actuating a brake or anti-backdrive

[cad321]

Originally Posted by notmattlythgoe

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

Yes but how did you actuate the caliper?

[Ether]

Originally Posted by asid61

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?

[adciv]

Originally Posted by cad321

Yes but how did you actuate the caliper?

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

[MrForbes]

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?

[lcoreyl]

Originally Posted by loafdog

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, cheapfree and simple were two of our main constraints, which may or may not be the case for your team...