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Butterfly exhaust valve
Launching-valve hydraulic lock valve

Aviation Boatswains Mate E 3 & 2 - Aviation theories and other practices
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exhaust valve from opening until the launching valve is closed and the keeper valve piston is shifted. HYDRAULIC-LOCK-VALVE PANELS There are two hydraulic-lock-valve panels, one for the launching valves (fig. 4-30) and one for the exhaust valve (fig. 4-3 1). The launching-valve hydraulic-lock- valve panel consists of two air-solenoid valves, the hydraulic lock valve, the launch pilot latch solenoid, and piping connections. The launching-valve hydraulic lock valve (fig. 4-32) provides a hydraulic lock to hold the launching-valve control valve in the FIRED position until launching is completed or until the launching- valve emergency cutout valve is placed in the EMER- GENCY position, by controlling the flow of fluid to the launching-valve control valve. The launch pilot latch solenoid controls a plunger that prevents the lock valve from being shifted to the FIRED position unless the catapult control system is in the FINAL READY phase of operation. (A manual lock screw [fig. 4-32] is provided to secure the valve during nonoperational periods.) When the catapult FIRE circuit is energized, the fire air-solenoid valve directs air pressure to shift the lock valve to the fired position. This causes pressurized fluid to be directed from port A through port B to the launching-valve control valve, the keeper valve, and port D via the launching-valve emergency cutout valve.   Fluid pressure in port D provides a hydraulic lock to prevent the valve from shifting. When the catapult LAUNCH COMPLETE circuit is energized, the close launch valve air-solenoid directs air pressure to again shift the lock valve, venting port D to gravity and directing pressurized fluid from port A through port C to the launching-valve control valve and closing the launching valves. (During a HANGFIRE condition, port D is vented and port C is pressurized when the launching-valve emergency cutout valve is placed in its EMERGENCY position, ensuring that the launching valves remain closed.) The exhaust-valve hydraulic-lock-valve panel consists of the exhaust-valve hydraulic lock valve, two air-solenoid valves, and piping connections (fig. 4-31). The exhaust-valve hydraulic lock valve (fig. 4-33) opens and closes the exhaust valve by controlling the flow of hydraulic fluid to the exhaust-valve actuator. When the exhaust-valve open solenoid is energized, air pressure is directed to the opening side of the lock valve, causing it to shift. This allows fluid to flow from port A, out port B, through the keeper valve, and into the opening chamber of the actuator. Fluid also flows from port D to lock the valve in the OPEN position. When the exhaust-valve closed solenoid is energized, air pressure shifts the lock valve to the closed position, allowing fluid to flow from port A, out port C, and into the closing chamber of the exhaust-valve actuator. The Figure 4-30.—Launching-valve hydraulic-lock-valve panel. 4-24







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