Limit Switch


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limit switch

[′lim·ət ‚swich]
(electricity)
A switch designed to cut off power automatically at or near the limit of travel of a moving object controlled by electrical means.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Limit Switch

 

(or end switch), an electrical device used in switching control circuits of electrical machine drives or their elements at certain points of their motion.

Limit switches are actuated by the motion of the mechanism itself, usually at the end of its travel or at a predetermined point on the path of its motion. For example, in hoisting machinery a limit switch disconnects the motor and applies the brake upon approaching the end point, thus protecting the mechanism from damage. Limit switches may be of the contact or contactless type. According to their design they are classified as pressure (push-button), lever, shaft, and rotary switches.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

limit switch

An electric switch, operated by a power-driven machine or by the movement of the car which it drives, which alters or controls the electric circuit associated with the machine, e.g., a switch which slows down and stops an elevator car or dumbwaiter car automatically at or near the top or bottom terminal landing; operates independently of the device which normally controls movement of the car.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
References in periodicals archive ?
You cannot simply mount a robot, wire up an extra full-mold-open limit switch to its controller, and then start running.
The IN65 series of standard limit switches available from Altech Corp.
That plate would compress the springs onto four limit switches wired to a safety mat control unit, which would stop the molding machine immediately.
The optional microelectric actuator determines accurate positioning without limit switches or user adjustment.
Emerson Process Management has expanded its Smart Wireless solutions family with the release of the Fisher[R] 4320 Wireless Position Monitor with On/Off Control Output Option, which changes the economics of automating discrete valves as an alternative to solenoids and limit switches. Project cost and project time are reduced by minimizing engineering time, materials, control system I/O, and installation labor.
For safety, the saws are equipped with a safety enclosure monitored by limit switches. The machine cover must be closed for the saw to cycle.
Products have IP 66 sealing against dust and heavy seas, internal limit switches, and optional potentiometer feedback.
The Vibracon LVL-B Series vibration limit switches are insensitive to material build-up, external vibration and flow noise, and have no mechanical moving parts for reliable, maintenance-free level sensing.
Options include control and monitoring of sequential valve gates and limit switches that indicate position (open/closed) of the gates.
Feedback units can incorporate any combination of encoders, resolvers, peteniometers, tachometers, rotary limit switches and specialized interface electronics.
"Some machines are designed with electronics and limit switches all over the place just waiting to be destroyed," he says.