Victor Braking Feature

[Alan Anderson]

Originally Posted by tdlrali

...To prevent falling, you have to power the motor slightly "upwards"...

Be very careful when choosing this option. The motor will be stationary, and a stalled motor draws a lot of current. Some motors will be okay with that for a while (I think the window motor is one). Others will heat up quickly but should survive because they're massive, like the CIM minibike motor. But others will fry if they're powered for very long without spinning -- the scent of a smoking Globe motor is familiar to many.

The other options are to provide a mechanical brake or to use a gearing system that won't backdrive.

[KTorak]

I think the issue you are having is with motors backdriving. The window motors and the denso are the only motors I know of that do NOT backdrive. Other wise, you'll need constant current as described above.

[tdlrali]

The window motors and the denso are the only motors I know of that do NOT backdrive.

Basically, any worm drive will not be backdriveable

Another option, although this is almost never possible on robots, is a counterweight

[KTorak]

Originally Posted by tdlrali

Basically, any worm drive will not be backdriveable

I almost made that generalization, but I wasn't 100% sure. Thanks!

[Tristan Lall]

Originally Posted by KTorak

I almost made that generalization, but I wasn't 100% sure. Thanks!

In reality, you can backdrive some worm gears. It's a function of the lead angle and the efficiency (which is itself dependent on material, finish, lubrication, wear, etc.). If you want to really be sure, test it with an equivalent torque, and see what happens. Also consider that the gear may wear out over time, and can begin to behave differently.

You're on the right track, though; locking the mechanism with a worm gear is better than stalling your motor to hold it in place.