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404—STEERING
CHRYSLER SERVICE MANUAL
puts the power system into operation, as shown
in Figure 14.
The instant the valve is moved, two impor-
tant things happen: (1) the inlet oil pressure
increases because of restricted openings ber
tween the valve and valve body, and (2) the
increased pressure is directed to one side of the
power piston. The restrictions causing the pres-
sure rise are marked "A and B" in Figure 14.
These narrow spaces "dam up" the oil that is
being forced through the system by the oil
pump. Because the pump is a positive-displace-
ment type, the oil must keep moving. As the oil
"piles-up" behind the restrictions, its pressure
increases tremendously, squeezing oil through
the narrow spaces at a very fast rate. Often
the restrictions may close completely, giving
operating pressure at the fastest possible rate.
The maximum pressure build-up is limited to
800 psi by a pressure relief valve in the pump
assembly.
The high oil pressure is directed to the lower
end of the cylinder (for this case through the
passages indicated in Figure 14). However, the
opposite end of the cylinder is open to the
return line. Therefore, a difference in pressure
exists in each end of the cylinder and the piston
moves. Oil trapped in the lower pressure cylin-
der is forced through the return passages as
the piston moves up.
By careful design, all of these elements have
been combined into two compact units which
are connected by a pair of flexible hoses. The
power unit contains the power piston, spool
valve, and hydraulic reaction chamber. Tne
supply unit incorporates the reservoir and the
oil pump with its valves.
If the driver stops turning the steering wheel
and holds it in a fixed position, the front wheels
immediately stop turning. This is how it hap-
pens: with the steering wheel held, the valve
remains in its pulled up position because the
valve is mechanically connected to the steering
wheel. The piston, on the other hand, is moving
up under the action of the pressure in the lower
end of the cylinder, and continues to move up
for the briefest instant until the relative motion
between piston and valve has returned them to
the neutral position. In neutral position, there
is very little flow restriction, as explained before,
UPPER PISTON ROD
CONNECTOR NUT
ADJUSTING DISC RETAINER
VALVE ADJUSTING DISC
VALVE
OPERATING
ROD
VALVE CONTROL
SPACER SEAL
ADJUSTING
TANG
WORM
CONNECTOR
PISTON ROD NUT AND LOCK CUP
-SEAL RETAINERS
53x861
Fig. 15—Hydraulic Reaction Assembly
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