What or how are the micro metal motors stalling?

Robotics and electronics discussion Mechanical design and actuators
1

I have a 1:16 die cast bulldozer that I have converted to radio control. I am currently using two of the low power 250:1 micro metal motors. They seem to stall a bit too early. This happens as the dozer is pushing forward against a pile of dirt or whatever. I want the tracks on the machine to slip/slide a bit even when the dozer is trying to push forward.

So, when the motors stall, exactly how or what is happening? Is the armature just stopping, even while the current is being put thru it? Or, is there some slipping clutch function of the gear motor assembly?

My confusion come as I watch the motors it seems as they stall, they “give up” completely, until I momentarily go to reverse, then when I go back to forward they try again until they stall.

I have ordered three additional sets of motors in the low, medium and high power groups. All of them are the 298:1 ratio. I suspect one of the three will be about right.

The motors are driving a pinion, which turns a similar size pinion that is turning the drive wheel on the dozer, giving about a 1:1 ratio at the wheel/tracks. I am also happy with the rpm of my current motors, so I’ll see how the new motors work out. Still interested in learning more on how they are working.

A good answer might include some description of how or why the 1:1000 ratio motors might damage the gearbox?

Thanks! Sorry for the long post!

Jim

2

When those motors stall, the armature simply stops turning, even though they are drawing the maximum possible amount of current. You are asking for more power (or torque) than the motors can deliver.

3

Jim,

Thanks. So are the medium and high power version of the same motor can and gear ratio wound differently that give them different stall values?

Thanks for the info!

Jim

4

The higher power versions use thicker wire on the rotor windings, so the winding resistance is lower and consequently, they draw more current.

5

Hello, Jim.

To answer your question about the 1000:1 micro metal gearmotors, the point is that they are capable of generating more torque than the final gears in the gear train can handle, so you need to make sure the loads you subject them to are within the range of what the gears can tolerate.

In general, stalling a motor can be rough on it electrically and mechanically. We typically recommend using our motors with a load torque of no more than 20% to 30% of the stall torque to avoid damaging or significantly decreasing the life of the motor.

-Brandon