Mechanically simple but highly innovative, it can satisfy many slowmoving, light-load applications, according to the parent company, Bishop-Wisecarver Corp., Pittsburg, Calif. (

The best drive and carriage fit into a slotted profile, effectively sealing the unit. It uses guide wheels as opposed to ball bearings because of their advantage in high-speed operation. When wheels run virtually friction-free on the inside surface of the profile, supporting the carriage plate and never needing lubrication. The PDU2 is rated for speeds to 6 m/sec, and the rated load, despite relatively small 60 3 51-mm cross section is 500 N.

Driveshafts can be configured left, right, or double. And a switch cam on the carriage plate can be rotated to change sides. The carriage plate accommodates mounting a second PDU2 unit, letting users quickly build a compact X-Y system. Other options include holding brakes, positioning encoders, and limit switches.