Sebring Convertible V6-2.5L VIN H (1997)
Power Steering Pump: Description and Operation
On all vehicles equipped with power steering, the hydraulic pressure for operation of the power steering gear is provided by a belt driven power steering
pump. The TTA power steering pump used on this vehicle is a droop flow rate and constant displacement, vane type pump.
In the event of a power steering pump drive belt failure, manual steering control of the vehicle can still be maintained. However, under these conditions,
steering effort will be significantly increased.
All vehicles use a remote mounted reservoir for the power steering fluid. The power steering fluid remote reservoir is mounted to the front side of the
engine between the cylinder heads.
The service procedures for the TTA power steering pump are limited to the areas and components listed below. No repair procedures are to be done on
internal components of the TTA power steering pumps.
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Repair of power steering fluid leaks from areas of the power steering pump sealed by O-rings is allowed (See Pump Leak Diagnosis). However
power steering pump shaft seal leakage will require replacement of the pump.
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Power steering fluid reservoirs, related components and attaching hardware.
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Power steering fluid reservoir filler cap/dipstick assemblies.
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 all power steering pumps are 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. 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, return hose and the remote power steering
fluid reservoir.
Rectangular pumping vanes in the shaft driven rotor, move power steering fluid from the intake to the cam ring pressure cavities of the power steering
pump. 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, the 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.
As the high pressure area is filled, oil flows under the vanes in the rotor slots, forcing the vanes to follow the inside 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 when the wheels are turned against the stops. The pressure built up in the
steering gear exerts pressure on the spring end of the flow control valve. The 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 conditions, pressure requirements of the pump are below maximum, causing the pressure relief valve to
remain closed.
