Help - Can't figure out way to connect spool to webbing

[GeeTwo]

Originally Posted by Sperkowsky

We did not do any calculations we just found the motor/gearbox combo on our supply shelf and used it. We knew we needed a high gear ratio but thats about it.

I would be interested in doing calculations though. Less for us and more for the people we are demoing for... But... I don't know where to start.

It's just a matter of following the torque and speed through the gear ratio and wheel (or in this case spool) circumfrence. From the last page of the motor performance curves, you can see that at a 50A draw, a CIM generates about 130 oz-in of torque. You're gearing down by 27:1, so you get, in the frictionless case, 130 * 27 oz-in of torque. Your spool radius is pretty close to 1" (measure where the webbing contacts the layer inside), so you can get as much as 3510 oz, or 219 lb. In practice, you'll probably get about 80% of that, or 180#, which is enough to pick up a tall stack of totes briskly.

For top speed, use the "free speed" of the CIM, (page 1 of the curves document) which is 5310 rpm. Divide this speed by 27, and multiply by the circumference of the spool (because the speed was given in revolutions, we need a whole wrap). This gives a total (for a 1" radius spool) of 1236 inches per minute. Divide by 12 to get 103 feet per minute, and by 60 to get 1.7 fps. Again, using an 80% frictional factor gives 1.4 fps. Note that this is for an empty load! Your speed will be reduced somewhat when carrying a load. For a given load, you track the lift force back to a torque, and find the speed associated with that torque, and follow back through forward.