the effect of the metering rod. At the beginning of the
opening stroke, fluid flows out of port A and port B.
When the piston has moved approximately 1 inch into
the cylinder, the metering rod shuts off the flow of fluid
from within the cylinder to port B. At the end of the
opening stroke, the orifice snubber controls the escape
of fluid from the cylinder, this prevents the moving
parts from slamming to a stop and possibly being
damaged.
When pressurized fluid is applied to port A, the
piston moves toward the opposite end of the cylinder to
close the steam valve. At the end of the closing stroke,
the tapered end of the piston rod enters the flange. This
prevents the moving parts from slamming to a stop and
possibly being damaged.
LAUNCH VALVE STROKE TIMER
ELECTRICAL SYSTEM
The launch valve stroke timer electrical system (see
fig. 4-5) provides a means of measuring the launch
valve performance by timing the stroke from fully
closed position to the point at which the crosshead has
moved 9 inches. When the catapult is fired, fluid
pressure from the hydraulic cylinder opening port E
actuates the start timing pressure switch. This starts two
clocks which measure and displays time in seconds and
hundredths of seconds. When the valve opens 3 1/2
inches, a limit switch on the crosshead opens and clock
number one stops and display time elapsed. At the
9-inch stroke, a second switch opens, stopping and
displaying elapsed time.
The timer clocks are located on the main control
console for CV-64, CVN-65, and CV-67 and the central
charging
panel
for
CVN-68
through
CVN
76.
Variations in the launching valve stroke rates may
seriously affect catapult performance. The launching
valve stroke timers provide a means of detecting
differences in the launching valve stroke. Deviations in
the launching valve stroke can be detected by
comparing current timer readings with previously
established timer readings.
THRUST EXHAUST UNIT
The thrust/exhaust units (fig. 4-9) absorbs the
thrust of the launch engine pistons and shuttle
assembly, connects the launch valve to the power
cylinders and to the exhaust valve, anchors the aft end
of the launching, engine and prevents aft expansion of
the launching engine cylinders.
4-8
STEAM TO
EXHAUST VALVE
ABEf0410
Figure 4-9.—Thrust exhaust unit.
