Johnson Electric is introducing a new brushed motor to FRC through FIRST choice round 2 and I thought I would do a little write up to give some detail so teams can make an informed choice if they want to consider. I will be supporting questions and feedback on this motor and I know FRC very well as I’ve been a mentor for almost 20 years. It was announced in an earlier FIRST blog but I’m sure largely overshadowed by the brush-less options being introduced. I too am excited to to see brush-less making its way into FRC although brushed motors still have a place in the medium to low power requirements and possibly for teams who don’t have large pocket books.
This motor is typically used in automotive applications to drive a lead screw for operating the tailgate in SUV’s. PLG stands for power lift Gate. Here are a few details to summarize…
- 2 stage planetary motor ~ 1.15" in diameter and 4" in length and ~1/2 lb.
- Gear reduction is 22.2:1
- Free speed is ~ 410RPM and stall torque is ~4.5Nm.
- 2 hall sensors are integrated in order to get output on motor direction, speed, and distance. There are 6 wires of which you really only need 2 (red and black) to operate. The 4 extra are for optional hall feedback.
Some initial thoughts for where this motor could be used…
- moving and indexing power cells inside the robot. Speed seems good for that.
- Since it’s light weight it’s a good motor to put on an end effector.
- Driving a lead screw for precise positioning of a mechanism (ie shooter positioning).
A link to the screen steps document can be found here. Trying to provide as much useful information as possible for mounting and interfacing. I’ll also include some videos to see actual speed and some application suggestions.
An adapter is being offered to covert the motor output to an FRC standard 1/2" hex. The adapter includes an 8mm hole if teams want to add a lead screw which is a typical size for many 3D printers and is readily available on Amazon. Suggest to drill and tap a set screw and grind a flat area to keep it locked.
I hope teams will consider this motor this year for their FirstChoice round 2 selections. I will do everything I can to make sure there is support if there are any issues and will monitor this forum often.