this case the initial valve opening is maximum. If the
ratio is 4:1, however, the valve sleeve rises only
one-fourth the distance that the plunger moves. In this
case the initial valve opening is minimum.
The lever setting may be adjusted to any setting
within the two extremes previously discussed; the
particular setting used is dependent upon the weight of
the aircraft to be arrested. The weight setting is made
with the engine in battery position prior to landing the
aircraft.
Adjustment of the setting determines the position
of the valve sleeve. Therefore, it also sets the amount
the valve will open at the beginning of the arrestment
stroke. Similarly, it determines the rate of closure
during the stroke so that the valve will always seat at the
same runout.
The valve stem sleeve allows a relatively unloaded
and cushioned opening at the beginning of the stroke.
The lever system, if set for a heavy aircraft, reduces
the allowable valve stem opening and thus increases the
resistance of the valve to the flow of fluid. The energy
of the aircraft is dissipated by forcing fluid through the
restricted valve opening.
ELECTRICAL SYSTEM
The electrical system provides, controls, and
safeguards the distribution of electrical energy to the
weight selector motor and the synchro indicators. The
electrical circuits (fig. 3-5) are the control valve weight
selector circuit and the indicator circuit.
AIRCRAFT WEIGHT SELECTOR SYSTEM
AND ELECTRICAL CIRCUIT
Due to the varying weights and landing speeds of
carrier-based aircraft, it is necessary to vary the initial
opening of the CROV and have a smaller initial opening
for heavier aircraft than for lighter aircraft. The
variation of the setting of the CROV is the function of
the aircraft weight selector motor unit. (See fig. 3-5.)
Normally, the settings are made electrically by
depressing an increase or decrease push button located
at the control valve. The settings can also be
accomplished manually by a handwheel at the control
valve.
The aircraft weight selector is motor operated from
the 440-volt, 60-hertz, 3-phase ship's power supply. A
fused switch box or breaker is provided to energize or
de-energize the control circuit. To increase and
decrease settings, the direction of the aircraft weight
selector motor rotation is controlled by the motor
controller. Should an electrical failure occur, the
settings can be made manually by pulling out on the
handwheel and turning in either the increase or the
decrease direction.
Settings on the aircraft weight selector are
monitored locally at the control valve motor unit dial
and remotely by synchro receivers located at Pri-Fly
and the deckedge control station.
3-8
FUSED SWITCH BOX
FUSED SWITCH BOX
AWIS
DECKEDGE
STATION
AWIS AT
PRI-FLY
CONTROL
STATION
SYNCHRO
SYNCHRO
MINIMUM
SETTING
MAXIMUM
SETTING
POINTER
ASSEMBLY
ENGINE 440V
TERMINAL BOX
MOTOR CONTROLLER
AIRCRAFT WEIGHT
SELECTOR MOTOR
UNIT , 440V
ABE30305
12
20
30
40
50
60
70
AIRCRAFT WEIGHT
SELECTOR DIAL
INDICATOR CIRCUIT
POWER SUPPLY
110V, 60
, 10
MOTOR CIRCUIT
POWER SUPPLY
400V, 60
, 30
ENGINE 110V
TERMINAL BOX
AIRCRAFT WEIGHT
SELECTOR PUSHBUTTON
STATION
Figure 3-5.Aircraft weight selector system.