Quote:
Originally Posted by Alex.Norton
No, it would be unwise to run two nippon-denso motors together because these motors use a worm gear. The worms would fight each other and eventually bind because they can't back drive each other.Even though they are the same type of motor does not mean that they will turn at exactly the same RPM.
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I think you are mixing up a few concepts here. First of all, it is a common misconception that you can not back drive a worm gear, this is false. With enough torque most well designed gearboxes (ones manufactured) can be back driven. The ability to hold position or lock of a thread (worm gear, or lead screw) is a factor of their pitch. It is possible to calculate the point in which the screw thread will lock and what it takes to overcome this. Now in worm drives within the FIRST community the drives typically have a very high gear ratio witch makes them almost impossible to back drive but none the less making broad statements isn't a good idea.
Now back to the question at hand. you are correct about motors moving different speeds in each direction. This has to do with the motor windings and the way that the internal brushes are designed. There are easy ways around this. you can tune your software to the motors by finding the difference in speed while changing the maximum signal given in each direction. You can use a feed back device on each motor with a closed loop system which will keep them going the same rate. Or mechanically you can make it so they are both moving in the same direction, utilizing an offset shaft and a coupling of some sort. The possibilities are really endless.
As for the application I
Would recommend using both motors of the same sort if you have to over 2 different motors geared together. Even if the speeds are different the offset is bound to be less then the closest ratio you can get through adapting another motor. Ideally if you could get away with using 1 motor you will save your self some issues in the long run but if you need to use 2, coupling the 2 motors together is a fine way of doing things.