Honeywell SPZ-8000 Maintenance Manual page 610

form and continues on through a pulse width command limiter and
servo amplifier.
The pulse width command limiter is a motor driver
that issues a continuous string of 28 V
dc pulses at a rate of one
pulse approximately every 2 milliseconds. The pulse amplitude and
polarity are determined by the yaw command input.
The servo amplifier drives the motor of the rudder linear actuator,
which
in turn drives the ballscrew. The ballscrew is mechanically
coupled to:
LVDT (Linear Variable Differential Transformer)
Hydraulic Package
The hydraulic package drives the aircraft's rudder control surface.
As the rudder control surface responds to the command, the LVDT
provides a position feedback signal to the FZ-820.
The servo amplifier output is also routed to the "A" processor
current monitor to check
for servo runaway current. As the actuator
drives the ball screw, the LVDT is
moved and provides an output that
equates to commanded rudder position. This signal is routed to the
FZ-820 where it is demodulated and then follows two paths.
The first path is through a rate taker, where the position signal is
converted to rate of position change. This signal is utilized as a
damping term to minimize excessive rudder travel.
The second path from the demodulator retains position information
and is summed with the command signal. When these two signals are
equal and opposite, the command has been satisfied and the rudder
stops moving.
As the aircraft responds to rudder clef"
movement through aerodynamic feedback,
rudder command processor diminish. Th
predominate and drives the rudder back
ection, the
IRS detects this
and the input signals to the
s allows the LVDT signal to
to its original position.
22-14-00
Page 298.144
Apr 15/93
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