Service Manual

Reelmaster 7000 Hydraulic SystemPage 4 -- 23
Steering Circuit
A four section gear pump is coupled to the piston (trac-
tion) pump. The gear pump section P3 supplies hydrau-
lic flow to the steering control valve and the lift control
manifold. Gear pump hydraulic flow is delivered to the
two c ircuits 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 P3 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 PB port to the oil filter and traction charge
circuit.
Left Turn
When a left turn is made with the engine running, the
turningofthesteeringwheelpositions thespoolvalveso
thatflowgoes throughthetop ofthespool.Flow entering
the steering control valve at the P port goes through the
spool and is routed to two places. First, most of the flow
throughthevalveisbypassedoutthePBportbacktothe
oil filter and traction charge circuit. Second, the remain-
der of the flow is drawn through the rotary meter and out
the L port. Pressure contracts the steering cylinder for
a left turn. The rotary meter ensures that the oil flow to
the cylinder is proportional to the amount of the turning
on the steering w heel. Fluid leaving the cylinder flows
backthroughthe spoolvalve thenthroughtheTport and
to the hydraulic reservoir.
The steering c ontrol valve returns to the neutral position
when turning is completed.
Right Turn
When a right turn is made with the engine running, the
turningofthesteeringwheelpositions thespoolvalveso
that flow goes through the bottom of the spool. Flow en-
tering the steering control v alve at the P port goes
through the spool and is routedto two places. As in a left
turn, most of the flow through the valve is bypassed out
the PB port back to the oil filter and traction charge cir-
cuit. Also like a left turn, the remainder of the flow is
drawn through rotary meter but goes out port R. Pres-
sure extends the steering cylinder for a right turn. The
rotary meter ensures that the oil flow to the cylinder is
proportional to the amount of the turning on the steering
wheel. Fluid leaving the cylinder flows back through the
spool valve then through the T port and to the hydraulic
reservoir.
The steering c ontrol valve returns to the neutral position
when turning is completed.
Figure 16
RIGHT TURN
STEERING
CONTROL
VALVE
STEERING
T
L
R
PPB
1050
PSI
6.1
CYLINDER
STEERING
T
L
R
PPB
1050
PSI
6.1
CYLINDER
NEUTRAL POSITION
STEERING
CONTROL
VALVE
STEERING
T
L
R
PPB
1050
PSI
6.1
CYLINDER
STEERING
CONTROL
LEFT TURN
VALVE
NO CYLINDER
MOVEMENT
Hydraulic
System