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3-24
GROUP 3-
SUSPENSION, STEERING, WHEELS & lYRES
POWER STEERING PUMP
The pump rotor has 8 slippers and
springs which rotate inside a cam in-
sert containing two lobes 180° from
each other. The cam insert and the
pump port plates provide a sealed
chamber within which the rotor and
slippers rotate between the two lobes
for pump operation.
As the rotor turns, the slippers are
forced outward against the inner
surface of the cam insert by a com-
bination of centrifugal force, slipper
spring force and fluid pressure acting
on the under side of the slipper. A
pair of adjacent slippers, along with
the surfaces of the rotor, cam and
pressure plates, form a sealed cham-
ber within the crescent-shaped void.
As
this sealed chamber
moves
throup the crescent shaped void its
volume cbanaes, resultina in a pump-
ina action.
As the rotor rotates 90° (Fig. 36),
the slipper slides outward in its slot,
ridina on 'the cam and the volume of
the sealed chamber increases. This
creates a vacuum and sets up a suc-
tion area. With the inlet port placed
in this are-a, the chamber will fill with
ftuid. As the rotor rotates from 90°
to 180°, the volume of the sealed
chamber decreases, thus creating a
pressure area. The pressure or outlet
port is located in this area. While this
pumpina action is goina on between
0° and 180°, the same condition is
occurring between 180° and
360°.
This combination creates what is
known as a balanced rotor pump.
The two pressure and suction quad-
FIG. 36-Power Steering Pump
Cycle
ORIFICE PLUG
FIG. 37 -Power Steering Pump-Sedional View
Gl479·8
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