Quantcast Retract launcher rail

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Retracting the launcher rail during a missile firing does not (directly) involve the solid-state circuit in figure 5-78. After the rocket motor of the missile ignites, the round travels about 20 inches up the rail. The forward missile shoe contacts the retract trigger located on the underside of the rail. The trigger shifts (or cams) a valve to start the hydraulic-mechanical actions that move the rail. The rail retracts to provide clearance for the tail-control surfaces of the missile as the round leaves the launcher.

However, in dud jettison, step-load, or exercise operations, the solid-state circuit is directly involved in initiating a retract cycle. Solid-state interlocks are used to ensure equipment conditions are correct before energizing the retract launcher rail solenoid LHL1-LC1. The solenoid, located in the guide arm, then initiates the hydraulic-mechanical actions to retract the rail.

Auto-Not-Unload Circuit (Jettison)

The auto-not-unload circuit is the primary signal path used to retract the launcher rail. The object of this circuit is to energize relay coil PC67-K5A, RETRACT LAUNCHER RAIL CYCLE (SET) (DETENTED). When the A- or set-coil energizes, the PC67-K5 contacts close. This action applies a +5-volt input signal to LHL1-LC1's solenoid driver circuit. The solenoid driver circuit activates and energizes the LC1 coil.

The following logic gate inputs must be satisfied to energize PC67-K5A. They are listed (and explained) by groups for ease of presentation. Locate them in figure 5-78.


1. SIR1-1-Launcher rail loaded

2. SIR3-1-Contactor and fin opener cranks disengaged

3. QCY5-1-Dud jettison

4. QCX7-1-Auto-not-unload selected


1. SIA1-1-Arming device extended and forward-motion latch unlocked

2. KPX4-1-Launcher power unit motor contactor energized

3. SIN1-2-Not strike-down fixture on launcher


1. SIL1-2-Not launcher rail retracted

2. PC67-K9B-1-Harpoon missile safe (detented)

3. PC67-K6-2-Not extend launcher rail cycle (detented)

GROUP A INPUTS.- Input SIR1-1 ensures that the launcher rail does not retract during a jettisoning operation unless the guide arm is loaded. The aft missile shoe contacts the rail-loaded indicator plunger. The plunger moves an actuator into proximity with launcher rail loaded switch SIR1. The switch activates and applies an input signal to an inverter-buffer circuit. The output line 1 of the circuit goes high. This high is applied to the OR-AND gate at 77-48.

Input SIR3-1 ensures the contactor and fin opener arm assembly has disengaged from the missile before the launcher rail retracts. Proximity switch SIR3 is activated and, through its inverter-buffer circuit, applies a high to gate input 77-46.

Input QCY5-1 ensures that dud jettison summary circuit QCY5 is activated. A summary circuit summarizes a variety of different input conditions into one output statement. The QCY5-1 input to 77-44 will be high when remote dud jettison pointing or local dud jettison pointing is selected.

Input QCX7-1 is high when auto-not-unload selected summary circuit QCX7 is activated. This signal is applied to 77-40 when the control system is placed in automatic control and the not-unload mode.

The step-load related input to 77-42 is low at this time. With four high inputs to the OR-AND gate, a high is produced at output 77-38. The high output is used as an input to 77-43, the next OR-AND gate.

GROUP B INPUTS.- Input SIA1-1 ensures the launcher rail does not retract until two equipment conditions are met. The arming device must be extended and the forward-motion latch must be unlocked. When these two conditions are satisfied, proximity switch SIA1 and its inverter-buffer circuit apply to high to 77-47.

Input KPX4-1 ensures the launcher power unit (LPU) motor contactor is energized. When the contactor is energized, the electric motor drives a hydraulic pump. The LPU supplies the required hydraulic fluid pressure to operate the launcher guide and blast door components. The high signal is applied to 77-49.

Input SIN1-2 ensures the launcher rail does not retract if the strike-down fixture is installed on the guide arm. If the fixture is not on the arm, an actuating lever is not in proximity with SIN1. The switch deactivates and its inverter-buffer circuit provides a high output on line 2. This high is applied to 77-51.

The step-exercise related input to 77-45 will be low at this time. The four high inputs at the OR-AND gate will produce a high output at 77-35. The high is then applied to 77-50.

GROUP C INPUTS.- Input SIL1-2 ensures that the circuit to LHL1-LC1 de-energizes after the launcher rail retracts. When the rail is in the extended position, a magnetic actuator is not in proximity with SIL1. The switch is deactivated and a high signal from output 2 of the inverter-buffer is applied to 77-37.

Input PC67-K9B-1 ensures a Harpoon missile has been disarmed and is safe to jettison. The Harpoon booster is electrically disarmed through a signal circuit of the 23-pin missile-to-launcher contactor. When this disarming is accomplished, PC67-K9B-1, Harpoon missile safe (reset) (detented) relay coil will energize. The input to 77-39 will go high.

Input PC67-K6-2 ensures an extend launcher rail cycle is not in progress. This action prevents LHL1-LC1 from energizing until an extend cycle has been completed. This high input is applied to 77-41.

The logic gate activates with four high inputs and produces a high at 77-36. A latching circuit (or holding circuit) is established by the high output at 77-36 feeding back to input 77-52. The latching circuit is used to keep the logic circuit energized whenever the launcher rail is retracted in exercise mode. That is required because the console operator will release the RETRACT push-button switch of the rail before the retract cycle ends.

The high signal from 77-36 is also used to forward bias the NPN transistor at 67-42. The transistor conducts and PC67-K5A relay coil energizes. When the contacts of the relay close, a high input signal is applied to the solenoid driver circuit. The LC1 solenoid energizes and initiates the hydraulic-mechanical actions to retract the launcher rail.


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