Chrysler Concorde 1993, Руководство по обслуживанию, Страница: 573 / 820

POWER STEERING PUMP SERVICE
The service procedures for the Saginaw power steer-
ing pump are limited to the areas and components
listed below. No repair procedures are to be done
on the internal components of the Saginaw
power steering pumps.
•
Repair of power steering fluid leaks from areas of
the power steering pump sealed by O-rings is allowed
(Fig. 2). However power steering pump shaft seal
leakage will require replacement of the pump.
•
Power steering fluid reservoirs, related components
and attaching hardware.
•
Power steering fluid reservoir filler cap/dipstick as-
semblies.
Because of unique shaft bearings, flow control levels or
pump displacements, power steering pumps may be used
only on specific vehicle applications. Be sure that the
pump is only replaced with a pump that is the correct
replacement for that specific application.
Hydraulic pressure is provided for operation of the
power steering gear by the belt driven power steering
pump (Fig. 1). It is a constant displacement, vane type
pump. The power steering pump is connected to the
steering gear by a power steering fluid pressure hose
and power steering return line.
Rectangular pumping vanes carried by a shaft driven
rotor move the fluid from the intake to the cam ring
pressure cavities. As the rotor begins to turn, centrifugal
force throws the vanes against the inside surface of the
cam ring to pickup residual oil. This oil is then forced into
the high pressure area. As more oil is picked up by the
vanes. That additional oil is forced into the cavities of the
thrust plate through two crossover holes in the cam ring
and pressure plate. The crossover holes empty into the
high pressure area between the pressure plate and the
housing end cover.
When the high pressure area of the power steering
pump is filled with power steering fluid. Power steering
fluid then flows under the vanes in the rotor slots, forcing
the vanes to follow the inside oval surface of the
cam ring. As the vanes reach the restricted area of the
cam ring, oil is forced out from between the vanes. When
excess oil flow is generated during high-speed operation. A
regulated amount of oil returns to the pump intake side
through a flow control valve. The flow control valve
reduces the power required to drive the pump and holds
down temperature build-up.
When steering conditions exceed maximum pressure
requirements, such as turning the wheels against the
stops. The pressure built up in the steering gear also exerts
pressure on the spring end of the flow control valve. This
end of the valve houses the pressure relief valve. High
pressure lifts the relief valve ball from its seat and allows
oil to flow through a trigger orifice located in the outlet
fitting. This reduces pressure on the spring end of the flow
control valve which then opens and allows the oil to return
to the intake side of the pump. This action limits maximum
pressure output of the pump to a safe level.
Under normal power steering pump operating condi-
tions. The pressure requirements of the pump are below
maximum, causing the pressure relief valve to remain
closed.
CHECKING POWER STEERING FLUID LEVEL
WARNING: FLUID LEVEL SHOULD BE CHECKED WITH
ENGINE OFF TO PREVENT INJURY FROM MOVING
PARTS. DO NOT USE AUTOMATIC TRANSMISSION
FLUID IN THE POWER STEERING SYSTEM. DO NOT
OVERFILL THE POWER STEERING SYSTEM.
Wipe remote power steering fluid reservoir filler cap
(Fig. 3) free of dirt. Then check fluid level in remote
reservoir. The dipstick should indicate FULL COLD when
fluid is at normal ambient temperature, approximately
21°C to 27°C (70°F to 80°F). In all pumps add fluid as
necessary, use only Mopar
t
Power Steering Fluid, or
equivalent. DO NOT USE ANY TYPE OF AUTO-
MATIC TRANSMISSION FLUID.
Fig. 3 Power Steering Fluid Remote Reservoir
Fig. 2 Power Steering Pump Leakage Diagnosis
19 - 8 STEERING