An interlock switch electrically indicates the position of a component or the position of a round of ammunition. The gun mount has two main types of external interlock switches-the proximity switch and the optical switch (refer to fig. 5-7).

EXTERNAL PROXIMITY SWITCH.- The proximity switch is a straight (or 90-degree) metal tube with threads on one end, a hex nut area around the center, and a cable jack at the other end. The switch element, which is sensitive to a magnetic field, is in the threaded end. A magnet, generally moved by a lever,

Figure 5-70.-TerminaI box.

slide, or cam, activates or deactivates the proximity switch.

OPTICAL SWITCH.- The optical switch, used on the lower and upper hoist, is a straight (or 90-degree) metal tube with a mounting flange near one end and a cable jack at the other end. An identically shaped transmitter unit, aimed directly at the optical switch (detector unit), sends pulses of infrared light to the detector unit. The modulated infrared detector circuit then activates the optical switch output. When a projectile, powder case, or other obstruction interrupts the light path, the switch deactivates.

Control Switches

Control switches on the EP2 are used by the EP2 operator to select, start, and stop various equipment operations. Three types of control switches are used-the light-e milling diode (LED) switch/indicator assembly (fig. 5-7 1) or the switch/indicator assembly

Figure 5-69.-Jack hex.

Figure 5-71.-Light-emitting diode switch/indicator assembly.

Figure 5-72.-Switch/indicator assembly.

(fig. 5-72), the thumbwheel switch (fig. 5-73), and the rotary switch (fig. 5-74).

LIGHT-EMITTING DIODE SWITCH/ INDICATOR ASSEMBLY.- The LED switch/indicator assembly (refer to fig. 5-71) is a rack-mounted, plug-in type, lighted push-button switch and LED indicating light assembly with a display face. The assembly consists of a switch module and a lens module.

The switch module contains a radio interference (RIF) ground and a momentary-type action switch that closes switch contacts whenever the lens module is pressed. A locating pin at the base of the switch module ensures that the LED switch/indicator assembly can only be plugged into the panel-mounted rack in one direction to avoid damaging the LEDs contained inside the lens module. The lens module contains LEDs which are isolated from the switch contacts and, therefore, are independently controlled. The lens module permanently connects to the switch module. The lens module contains a colored (red, green, or amber) LED capsule seal.