has capabilities for both land- and carrier-based
operations are discussed.
During land-based operation, steering is armed or
activated by the pilot. During shipboard operations, the
steering system is armed or activated automatically by a
switch actuated by the arresting hook when it is
extended. Both switches work in conjunction with a
weight-on-wheels proximity switch (scissor switch)
located on one of the main landing gears. When the
strut is compressed a certain amount, the scissor switch
completes the electrical circuit to activate the
nosewheel steering. Nosewheel steering is desired for
carrier landing operations to prevent the nosewheel, or
wheels, from swiveling during rollback after arrest-
ment.
Hydraulic Components
The main hydraulic components of the nosewheel
steering system are the nosewheel steering power unit
and selector valve. See figure 15-2.
NOSEWHEEL STEERING POWER UNIT.--
The nosewheel steering power unit incorporates a
rotary, vane-type motor that is powered hydraulically
Figure 15-1.--Nosewheel steering power unit.
and is electrically controlled through various system
Figure 15-2.--Nosewheel steering system schematic.
15-2
