SkyTrak 8042 Service Manual - Manual (Page 465)

Hydraulic System
8.50 Model 8042, 10042, 10054 Legacy Rev. 10/03
8.8.17 Four-Wheel Steering Circuit (Left Turn) and Troubleshooting
(Refer to Section 8.8.29, “Steering Circuit Descriptions,” for a more detailed explanation of this circuit.)
HYDRAULIC
OIL COOLER
HYDRAULIC
RESERVOIR
SECONDARY
FUNCTION
MANIFOLD
PUMP
MAIN CONTROL VALVE
SHUTTLE
VALVE
POWER
STEERING
UNIT
FRONT AXLE
REAR AXLE
STEER SELECT
VALVE
RETURN
FILTER
P
T
C
PS PB
PLT
PSG
PBG G
IN T
T
AT
TA
C
H
TI
LT P
FRAM
E
SW
AY
EXT/
R
ET
LFT/
LW
R
AU
X
R
T
P
L
E
SOLENOID COIL
STATE
ENERGIZED
DE-ENERGIZED DE
E
LS
LS
Pressure
Suction
Return
Load Sense
a b
A B
P T
DE
MH3820
NOTE:
When checking pressures
in circuits, refer to Section
8.7, “Hydraulic System
Testing,” for correct
pressure readings.
Before troubleshooting
any hydraulic circuit,
ALWAYS begin by
checking the
following:
1. Hydraulic oil level in
the reservoir
2. All hoses, tubes,
fittings for leaks,
kinks, interference,
etc.
3. Air in the lines
Not
OK
Not
OK
If the steering is slow or difficult,
check the pressure at the “PSG” port
of the secondary function manifold.
If OK
Check packing in steering cylinders.
If OK
Repair/replace steering cylinder(s).
Not
OK
Not
OK
Check the power steering unit. Replace power steering unit.
Check the shuttle valve. Replace shuttle valve.
If OK
If OK
Adjust/repair/replace pressure reducing
valve on secondary function manifold.
Not
OK
Verify that the check valve fitting at the
power steering unit is operating properly.
Replace check valve fitting.