Chief Delphi - actuating a brake or anti-backdrive

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- - actuating a brake or anti-backdrive (http://www.chiefdelphi.com/forums/showthread.php?t=133272)

Re: actuating a brake or anti-backdrive

Quote:

Originally Posted by notmattlythgoe (Post 1431599)

We used a bike brake and caliper on our elevator prototype. You can see it here.

Yes but how did you actuate the caliper?

Re: actuating a brake or anti-backdrive

Quote:

Originally Posted by asid61 (Post 1432529)

Where is that 20-30lb estimate from?

It's not an estimate. It's just a scenario to illustrate a concept.

Or were you asking why there's a range, rather than just a single number?

Re: actuating a brake or anti-backdrive

Quote:

Originally Posted by cad321 (Post 1432588)

Yes but how did you actuate the caliper?

It's a pneumatic cylinder. You can see it in the video near the disk brake.

Re: actuating a brake or anti-backdrive

I'm drawing a blank...probably because I can't see what it is we're trying to figure out how to stop moving. Can you post some pictures or drawings or renderings of the robot or design?

Re: actuating a brake or anti-backdrive

Quote:

Originally Posted by loafdog (Post 1431528)

Hi,

We don't plan on using pneumatics on our robot so I was looking for ideas that used something else to control/move a mechanism that would brake/stop elevator.
I was wondering if servos can be used to control brakes or some other kind of anti-backdrive component. Poking around andymark I saw shifting gearboxes controlled by servos for example. I've seen people on CD discuss bike brakes, ratchets, etc..
But I haven't seen anyone discuss how you can implement these ideas. Anyone done this before and have details/pics they can share?

(note, I'm not a mechanical type.. i do software, just trying to get ideas to share with my team).

THanks.
-Maciej

we had success with a "ratchet/pawl" where the pawl was a heavy enough piece of scrap steel on a hinge that gravity lowered it to engage the ratchet, and a window motor pulled a piece of cable attached to the pawl to release it. a window motor hub can be easily altered to actuate a simple switch which would then (after adding some simple code) make this window motor into a sort of binary servo motor.
while mechanically this worked fine for us, ~~cheap~~free and simple were two of our main constraints, which may or may not be the case for your team...