engine. The • Right side of engine
engine compartment cover provides access to this component.

The engine ECM (11) controls the engine. The engine ECM receives • Component location
input from sensors around the engine and the machine. The ECM 11. Engine ECM
then compares the input signals to parameters already stored in the
software, and generates an appropriate output response for the
current conditions.

The software inside the engine ECM (11) stores operating maps
which define horsepower, torque curves, RPM, and other operating
parameters. These maps provide the logic necessary for the engine
ECM to operate the engine at the proper setting. The engine ECM
has a self-diagnostic capability to assist in troubleshooting engine
problems.

When the ECM breaker is closed, power transfers from the batteries
to terminal “J1-7,” terminal “J1-8,” terminal “J1-15,” and terminal
“J1-16” of the engine ECM (11). The engine ECM is grounded at
terminals “J1-1” to “J1-3,” terminal “J1-9,” and terminal “J1-10.”

The engine ECM (11) monitors the intake air temperature. If the
temperature is less than the factory-set parameter, the engine ECM
directs an output signal from terminal “57” and from terminal
“63.” The signal from terminal “57” is sent to the start-aid relay.
The signal from terminal “63” is sent to the start-aid indicator.

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IMG_5026

SLIDE 32

Propulsion Control System

GENERAL INFORMATION (PROPEL SYSTEM)

The axle and the drum on the machines are hydrostatically driven. • Propulsion system
The drum drive system consists of a piston-type pump, a two-speed general information
piston-type motor, and a planetary gear reducer with an integral
spring applied, hydraulically released brake. The axle drive consists
of a piston-type pump, a two-speed piston-type motor, and an axle
with a limited slip differential, a planetary gear reducer for each
wheel, and a spring applied, hydraulically released brake for each
wheel. The steering pump and fan pump supply charge oil to the
propulsion system.

The propulsion system section of this presentation is divided into • Section description
segments. The first segments show the location of all electrical and
hydraulic components on the machine which are part of the
propulsion system. A brief discussion of each component is provided
in these segments.

The last two sections explain the operation of the electrical and
hydraulic systems. Schematics are used in this segment to trace
current through the electrical system and hydraulic oil through the
hydraulic system.

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INSTRUCTOR NOTE: Because this section is meant to stand

alone, some components may have been discussed in previous
sections.

IMG_4780_1_10

SLIDE 33

OPERATOR CONTROLS (PROPEL SYSTEM)

• Right console The propulsion lever (1) is located on the console to the right of the
operator’s seat. This lever controls the hydrostatic drive system. A
cable connects the propulsion lever to the pump controls.

• Component location The machine moves forward when the propulsion lever (1) is moved
1. Propulsion lever out of the center NEUTRAL position and towards the front of the
machine. The machine moves backwards when the lever is moved
out of the center and towards the rear of the machine. The farther
the operator moves the propulsion lever towards the front of the
machine or towards the back of the machine, the faster the machine
travels.

The machine stops when the propulsion lever is returned to the

NEUTRAL position. This is the primary braking method.

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PROPULSION LEVER GROUP

BACKUP ALARM SWITCH

2620887S1V1_2_3_4

SLIDE 34

The back-up alarm switch is located in the base of the propulsion • Back-up alarm switch
lever (1). When the propulsion lever is in the REVERSE position, the
back-up alarm switch is closed. The back-up alarm switch is open
when the propulsion lever is in the NEUTRAL position. This switch
is also open when the propulsion lever is in the FORWARD
position. The back-up alarm switch receives power from the
“REV_ALARM” fuse. The back-up alarm switch controls the
ground path for the backup alarm. When the switch is closed, the
ground path is complete, and the backup alarm sounds.

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2 3

IMG_4779_1_10

SLIDE 35

• Right console The parking brake switch (3) is located on the right console. This
switch is a push-button switch with two positions. The parking
brake switch is in the ON position when the switch is pushed in.
The switch is in the OFF position when the switch is pulled out. The
parking brake switch contains an integral indicator (2). The
indicator is illuminated when the parking brake is engaged,
regardless of the position of the parking brake switch.

• Component location The parking brake switch (3) works in conjunction with the brake
2. Parking brake indicator relays and neutral start relay “P4” in order to control the axle
3. Parking brake switch interlock solenoid and the drum interlock solenoid. These devices
ensure that the machine does not propel when the brake is engaged
and the propulsion lever (1) is out of the NEUTRAL position.

Contact “1” and contact “3” of the parking brake switch (3) receive
power from the “PARK BRAKE” fuse. When the switch is in the
OFF position, power transfers from contact “2” of the switch to
contact “30” of parking brake relay “P1.” When the switch is in the
ON position, power transfers to the indicator in the switch and to
contact “86” of parking brake relay “P1” and to contact “86” of
parking brake relay “P2.”

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IMG_4778_1_12

SLIDE 36

The shift switch (4) is located on the left side of the instrument • Left side of instrument
panel. The shift switch is electrically connected to the shift solenoid. console

The shift switch (4) has two positions. The bottom position of the • Component location
switch is the LOW-SPEED position. The top position of the switch is 4. Shift switch
the HIGH-SPEED position.

When the shift switch (4) is moved to the HIGH-SPEED position,

the shift solenoid is energized. Contact “2” of the shift switch
receives power from the “PARK BRAKE” fuse. When the switch is
in the HIGH-SPEED position, power transfers from contact “3” of
the switch to contact of “1” the shift solenoid.

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5
6

IMG_5004_1_7

SLIDE 37

• Indicator cluster The low hydraulic oil pressure indicator (5) and the high hydraulic
oil temperature indicator (6) are located on the indicator cluster on
the instrument console.

• Component location The low hydraulic oil pressure indicator (5) receives a signal from
5. Low hydraulic oil pin “J1-18” of the engine ECM. The engine ECM monitors the
pressure indicator hydraulic oil pressure switch and sends a low pressure signal to the
6. High hydraulic oil hydraulic oil pressure indicator when hydraulic oil pressure is less
temperature indicator than 1100 kPa (160 psi). When this indicator is illuminated, the
engine ECM logs a fault, and the alarm horn sounds.

The high hydraulic oil temperature indicator (6) receives a signal

from pin “J1-19” of the engine ECM. The engine ECM monitors the
hydraulic oil temperature switch located in the hydraulic oil tank
and sends a high temperature signal to the hydraulic oil temperature
indicator when hydraulic oil temperature is greater than 85 °C (185
°F). When this indicator is illuminated, the engine ECM logs a fault,
and the alarm horn sounds.

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The coil of brake relay “P1” is energized when the parking brake • Brake relay “P1”
switch is in the ON position. The coil of brake relay “P1” will
remain energized when the parking brake switch is moved to the
OFF position under the following conditions:

• The engine start switch is in the ON position or in the START

position.

• The neutral start switch is open.

• The coil of neutral start relay “P4” is de-energized.

Contact “30” of brake relay “P1” receives power from contact “2”
of the parking brake switch when the switch is in the OFF position.
When the relay is de-energized, power transfers from contact “87A”
to the axle interlock solenoid and to the drum interlock solenoid.

The coil of brake relay “P2” is energized when the parking brake • Brake relay “P2”
switch is in the ON position. The coil of brake relay “P2” will
remain energized when the parking brake switch is moved to the
OFF position under the following conditions:

• The engine start switch is in the ON position or in the START

position.

• The neutral start switch is open.

• The coil of neutral start relay “P4” is de-energized.

Contact “30” of brake relay “P2” receives power from contact

“87A” of neutral start relay “P4.” When the relay is energized,
power transfers from contact “87” to the following places:

• the coil of brake relay “P1”

• the coil of brake relay “P2”

• contact “4” of the parking brake switch

• contact “X1” of the parking brake indicator

• the brake lights

The coil of neutral start relay “P4” is energized when the neutral • Neutral start relay “P4”
start switch is closed and the engine start switch is in the ON
position or in the START position. Contact “30” of the relay
receives power from the “PARK BRAKE” fuse. When the coil of
neutral start relay “P4” is energized, power transfers from contact
“87A” of the relay to contact “30” of brake relay “P2.”

43
QESV1336-01

1 2

IMG_4782_1_3

SLIDE 40

HYDRAULIC TANK

• Right side of machine The hydraulic tank is in front of the engine and below the
hydrostatic pumps. Access to the hydraulic tank is from the right
side of the machine. The drum propulsion hydraulic system, the axle
propulsion hydraulic system, the vibratory hydraulic system, the
steering hydraulic system, and the fan hydraulic system share a
common hydraulic tank.

• Component location The hydraulic tank is non-pressurized. The fill port (1) is located on
1. Fill port the right side of the hydraulic tank. A cover plate (removed)
2. Sight gauge provides access to the fill port and protects the fill cap during
machine operation.

The sight gauges (2), on the right side of the hydraulic tank, indicate
the oil level in the hydraulic tank. The sight gauges are visible when
the cover plate is installed. Oil should always cover the bottom sight
gauge. The oil level may be visible in the upper sight glass, but
should not be over the center of the glass. The capacity of the
hydraulic tank is 90 L (23 U.S. gal).

NOTE: If the hydraulic oil and the filters are changed at the same
time, 96 L (25 U.S. gal) is needed to refill the system.

44
 QESV1336-01

IMG_4989_1_3

SLIDE 41

The hydraulic oil temperature switch (3) is mounted to the rear side • Rear of hydraulic tank
of the hydraulic tank. Contact “B” of this switch is connected to
terminal “J1-44” of the engine ECM. Contact “C” of this switch is
connected to the common return line at terminal “J1-35” of the
engine ECM.

The engine ECM monitors the circuit at terminal “J1-44.” When the • Component location
hydraulic oil temperature is less than the actuation temperature of 3. Hydraulic oil
the switch, the switch is open. In this case, the engine ECM reads an temperature switch
open circuit at terminal “J1-44.” When the hydraulic oil
temperature is greater than the actuation temperature of the switch,
the switch opens. When the switch is open, the engine ECM reads an
open circuit at terminal “J1-44.” In this case, the engine ECM
illuminates the hydraulic temperature indicator on the instrument
panel.

45
QESV1336-01

IMG_4785_1_3

SLIDE 42

HYDRAULIC OIL FILTERS (CHARGE)

• Left side of machine The hydraulic filters are located under the operator’s platform, on
the left side of the machine.

• Component location Charge oil from the steering hydraulic system flows through the
1. Front charge filter front charge filter (1). This oil is directed to the vibrator pump and
2. Rear charge filter to the drum pump. Charge oil from the fan hydraulic system flows
through the rear charge filter (2) to the axle pump and to the shift
solenoid.

The housing of each charge filter contains a bypass valve. If the

pressure differential across the filter is greater than 350 kPa (51 psi),
the bypass valve opens. When the bypass valve is open, charge oil
flows to the hydraulic tank, bypassing the hydraulic pumps.

46
 QESV1336-01

IMG_4818_1_3

SLIDE 43

A pressure switch (3) is installed in the outlet line of the front charge • Left side of machine
filter. Contact “A” of the pressure switch is connected to the
common return line at terminal “J1-35” of the engine ECM.
Contact “B” of the switch is connected to terminal “J1-45” of the
engine ECM.

On start-up, the switch closes when the pressure reaches 1400 kPa • Component location
(203 psi). During operation the switch will open and the indicator 3. Pressure switch
will illuminate when the pressure is below 1100 kPa (160 psi). The
indicator will remain illuminated until the pressure reaches 1400
kPa (203 psi).

47
QESV1336-01

6 8
4 3 7
1

10 2

9 11

IMG_4878_1_3

SLIDE 44

PISTON PUMP (PROPEL)

• Under operator’s platform The machine is equipped with two propulsion pumps. One pump is
for the axle drive system, and one pump is for the drum drive
system.

• Component location The propulsion pumps are located under the operator’s platform.
1. Axle interlock solenoid The axle pump is driven by the engine flywheel, and the drum pump
2. Reverse pressure tap is splined to the axle pump. The propulsion pumps provide flow to
(axle pump) the closed-circuit, hydrostatic-drive system. Functionally, the axle
3. Reverse balance line and drum pumps are identical.
4. Forward balance line
5. Reverse pressure tap The forward circuits of the axle and drum propulsion systems are
(drum pump) connected by the forward balance line (4). The reverse circuits of the
6. Drum interlock axle and drum propulsion systems are connected by the reverse
solenoid balance line (3). Each balance line contains an orifice that restricts
7. Forward pressure tap oil flow between the axle circuit and the drum circuit. The orifices
(axle pump) prevent all flow from the drum circuit to flow to the axle circuit if
8. Forward pressure tap the tires begin to spin. The orifices also prevent all flow from the
(drum pump) axle circuit to flow to the drum circuit if the drum begins to spin.
9. Reverse combination
valve (drum pump) The balance lines allow oil to transfer between the drum and axle
10. Displacement control propulsion circuits. This oil transfer modulates the pressure
spool (drum pump) difference in the hydrostatic drive circuits of the drum and axle
11. Synchronization link propulsion systems. Oil transfer between the two systems is
necessary to compensate for the following situations:

• differences in underfoot conditions

48
 QESV1336-01

• differences in speeds between the drum and the wheels during

turns

• differences in rolling radii between the drum and the tires.

Each pump housing contains two combination valves. One • Combination valve (drum
combination valve is for the reverse drive circuit and one is for the pump)
forward drive circuit. The reverse combination valves (9, one
shown) are located on the left side of the pumps.

The makeup section of the combination valves allows charge oil to

flow into the low-pressure circuit in order to replenish the oil lost to
loop flushing and internal leakage.

Each combination valve is equipped with a towing plunger. When

this plunger is screwed in, the high-pressure relief valve in the circuit
is opened. When the forward and reverse towing plungers are both
screwed in, the forward circuit and the reverse circuit are connected.
In this case, pressure cannot build in the system, and the machine
can be towed.

The forward combination valves (not shown) are located on the

right side of the pumps. The combination valves act as high-pressure
relief valves, makeup valves, and towing valves. The high-pressure
relief function of the combination valves limits maximum system
pressure in the forward circuit and the maximum system pressure in
the reverse circuit to 46 500 ± 1000 kPa (6740 ± 145 psi).

NOTE: The pressure override relief (POR) valves (not shown) are
located on the lower left sides of the pumps. Each pump contains
one pressure override relief valve. These valves destroke the pumps
at a system pressure of 44 000 ± 1000 kPa (6380 ± 145 psi).

NOTE: The high-pressure relief function of the combination valve

is fast acting. The purpose of the high-pressure relief valve is to
relieve peak pressure in the closed circuit. The high-pressure relief
valve bypasses all pump flow until the slower-acting POR valve has
time to respond.

The reverse pressure taps (2 and 5) measure pressure in the reverse • Pressure taps
drive loops of the propulsion circuit. The forward pressure taps (7
and 8) measure pressure in the forward drive loop of the propulsion
circuit.

49
QESV1336-01

• Axle interlock solenoid Axle interlock solenoid (1) is controlled by brake relay “P1.”
Contact “1” of the solenoid is connected to contact “87A” of the
relay. When the axle pump interlock solenoid is energized, charge oil
is directed to the displacement control spool in the axle pump. The
displacement control spool controls the flow of charge oil which acts
against either side of the servo piston. The servo piston moves in the
servo cylinder bore in order to control the position of the swashplate
in the pump.

When the solenoid is de-energized, charge pressure cannot reach the

control spool. In this case, the pump destrokes since charge pressure
is not available to the servo cylinder bore.

• Drum interlock solenoid Drum interlock solenoid (6) is controlled by brake relay “P1.”
Contact “1” of the solenoid is connected to contact “87A” of the
relay. When the drum pump interlock solenoid is energized, charge
oil is directed to the displacement control spool in the drum pump.
The displacement control spool controls the flow of charge oil which
acts against either side of the servo piston. The servo piston moves
in the servo cylinder bore in order to control the position of the
swashplate in the pump.

When the interlock solenoid on the drum pump is energized, charge

oil is also directed to the brake release port in the drum drive
planetary and to the brake release port on the axle. In this case, the
parking brakes are released.

When the interlock solenoid on the drum pump is de-energized,

charge pressure cannot reach the control spool. In this case, the
pump destrokes since charge pressure is not available to the servo
cylinder bore.When the solenoid is de-energized, the brake release
ports are vented to the hydraulic tank, and the parking brakes are
engaged. The brakes are spring-applied and hydraulically released.

NOTE: The charge relief valves are located on the bottom of the
pumps. Each pump has a charge relief valve.

• Displacement control The servo piston in each pump controls the angle of the swashplate
spool in the pump. The displacement control lever (10, drum pump
shown) on each pump provides input to the displacement control
spool in the pump and the pump servo.

• Synchronization link The synchronization link (11) connects the displacement control
levers on the two pumps. If the axle pump control lever is not in the
center position, the neutral start switch is open, and the start relay
will not energize.

50
 QESV1336-01

12

IMG_4907_1_3

SLIDE 45

The neutral start switch (12) is activated by the position of the • Under operator’s platform
displacement control lever. This switch ensures that the parking
brake remains engaged if the parking brake switch is moved from
the ON position to the OFF position while the propulsion lever is
out of the NEUTRAL position. The neutral start switch also
prevents the starter from cranking the engine when the propulsion
lever is out of the NEUTRAL position.

When the propulsion lever is in the NEUTRAL position, the neutral • Component location
start switch (12) is closed. When the propulsion lever is in the 12. Neutral start switch
FORWARD position, the neutral switch is open. When the
propulsion lever is in the REVERSE position, the neutral start
switch is open.

Contact “1” of the neutral start switch (12) receives power from
contact “R” of the engine start switch when the switch is in the ON
position or in the START position. When the neutral start switch is
closed, power transfers to contact “86” of neutral start relay “P4.”

51
QESV1336-01

An orifice in the system causes the pressure in the high-pressure

servo piston cavity to decrease. The springs in the servo then move
the swashplate to a lesser angle, and the flow from the pump
decreases. Decreased pump flow results in reduced pressure in the
high pressure circuit. When the pressure drops below 44 000 ± 1000
kPa (6380 ± 145 psi), the POR valve begins to close. The POR valve
will reach equilibrium. At this point, the POR valve maintains the
pressure in the high pressure circuit at 44 000 ± 1000 kPa (6380 ±
145 psi) until the pressure required to propel the machine decreases.

The pressure override relief valve is set to a lower pressure than the
high-pressure relief valves in the combination valves. The lower
setting allows the machine to work at high pressures with less heat
generation. The pressure override relief valve also reduces the
horsepower draw on the engine when the machine is being
accelerated.

IMG_4966_1_5

SLIDE 48

DIRECTION AND SPEED CONTROL

• Left side of machine Shift solenoid (1) is mounted to the inside face of the left machine
frame. The operator’s platform can be lifted in order to allow access
to this component.

• Component location Shift solenoid (1) is controlled by the shift switch. When the shift
1. Shift solenoid switch is moved to the HIGH-SPEED position, power is transferred
from contact “3” of the switch to the coil of the shift solenoid.

56
 QESV1336-01

When the shift solenoid (1) is de-energized, the axle motor and the
drum motor operate in the low-speed range. When the shift solenoid
is energized, charge oil is directed to the shift spools in the drum
motor and the axle motor. In this case, the motors operate in the
high-speed range.

4
2

3
5

6
IMG_4986_1_3

SLIDE 49

PISTON MOTOR (DRUM PROPEL)

The drum motor is located on the left side of the drum. This motor • Left side of drum
is a piston motor with two speeds. The drum motor drives the drum
through a planetary gear reducer. The planetary gear reducer
contains an integral parking brake.

The parking brake is spring applied and hydraulically released. The • Component location
brake inlet line (1) on the gear box provides charge oil to release the 1. Brake inlet line
parking brake. 2. Drum motor
3. Flushing valve
The drum motor receives supply oil from and returns low pressure 4. Drum motor case drain
oil to the drum propulsion pump, through the forward and reverse line
circuit lines. 5. Shift valve line
6. Flushing relief valve
When the machine is in the high-speed range, the shift solenoid is
energized. In this case, charge oil enters the propulsion motor
through the shift valve line (5). In the high-speed range, the
propulsion motor operates at the minimum angle.

57
QESV1336-01

The drum motor contains a flushing valve (3). The flushing valve
spool directs oil from the low-pressure side of the drum propulsion
loop to the flushing relief valve (6). When the pressure in the low-
pressure side of the propulsion loop is greater than 1800 kPa (261
psi), the flushing relief valve opens. When the flushing relief valve is
open, an orifice diverts 8.7 L/m (2.3 U.S. gal/min) of oil from the
low-pressure side of the drum propulsion loop into the drum motor
case drain.

The drum motor case drain line (4) directs oil from the drum motor
case to the return manifold.

DRUM MOTOR
NEUTRAL
MINIMUM DISPLACEMENT LIMITER CONTROL SPOOL

BARREL ASSEMBLY

PISTON
SHIFT PORT

CHECK VALVE
FLUSHING RELIEF VALVE

CONTROL PLATE
ROD

MAXIMUM DISPLACEMENT LIMITER FLUSHING BLOCK

ACTUATOR PISTON
FLUSHING SPOOL

1117060910_A6VE55H23_2_4

SLIDE 50

• Motor cross section The drum motor has a bent axis. The speed of this type of motor
shifts when the bend angle of the motor is changed. The motor can
be operated against either the minimum displacement limiter or the
maximum displacement limiter. The minimum displacement limiter
or the maximum displacement limiter can be adjusted to control the
minimum and maximum motor speeds.

58
 QESV1336-01

A pressure differential between the forward port and the reverse • Motor control
port of the motor causes the motor to rotate. When the supply pump
is not generating flow, pressure in the forward circuit and pressure in
the reverse circuit is equal to charge pressure. In this case, a pressure
differential does not exist, and the motor will not turn.

When the motor is not operating, the springs of the flushing spool • Flushing spool
move the spool into the center position. Also, the flushing relief
valve is closed. In this condition, oil is trapped between the inner
lands of the shuttle spool and the relief valve, and no flushing flow
occurs.

DRUM MOTOR
FORWARD, LOW SPEED
MINIMUM DISPLACEMENT LIMITER CONTROL SPOOL

BARREL ASSEMBLY

PISTON
SHIFT PORT

CHECK VALVE
FLUSHING RELIEF VALVE

CONTROL PLATE
ROD

MAXIMUM DISPLACEMENT LIMITER FLUSHING BLOCK

ACTUATOR PISTON
FLUSHING SPOOL

1117060910_A6VE55H23_3_4

SLIDE 51

When the supply pump is generating flow, supply oil enters the • Hydraulic motor cross
motor. Supply oil is directed to the inlet port of the control plate. section
The control plate directs oil into the piston chamber in the barrel
assembly. This pressure forces the pistons which are aligned with the
inlet port to move out of the cylinder block.

59
QESV1336-01

• Barrel assembly and As the pistons are forced out of the barrel assembly, the barrel
pistons assembly and pistons rotate. Since the pistons are connected to the
output shaft, the output shaft also rotates.

As the barrel assembly rotates, pistons align with the outlet port in
the control plate. The rotation of the barrel assembly forces oil out
of the piston chambers and into the low-pressure side of the
hydrostatic loop. The low-pressure oil then returns to the inlet side
of the hydraulic pump, which completes the hydrostatic circuit.

• Shift mechanism With the hydraulic system is in the LOW-SPEED condition, the shift
port is connected to the tank. The springs of the control spool move
the spool. In this condition, the control spool directs oil from the
high-pressure circuit to the top of the actuator piston. This action
shifts the actuator piston and control plate down. The bottom of the
actuator piston is vented to the motor case.

NOTE: In order to shift the motor to the HIGH-SPEED condition,

charge oil is routed to the shift port. Charge oil then shifts the
control spool against the spring force. With the control spool shift,
the top of the actuator piston will be open to the motor case, and oil
from the high-pressure circuit will be directed to the bottom of the
actuator piston. The piston and control plate will shift up.

• Loop flushing When the supply pump produces flow, oil flushes through the
circuit. Oil in the high-pressure circuit causes the flushing spool to
shift. Oil in the low-pressure circuit now flows to the relief valve.

The flushing relief valve opens at 1800 kPa (261 psi). This pressure
is lower than the setting of the charge relief valve in the supply
pump. Therefore, during normal operating conditions the flushing
relief valve opens when the supply pump is producing flow. This
results in oil being flushed from the hydrostatic circuit. An orifice in
the motor controls the flow rate. The oil is flushed through the
motor case.

NOTE: The orifice in the motor only allows a small amount of oil
from the low-pressure loop to flow into the motor case compared to
the total amount of charge flow available. Therefore, even though
the flushing relief valve opens at 1800 kPa (261 psi), because of the
orifice, charge pressure only drops slightly when the machine is
moving.

60
 QESV1336-01

The main purpose of the flushing relief valve is to maintain sufficient

pressure to release the parking brakes if charge flow decreases in the
system. Charge flow can decrease for several reasons, including
excessive internal leakage in the hydraulic system. Without a
flushing relief valve, the orifice in the flushing system could allow the
pressure in the charge system to fall below the level necessary to
release the parking brakes. However, once the charge pressure
reaches 1800 kPa (261 psi) on this machine, the flushing relief valve
closes. This action blocks the oil flow through the orifice. In this
case, flushing flow will stop, and the system may be capable of
creating enough pressure to unlock the parking brake so the
machine can be loaded onto a truck.

IMG_4991_1_3

SLIDE 52

PISTON MOTOR (WHEEL PROPEL)

The axle motor is located under the machine on the front side of the • Under machine, behind
axle. This motor is a piston motor with two speeds. The axle motor hydraulic tank
drives the axle through a planetary gear reducer. The axle is
equipped with two parking brakes. One parking brake is located on
either side of the differential.

When the machine is in the high-speed range, the shift solenoid is • Component location
energized, and charge oil enters the axle motor through the shift 1. Axle hydraulic motor
valve line (3). In the high-speed range, the propulsion motor 2. Flushing valve
operates at the minimum angle. 3. Shift valve line

The flushing valve block (2) is identical to the flushing valve block
which is used on the drum motor.

61
QESV1336-01

The axle case drain line (not shown) directs oil from the axle motor
case to the return manifold.

AXLE MOTOR
FORWARD, LOW SPEED
MINIMUM DISPLACEMENT LIMITER

BARREL ASSEMBLY

PISTON

FLUSHING RELIEF VALVE

CHECK VALVE
FLUSHING SPOOL

CONTROL PLATE
MAXIMUM DISPLACEMENT LIMITER
ACTUATOR PISTON CONTROL SPOOL

ROD
CONTROL SPOOL SHIFT PORT
FLUSHING BLOCK

1130061537_A6VM55H23_2

SLIDE 53

• Motor cross section The axle motor has a bent axis. The speed of this type of motor
shifts when the bend angle of the motor is changed. The motor can
be operated against either the minimum displacement limiter or the
maximum displacement limiter. The minimum displacement limiter
or the maximum displacement limiter can be adjusted to control the
minimum and maximum motor speeds.

• Motor control When the supply pump is generating flow, supply oil enters the
motor. Supply oil is directed to the inlet port of the control plate.
The control plate directs oil into the piston chamber in the barrel
assembly. This pressure forces the pistons which are aligned with the
inlet port to move out of the cylinder block.

• Barrel assembly and As the pistons are forced out of the barrel assembly, the barrel
pistons assembly and pistons rotate. Since the pistons are connected to the
output shaft, the output shaft also rotates.

62
 QESV1336-01

As the barrel assembly rotates, pistons align with the outlet port in
the control plate. The rotation of the barrel assembly forces oil out
of the piston chambers and into the low-pressure side of the
hydrostatic loop. The low-pressure oil then returns to the inlet side
of the hydraulic pump, which completes the hydrostatic circuit.

With the hydraulic system in the LOW-SPEED condition, the shift • Shift mechanism
port is connected to the tank. The springs of the control spool move
the spool. In this condition, the control spool directs oil from the
high-pressure circuit to the top of the actuator piston. This action
shifts the actuator piston and control plate down. The bottom of the
actuator piston is vented to the motor case.

NOTE: In order to shift the motor to the HIGH-SPEED condition,

charge oil is routed to the shift port. Charge oil then shifts the
control spool against the spring force. With the control spool shift,
the top of the actuator piston will be open to the motor case, and oil
from the high-pressure circuit will be directed to the bottom of the
actuator piston. The piston and control plate will shift up.

When the supply pump produces flow, oil flushes through the • Loop flushing
circuit. Oil in the high-pressure circuit causes the flushing spool to
shift. Oil in the low-pressure circuit now flows to the relief valve.

The flushing relief valve opens at 1800 kPa (261 psi). This pressure
is lower than the setting of the charge relief valve in the supply
pump. Therefore, during normal operating conditions the flushing
relief valve opens when the supply pump is producing flow. This
results in oil being flushed from the hydrostatic circuit. An orifice in
the motor controls the flow rate. The oil is flushed through the
motor case.

NOTE: The orifice in the motor only allows a small amount of oil
from the low-pressure loop to flow into the motor case compared to
the total amount of charge flow available. Therefore, even though
the flushing relief valve opens at 1800 kPa (261 psi), because of the
orifice, charge pressure only drops slightly when the machine is
moving.

63
QESV1336-01

The main purpose of the flushing relief valve is to maintain sufficient

pressure to release the parking brakes if charge flow decreases in the
system. Charge flow can decrease for several reasons, including
excessive internal leakage in the hydraulic system. Without a
flushing relief valve, the orifice in the flushing system could allow the
pressure in the charge system to fall below the level necessary to
release the parking brakes. However, once the charge pressure
reaches 1800 kPa (261 psi) on this machine, the flushing relief valve
closes. This action blocks the oil flow through the orifice. In this
case, flushing flow will stop, and the system may be capable of
creating enough pressure to unlock the parking brake so the
machine can be loaded onto a truck.

IMG_3157_1_3

SLIDE 54

THERMAL BYPASS MANIFOLD

• Left side of machine The return manifold (1) is located under the machine, on the left
side and behind the hydraulic tank. Case drain lines from the axle
pump, drum pump, axle motor, drum motor, and the vibratory
motor are connected to the return manifold. Oil from these lines is
combined and directed to the thermal bypass valve which is located
inside the return manifold.

• Component location The thermal bypass valve contains a wax pellet. The wax pellet
1. Return manifold expands as the hydraulic oil temperature increases. As the wax
expands, the bypass spool moves. The bypass spool controls the oil
flow through port “R” of the return manifold. This port is
connected to the hydraulic tank. Oil flowing through this port
bypasses the oil cooler.

64
 QESV1336-01

IMG_5026

SLIDE 59

Vibratory Hydraulic System

GENERAL INFORMATION (VIBRATORY SYSTEM)

The principal working component in the vibratory system is the • Vibratory system general
eccentric weight, which the vibratory motor rotates on a shaft inside information
the rolling drum. The rotation of the weight generates a dynamic (or
centrifugal) force that is significantly greater in magnitude than the
static weight of the machine.

The rotational speed of the eccentric weight shafts determines the

vibratory frequency. Frequency is expressed in Hertz (Hz) or in
vibrations per minute (VPM). The vibratory frequency on the
standard machine is controlled by the engine speed. On machines
which are equipped with the variable frequency vibratory system, a
potentiometer controls the vibratory frequency.

The vibratory system section of this presentation is divided into • Section description
segments. The first segments show the location of all electrical and
hydraulic components on the machine which are part of the
vibratory system. A brief discussion of each component is provided
in these segments.

The last two sections explain the operation of the electrical and
hydraulic systems. Schematics are used in this segment to trace
current through the electrical system and hydraulic oil through the
hydraulic system.

77
QESV1336-01

INSTRUCTOR NOTE: Because this section is meant to stand

alone, some components may have been discussed in previous
sections.

IMG_4780_1_3

SLIDE 60

OPERATOR CONTROLS (VIBRATORY SYSTEM)

• Right console The vibratory control switch (1) is on top of the propulsion lever.
The vibratory control switch is a push-button switch which toggles
between the ON position and the OFF position. A single depression
of the button changes the condition of the switch. This switch serves
as the primary switch for the vibratory system.

• Component location The vibratory control switch (1) receives power from contact “6” of
1. Vibratory control the throttle switch when the throttle switch is in the HIGH-SPEED
switch position. On machines with the fixed frequency vibratory system,
power transfers from the vibratory control switch to the amplitude
selector switch when the vibratory control switch is closed. On
machines with the variable frequency vibratory system, power
transfers from the vibratory control switch to the coil of the
vibratory relay when the vibratory control switch is closed.

78
 QESV1336-01

2 3

IMG_4779_1_3

SLIDE 61

The amplitude selector switch (2) and the vibratory frequency dial • Right console
(3, if equipped) are located on the right console.

The amplitude selector switch (2) is a rocker switch with three • Component location
positions. The top position is the HIGH-AMPLITUDE position. The 2. Amplitude selector
center position is the OFF position. The bottom position is the switch
LOW-AMPLITUDE position. 3. Vibratory frequency
dial (not in photo)
On machines with the fixed frequency vibratory system the
amplitude selector switch (2) operates in the following way. Contact
“2” of the amplitude selector switch receives power when the
vibratory control switch is closed. When the amplitude selector
switch is in the HIGH-AMPLITUDE position, power is transferred
from contact “3” of the switch to the high-amplitude solenoid.
When the amplitude selector switch is in the LOW-AMPLITUDE
position, power is transferred from contact “1” of the switch to the
low-amplitude solenoid.

On machines with the variable frequency vibratory system the

amplitude selector switch (2) and the vibratory frequency dial
operate in the following way. Contact “5” of the switch receives
power when the throttle switch is in the HIGH-IDLE position.
When the amplitude selector switch is in the HIGH-AMPLITUDE
position, power transfers to contact “F1” of the vibratory controller.
The controller then generates an output signal from contact “B1.”
This signal transfers to the high-amplitude solenoid. The strength of
the signal is proportional to the position of the vibratory frequency
dial (3).

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QESV1336-01

When the amplitude selector switch (2) is in the LOW-AMPLITUDE

position, power transfers to contact “F2” of the vibratory controller.
The controller then generates an output signal from contact “B2.”
This signal transfers to the low-amplitude solenoid. The strength of
the signal is proportional to the position of the vibratory frequency
dial (3).

IMG_4778_1_3

SLIDE 62

• Left side of instrument The vibratory tachometer (4) and the throttle switch (5) are located
console on the left side of the instrument console.

• Component location Contact “1” of the vibratory tachometer (4) receives power from the
4. Vibratory tachometer “GAUGES” fuse. Contact “2” of the tachometer is connected to
5. Throttle switch frame ground. Contact “3” and contact “4” of the vibratory
tachometer receive input signals from the vibratory sensor. The
frequency is displayed in vibrations per minute.

The throttle switch (5) controls the engine speed. The throttle switch
is a rocker switch with two positions. The top position is the HIGH-
IDLE position. The bottom position is the LOW-IDLE position. The
vibratory system can only be operated while the throttle switch is in
the HIGH-IDLE position. When the throttle switch is in the HIGH-
IDLE position, power is transferred from the “VIBE” fuse to the
vibratory control switch.

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QESV1336-01

2 1

3
IMG_4969_1_3

SLIDE 64

PISTON PUMP (VIBRATORY)

• Under operator’s The vibratory pump is located under the operator’s compartment.
compartment The vibratory pump is splined to the drum pump. The vibratory
pump provides flow to the closed-circuit, vibratory system.

• Component location The vibratory pump is similar to the propulsion pumps, except that
1. Solenoid “A” the direction control valve is solenoid operated. The swashplate
2. High-amplitude control mechanism on the pump for the fixed frequency vibratory
frequency adjustment system does not have a feedback link.
3. Low-amplitude
frequency adjustment The vibratory pump is controlled by two solenoids. On machines
4. Solenoid “B” with the fixed frequency vibratory system, the pump control
5. Low-amplitude relief solenoids are on/off solenoids. On machines with the variable
valve frequency vibratory system, the pump control solenoids are
proportional solenoids. The control valves are the only difference
between the hydraulic pumps used on the two different vibratory
systems.

Solenoid “A” (1) is located on the top of the pump for both
vibratory systems. On machines with the fixed frequency vibratory
system, the amplitude control switch controls the power supply to
the coil of solenoid “A.” When the switch is in the HIGH-
AMPLITUDE position, solenoid “A” is energized. On machines
with the variable frequency vibratory system, the vibratory
controller uses solenoid “A” in order to control the vibration
frequency when the amplitude control switch is in the LOW-
AMPLITUDE position.

82
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The pump is equipped with displacement limiters. The high-

amplitude frequency adjustment screw (2) is located on the top face
of the pump on both vibratory systems. This adjustment screw limits
the maximum position of the swashplate when the amplitude
control switch is in the HIGH-AMPLITUDE position. The position
of the swashplate controls pump output, and therefore, controls
vibratory frequency.

NOTE: The position of the high-amplitude frequency adjustment

screw is the same for all machines. While function of the pump
control solenoids is opposite between the two vibratory systems, the
function of the frequency adjustment screws is the same between the
two systems.

The solenoid “B” (4) is located on the bottom of the pump. On

machines with the fixed frequency vibratory system, the amplitude
control switch controls the power supply to the coil of the low-
amplitude solenoid. When the switch is in the LOW-AMPLITUDE
position, the low-amplitude solenoid is energized. On machines with
the variable frequency vibratory system, the vibratory controller
uses solenoid “B” in order to control the vibration frequency when
the amplitude control switch is in the HIGH-AMPLITUDE position.

The low-amplitude frequency adjustment screw (3) is located on the

bottom face of the pump. This adjustment screw limits the
maximum position of the swashplate when the amplitude selector
switch is in the LOW-AMPLITUDE position. The position of the
swashplate controls pump output, and therefore, controls vibratory
frequency.

The pump housing contains two makeup and relief valves: one for
the low-amplitude circuit (5) and one for the high-amplitude circuit
(not shown). The relief function of the valves limits maximum
system pressure in the high-and-low-amplitude circuits to 39 000 ±
1500 kPa (5656 ± 218 psi).

The pump is also equipped with a charge relief valve (not shown).
This valve is located on the bottom face of the pump.

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QESV1336-01

1 2

IMG_4987_1_3

SLIDE 66

PISTON MOTOR (VIBRATORY)

• Right side of drum The vibratory motor (3) is mounted on the right side of the drum.
The vibratory motor is a piston-type motor with a fixed
displacement. This motor turns the eccentric weight drive shaft
when the vibratory system is operating.

• Component location Rubber isolation mounts dampen the vibration which is transmitted
1. Speed sensor from the drum to the machine when the vibratory system is
2. Case drain line operating.
3. Vibratory motor
The vibratory motor contains an integral flushing valve. This valve
operates in the same manner as the flushing valves on the propel
motors, except that the flushing relief valve is set to open when
pressure in the low-pressure side of the loop is above 1600 kPa (232
psi). The case drain line (2) directs oil to the return manifold.

• Speed sensor The speed sensor (1) is mounted to the vibratory support. The
sensor is located to the rear of the vibrator motor. The speed sensor
is a frequency-type device. A gear on the output shaft of the
vibratory motor rotates past the tip of the speed sensor. Each time a
tooth passes the sensor, an electrical impulse is sent to contact “3”
of the vibratory tachometer.

86
 QESV1336-01

VIBRATORY MOTOR
WITH FLUSHING VALVE
OUTPUT SHAFT FLANGE

PISTON

VALVE PLATE
OUTPUT SHAFT

FLUSHING RELIEF VALVE

BARREL ASSEMBLY
FLUSHING SPOOL

0820071516A2FM_2

SLIDE 67

The vibratory motor is a bent-axis motor with a fixed displacement. • Motor cross section
The motor is equipped with a loop flushing valve.

When the vibratory system is operating, supply oil from the • Rotating group
vibratory pump enters the motor. Supply oil is directed to the inlet
port of the valve plate. Supply oil is also directed to the flushing
spool. The valve plate directs oil into the piston chamber in the
barrel assembly. This pressure forces the pistons which are aligned
with the inlet port to move out of the barrel assembly.

As the pistons are forced out of the barrel assembly, the pistons exert
a thrust against the output shaft flange. This thrust causes the
output shaft to rotate. The barrel assembly and pistons rotate with
the output shaft.

As the barrel assembly rotates, pistons align with the outlet port in
the valve plate. The rotation of the barrel assembly forces oil out of
the piston chambers and into the low-pressure side of the
hydrostatic loop. The low-pressure oil acts on the flushing spool and
then returns to the inlet side of the hydraulic pump.

87
 QESV1336-01

IMG_5026

SLIDE 75

Steering System

GENERAL INFORMATION (STEERING SYSTEM)

The steering system shares a common hydraulic tank with the • Steering system general
propulsion system, the vibratory system, and the fan system. The information
steering pump provides the oil to operate the steering system and
also provides charge oil to the drum propulsion system and the
vibratory system.

The steering system section of this presentation is divided into • Section description
segments. The first segments show the location of all components on
the machine which are part of the steering system. A brief discussion
of each component is provided in these segments.

The last section explains the operation of the hydraulic system.

Schematics are used in this segment to trace hydraulic oil through
the hydraulic system.

INSTRUCTOR NOTE: Because this section is meant to stand

alone, some components may have been discussed in previous
sections.

101
QESV1336-01

IMG_4848_1_3

SLIDE 76

GEAR PUMP (STEERING)

• Right side of engine The steering pump (1) is located in the engine compartment, on the
right side of the machine. The engine drives this gear-type pump.
The steering pump and the fan pump share a common housing. The
fan pump is splined to the steering pump. The steering pump and the
fan pump also share a common inlet port. The pump draws oil from
the hydraulic tank through a suction strainer.

• Component location Flow is sent to the steering control unit through the steering outlet
1. Steering pump line. Steering system pressure can be measured at the pressure tap (2)
2. Outlet pressure tap in the steering outlet line. After the steering requirements have been
met, the remainder of the flow from the steering pump is sent to the
front charge filter. This oil then becomes charge oil for the vibratory
hydraulic system and charge oil for the drum propulsion system.

102
 QESV1336-01

IMG_4981_1_3

SLIDE 77

METERING PUMP (STEERING)

Oil from the steering pump flows to the steering control unit (1). • Under operator’s
This component is located under the steering wheel. The steering compartment
control unit consists of a steering control valve and a metering
pump. The steering control valve is a spring-centered, sleeve-type
rotary valve. The metering pump is a gerotor-type pump. The
control valve governs the direction of the turn, while the metering
pump controls the rate of the turn.

The steering control unit (1) contains four ports. Each port is • Component location
identified with a letter. Pump supply oil enters the steering control 1. Steering control unit
unit through port “P.” During machine steering, metered oil flows to
and from the rod and the head end of the steering cylinders through
port “L” and port “R.” Oil is sent to the charge filter through port
“T.”

The main relief valve in the steering control unit (1) limits the
pressure in the steering circuit. Steering relief pressure varies with oil
temperature. For example, when the oil temperature is 43 °C (110
°F), steering relief pressure is 20 000 kPa (2900 psi). When the oil
temperature is 60 °C (140 °F), steering relief pressure is 19 000 kPa
(2755 psi). The main relief valve ensures that flow is directed into
the charge circuit when the steering system is stalled.

103
QESV1336-01

IMG_4980_1_3

SLIDE 78

HYDRAULIC CYLINDER (STEERING)

• Behind drum Hydraulic cylinders (1, left shown) for the steering system are
located in the articulation area. The steering system contains two
hydraulic cylinders. The steering cylinders and a vertical pin (3) in
the articulation are allow a ±30-degree steering angle.

• Component location The left hydraulic cylinder (1) and right hydraulic cylinder receive
1. Hydraulic cylinder oil from the steering control unit. The cylinders are hydraulically
2. Locking pin interlocked. The cylinders extend and retract in opposition to each
3. Steering pin other in order to cause the machine to articulate.

A locking pin (2) can be inserted in the pivot joint in order to lock
the front frame and the rear frame together.

104
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STEERING HYDRAULIC SYSTEM

STRAIGHT TRAVEL

STEERING HMU
STEERING CONTROL
VALVE SPOOL
T

TP
RELIEF
TO FAN MOTOR
VALVE

L
MAKEUP
VALVE
STEERING AND
FAN PUMP CHARGE PUMP
MAKEUP
R VALVE

RELIEF
VALVE
METERING
PUMP
DRUM
CHECK PRESSURE
VALVE SWITCH

CHECK RELIEF
STEERING P VALVE VALVE FRONT
CYLINDERS CHARGE
FILTER

TO VIBRATORY
PUMP AND
DRUM PUMP

SUCTION
STRAINER
BLOCKED FILTER
BYPASS VALVE TANK

0724071000_3_4

SLIDE 79

HYDRAULIC SCHEMATIC (STEERING SYSTEM)

This slide shows the steering system in straight travel. • Hydraulic schematic

When the steering wheel is in the center position, the center envelope • Oil flow
of the steering control valve is active. Pump supply oil enters the
steering control unit through port “P.” This oil opens the inlet check
valve and flows across the steering control valve spool to port “T.”
Oil leaving the outlet of the steering control unit is directed to the
front charge filter.

The line relief valves limit the maximum pressure in the steering • Line relief valves
cylinders. These relief valves act as shock valves for the steering
system. The valves are set at the factory to open when the pressure
in the steering cylinder reaches 22 500 kPa (3265 psi). The line relief
valves are not adjustable.

105
QESV1336-01

• Makeup and check valves The anticavitation check valve and makeup valves allow for limited
manual steering when the engine is not operating. The inlet check
valve prevents the backflow of oil to the steering pump during
manual steering of the machine.

STEERING HYDRAULIC SYSTEM

RIGHT TURN

STEERING HMU
STEERING CONTROL
VALVE SPOOL
T

TP
RELIEF
TO FAN MOTOR
VALVE

L
MAKEUP
VALVE
STEERING AND
FAN PUMP CHARGE PUMP
MAKEUP
R VALVE

RELIEF
VALVE
METERING
PUMP
DRUM
CHECK PRESSURE
VALVE SWITCH

CHECK RELIEF
STEERING P VALVE VALVE FRONT
CYLINDERS CHARGE
FILTER

TO VIBRATORY
PUMP AND
DRUM PUMP

SUCTION
STRAINER
BLOCKED FILTER
BYPASS VALVE TANK

0724071000_2_4

SLIDE 80

• Hydraulic schematic This slide shows the steering system operating during a right turn.

• Oil flow When the steering wheel is rotated to the right, the bottom envelope
of the steering control valve is active. Pump supply oil entering the
steering control unit through port “P” flows across the steering
control valve spool and sleeve to the metering pump. Oil leaving the
metering pump flows to the rod end of the right steering cylinder
and to the head end of the left steering cylinder.

106
 QESV1336-01

The metering pump rotates when the steering wheel is turned, and • Steering control unit
directs flow through the steering control valve spool and to the head operation
end of the left steering cylinder and to the rod end of the right
steering cylinder. Oil flowing into the steering cylinders causes the
machine to turn right. Oil in the head end of the right steering
cylinder and in the rod end of the left steering cylinder flows out the
steering control unit through port “T.” Oil leaving the outlet of the
steering control unit is directed to the front charge filter.

As the operator turns the steering wheel faster, the metering pump
increases the flow to the steering cylinders, and therefore, the
machine turns faster. The steering control spool directs return oil
from the rod end of the left steering cylinder and head end of the
right steering cylinder into the charge line.

The metering pump directs flow to the steering cylinders until the
operator stops turning the steering wheel. When the steering wheel
stops turning, the centering springs center the control spool inside
the sleeve. Oil is blocked at the steering cylinders, and the steering
angle does not change until the operator moves the steering wheel
again.

If the operator continues to turn the steering wheel after the steering • Main relief valve
cylinders reach the end of their stroke, the main relief valve opens.
This valve maintains pressure in the steering system while allowing
the excess pump flow to enter the charge circuit.

107
QESV1336-01

IMG_5026

SLIDE 81

Fan Drive Hydraulic System

GENERAL INFORMATION (FAN DRIVE HYDRAULIC

SYSTEM)

• Fan system general The fan system shares a common hydraulic tank with the propulsion
information system, the vibratory system, and the steering system. The fan pump
provides the oil to operate the fan motor and also provides charge
oil for the axle propulsion system.

• Section description The fan system section of this presentation is divided into segments.
The first segments show the location of all hydraulic components on
the machine which are part of the fan system. A brief discussion of
each component is provided in these segments.

The last section explains the operation of the hydraulic system.

Schematics are used in this segment to trace hydraulic oil through
the hydraulic system.

INSTRUCTOR NOTE: Because this section is meant to stand

alone, some components may have been discussed in previous
sections.

108
 QESV1336-01

1
2

IMG_4850A_1_3

SLIDE 82

GEAR PUMP (FAN DRIVE)

The fan pump (1) is located in the engine compartment, on the right • Right side of engine
side of the machine. The engine drives this gear-type pump. The
steering pump and the fan pump share a common housing. The fan
pump is splined to the steering pump. The steering pump and the fan
pump also share a common inlet port. The pumps draw oil from the
hydraulic tank through a suction strainer.

Oil flow is sent to the fan motor through the fan pump outlet line • Component location
(2). After the fan requirements have been met, the flow from the fan 1. Fan pump
pump is sent to the rear charge filter. The rear charge filter directs 2. Outlet line
charge oil to the axle propulsion system.

109
QESV1336-01

4
1

5
2

IMG_4933_1_3

SLIDE 83

GEAR MOTOR (HYDRAULIC FAN)

• Rear of engine The fan motor (2) is a gear-type motor with a fixed displacement.
The motor drives the cooling fan. The fan pump directs oil flow to
the inlet (1) of the fan motor.

• Component location The speed adjustment screw (4) controls the setting of a differential
1. Fan motor inlet line pressure valve in the rear housing. This valve maintains the pressure
2. Fan motor drop across the motor in order to control the amount of oil that is
3. Fan motor outlet line forced through the fan motor. As the adjustment screw is turned in,
4. Fan speed adjustment more oil is sent through the fan motor, and fan speed increases. As
screw the adjustment screw is turned out, more oil bypasses the fan motor,
5. Case drain line and fan speed decreases.

NOTE: Denser air requires higher pressure in the fan circuit in

order to maintain the same fan speed. Less dense air requires lower
pressure in order to maintain the same fan speed. Fan speed will be
higher if the machine is moved to higher elevations. Fan speed will
be lower if the machine is moved to lower elevations. Fan speed
should be 1700 ± 25 rpm when the machine is operating at
elevations of up to approximately 150 m (500 ft). Fan speed will
increase 100 rpm for each 750 m (2500 ft) increase in elevation.

Oil leaving the outlet (3) of the fan motor is directed to the rear
charge filter. The fan motor case drain line (5) dumps oil from the
motor case directly into the hydraulic tank.

110
 QESV1336-01

CS/CP76 FAN HYDRAULIC SYSTEM

OPERATING

PUMP
ASSEMBLY FAN MOTOR
TO STEERING
HMU ASSEMBLY

FAN PUMP
FAN MOTOR
STEERING PUMP

RELIEF
REAR VALVE
CHARGE
FILTER
ASSEMBLY

TO AXLE PUMP

SUCTION
STRAINER

TANK

0724070900_2_3

SLIDE 84

HYDRAULIC SCHEMATIC (HYDRAULIC FAN)

The fan pump is driven by the engine. The fan pump draws oil from • Hydraulic schematic
the hydraulic tank through a suction strainer. The fan motor is
connected to the cooling fan. The fan pump directs oil flow to the
inlet of the fan motor.

Inside the fan motor, supply oil seats the anticavitation check valve
and acts on the differential pressure valve. As pump supply pressure
increases, the fan motor begins to rotate. Oil leaving the outlet side
of the fan motor acts against the differential pressure valve. This oil
acts in conjunction with the spring and in opposition to supply
pressure. The differential pressure valve maintains the pressure drop
across the fan motor in order to control fan speed.

111
QESV1336-01

When the engine is stopped, the inertia of the fan blades and of the
rotating components in the fan motor cause the fan motor to
continue to turn for a brief period. Since the engine is not operating
during this time, the fan pump does not provide flow to prevent
motor cavitation. In this case, the anticavitation check valve opens.
The anticavitation check valve prevents motor cavitation by
allowing the fan motor to draw oil from the return line.

The fan motor case drain line dumps oil from the motor case
directly into the hydraulic tank.

Supply oil from the fan motor is directed to the rear charge filter.
The rear charge filter directs charge oil to the axle propulsion
system.

112
 QESV1336-01

IMG_5026

SLIDE 85

Conclusion

SUMMARY

This presentation gave a general overview of the machine and then

covered the power distribution and machine starting circuit, and the
propulsion, vibratory, and machine systems in detail. Service
personnel who observed the presentation should now be able to:

1. locate and identify major components on the machine;

2. explain the function of and properly use all machine controls;
3. explain operation of the machine’s hydraulic systems by tracing
oil flow through each of the systems;
4. explain operation of the machine’s electrical system by tracing
current flow through the system.

When used in conjunction with the service manual and other service
publications, the information in this package should permit service
personnel to thoroughly analyze machine problems.

113