Andantex USA Premiers Preloaded Rack and Pinion Drive Systems

Preloaded rack and pinion drive systems introduced by Andantex USA Inc. (Wanamassa, NJ) are designed to eliminate axis backlash in drive applications requiring high-accuracy positioning such as CNC machine tools. This system effectively eliminates the backlash between the rack and pinion by using two pinions, one to drive the axis and one to preload the axis to eliminate the backlash.

Eliminating the system backlash preserves accurate axis positioning during the transition period between acceleration/steady state and deceleration, when the rack and pinion flank contact and the load reverses direction. To ensure that no backlash develops, the preload torque must be set higher than the deceleration torque. A preloaded drive system usually consists of a length of rack, two pinions and a reducer/motor drive system.

There are two different types of preloaded rack and pinion drive systems: mechanically preloaded and electrically preloaded. Mechanically preloaded systems achieve the preload by spring loading or torsionally winding one pinion against the other. These systems are typically driven by only one motor and do not require a special motor controller.

Electrically preloaded systems achieve the preload by electrically braking one pinion against the other. These systems require two motors/gearboxes, and usually a special motor controller to handle the preload.