Edited by Stephen Mraz

The TPM Series of ac servomotors from alpha gear drives Inc., Elk Grove Village, Ill. (alphagear.com), can handle highly dynamic moves and are half as long and weigh less than conventional servomotor gearheads. Ratios range from 21:1 to 91:1 and torques go from 15 to 425 Nm. Peak torque can be as high as 1,300 Nm. It works with most servocontrollers from leading manufacturers.

The unit is stiffer than most, thanks to a motor shaft that includes the pinion gear. The distance between the motor and pinion are also shorter. The resulting stiffness gives the gearmotor greater positioning accuracy and less than 1 arc-min of backlash. It is lubricated for life, UL listed, and needs no maintenance for the first 20,000 hr. It also has a multiturn absolute encoder, eliminating the need to return to home for referencing after a power loss or emergency stop.