Quote:
Originally Posted by Clem1640
This is a harmonic drive, also known as strain wave gearing.
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No, harmonic/strain wave has all three gears concentric in the same plane, with a flexible intermediate gear, forming a single stage of reduction. This unit has none of those features:
- all of the pieces are nominally rigid
- the drive gear unit is not concentric with the two annular gears
- it is two stage - the input
utput gear ratio is the product of two stages (or it can be more physically viewed as the difference between the two ratios (for a<b, 1/a - 1/b = 1/ab, or if you swap a and b, you get -1/ab).
This drive can also be used to generate a rotation in the same direction as the input, or the opposite direction, by switching which of the two annular gears is fixed and which is rotating.