through the primary control valve of the power
steering control unit (dashboard mounted) and
back to the pump reservoir. When steering
action is initiated by rotation of the steering
wheel, the control spool is rotated, thereby
allowing fluid to be fed to the power steering
control metering section. This section meters
out only the amount of oil required to make the
turn indicated by the steering wheel position.
The fluid is then ported to feed the proper
actuator control port and thus the correct
steering cylinder end. The alternate actuator
p o r t is simultaneously coupled to return
displaced fluid from the opposite end of the
cylinder to the system reservoir.
9-8. Once the correct amount of fluid is
measured out, the control valve is repositioned
by a spring to its open center, neutral setting,
hence causing a rotary follow-up action in the
steering wheel. The spool then maintains
pressure in the steering cylinder for the desired
turn until steering action is again initiated.
9-9. MANUAL OPERATION.
9-10. In manual operation the fluid metering
section becomes a rotary pump and directs
fluid to move the spool in either direction when
the steering wheel is manually rotated. A check
valve within the unit develops a closed circuit
b e t w e e n the hydraulic cylinder and the