Elevator Design Help

[GeeTwo]

Originally Posted by grem110

Thanks for all the advice! We will definitely reduce the diameter of the spool. I assume that keeping the worm gear for its anti-backdrive ability is a must? I ran some numbers and discovered that using an RS-775-18 with a 35:1 reduction would work pretty well--I may have forgotten to mention we have a block and tackle pulley system that acts as a 2:1 reduction, so the system would have an overall 70:1 reduction.

Also, how does amperage fit into all of this? Not sure how much amperage to give this motor when I still want to have the robot drive and grab the totes (grabber is motor driven).

Thanks so much for everyone's help.

Not necessarily on the worm gear. We have a spur gear system (AndyMark Toughbox Mini) driving through a reducing chain, powering two lift chains, actuating a sliding (not rolling) lift plate. Among all this, we have enough drag that four totes will hold their position without extra braking. Other options include active brakes (such as a bicycle, drum, or disc brake -- usually powered by pneumatics, but you can use a lead screw) and motor brakes (applying a bit of current, but you do need to be careful that your motor can handle it for a long period of time), and anti-backdrive clutch (e.g. an adaptation of Dewalt a drill clutch).


Current (amperage) is the real limiting factor when you get to the larger motors. FRC rules essentially mandate that no single motor can draw more than 40A continuous because otherwise you will trip a breaker. A CIM motor delivers its peak 12V power at about 70A and 2500 RPM. You can get away with this for a second or so, but if you sustain it, you lose all use of the motor until the breaker resets. If you do this with two or more motors at the same time, you'll trip the 120A main breaker, and your match is over.
Here's a link to some motor performance curves at 12V.

And of course, on behalf of everyone, you're welcome. Always glad to help out.