Service Manual

Reelmaster 7000−D Hydraulic SystemPage 5 − 19
Steering Circuit
A four section gear pump is coupled to the piston (trac-
tion) pump. The gear pump section P4 supplies hydrau-
lic flow to the steering control valve and the lift control
manifold. Gear pump hydraulic flow is delivered to the
two circuits through a proportional flow divider located
in the fan control manifold. The steering circuit receives
priority flow from the flow divider. Steering circuit pres-
sure is limited to 1050 PSI (72 bar) by a relief valve lo-
cated in the steering control valve.
With the steering wheel in the neutral position and the
engine running, pump section P4 flow enters the steer-
ing control valve at the P port and goes through the
steering control spool valve, bypassing the rotary meter
and steering cylinder. Flow leaves the control valve
through the E port to the traction charge circuit.
Left Turn
When a left turn is made with the engine running, turning
the steering wheel to the left positions the spool valve so
that flow goes through the top of the spool. Flow entering
the steering control valve at the P port goes through the
spool and is routed to two places. Most of the flow
through the valve is bypassed out the E port back to the
traction charge circuit. The remainder of the flow is
drawn through the rotary meter and out the L port. Pres-
sure to the rod end of the steering cylinder retracts the
cylinder for a left turn. The rotary meter ensures that the
oil flow to the cylinder is proportional to the amount the
steering wheel is turned. Fluid leaving the cylinder flows
back through the spool valve, out the T port, and returns
to the hydraulic reservoir.
The steering control valve returns to the neutral position
when turning is completed.
Right Turn
When a right turn is made with the engine running, turn-
ing the steering wheel to the right positions the spool
valve so that flow goes through the bottom of the spool.
Flow entering the steering control valve at the P port
goes through the spool and is routed to two places. Most
of the flow through the valve is bypassed out the E port
back to the traction charge circuit. The remainder of the
flow is drawn through the rotary meter and out the R port.
Pressure to the cap end of the steering cylinder extends
the cylinder for a right turn. The rotary meter ensures
that the oil flow to the cylinder is proportional to the
amount the steering wheel is turned. Fluid leaving the
cylinder flows back through the spool valve, out the T
port, and returns to the hydraulic reservoir.
The steering control valve returns to the neutral position
when turning is completed.
Figure 12
1050 psi
PT
STEERING
CYLINDER
STEERING
UNIT
RETRACT
6.1
CIR
TO TURN LEFT
E
RIGHT TURN
NEUTRAL POSITION
LEFT TURN
1050 psi
PT
STEERING
CYLINDER
STEERING
UNIT
EXTEND
6.1
CIR
TO TURN RIGHT
E
1050 psi
PT
STEERING
CYLINDER
STEERING
UNIT
6.1
CIR
E
Hydraulic
System