Chief Delphi

Chief Delphi (http://www.chiefdelphi.com/forums/index.php)

- General Forum (http://www.chiefdelphi.com/forums/forumdisplay.php?f=16)

- - Winch (http://www.chiefdelphi.com/forums/showthread.php?t=23902)

I heard people talking about how the motors can be backdriven. This is just a quick easy way to keep the spool from backdriving. the pins on top of the spool have one flat side and the stop would basically act as a ratchet so you can spin one way but not the other. The brake would have to be hinged at the red part in the back.

Quote:

Originally Posted by mightywombat

As an offshoot of the winch idea and as a way to save weight I would suggest researching lightweight stronger than anything rope. Particularly the type used on sailboats that is designed to hold incredible loads. Check it out:
http://www.layline.com/llf/llpages/h...riga/page2.htm

Just an example:
1/8" diameter
.6 lbs/100 feet
2200 lbs break load

Just as another example, in case you want something that winds better than 1/8" stuff, Small parts has some pretty strong Spectra Cord. 0.060" Dia, 861 lbs tensile strength. Pretty nice stuff, I think.

1 word for cable material: 3/16" galvanized aircraft cable :) 2,500lbs test.

Question: can chippawas be back driven? I'm an ignorant fool about this kinda stuff but I'm wondering 'cause I think I have an idea.

Quote:

Originally Posted by psycho7

Question: can chippawas be back driven? I'm an ignorant fool about this kinda stuff but I'm wondering 'cause I think I have an idea.

In a word, yes. The Chip's can be backdriven, and it's not terribly hard to do so, especially when the power is off.

Clarification Post: Please do not follow-up on this

Quote:

Originally Posted by Jeremy_Mc

Quote 1:
I don't want to thrash, insult, or even knock the idea of a winch (trust me we would be using one...), but given the 10ft/s rule, how do you plan to address the case of missing the bar with your winch (I'm assuming you're throwing it or somethng of that nature)?

Quote:

Originally Posted by Gadget470

Quote 2:
Tytus made a good point that this is not the place to discuss methodology of attaching a winch to a surface. However, note: The bar is 9' from the platform and probably 5' from the average robot's winch "launch" point.
Vmax = 10 f/s
or
Vmax = 5 f / .5 s

I don't think it will be too much of a problem to "launch" a latch by a vertical means in over .5 seconds. Yes, I understand that a vertical launch is different from an arc'd launch, but you get the idea. 10 f/s is pretty darn fast.

Quote:

Originally Posted by Mike Norton

Quote 3:
I would not launch anything, I would use a arm to deploy the cable. then bring the arm back in.

Sorry I didn't clarify, my point about the Vmax was intended towards Jeremy_Mc's coment earlier in the thread.

i just tested whe vandoor motor with a 1.5" spool on it. with no power i just leand back with the cable in hand and iot was backdriving

Quote:

Originally Posted by Tytus Gerrish

i just tested whe vandoor motor with a 1.5" spool on it. with no power i just leand back with the cable in hand and iot was backdriving

When I started thinking about how I was going to pick up the robot this year, I also thaught winch, and at first I thaught van door motor, but yes, that darn backdriving thing killed that, So, I looked at some of the other motors in the kit, and I decided on using the globe motors, now each globe produces 150 in-lbs of torque, not too shabby, but cant have a side load, not a real big issue, as long as you have good bearings, and a tight assembly with little slop. it runs at about 100 rpm's no load, and that gets cut by a little more than half when there is this much load on it. now, you could get away with just one globe motor, and say a 2 inch dia. spool, would give you 150 lbs of lifting force, but it would be slow, you could increase the spool size, but then you loose force, again it would be slow, and one thing is, you don't want to sacrifice twenty seconds to just lifting the bot. so, like everything I've designed this year, im using two motors, and a drum, which will provide over 300 lbs of lifting force, and I can tell you it will take less than 5 seconds to live the robot two feet off the ground.

example:
torque(in-lbs)=force(lbs)*radius(in)
300in-lbs = 300lbs * 1in.

power(hp) = force(lbs) * radius(in) * rpm / 63025

If we know the hp rating of the globes, which we do, and it is just over .2hp, (.21hp), you can find out the rpms of the motor under a specific load.

yes, it really is that easy. but if you do use the globes, make sure whatever your turning is supported right, and with bearings, so that the motor dosnt see any side load, because no good can from that.

Globe motors are good for lifting the robot but we use it not on the winch but as a lifter to get over the 6" side. We use the globe as it came and gear that down to 12:1 we only needed to turn the last sprocket 1/4 turn. so it takes 1.8 second to lift our robot 8 inches off the ground

http://www.valleytech.k12.ma.us/robo..._24wheels2.JPG

The winch we are using the Tyco motors and gear them down to 200:1. we are making our own gearbox and putting both Tyco motors into them.

We go up at a rate of 18" per second. pretty fast with power. This way if we have to go from the carpet we should be there quickly.

it was kinda funny but dangerous at the same time last thurs, we were testing out winch w/ one of the guys standing on a platform he mounted to winch to, a combined weight of about 160lbs, a 500 pound test aircraft snapped like fishing line. Anyone else think we got jipped on 15' of cable?

We have designed a winch that is "attached" to one of the gear boxes. We will have then have a low (power) and high speed wench. I will post some pictures of it when we are done. I believe we are using stainless, boat cable. It's breaking point is at 1,200 lbs. We shall see if it all works in the next couple of days.

Shawn

All great ideas but what about using the drill motors for the winch?

We have a winch built using the Tiagene Motor. We tested it out and our robot hangs almost completely level. It works WONDERFULLY. It has about a 500 lifting capacity, but CAUTION to other teams using this motor as a winch: Despite the fact that the motor utilizes a worm gear and lead screw and cannot be technically backdriven the drive shaft can and does slip inside of the worm gear. The shaft is not keyed and does slip causing the motor to backdrive. We are not using cable as most other team have discussed since it has to be stacked by a special sliding guide. Instead we are using winch strap which work better than cable. It has a 27,000LB. breaking load and stacks itself.