If you would "pull-up"...
 

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

Re: If you would "pull-up"...
 

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

Re: If you would "pull-up"...
 

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

Re: If you would "pull-up"...
 

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

Re: If you would "pull-up"...
 

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.

Re: If you would "pull-up"...
 

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

Re: If you would "pull-up"...
 

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

Re: If you would "pull-up"...
 

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!

Re: If you would "pull-up"...
 

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

Re: If you would "pull-up"...
 

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

Re: If you would "pull-up"...
 

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

Re: If you would "pull-up"...
 

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.

Re: If you would "pull-up"...
 

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 :^)

Re: If you would "pull-up"...
 

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.

Re: If you would "pull-up"...
 

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

Re: If you would "pull-up"...
 

A caution about the Van Door motor... we made a winch with it in 2000, but we had to use two of them to get enough torque to do it.

Also, if you're using the Globe motors for anything, make absolutely sure there are NO SIDE LOADS on the Globes. They can't handle side loads, and will burn out very fast otherwise. We went through about 6 of them making a lock mechanism for our winch in 2000.

Re: If you would "pull-up"...
 

The team I was on in 2000 (Team 49) also used the 2 van door motors to lift our bot in 2000.

We were under the impression that worm drives cannot be backdriven so we were a little disapointed to see that when we turned the power off after lifting, our robot slowly settled back to the ramp. We ended up having to make a possitive clamping mechanism.

MattB

Re: If you would "pull-up"...
 

other ways? dont forget we are allowed to use springs - you could come up with a mechasim that is spring loaded - once you hook on the enegry is release and up we go!

or how about retractable wheels! dont lift your bot, raise your feet :c)

Re: If you would "pull-up"...
 

I can confirm that the Van door motor do back drive. Actually, it would make sense that if these motors are used in real van doors, it is designed to be back-drivable so that whoever get trapped when the van door closes will not be crushed by the force.

So, if you are using the van door motor to lift your bot, you may want to design a locking mechanism. That is exactly what we did at 2000 when we used them to power a big arm that lift the robot body off the ground. Otherwise it will slip back down.

Re: If you would "pull-up"...
 

Fisher Price motors, I believe, can handle the task.

Re: If you would "pull-up"...
 

what we've got in the works for this year is a 2" bore pneumatic tube on a double solenoid. of course, its not neccisarily a motor, but it's what we're counting on.

Re: If you would "pull-up"...
 

About the Van Door Motors:
They can be back-driven. It has nothing to do with internal clutches, or anything else. (The drill motors, however have anti-backlash pins).

You can open the vand-door motors covers up by prying off about 6 or 7 plastic tabs. Inside you will see a big plastic gear connected to a work gear. Take a large (>8") vise-grip, and attach it to the output shaft. If you turn the wrench, you will see the plastic gear inside backdrive the work gear. The fact that the gear is plastic and liberally coated with grease may have something to do with it.

For those of you who have had the van-door motor stay: perhaps you had your victor's in brake mode, which prevents a motor from spinning when a neutral signal is received.

Also, believe it or not, the Fisher-Price motors are more powerful than the van door's. Check the specs.

Re: If you would "pull-up"...
 

You could use the Window Motor with a tape drive to push yourself up, but IIRC, the pushing force of the tape is only around 100lbs, so you would need a light robot. On the other hand, using the Window Motor with a tape to pull yourself up might not be a bad idea...

Re: If you would "pull-up"...
 

I bet pneumatics would be fastest.

We will probably use a van door/winch setup this year, though, as we have a design that makes getting the hook on the bar quite easy.

Re: If you would "pull-up"...
 

Tape measures ought to do nicely.

Re: If you would "pull-up"...
 

I don't want to reiterate the idea of pneumatics too much, but it seems like some are talking just about the new motor we have available this year and the rest aren't clear.

My thought with pneumatics is that you can easily put up a stiff arm 9' tall (10 from the floor, 9 from the platform) and then on the end of it have a nice wide pneumatic piston with a clasp/hook/whatever on it. You can activate the raising with a telescope or some simple lighter pneumatics - then you can lift up in an instant with the other one on the end. I think this might be a good approach for rookies since my experince is that pneumatics tend not to go wrong as often as the rest of the stuff.

Re: If you would "pull-up"...
 

We've trusted the CIMs for two years straight as drive motors, and they haven't let us down yet.

We're using a drill for getting ourselves off the ground, but that's all I'm saying right now :)