P27 Gearmotor

[stopyourself]

Hello,

My mentor told me to ask if this motor, the P27 Gearmotor with backshaft http://www.andymark.com/product-p/am-0915a.htm ran at similar speed/torque while running backwards. He could not find the information online, does anyone know?

[Knufire]

Within a margin of error, yes.

[GeeTwo]

Yes, both the motor and the gearbox are symmetrical. I can't think of any motors or gearboxes in common FRC usage that have a systematic bias. If they did, it would require some interesting gearing to use them in a skid-steer drive. In the normal configurations, driving forward requires the motors on the opposite sides to spin in opposite directions.

[Joe Ross]

Originally Posted by GeeTwo

Yes, both the motor and the gearbox are symmetrical. I can't think of any motors or gearboxes in common FRC usage that have a systematic bias. If they did, it would require some interesting gearing to use them in a skid-steer drive. In the normal configurations, driving forward requires the motors on the opposite sides to spin in opposite directions.

While I agree that current FRC motors do not have a bias, this wasn't the case at the turn of the century. By far the most common drive motor was from a drill, which did go faster clockwise. Given a little bit of time at the sticks, humans learn to compensate really well.

[timytamy]

Originally Posted by GeeTwo

Yes, both the motor and the gearbox are symmetrical. I can't think of any motors or gearboxes in common FRC usage that have a systematic bias.

The only non-symetric motor that I can think of are the window motor/snow blower/van door style motors. I can't visualize how the mechanics of it would change their characteristics in CW or CCW but I'd be curious to know if anyone has tested/has any data on this.

[PAR_WIG1350]

Originally Posted by timytamy

The only non-symetric motor that I can think of are the window motor/snow blower/van door style motors. I can't visualize how the mechanics of it would change their characteristics in CW or CCW but I'd be curious to know if anyone has tested/has any data on this.

In directionally biased motors, the angles at which the coils are switched on and off are optimized for one direction. this leads to degraded performance in the opposite direction. In unbiased motors, performance is degraded equally in both directions since it isn't optimised for either direction.

The drill motors used in most drivetrains prior to 2005 had a CCW bias when viewed from the the shaft end. This is because most drill bits are designed to cut in that direction. As a result, it was common to see the drive motors mounted on the inside of one side and the outside of the other. This allowed the motors on both sides to turn in the same direction (and thus provide similar amounts of power) while driving straight forward.