Sensitive Switches.- The most common type of interlock switch is the sensitive switch. There are various kinds of sensitive switches with different means of actuation.

These are small, short-traveling, snap-action switches (fig. 5-6, view A). They are manufactured as normal] y open, normally closed, and double-throw. The latter has no OFF position. The microswitch is frequently used in referring to this type of switch.

Sensitive switches are usually of the push-button variety and are often used as interlock switches. These switches usually depend on one or more springs for their snap action. For example, the heart of the microswitch is a beryllium copper spring, heat-treated for long life and reliable action. The simplicity of the one-piece spring contributes to the long life and dependability of this switch.

Figure 5-6.-A. Sensitive microswitch; B. Manual push-button switch.

When a sensitive switch is used as an interlock, the plunger (push button) is actuated by mechanical means. The device for moving the plunger can include a rotating cam, lever, wedge, or bellows arrangement.

Sensitive switches of the micro type are also used as manual push-button switches on the control panels for the 5"/54 gun mounts. Figure 5-6, view B, shows a cutaway view of this type of switch. Note that this switch has indicator lamps built into the body of the switch.

Proximity Switches.- Proximity switches, also called Hall-effect switches, are extensively used on gun

Figure 5-7.-Proximity and optical switches.

mounts and missile launchers. These switches (fig. 5-7) are magnetically actuated devices that sense component positions. A typical proximity switch consists of a switch circuit and a housing with a bayonet connector on one end and an epoxied magnetic-sensitive area on the other end. The switch, enclosed in either a straight or a 90-degree switch housing, is normally mounted on a stationary component. The housing has a quick-disconnect bayonet connector that connects the internal circuitry to the gun mount control system cable.

In operation, the switch senses the position of a magnetic field. The magnet, in a protective housing, normally is mounted on a moving component. As the actuator approaches (comes into proximity), the switch actuates; as the actuator departs (not in proximity), the switch deactuates.