Rotary Limit Switches

Rotary limit switches use physically-actuated levers to rotate a shaft and operate the contacts in a switch, making them change state. There are three basic types of rotary limit switches. Momentary or spring return switches return to their normal state as soon as the actuator passes its release point. By contrast, maintained contact switches remain in the triggered position after the actuator is released and are reset only by further mechanical action of the operating head. Positive opening switches remain in the activated position even in the event of mechanical failure such as the breakage of a spring or contact weld. Most linear limit switches feature a rugged design and are suitable for a variety of industrial applications; however, because these devices contain mechanical parts, they wear over time. Typically, rotary limit switches are slower than noncontact, electrical devices such as proximity sensors and photoelectric sensors. Common actuation methods include standard rollers, offset rollers, adjustable rollers, fork lever rollers, wide rollers, rods or wire, loops, and wobble-type springs. Top-mounted devices position the actuator on the top of the limit switch. Side-mounted devices locate the actuation mechanism on the side.

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