Pontiac FIREBIRD 1972 Service Manual page 1174

STEERING 9-2 1
done by flow controlling. The control valve in the steering
gear is an open center rotary valve. When this valve is in
the straight ahead position, oil flows from the pump
through the open center valve and back to the pump reser-
voir without traveling through the power cylinder. When
this flow exceeds the predetermined system requirements,
oil is bypassed within the pump.
This is accomplished by the pressure drop which occurs
across the flow control orifice (2). The pressure drop is
transmitted to the bottom of the flow control valve (9) via
orifice (1 1) and passage (8). The pressure unbalance on the
valve is sufficient to overcome the force of the spring (lo),
allowing the valve to open the bypass hole ( 5 ) , and divert-
ing oil into the intake chamber ( 6 ) . Supercharging of the
intake chamber occurs under these conditions. Oil at high
velocity discharging past the valve into the intake cham-
ber picks up make-up oil at hole (4) from the reservoir on
INTERNAL AND DISCHARGE HIGH PRESSURE OIL
PRESSURE RELIEF ORIFICE 0 1 FLOW
RESERVOIR AND RETURN OIL
'ifl
RING, ROTOR LEAKAGE OIL
m
S u p E R ~ ~ ~ ~ E 011
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...%..,'
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- - - -
Fig. 9-19 Oil Flow
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Cornering Against Wheel S t o ~ s (Pressure Relief)