Figure 2-13.--Lever-operated switch.

IC/L Pressure Switches

Lever-Operated Switches

Pressure-operated switches are normally SPST,

Many types of lever-operated switches are used in

quick-acting switches. Each contains either a bellows

Navy alarm and warning systems to complete an

or a diaphragm that works against an adjustable

electric circuit to various types of audible and visual

spring. The spring causes the contacts to close

alarm signals. The type depends upon the circuit in

automatically when the operating pressure falls below

which it is installed.

a specified value. The pressure at which the switches

operate is adjustable within ranges, such as 0-15,

Most lever-operated switches use JR interiors

15-50, and 50-100. Make this adjustment at the screw

(fig. 2-13). These switches are operated by a lever

marked HIGHER (fig. 2-14). These switches can be

with a suitable locking plate. In the interests of

used also to indicate an increase in pressure above a

standardization, two types of interiors are available,

predetermined point.

each containing three 2JR sections. One type is the

JRM-300, which has a spring return mechanism; and

Pressure-operated switches are used with the

the other type is the JR-304, which has a positive

lubricating oil, low-pressure alarm system; air-

detent mechanism. Through slightly different

pressure alarm system; and booster-feed pressure

arrangements of pins, lever, and locking plate, various

alarm system.

types of switches can be obtained.

IC/N Thermostatic Switches

Special switches are used where the standard

Thermostatic, or temperature-operated, switches

switches cannot be used. For example, the diving

are usually SPST, quick-acting, normally open

alarm switch on the submarine bridge must be

switches. Each switch contains a bellows that works

pressureproof. For submarine service, a distinctive

against an adjustable spring, Y (fig. 2-15). The spring

shape is used for the operating lever knob or heads of

causes the contacts to close automatically when the

alarm switches in the conning tower and the control

operating temperature exceeds a specified value. The

room (where illumination is low) to avoid the

bellows motion is produced by a sealed-in liquid that

possibility of confusion in operating the proper

expands with rising temperature. The sensitive

switch. A square-shaped knob is used for the diving

element containing this liquid may be built into

alarm switch, a star-shaped head for the collision

alarm switch, and a standard rounded head for the

general alarm.

Lever-operated switches are available in 1-, 2-,

and 3-ganged types. These switches are used in such

systems as the fire room emergency signal, general

alarm, chemical-attack alarm, steering emergency

signal, whistle operation, lifebuoy-release, and

flight-crash signal.

Figure 2-14.--Type IC/L pressure switch.

Figure 2-13.--Lever-operated switch.

2-8