The EP2 panel must be activated to prepare for an onload operation. The launcher is moved to and secured at a convenient location to install the strikedown gear. Additionally, the launcher rail must be extended, the arming device retracted (disarmed), and the aft-motion latch retracted.
After the chain-drive fixture and the supply air hoses are attached, the EP2 operator activates the system and (carefully) returns the launcher to a LOAD position. The GMLS is secured once more. Topside, the deck control box is connected to its receptacle. The EP2 operator activates the GMLS, selects step control and strikedown, and retracts the train positioner. All subsequent launcher movements are controlled by the deck control box operator.
Strikedown Onload Operations
As the loaded transfer dolly arrives on board, the deck control operator assumes control. The train brake is released, and the strikedown port (or starboard) train control is selected. Fixed-position synchros drive the launcher to the predetermined strikedown position. When the launcher arrives at the strikedown position, the operator resets the train brake.
When ready to engage the dolly, the operator retracts and releases the elevation positioner and brake. The guide slowly depresses from the 90 degree load position when the elevation control switch is actuated. The guide mates with and picks up the dolly. The guide continues to depress until the elevation strikedown angle is reached. The operator resets the elevation brake and extends the positioner. Chain-drive operations can then begin.
EXTEND CHAIN.- The manual air-control valve handle is turned to EXTEND. This ports supply air to shift the air-throttle valve. From the air-throttle valve and the pressure regulator, 20-25 psi air causes the air motor to extend the chain slowly. The chain travels the length of the retractable rail of the launcher. It also extends along a portion of the guide rail of the dolly to reach the forward missile shoe.
Near the end of the chain travel, a cam on one of the chain links contacts and shifts linkage connected to the air-throttle valve. The main air port of the valve closes. However, through a restricting orifice, supply air continues to reach the motor. As a result, chain-drive speed is reduced even further. When the latches of the chain engage the forward missile shoe, chain movement stops. The air-control valve handle is returned to its NEUTRAL position.
System personnel visually verify that the spring-loaded chain latches have fully engaged behind the forward shoe of the missile. If the latches are only partially engaged, the missile may break loose as the strikedown chain is retracted. The missile will slide down the rail, shear off the shoe plate on the dolly, and drop on deck. Do not even hang around to explain that one to the chief!
RETRACT CHAIN.- To move the missile onto the guide, system personnel must shift the manual air-control valve handle to RETRACT. Full supply air pressure drives the motor at this time, and the missile is pulled onto the guide arm. As the aft shoe of the missile nears the forward-motion latch in the guide, another chain cam shifts the air-throttle valve. An orifice restricts air flow to slow motor speed again. Movement stops when the aft shoe of the missile contacts the forward-motion latch. The aft-motion latch automatically extends behind the aft shoe, and the manual air-control valve handle is turned to NEUTRAL.
After verifying that the aft-motion latch has fully extended, system personnel release the two chain latches. That is done by depressing a latch lever. See figure 8-6. The manual air-control valve handle is turned to RETRACT again. The chain is returned to its stowed position in the fixture. The manual air-control valve handle is placed in NEUTRAL to conclude air-drive operations.
Return Launcher to Load
The EP2 operator is instructed to select the unload mode. An empty cell in the ready service ring (RSR) is indexed to the hoist station. The deck control operator releases and retracts the elevation brake and positioner. The guide is elevated slowly to the 90 degree load/unload position, disconnecting from the dolly as it travels. When the dolly is rolled clear, the deck control operator releases the train brake. The launcher slews to align with the blast door.
The EP2 operator takes control and proceeds with normal unload operations. The identification probe of the fin opener arm assembly must be extended to identify the missile type on the guide arm. If strikedown operations are completed, the deck control box is disconnected and replaced by a dummy plug. This device restores full GMLS control to the EP2 panel. The launcher is moved to a convenient location for removal of the strikedown gear.
Strikedown Offload Operations
Strikedown offload operations are basically the reverse of onload operations. The one difference concerns the aft-motion latch of the guide arm. Control system circuits normally prevent the aft-motion latch from retracting with a missile on the rail unless the hoist pawl is extended and engaged.
During a strikedown offload operation, the aft-motion latch is retracted with a special tool inserted into a slot on the fixed rail. The tool is turned manually to simulate the presence of the hoist pawl. The EP2 operator may then retract the aft-motion latch. The missile can then be lowered onto the transfer dolly.