Is using two default torque (V4) motors on opposite sides of a 8 motor drive and the rest high speed a good idea?


#1

I want to add some power to our 8 motor drive. Currently our drive has all high speeds and on a 5:3 gear ratio and I want add a default 393 motor to add some power is this a good idea?


To elaborate
#2

No, since the default motor will be spinning at 100 rpm, it’s spinning slower than the rest of the motors and thus it’ll probably make your drive skip or at best do nothing. High speeds plus 5:3 is a lot of speed, have you considered going to just high speeds? Even if you want to keep the speed, you should be able to run that ratio if your friction is low and your bot isn’t that heavy.


#3

Thanks for the feedback, I’ll keep all the high speeds and make sure to keep it light, my coach has been stubborn about our old base with 6 torque motors and one high speed on each side, he is certain that it works but I’m not sure how it’ll deal in the long run :confused:


#4

Since the torque motor will not be spinning at the same speed as the “speed” motors, it will just cause a drag on them and will NOT add any more power to the drive and most likely will have the opposite effect to what you are trying to accomplish.


#5

What needs to be understood here is the fundamental relationship between the base speed of a motor/geartrain combination and its torque output. As the speed increases, the torque decreases. It sounds like your coach wants to put one speed motor on each side to speed up the drive? You can’t do this directly without matching the speed of the existing motors.

Theoretically you could gear everything so the net speed output of the system would be the same across all 6 motors, but then what is the point?

Note - this is not changing the commanded speed, this is the base output speed. You can’t simply slow down the motor and get more torque.

Really… at this point, build it. What you lose - time. What you gain - lots of experience and learning of physical constraints and design tradeoffs. Then you will see the effects and what is being explained here will be obvious in front of you.


#6

My guess is your plan will only reduce your top speed without dramatically increasing your ability to push. It might be useful if the torque motor wheels connected to the parking platform at some critical moment in the climb – but generally, your plan would put your motors in conflict.

If you are already gearing your drive train 5:3, you could use one motor to slide an axle to reverse that gearing. If your goal is to have a drive that is both speed and torque, going from 5:3 to 3:5 will do so.

If you search this forum for transmissions, you will find examples of builds.


#7

No. Different speeds on the motors will cause stalling, especially if they are geared together.