A wooden police baton has to be hung on the back of an officer and released only when s/he wants it to be released. I thought about "push to stow, push to release". This is a thought experiment, I am not a manufacturer...

The baton is smooth without grooves so alternative solution of releasing by rotation (like BNC plugs, or push/push pen) won't work.

Where can I find a simple design of such contraption or what terms would I use to describe this?

This is a rough model of a four bar (ABCFD) which push point E toward the object to hold (LMNOQ)

The object, represent here as rectangle LMNOQ, moves on a fixed bar (HL). When pushed up (represented by piston A1 expanding), point E moves towards the edge NQ. The angle FDB (in the locked position) is > 180 , so it should be locked, as with locking pliers.

In the open position, LMNOQ is lower, and point E is far from it. (this model is only for showing the idea. I am sure it should be modified to work in the real world)

HOW can a SECOND push unlock point D?

[partial clamping mechanism] [baton is held baton released

  • $\begingroup$ Open up a "clicky-top" ballpoint pen for one standard example. $\endgroup$ – Carl Witthoft Dec 14 '15 at 13:14
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    $\begingroup$ I can't tell what you're trying to do here; what does "hang this stick vertically" mean? How does it constitute a "mechanical latch" per the title? Please edit your question to clearly describe the application. A diagram wouldn't hurt. $\endgroup$ – Air Dec 14 '15 at 17:26
  • $\begingroup$ is the stick going to support a load or just the stick itself? Can just the end of the stick have some type of engagement features? $\endgroup$ – GisMofx Dec 15 '15 at 3:24
  • $\begingroup$ the stick (baton) has to carry its own weight. It has to be smooth, so no grooves or other engagement features $\endgroup$ – noam cohen Dec 15 '15 at 10:47
  • $\begingroup$ how about you replace the "magic" with a spring and the two clamping trapezoids with urethane wheels. Put the Urethane wheels on some type of a friction inducing bearing. Now you can freely insert and remove the baton as needed as long as the friction of the wheels is correct, they won't slide out. $\endgroup$ – GisMofx Dec 15 '15 at 13:59

The mechanism you're looking for is named push-push latch. They are used in a lot of places and there are various patents for that. You can check this patent granted at 2005. It is for a small holder but it can be modified for bigger projects. Figure from Patent EP1596030 A2

However if I were you I'd desing a plastic holder such as the stress holder at Kinetxbatons picture given below. Moving parts and mechanisms are prone to errors and dirt is a real problem. You can check snap-fit design books I've linked in another answer.

Kinetxbatons stress holder

  • $\begingroup$ very nice! The patent is from 2005 which is pretty amazing for me. I would expect such machines to be invented in the end of 19th century when everything was done mechanically. As for "less moving parts is better" - totally agree. $\endgroup$ – noam cohen Dec 17 '15 at 22:30
  • $\begingroup$ Patent date isn't an indication of uniqueness of solution. There might be a lot patents that resemble and solve the problem but you'll find a new aspect and get that patented. So I'm sure there were prior art. $\endgroup$ – Gokce Mehmet AY Dec 18 '15 at 11:44

From the limited information given in your question, it sounds like you might want a mechanism similar in operating principal to what is called a "push to open" drawer slide. On these drawers the draw doesn't open when you pull on it, you have to push it past a detent point and then it opens by itself basically. Hope this helps !

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    $\begingroup$ This would be greatly improved if you were to add a diagram. As it stands it's practically a copy of the question. $\endgroup$ – Carl Witthoft Dec 14 '15 at 13:13
  • $\begingroup$ Hi Carl, if I had one I would post it, order one of the slides from Grizzly, John Dewey called it learn by doing ;-) $\endgroup$ – William Hird Dec 14 '15 at 22:38

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