GROUP 2 OPERATIONAL CHECKS AND TROUBLESHOOTING

1. OPERATIONAL CHECKS
This procedure is designed so the service man can make a quick check of the steering system using
a minimum amount of diagnostic equipment. If you need additional information, prefer to structure
and function in group 1.
A location will be required which is level and has adequate space to complete the checks.
The engine and all other major components must be at operating temperature for some checks.
Locate system check in the left column and read completely, following this sequence from left to right.
Read each check completely before performing.
At the end of each check, if no problem is found(OK), that check is complete or an additional check is
needed. If problem is indicated(NOT OK), you will be given repair required and group location.
If verification is needed, you will be given next best source of information :

Chapter 2 : Troubleshooting
Group 3 : Tests and adjustments

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※Hydraulic oil must be at operating temperature for these checks(Refer to page 6-55).
Item Description Service action

Steering unit check Run engine at low idle. OK

Check completed.

A
Turn steering wheel until frames
are at maximum right(A) and then NOT OK
left(B) positions. Go to next check.

B
LOOK : Frames must move
smoothly in both directions.
When steering wheel is stopped,
frames must stop.
FEEL : Excessive effort must not
be required to turn steering
wheel.
NOTE : It is normal for steering to
drift from stops when steering
wheel is released.
Steering system leakage Turn steering wheel rapidly until OK
check Left Right frames are against stops. Check completed.
Heat hydraulic oil to
operating temperature. Hold approximately 2kgf on NOT OK
Run engine at high idle. steering wheel. Do steering system
leakage test in group 3 to
Count steering wheel revolutions isolate the leakage.
for 1 minute.
Repeat test in opposite direction.
LOOK : Steering wheel should
rotate less than 5rpm.
NOTE : Use good judgment;
Excessive steering wheel rpm
does not mean steering will be
affected.
Priority valve low Park machine on a hard surface. OK
pressure check Check completed.
Hold brake pedal down.
NOT OK
Run engine at high idle. Do priority valve pressure
Steer machine to the right and left test in group 3.
as far as possible.
LOOK : Machine must turn at
least half way to the right and left
stops.

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 Item Description Service action

Priority valve high Steer to steering stop and release OK

pressure check wheel. Check completed.
Run engine at high idle.
Roll bucket back and hold over NOT OK
relief and observe engine rpm. Priority pressure is set
too high. Do priority valve
Turn wheel to steering stop and pressure test in group 3.
hold, observe engine rpm.
LOOK : Steering stall engine rpm
must be higher than hydraulic stall
rpm.

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2. TROUBLESHOOTING
※Diagnose malfunction charts are arranged from most probable and simplest to verify, to least
likely, more difficult to verify. Remember the following steps when troubleshooting a problem :
Step 1. Operational check out procedure(See group 3 in section 1)
Step 2. Operational checks(In this group)
Step 3. Troubleshooting
Step 4. Tests and adjustments(See group 3)

Problem Cause Remedy

No steering Low oil level. Add recommended oil.

Restricted suction line. Check.
Failed hydraulic pump. Remove and inspect return filter for metal
pump particles.
Failed main hydraulic pump drive. Remove main hydraulic pump and
inspect drive gear.
Stuck priority valve spool. Remove and inspect priority valve spool.
Broken priority valve spring. Remove and inspect spring.
Relief valve in steering unit stuck open. Do relief cartridge leakage test in group 3.
Failed hydraulic lines. Check.
Slow or hard steering Too much friction in the mechanical parts Lubricate bearings and joints of frame or
of the machine. cylinders or repair if necessary.
Check steering column installation.
Cold oil. Warm the hydraulic oil.
Low priority valve pressure setting. Do priority valve pressure test in group 3.
Worn hydraulic pump. Do hydraulic pump performance check.
Sticking priority valve spool. Remove and inspect.
Broken priority valve spring. Remove and inspect.
Pinched or restricted LS line. Inspect line. Do priority valve LS port
flow test in group 3.
Low system relief valve setting. Test and adjust if necessary.
Low overload relief valves setting. Test and adjust if necessary.

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 Problem Cause Remedy

Constant steering to Air in system. Check for foamy oil.

maintain straight travel
Leakage in steering system. Do steering system leakage check.
Worn steering unit. Do steering unit neutral leakage test in
group 3.
Leaf spring without spring force or Replace leaf springs.
broken.
Spring in overload relief valve broken. Replace overload relief valve.
Gear wheel set worn. Replace gear wheel set.
Cylinder seized or piston seals worn. Replace defects parts.
Slow steering wheel Leakage in steering system. Do steering system leakage check.
movement will not cause
Worn steering unit gerotor. Do steering unit leakage check.
any frame movement
Steering wheel can be Leakage in steering system. Do steering system leakage check.
turned with frames
against steering stop
Steering wheel turns Broken steering column or splined of Remove and inspect.
with no resistance and steering unit.
causes no frame
Lack of oil in steering unit. Start engine and check steering
movement
operation.
Leakage in steering system. Do steering system leakage test in group
3.
Erratic steering Air in oil. Check for foamy oil.
Low oil level. Add recommended oil.
Sticking priority valve spool. Remove and inspect spool.
Loose cylinder piston. Remove rod to inspect piston.
Damaged steering unit. Remove and inspect.
Spongy or soft steering Air in oil. Check for foamy oil.
Low oil level. Add recommended oil.
Free play at steering Loose steering wheel nut. Tighten.
wheel
Worn or damaged splines on steering Inspect.
column or valve.
Steering unit binding or Binding in steering column or Inspect.
steering wheel does not misalignment of column.
immediately return to
High return pressure. Check for a pinched or damaged return
neutral when released
line.
Contamination in steering unit. Inspect hydraulic filter for contamination.
Repair cause of contamination. Flush
hydraulic system.

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 Problem Cause Remedy

Steering unit locks up Large particles of contamination in Inspect hydraulic filter for contamination.
steering unit. Repair cause of contamination. Flush
hydraulic system.

★ Thermal shock Do priority valve LS port flow test in

group 5. This oil flow provides a warm-
up flow to steering unit when not using
the steering.
Worn or damaged steering unit. Repair or replace steering unit.
Abrupt steering wheel Improperly timed gerotor gear in steering Time gerotor gear.
oscillation unit.
Steering wheel turns by Lines connected to wrong port. Reconnect lines.
itself
Worn or damaged steering unit. Repair or replace steering unit.
Vibration in steering High priority valve setting. Do priority valve pressure test in group 3.
system or hoses jump
Neutral position of Steering column and steering unit out of Align the steering column with steering
steering wheel cannot be line. unit.
obtained, i.e. there is a
Too little or no play between steering Adjust the play and, if necessary, shorten
tendency towards
column and steering unit input shaft. the splines journal.
"motoring"
Pinching between inner and outer Contact the nearest service shop.
spools.
"Motoring" effect. Leaf springs are stuck or broken and Replace leaf springs.
The steering wheel can have therefore reduced spring force.
turn on its own
Inner and outer spools pinch, possibly Clean steering unit or contact the
due to dirt. nearest service shop.
Return pressure in connection with the Reduce return pressure.
reaction between differential cylinder and
steering unit too high.
Backlash Cardan shaft fork worn or broken. Replace cardan shaft.
Leaf springs without spring force or Replace leaf springs.
broken.
Worn splines on the steering column. Replace steering column.
Jerky steering LS port orifice missing. Inspect orifice.
Orifice in top end of priority valve spool Disassemble and inspect.
missing.
★ Thermal shock is caused by a large temperature differential(Approx 30° C, 50°
F) between the steering unit
and hydraulic oil. If the steering is not operated for a long period of time and the orifice in the bottom of
the priority valve spool is plugged, the steering unit may bind up when the steering is operated if the
hydraulic oil is hot enough.

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 Problem Cause Remedy

"Shimmy" effect Air in the steering cylinder. Bleed cylinder.

The steered wheels Find and remove the reason for air
vibrate collection.
(Rough tread on tires gives
Mechanical connections or wheel Replace worn parts.
vibrations.)
bearings worn.
High priority valve setting pressure. Set pressure as regular value.
Steering wheel can be Oil is needed in the tank. Fill with clean oil and bleed the system.
turned the whole time
Steering cylinder worn. Replace or repair cylinder.
without the steered
wheels moving Gear wheel set worn. Replace gear wheel set.
Spacer across cardan shaft forgotten. Install spacer.
Steering wheel can be One or both anticavitation valves are Clean or replace defect or missing
turned slowly in one or leaky or are missing in overload relief valves.
both directions without valves.
the steered wheels
One or both overload relief valves are Clean or replace.
turning
leaky.
Steering is too slow and Insufficient oil supply to steering unit, Replace pump or increase number of
heavy when trying to pump defective or number of revolutions revolutions.
turn quickly too low.
Relief valve setting too low. Adjust valve to correct setting.
Relief valve sticking owing to dirt. Clean the valve.
Spool in priority valve sticking owing to Clean the valve, check that spool moves
dirt. easily without spring.
Too weak spring in priority valve. Replace spring by a stronger.
"Kick back" in steering Fault in the system. Contact authorized man or shop.
wheel from system
Kicks from wheels
Heavy kick-back in Wrong setting of cardan shaft and Correct setting as shown in group 4.
steering wheel in both gear-wheel set.
directions
Turning the steering Hydraulic hoses for the steering cylinders Connect lines to correct ports.
wheel activates the have been switched around.
steered wheels opposite
Hard point when starting Spring force in priority valve too weak. Replace spring by a stronger.
to turn the steering
Air in LS and / or PP line. Bleed LS and PP line.
wheel
Clogged orifices in LS or PP side in Clean orifices in spool and in connecting
priority valve. plugs for LS and PP.
Oil is too thick(Cold). Let machine run until oil is warm.
Too little steering force Pump pressure too low. Correct pump pressure.

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