If you would "pull-up"...

[Mr. Ivey]

I was just wondering if what motors people would use in order to raise their bot up on the pull-up bar in compeititon. I know you need a good drive motor, so let's leave out the Bosh Drill motors, for doing a pull up. I'm just thinking that this will help not only me in my design work, but other teams, especially rookies, to find out what kind of power they need in order to lift the 130 bot off the ground.
Thanks everyone!
Ivey

[Stephen Kowski]

in 2000, 312 "pulled up" every match using two globe motors....it worked very well.

[Mike Betts]

With the proper gear ratio, any motor will work... It just may take a little longer.

[Mr. Ivey]

Originally Posted by Mike Betts

With the proper gear ratio, any motor will work... It just may take a little longer.

Very true, but you want to get up their quickly. So what motors would you use to get up quickly? Also it costs money to build a gear box, money some teams may not have to spend.
Ivey

[Joe Ross]

in 2000, 330 used 2 fischer price motors with the included gear boxes. The diameter of the winch we used was about 3". Teams constantly commented on how fast we got our arm up there, and how fast we pulled up. we used a detent mechanism to clamp once we were up there, since the fisher price motors would slowly backdrive otherwise.

[Cory]

It really depends how you're going to lift yourself. If you were making a winch of some sort, Id say the easiest would be the Van door, sinceit already has a decent amount of torque, which you could reduce with sprockets and chains. Im not going to go into anything else, because I dont want to give any of my ideas away

Cory

[patrickrd]

I think this would be a good example of where a worm gear would be useful. It will provide a large gear ratio and will not slip unless powered.

- Patrick

[KenWittlief]

I would use the compressor motor

connected to a 2" diameter cylinder with pnuematic tubing

a 2" diameter cylinder driven with 60 psi produces 180 lbs of force directly

on a 130 lb bot it would lift you within a second

and I would be sure to have it latch (mechanically) in the up postion

remember, you dont have to be doing a chin-up - you only need to be off the floor.

1/10th of an inch is 'off' the floor!

[Matt Adams]

Originally Posted by patrickrd

I think this would be a good example of where a worm gear would be useful. It will provide a large gear ratio and will not slip unless powered.

You need to be a little careful with worm gears, they CAN be back driven. The van door motor for instance can be back driven. Some sort of a ratcheting mechanism might be a better choice, since it's a firm mechanical stop.

2 cents...

Matt

[Matt Leese]

Originally Posted by Matt Adams

You need to be a little careful with worm gears, they CAN be back driven. The van door motor for instance can be back driven. Some sort of a ratcheting mechanism might be a better choice, since it's a firm mechanical stop.

2 cents...

Matt

Perhaps I'm mistaken, but I was under the impression that a fundemental aspect of the worm gear was that it was impossible for it to be back driven. I've never seen the van door motors backdriven so it may be something else you've seen. Worm gears can break however as the stress of resisting back driving can be great.

Matt

[M. Hicken]

i agree with Ken, all you have to do is get the large ~14"throw cylinder and hook cable up to it, its more than strong enough. but a globe motor or 2 would surfice

[Joe3]

Actually...whether a worm gear can be backdriven or not is dependent on the pitch of the teeth. If you give yourself a decent lever arm, such as a wrench, on the end of the van door shaft, it is backdriven quite easily.

[KenWittlief]

I thought the van door motor has an internal clutch mechanism, adjustable with the allen screw - so the motor would slip when pushed against a hard stop.

maybe thats what is 'backdriving' - is the motor really turning or is the output shaft slipping internally?

I could be mistaken on this

(I could be mistaken about everything really :^)

[maxgebhardt]

I dont think it will start slipping! last year we used it to winch up our forklift, and when it got stuck (on two occations), rather than stop, it ripped through some fairly thick plastic, and another time ripped a 6 inch nail sideways, clean through about 2" of pine, it darn near split the nail in half.

[Mr. Ivey]

O.K. So far you guys have listed using the window motors, a pnumatic piston, and two globe motors. Now yes you could use any motor out of the box, as long as you gear it correctly, but besides the window motors, globe motors, and pnumatic motors. What is a quick way to move these bots upward. I'm almost thinking something like a track that the bot can run up that doesn't actually pull, but pushes against the track.
Ivey