SkyTrak 3606 Service Manual User Manual

Page 238

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Section 9

9-44

c. Four-wheel Steer

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

PPG

PS PP

PSG

550
PSI

2500
PSI

650
PSI

C D

SHUTTLE

RESERVOIR

SERVICE

BRAKE

INLET

AUXILIARY FUNCTION MANIFOLD

0.090”

4-WHEEL

STEER

LEFT

MS0160

MS0150

PBG

PPG