Editing ITW magnetic valve

{{TODO photo}}
 
{{infobox dswitch
| image name          = 
| manufacturer        = [[ITW]], [[Devlin]]
| product code        = 
| contact mechanism   = Magnetic valve
| switch type         = Linear, tactile
| force               = 
| introduced          = Possibly ca. 1974
| discontinued        = 2005
| switch mount        = [[switch mount#Plate mount|Plate mount]]
| keycap mount        = 
| patents             = [http://www.google.com/patents/US4099176 US4099176] (1974)<br>[http://www.google.com/patents/US4017850 US4017850] (1976)<br>[http://www.google.com/patents/US4227163 US4227163] (1979)
}}
 
'''ITW magnetic valve''' is a provisional name which refers to a type of electromagnetic switch patented by [[ITW]] and manufactured by ITW and [[Devlin]].
 
==History==
ITW filed a patent for their magnetic valve switch in 1974. The tooling was later sold to [[Devlin]]; these Devlin-made switches are reported to have been very popular in the newspaper editing industry, with most European and North American newspapers specifying them across their operations.<ref name="priv-1" /> Devlin ended production of them in 2005, choosing to use only [[Cherry MX]] switches.

Devlin referred to these switches as "Cortron" switches. No further details are known, as all documentation was disposed of (along with the tooling) at the termination of production.

==Variants==
===Full-height===
One variant of these switches uses a helical [[return spring]], and appears to be linear.<ref name="HP" /> The switch has a fairly typical late 1970s design, similar to contemporary metal contact switches.

These have been sighted with both cruciform keystems.<ref name="HP" /> and with a keycap mount that appears to be compatible with Honeywell keycaps.<ref name="X998" /> Options include alternate action and mechanical shift lock.<ref name="X998" />

Patents for these switches were filed in 1974 and 1976.

===Intermediate===
This design has a lot more in common with the low-profile design than the earlier designs. The switches are branded "itw".<ref name="DT-PST100" /> A patent for this switch was filed in 1979. The patent notes that the shell and slider are designed to hold either a contactless analogue sensing arrangement (magnetic valve) or a "mechanical" contact arrangement using a separator bar to hold the contacts apart.

<gallery widths="250" heights="187">
File:ITW magnetic valve G2 stabiliser -- top.jpg    | Dummy switch, used as a stabiliser
File:ITW magnetic valve G2 stabiliser -- opened.jpg | Dummy switch opened; note the lack of magnet and ferrite core
</gallery>

===Low-profile===
The most common variant of this switch is the low-profile version with an open shell. The switch should not be be confused with the [[RAFI RS 76 C]] Hall effect switch, with which it bears more than a passing resemblance, in particular the open low-profile shell, slider, and keycap mount.

The low-profile version has no spring under the slider; consequently, a [[buckling rubber sleeve]] is placed within the keycap to act as the return spring. These switches are tactile, with around 60 cN force.<ref name="gh-KMX-144" />

The switch contains a circular recess for an LED.<ref name="DT-LED" />

Comparing the switches in the Devlin KMX-144 and Decision Data keyboards, it's clear that at least two subtle variations of this switch were made, evident by examining the LED recess.

==Low-height Keyboards==
*Some Aydin keyboards (low-profile, white)<ref name="Aydin" />
*Decision Data Computer Corporation keyboard (low-profile, white)<ref name="DDDC" />
*[[Devlin KMX-144]] (low-profile, white)
*Some Gilbarco Marconi gas terminal keyboards, made by Cortron (low-profile, white)<ref name="Gilbarco" />
*Some [[Symbolics 365407]] (low-profile, white)
*Some Texas Instruments Low Profile 2230528-0001 (low-profile, grey)<ref name="TImag" />
*[[Xerox 820 II keyboard]] (low-profile, red)

==Intermediate-height Keyboards==
*[[Prime Computer PST100]] terminal keyboard (intermediate)<ref name="DT-PST100" />

==Full-height Keyboards==
*HP 02645-60023<ref name="HP" /> (full-height, cruciform mount, black)
*[[Raytheon 6104-04]]
*[[Sperry UNIVAC UDS-2000 2502]] (full-height, Honeywell mount, white)
*[[Xerox X998]] (full-height, Honeywell mount, various)<ref name="X998" />

==References==
<references>
<ref name="HP">Google+ — [https://plus.google.com/photos/113845661925823397356/albums/5735481286874647233 HP 02645-60023] Dated 2012-04-26. Retrieved 2015-07-28.</ref>
<ref name="Aydin">Google+ — [https://plus.google.com/photos/113845661925823397356/albums/5712195834961029921 Misc Aydin Keyboards] Dated 2012-02-23. Retrieved 2015-07-28.</ref>
<ref name="DDDC">Kaineko2 — [http://park8.wakwak.com/~kaineko2/keyboard/album20110107.html Decision Data Computer Corporation keyboard] (Japanese only) Retrieved 2015-07-28.</ref>
<ref name="priv-1">Private correspondence with Devlin employee</ref>
<ref name="gh-KMX-144">Geekhack — [http://geekhack.org/index.php?topic=26959.msg531343#msg531343 Devlin KMX-144 find - thread reload....] Dated 2012-02-06. Retrieved 2015-07-28.</ref>
<ref name="DT-LED">Deskthority — [http://deskthority.net/keyboards-f2/reverse-rubber-dome-switch-t449.html Reverse Rubber Dome Switch?]</ref>
<ref name="DT-PST100">Deskthority — [http://deskthority.net/photos-videos-f8/pr1me-pst100-itw-magnetic-valve-t6686.html Pr1me PST100 (ITW magnetic valve)]</ref>
<ref name="Gilbarco">Imgur of Gilbarco switches and label on ebay — [http://i.imgur.com/2BLc3eD.png] [http://i.imgur.com/djJIS18.jpg] Retrieved 2015-07-28.</ref>
<ref name="X998">Deskthority — [https://deskthority.net/photos-f62/xerox-x998-t12336.html Xerox X998]</ref>
<ref name="TImag">Imgur — [https://imgur.com/a/D3Nz6Nm TI - ITW Mag Valve Low Profile] Retrieved 2022-02-02.</ref>
</references>

[[Category:ITW switches]]
[[Category:Devlin switches]]
[[Category:Keyboard switches with a square post mount]]
[[Category:Magnetic valve switches]]
[[Category:Linear switches]]
[[Category:Tactile switches]]
[[Category:Alternate action switches]]
[[Category:Mechanical shift lock switches]]
[[Category:Rubber domes]]
[[Category:List of all keyboard switches]]