How Does a Winch Work?
 

I have searched far and wide for an answer to this question and I can not find it. Does a winch, more specifically a small electrical winch, use worm gears/spur gears/helical gears/other types of gears in order to lift the heavy loads that winches lift. Any information would be very helpful, How Stuff Works does not have any info, and that is usually where I fin dall the info I need. Thanks.

Aaron

Re: How Does a Winch Work?
 

Im really not sure about what gears they use but they generally have some method of locking the gearing in place. Usually they use a rachet to lock the gears and to ensure that the items do not fall down.

Re: How Does a Winch Work?
 

I believe they ratchet, with the motor usualy mounted parralel to the axis of the spool

Re: How Does a Winch Work?
 

In 2000 we had a "wench" on our robot to pull the bot off the ground while hanging on the bar. I have a really good picture of it but I cant find it. When I find it i'll post it.

Re: How Does a Winch Work?
 

What you are trying to think of is a Ratcheting Winch.

A winch itself is very simple, defined as "A stationary motor-driven or hand-powered machine used for hoisting or hauling, having a drum around which is wound a rope or chain attached to the load being moved."
In our case, a Stationary motor-driven machine used for hoisting, having a drum which is wound a rope or chain attached to the load being moved.

A very useful site for information on winches (and a few other things) is:
http://pergatory.mit.edu/2.007/hando...c.html#winches

It also has an excel file for calculating data about the winch using real values from the motor.

A ratcheting winch however is very slightly different. It has something to ratchet along the gears

Note the shape of the ratcheting gear. When turning clockwise, the gear pictured will lock into the two pieces that ratchet along the gear. when turning counter-clockwise, the two pieces will "jump" to the next tooth. This is a means for safety and preventing slipping.

The effect of this can however be replicated without a ratcheting gear. There is more than one way to lock a gear box.

Re: How Does a Winch Work?
 

The van door motor has a worm gear built onto it. The thing about worm gears is that they cannot be backdriven, so it will accomplish the same thing that a ratchet would . . . except you can reverse direction with it, which you could not do with a ratchet unless you had a servo-powered release mechanism.

I don't know the specs for the van door, but I would assume that it has enough torque after the worm gear transmission to directly power a winch that can lift 130lbs . . if the spool diameter is small enough, anyway.

I'll look into that.

Re: How Does a Telescoping arm work?
 

While we are on the topic of how things work… Does anyone know how telescoping arms work? I had seen last year team 890 had a telescoping arm but I can’t figure out how to get it to work. Please help me.
Drew Hopman
Team 801

Re: How Does a Telescoping arm work?
 

heh, you must have the same idea we do.

Ok, telescoping arms.

They are relatively simple, and this idea on making one is just something that hit me in the face while I was thinking about it. Call it intuition, or whatever. There are probably better methodes, but here goes:

You have the man (non moving) stage of you arm, right? you make the secondary (moving) stage of your arm capable of sliding up and down the main stage. Now, at the TOP of the main stage, attach a roller chain sprocket, a small nylon one with a built in bearing would probably be best on weight considerations. Now, run a chain (you can use really small chain for this) over the sprocket and anchor it at the BOTTOM of the secondary stage. Now, with the other end of the chain you can attach a motor, so the motor can real in the chain. As it does this, the secondary shaft is forced to slide up the main shaft, and you have a powered, telescoping arm. You can make the chain complete the loop if you want more control (I.E. you attach the secondary stage to one link in a continuos loop of chain . . that loop is your main stage.

You can expand this into a three stage arm if you add a sprocket at the top and bottom of the secondary shaft . . so the chain goes over the main shaft's top sprocket, under the secondary's bottom sprocket, over the secondary's top sprocket, and is anchored to the bottom of the third stage.

Another simple design I saw last year is using your elastic tubing to load your telescoping arm, and you could pull a locking pin out allowing the elastic tubing to extend the arm. You can't retract it, though.

Pneumatics could work for a short one, but I'm currently working on an inventor design of my chain one.

Re: How Does a Telescoping arm work?
 

If you come up with something in inventor i would liket to see it. Thanks for the help.
Drew Hopman

Re: How Does a Winch Work?
 

telescoping arms take a look at this.

We use a push pull system. this system is always under tension. we we 14' with this arm in 2001


http://www.valleytech.k12.ma.us/robo...1Robot2001.jpg

went down to 17"

http://www.valleytech.k12.ma.us/robo...Bridge2001.jpg

In 2000 we use a telescope system that will go in both direction with a lot of power this one went as high as 10'

http://www.valleytech.k12.ma.us/robo...s/roboti86.jpg


http://www.valleytech.k12.ma.us/robo...s/roboti87.jpg


with a system like this you only tighten one nut to put the whole system into tension. this might look big and heavy but this telescope was made with thin alum. and light rollers. this only wieghed 15 lbs just the telescope part


I will say we have something even better than this. :cool:

Re: How Does a Winch Work?
 

What did you use to tension this system?

Re: How Does a Winch Work?
 

The van door motor can be back driven unless the bearing screw (at the end of the worm gear) is tightened quite a bit. The problems with doing this are:
1) You lose power output by tightening it
2) It wears out and you have to keep tightening it to keep it from backdriving

Plus it might still back drive if it sees excessive force.

Re: How Does a Telescoping arm work?
 

I'm working on it. Maybe I'll have it finished in a day or two.

It will be pretty rudimentary, I'm relatively new to inventor.

Re: How Does a Winch Work?
 

25's made a 12' telescoping arm in 2000. I attached a picture. If you have any questions, PM me.

Re: How Does a Winch Work?
 

Do you have any more pictures or diagrams? My team is trying something similar this year, and any information would be helpful. Some of the doubters are still not quite seeing how the arm would work, and any concrete evidence would be useful.

Re: How Does a Winch Work?
 

go to http://www.valleytech.k12.ma.us/robo...photos2000.htm

there more there.

Re: How Does a Winch Work?
 

Also, if you're worried about keeping a motor from slipping (such as when the power gets cut at the end!) you could use a little pneumatic piston to lock something in place. If you were pulling in a cable on spindle like thing (i'm bad at the right names, forgive me) then on the side of that you could have ridges (think raised spokes) and then all you have to do is fire the piston into the side of the thing to lock the spindle in place. As long as you set up the pneumatics right, it won't move when the power gets cut.

Re: How Does a Winch Work?
 

Thank you.

Re: How Does a Winch Work?
 

Back on the subject of winches:

Planetary Gears are what gear down most winches for automotive purposes. (Warn Winches, etc.)

I'm working on getting some write-ups from some fellow Jeepers.

Stay Tuned.

Jeff

Re: How Does a Winch Work?
 

And when it wears out, no amount of tightening will do you any good.
During the summer of 2000, I did a study on the brakes. What they are exactly is a set screw (did someone inhale?) with a spring mounted 'brake pad' on the end. When you tighten it, you force the 'brake pad' onto the side of a plastic (final drive?) gear in the motor. This pad will eventually wear down and break. At that point, tightening it will do no good, as it is just a tapered end of a set screw with a hole in the middle against hard plastic. I have pictures somewhere of various van door motor brakes, but I can't seem to find them right now.

However, the bottom line is the brake should really only be used to get rid of very minor problems with backdrive. In '99, we used a van door as a winch motor to raise the lift carrying floppies over 8 feet and friction plus the brake kept the lift in the air without a hitch. In 2000 we tried to do the same thing, burning up brakes in the process on the motor that drove the shoulder of our arm. The final solution I came up with was to use a PD control system for the arm, so that 'sag' during a match didn't matter because the motor always ran to keep it in the right position, something it could do easily for 2+ minutes.

I would suggest something along the lines of what generalbrando said, and using a pin to stop the drum from rotating or perhaps some type of one-way action with a release like what rachet straps and come-alongs use.

Re: How Does a Winch Work?
 

There are many types of gears that drive different types of motors but the most popular for high torque winches is called a planetary gear. This type of gear is used on the bosch drill motor gear box. It allows for nearly a 500:1 reduction which surpaces any other type of gear box drastically. As far as Telescoping arms go...i dont want to give away of any of my teams secrets but think power car antenna.

Re: How Does a Winch Work?
 

correct me if I'm wrong, but arent all these spring loaded or pre tensioned systems that are released during the match illegal because that is considered another source of energy (not compressed air tank or battery)?

Re: How Does a Winch Work?
 

spring loading or pre-tensioned is ok this year (the rules for how much energy can be stored in your bot at the start have been backed off this year)

but if your arm is going to be used to go after the chinup bar, its tip cannot extend faster than 10 feet per second - so you cant just have some big piece of springy material that you release and it snaps out - you would have to dampen the rate at which its released somehow.

Re: How Does a Winch Work?
 

BTW - the telescoping stuff is off topic for this thread, but I have a really cool idea, so I will try to find an appropriate thread and post my incredible idea for it there. :c)