Service Manual User Manual

Section 9
9-42
9.8.6 Steering Circuit
Vehicle steering modes are two-wheel steer, four wheel
steer and crab steer. Fig. 9– 35 shows an exploded view
of the steering circuit components.
a. Two-wheel Steer
• Left Turn
(Fig. 9– 28)
With the steer select switch in the two-wheel steer posi-
tion, when a left turn is made, system pressure from the
auxiliary function manifold is applied through ports E-C of
the intake side of the steering unit metering section. A
specific amount of hydraulic oil is exhausted from the
metering section and routed to the control 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-T
of the steer select valve and through ports D-F of the
steering control valve, to the reservoir (Fig. 9– 30).
Figure 9– 28. Two-wheel steer mode, left turn.
b. Two-wheel Steer
• Right Turn
(Fig. 9– 29)
With the steer select switch in the two-wheel steer posi-
tion, when a right turn is made, the steering control valve
spool is shifted so that system pressure is applied
through ports E-B of the intake side of the steering unit
metering section. A specific amount of hydraulic oil is
exhausted from the metering section and routed to the
control section, where it is channeled through ports C-D.
System oil is routed from port T-P in the steer select
valve. Both solenoids in the steer select valve are de-
energized. Oil flows to the right side rod end of the front
steering cylinder. Oil from the left side rod end of the
same cylinder flows to ports A-F in the steering control
valve section and then to the reservoir (Fig. 9– 30).
Figure 9– 29. Two-wheel steer mode, right turn.
MS0140
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
2
WHEEL
STEER
LEFT
MS0130
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”
2-WHEEL
STEER
RIGHT
a
B
b
A
T
P
Model 3606 • Origin 10/99