Torque Control

Bit of a newby here...more of an amateur tinkerer:)

I am looking at basically making a propeller type device wherein the propeller (shaft remains still) will turn when I push it with my hands but only when force is applied. Once I let go - I'd like the propeller to stop turning. 1/4 Metal tubing for the shaft, just want to slide the prop on over the tubing. Are there bearings or bushings that will essentially only allow movement when force is applied? This is for a classroom so I appreciate the help!

Hi, we have a homework policy here that this would fall under, but it's almost christmas so I will give you a little hint. "Drag Clutch!" No, that is not a purse a ...... might take to a Prom dance. :)

Picture this -- a light spring over the shaft, a flat metal washer, a flat leather washer (Hardware store Plumbing) the back of the propeller. The strength (compression or wire diameter) of the spring will determine the load to prevent free-spinning.

[QUOTE=PinkertonD;4998]Hi, we have a homework policy here that this would fall under, but it's almost christmas so I will give you a little hint. "Drag Clutch!" No, that is not a purse a ...... might take to a Prom dance. :)

Picture this -- a light spring over the shaft, a flat metal washer, a flat leather washer (Hardware store Plumbing) the back of the propeller. The strength (compression or wire diameter) of the spring will determine the load to prevent free-spinning.[/QUOTE]


Haha! I appreciate the concern - but I AM the teacher :) Just failing at trying to demonstrate a point....I will look into this idea you've presented. Thanks!

What subject do you teach and specifically what is the point you are trying to demonstrate?

Might be surprised to know that its not physics.....I teach a couple classes on business and I am a soccer coach. Oddly enough, the device is for teaching a zone principle in soccer. Controlled movement, how one side reacts when another is pressured....love to build things and can usually figure most things out. This one stumped me and a friend of mine told me about this site. Love it!

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The strap material can be bought at and hardware store in the pumbing section. Normally used for hanging pipes (PVC, etc.).

A rubber band around the blade on the propeller and the shaft. Such that the rubber band drags on the shaft slowing the rotational movement. More rubber bands or smaller (tighter) rubber bands to adjust drag.

Why am I have such a fixation with "drag?" Might be time to see my therapist again. :D

You have to understand that the propeller itself will have some momentum which will cause it to continue rotating after the motivating force is removed. The only thing that will stop it is friction. So you have to control that friction. You want to create something that will rub on the hub of the propeller as it turns. If you can control the force that part exerts on the propeller hub you are controlling the friction. There are lots of ways to do that so maybe you are in the best position to figure out what way suits you best.

[QUOTE=PinkertonD;5007]A rubber band around the blade on the propeller and the shaft. Such that the rubber band drags on the shaft slowing the rotational movement. More rubber bands or smaller (tighter) rubber bands to adjust drag.

Why am I have such a fixation with "drag?" Might be time to see my therapist again. :D[/QUOTE]

Just an update...I have been goofing off with the spring and washer idea. I appreciate your help especially in this. Haven't dialed it in just yet but thanks!

Ryan