Anti-Backlash Screw Jacks Position Accurately

Position Accurately

Machine Screw jacks are used for positioning loads in numerous applications, however when the load direction alternates between tension and compression within the operating cycle and a high position accuracy must be maintained then a specific type of screw jack is required. The Anti-Backlash Screw Jack is recommended for such applications, as it is able to reduce the axial backlash between the lead screw and the trapezoidal screw thread in the gear to a practical minimum.

Axial backlash exists in standard screw jacks as the “gap” or “play” between the flanks of the lead screw thread and the internal thread on the worm gear nut. This “gap” or “play” is due not only to normal manufacturing tolerances, but to the fact that there must be some clearances to prevent binding and galling when the screw jack is operating under load. In most applications either the load direction is constant so axial backlash does not occur or the position error caused by the axial backlash is considered negligible for the application. However some applications require minimal or regulated axial backlash for accurate and repeatable positioning. Such an application is for positioning the rollers in steel straightening machines for tube, bar or sheet steel production.