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- Oct 16, 2019
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Bill, I'm not sure fully understand what you mean.One major point that the discussion has (conveniently?) overlooked in the use of a small gear reduction motor such as a winshield wiper or electric window motor or a reduction drive from Amazon. A D-C motor is easily reversed. However, the motor cannot normally be overhauled in reverse.
In most cases of the automotive motors, the reduction is accomplished with a "worm" drive that is not reversible. The motor can be reversed, but the drive cannot be overhauled from a hand wheel or the like. The other type of reduction is with a "planetary" gear system. They can be overhauled but at a high cost. Basically a battery powered drill, there is no need to order a motor from Amazon, just locally acquire a used (even dead) battery drill and disassemble it.
If I were facing the particular situation described above, I think he is describing running the motor in reverse. That is easy, the exact method being a function of the method, not the motor. As also is speed control. On the other hand, using the handwheel manually and overhauling the motor is mostly out of the question. The D-C motor will require a lot of reduction to be truely functional, reducing or eliminating such overhauling. That eliminates most of the possibilities.
Were I doing the process, I would use a stepper with a reduction of, maximum, say 4:1. That would reduce the "poling" of a stepper to a usable level. While still allowing it, the stepper, to be overhauled. There would be resistance at the start, but once the leadscrew was moving it would be fairly easy to continue.
Looking at the problem from the view of industrial operation, possibly with complete automation, the use of a mechanically reduced "servo" motor makes plenty of sense. However, from the view of a hobbyist, there is still need for manual control on a (regular) basis.
I've lectured enough, you need to look into every angle of the problem.
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Are you saying that a wiper motor cannot be run in reverse?