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[IMTS Preview] Master-Slave Rack Combination Offers Zero Backlash

Aug. 31, 2010
Wittenstein supplies intelligent mechatronic drive technology, servo systems, and mechanical components. At IMTS it will show a new set-up for linear applications requiring zero backlash — the master slave combination of the alpha rack. This setup ...

Wittenstein supplies intelligent mechatronic drive technology, servo systems, and mechanical components. At IMTS it will show a new set-up for linear applications requiring zero backlash — the master slave combination of the alpha rack.

This setup consists of two pinions running on the same rack. A master pinion drives the mechanism as in a usual setup; meanwhile, a slave pinion can generate torque to apply an opposing force to the teeth that it engages. In this way, inertia and resistance remove backlash, even during load changes; system rigidity also increases and boosts control dynamics.

In more sophisticated rack-and-pinion sets, electronic preload is held to its maximum while the system is still. The master and slave pinions, both actively powered, push on rack teeth facing in opposite directions. Then, when the machine accelerates, the master pinion drives the machine forward, while the slave pinion eases off opposing force preload. When the system slows to a steady speed, the slave pinion comes to contact the tooth flank equivalent to the one engaged by the master pinion; then the two pinions drive in the same direction, while still preventing backlash.

Finally, when the system decelerates, the slave pinion returns to applying force on the opposing tooth flank to help slow the load.

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