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Unread 16-09-2008, 09:20
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Re: 2 motors on 1 Andy Mark transmission

Quote:
Originally Posted by Japper View Post
During last year's competition I saw a few teams use 2 motors on 1 Andy Mark transmission and their bots were fast and a couple of them were only 2 wheel drive....

What is the benefit of using 2 motors on 1 Andy Mark transmission?
...
If you used this type of configuration on your robot last year, what was your rationale?

Thanks
The total current used on the drive train is roughly the same whether it's 2 motor or 4 motor. The difference is that with 4 motors, the current to each individual motor is half of a 2-motor drive train. This also means that each motor in a 4-motor drive train has half of the load that a 2-motor does. Upon viewing the motor curve graphs, you can see that at the lower load the motor has more torque and an overall higher efficiency.

In the end, 4 motors have the same maximum speed as 2 motors. However, 4 motors have much more acceleration and can take a beating whereas two motors have much shorter lifespans. The advantage of using only two motors is that you can use the 2 other CIMs somewhere else on your bot -- most commonly on elevators/telescopic arms.

This is all easy to see when using JVN's calculator. The biggest use of this spreadsheet I've found is to design a drive train that's capable of pushing someone while also having enough current leftover in the overall system to use other motors on the bot.
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