Service Manual User Manual

Section 9
9-44
c. Four-wheel Steer
• Left Turn
(Fig. 9– 31)
With the steer select switch in the four-wheel steer posi-
tion, the steering unit control valve spool is shifted so that
the system pressure is applied through ports E-C to the
intake side of the power steering unit metering section. A
specific amount of hydraulic oil is exhausted from the
metering section and routed back to the control valve
section where it is channeled through ports B-A to the left
rod end of the front steering cylinder. Return oil from the
right side rod end of the front steering cylinder flows
through ports P-A of the steer select valve to the left side
rod end of the rear steer cylinder. Oil from the right side
rod end of the rear steer cylinder flows through ports B-T
in the steer select valve to ports D-F in the steering con-
trol valve, then to the reservoir.
Figure 9– 31. Four-wheel steer mode, left turn.
• Right Turn
(Fig. 9– 32)
With the steer select switch in the four-wheel steer posi-
tion, the steering unit control valve spool is shifted so that
the system pressure is applied through ports E-B to the
intake side of the power steering unit metering section. A
specific amount of hydraulic oil is exhausted from the
metering section and routed back to the control section
where it is channeled through ports T-B in the steer select
valve; oil flows to the right side rod end of the rear steer-
ing cylinder. Oil from the left side rod end of the same cyl-
inder flows through ports A-P in the steer select valve, to
the right side rod end of the front steer cylinder. Return
oil from the left side rod end of the front steer cylinder
flows through ports A-F in the steering control and to the
reservoir.
Figure 9– 32. Four-wheel steer mode, right turn.
PBG
PB
PPG
PS
PP
PSG
550
PSI
2500
PSI
650
PSI
P
T
B
A
C
D
E
FEF
SHUTTLE
RESERVOIR
SERVICE
BRAKE
INLET
AUXILIARY FUNCTION MANIFOLD
0.090”
a
B
b
A
T
P
4-WHEEL
STEER
LEFT
MS0160
MS0150
PBG
PB
PPG
PS
PP
PSG
550
PSI
2500
PSI
650
PSI
P
T
B
A
C
D
E
FEF
SHUTTLE
RESERVOIR
SERVICE
BRAKE
INLET
AUXILIARY FUNCTION MANIFOLD
0.090”
a
B
b
A
T
P
4-WHEEL
STEER
RIGHT
Model 3606 • Origin 10/99