238:. A long flat spring is hinged at one end of the switch (the left, in the photograph) and has electrical contacts on the other. A small curved spring, preloaded (i.e., compressed during assembly) so it attempts to extend itself (at the top, just right of center in the photo), is connected between the flat spring near the contacts and a fulcrum near the midpoint of the flat spring. An actuator nub presses on the flat spring near its hinge point.
25:
804:
345:. In these latter applications, the repeatability of the actuator position when switching happens is essential for long-term accuracy. A motor-driven cam (usually relatively slow-speed) and one or more micro switches form a timer mechanism. The snap-switch mechanism can be enclosed in a metal housing including actuating levers, plungers, or rollers, forming a
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Because the flat spring is anchored and strong in tension the curved spring cannot move it to the right. The curved spring presses, or pulls, the flat spring upward, that is away, from the anchor point. Owing to the geometry, the upward force is proportional to the displacement which decreases as the
253:
As the flat spring moves downward the upward force of the curved spring reduces causing the motion to accelerate even in the absence of further movement of the actuator until the flat spring impacts the normally-open contact. Even though the flat spring unflexes as it moves downward, the switch is
273:
Secondly, they are used when long-term reliability is needed. This is a result of the internal mechanism and the independence of the closing force on the switch contacts from the operating force. Switch reliability is largely a question of the contact force: a force that is reliably adequate, but
257:
In the actuated position the curved spring provides some upward force. If the actuator is released this will move the flat spring upward. As the flat spring moves, the force from the curved spring increases. This results in acceleration until the normally-closed contacts are hit. Just as in the
168:, meaning that a small reversal of the actuator is insufficient to reverse the contacts; there must be a significant movement in the opposite direction. Both of these characteristics help to achieve a clean and reliable interruption to the switched circuit.
249:
As the actuator depresses it flexes the flat spring while the curved spring keeps the electrical contacts touching. When the flat spring is flexed enough it will provide sufficient force to compress the curved spring and the contacts will begin to move.
122:
164:, which occurs at high speed (regardless of the speed of actuation). Switching happens reliably at specific and repeatable positions of the actuator, which is not necessarily true of other mechanisms. Most successful designs also exhibit
333:, lamps, or other devices. Special low-force versions can sense coins in vending machines, or with a vane attached, airflow. Microswitches may be directly operated by a mechanism, or maybe packaged as part of a
258:
downward direction, the switch is designed so that the curved spring is strong enough to move the contacts, even if the flat spring must flex, because the actuator does not move during the changeover.
329:
tops, and many other places for control of electrical circuits. They are usually rated to carry current in control circuits only, although some switches can be directly used to control small motors,
42:
658:
179:, greater than 1 million cycles, and up to 10 million cycles for heavy-duty models. This durability is a natural consequence of the design.
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flat spring moves downward. (Actually, the force is proportional to the sine of the angle, which is approximately proportional to the angle
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designed so the net effect is acceleration. This "over-center" action produces a very distinctive clicking sound and a very crisp feel.
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buttons, and to detect paper jams or other faults in photocopiers. Microswitches are commonly used in tamper switches on
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at the time. In 1937 W.B. Schulte, McGall's employer, started the company MICRO SWITCH. The company and the
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for any snap-action switch. Companies other than
Honeywell now manufacture miniature snap-action switches.
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Firstly, they are used when a low operating force with a clearly defined action is needed.
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has been owned by
Honeywell Sensing and Control since 1950. The name has become a
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The defining feature of micro switches is that a relatively small movement at the
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systems, where it is necessary to know if a valve has been opened or shut.
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The internals of a micro switch. Contacts, from left to right, are common,
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useful for control of machine tools or electrically-driven machinery.
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Micro switches are very widely used; among their applications are
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In one type of microswitch, internally there are two conductive
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Honeywell celebrates the 75th anniversary of the Micro Switch
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Common applications of micro switches include the door
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Electric switch actuated by very little physical force
160:button produces a relatively large movement at the
49:. Unsourced material may be challenged and removed.
341:switch, operated by a sensing mechanism such as a
266:Microswitches have two main areas of application:
195:, patent 1,960,020. McGall was an employee of the
153:, sometimes called an "over-center" mechanism.
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133:, also trademarked and frequently known as a
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145:that is actuated by very little physical
109:Learn how and when to remove this message
375:
187:The first micro switch was invented by
659:Motion-triggered contact insufficiency
274:never excessive, encourages long life.
171:They are very common due to their low
125:Comparison of some different switches
7:
47:adding citations to reliable sources
286:, leveling and safety switches in
14:
802:
23:
399:"MICRO SWITCH Timeline - 1950s"
34:needs additional citations for
58:"Miniature snap-action switch"
1:
383:Shouer, Dick (1 March 2015).
654:Miniature snap-action switch
131:miniature snap-action switch
840:
214:Construction and operation
800:
504:
784:Vandal-resistant switch
634:Magnetic proximity fuze
321:, industrial controls,
197:Burgess Battery Company
151:tipping-point mechanism
149:, through the use of a
729:Silicone rubber keypad
304:fire sprinkler systems
231:
189:Phillip Kenneth McGall
126:
789:Wireless light switch
403:sensing.honeywell.com
221:
124:
569:Electric switchboard
43:improve this article
409:on February 9, 2011
162:electrical contacts
539:Contact protection
529:Centrifugal switch
433:www.unionwells.com
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193:Freeport, Illinois
127:
811:
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794:Zero speed switch
385:Honeywell History
208:generic trademark
141:, is an electric
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639:Magnetic starter
629:Lightning switch
579:Half-moon switch
549:Crossover switch
519:Battery isolator
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435:. Archived from
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405:. Archived from
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292:vending machines
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774:Transfer switch
754:Strowger switch
749:Stepping switch
744:Staircase timer
699:Railroad switch
644:Magnetic switch
619:Latching switch
594:Inertial switch
589:Infinite switch
544:Crossbar switch
509:Analogue switch
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679:Placebo button
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664:Optical switch
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649:Mercury switch
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534:Company switch
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455:External links
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429:"Micro switch"
427:Piter, Tiago.
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359:Mercury switch
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284:microwave oven
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779:Vacuum switch
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709:Rotary switch
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439:on 2020-08-07
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60: –
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54:Find sources:
48:
44:
38:
37:
32:This article
30:
26:
21:
20:
769:Touch switch
724:Sense switch
674:Piezo switch
653:
624:Light switch
614:Limit switch
609:Knife switch
574:Float switch
441:. Retrieved
437:the original
432:
422:
411:. Retrieved
407:the original
402:
393:
387:. Honeywell.
384:
378:
347:limit switch
343:Bourdon tube
312:
277:
265:
262:Applications
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248:
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201:Micro Switch
200:
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170:
155:
138:
135:micro switch
134:
130:
128:
105:
96:
86:
79:
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53:
41:Please help
36:verification
33:
764:Time switch
714:Sail switch
704:Reed switch
694:Push-button
689:Push switch
684:Pull switch
669:Photoswitch
599:Kill switch
564:Dry contact
364:Reed switch
339:temperature
337:, flow, or
327:convertible
300:gate valves
191:in 1932 in
139:microswitch
759:Thermostat
734:Softswitch
719:Sea switch
604:Key switch
584:Humidistat
559:DIP switch
524:Cam switch
443:2020-10-07
413:2020-01-13
370:References
315:appliances
308:water pipe
306:and other
177:durability
166:hysteresis
99:March 2011
69:newspapers
739:Spark gap
331:solenoids
319:machinery
288:elevators
280:interlock
204:trademark
175:but high
824:Switches
818:Category
554:Cryotron
353:See also
335:pressure
323:vehicles
158:actuator
236:springs
183:History
83:scholar
497:Switch
296:arcade
226:, and
143:switch
85:
78:
71:
64:
56:
499:types
282:on a
147:force
90:JSTOR
76:books
173:cost
62:news
302:on
246:.)
137:or
45:by
820::
431:.
401:.
325:,
317:,
294:,
290:,
129:A
489:e
482:t
475:v
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416:.
230:.
112:)
106:(
101:)
97:(
87:·
80:·
73:·
66:·
39:.
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
