Anti-Backlash Machine Screw Jack
Anti-backlash Machine Screw Jacks are used wherever reversible load conditions require precision positioning control. Adjustable backlash Machine Screw Jack models are available to reduce backlash to approximately 0.003".
An Anti-backlash Machine Screw Jack allows the lash between the drive sleeve thread and the lifting screw thread to be controlled by adjusting the top cover of the jack. The anti-backlash jack design has an upper drive sleeve and a lower drive sleeve. Adjustment of the cover changes the relative distance between the drive sleeves. This change in distance compensates for any lash. Because the drive sleeve is split, the life of an Anti-backlash Machine Screw Jack will be less.
Anti-backlash Machine Screw Jacks minimize backlash, but should not be used to completely eliminate backlash. While it may be desirable to totally eliminate backlash, the result would be a lock-up of lifting shaft and drive sleeve.
Ball Screw Jacks can be factory adjusted to reduce backlash by selecting bearing ball size in the ball nut. This selective fit technique can be used to achieve a lash between the ball nut and ball screw of 0.003" - 0.005". Precision ball screws with preloaded ball nuts can be supplied to achieve zero lift shaft backlash.
In this steel press application (See Image Below), the inverted translating anti-backlash jacks set the roller height with precision control.