Harmonic Drive
Folder "Back-to-back" Differential Drive
Differential gear
"Back-to-back" gear arrangement
The transmission shown in this design example is used for phase adjustment in a folder connected to an offset printing machine. With this design phase adjustment may take place either when the machine is idle or when it is running. This presents a significant advantage over some other methods of phase adjustment which can only be employed when the machine is at a standstill.
A further advantage of this design is the capability for bi-directional phase adjustment through 360° in either direction. Power is transmitted to the adjustment drive from the main power shaft via spur gears. In this design example two HDUF flat-type gears are combined in a "back-to-back" or "tandem" arrangement. To counteract the internal ratio of the Harmonic Drive gears, the two Dynamic Splines are combined. The Wave Generator of one gear is fixed, while the other is used as trim input.
The result is that when the trim input does not rotate, the Circular Splines of both gears rotate at the same speed. This configuration therefore gives equal primary input and output speeds. Precise phase control can then be achieved in both rotation directions via the trim input. This solution provides a very high power density and coaxial arrangement of input and output.
