TM 55-1520-240-23-6
7-290
POWER STEERING
(Continued)
7-290
Energizing the solenoid valve on the control module
opens it to allow hydraulic pressure to the power steering
actuator on the aft right gear. Putting power to the
control box power supply energizes a servo valve within
the power steering actuator.
NO BREAK - WORK HARDER
Turning the knob on the control box to the left or right
produces a command potentiometer signal in a servo
amplifier within the box. This generates an output
voltage to the servo valve on the actuator. The servo
valve responds by routing fluid flow within the actuator
to turn the wheel in the selected direction.
NO BREAK - WORK HARDER
A feedback potentiometer on the actuator generates a
signal proportional to the degree of wheel swiveling.
When the feedback and command potentiometer signals
are equal, the servo loop is balanced. The actuator
stops and the wheel will halt in the selected position. If
the wheel goes beyond a preset limit, the out-of-phase
switch will close, grounding relay 137K1 in the center
console. This shuts off hydraulic pressure to the system
and lights the PWR STEER light in the master caution
panel.
NO BREAK - WORK HARDER
A fail-safe module in the control box monitors the
system for shorts and open circuits. If either occurs,
the module grounds relay 137K1 in the same manner
as the out-of-phase switch does. Hydraulic pressure
is shut off and the PWR STEER master caution panel
light comes on.
NO BREAK - WORK HARDER
A balance potentiometer within the steering control box
allows compensation for variations in servo valve and
amplifier performance. Adjustment of this potentiometer
permits proper tracking of the wheel and the control
knob and ensures that the swivel lock will engage
without binding.
END OF TASK
7-1080
