When do you need a left-handed screw?

Just like people,ball screws and lead screws can also be either right-handed or left-handed.But in screw terminology,handedness indicates the movement direction of the nut relative to the rotation direction of the screw.By far the most common version is the right-handed screw,which moves the nut towards you as the screw turns clockwise.But the left-handed version,which moves away from you,is useful in some cases.

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Screw handedness

For a right-handed screw,when the screw turns clockwise,the nut will move towards you.For a left-handed screw,the nut will be away from you when it turns clockwise.The popularity of right-handed power transmission screws stems from the dominance of right-handed fastening screws.Fastening screws are thought to be developed with right-handed threads - they tighten when rotated clockwise - and since most people are right-handed,their right hand is rotated clockwise,allowing them to apply more torque in this direction (tightening the fastener).To demonstrate the supination and its relationship to tightening,start by marking a fist with your right hand,like you are grasping something,with the back of your hand facing up and your thumb on the left side.Then turn your hand to the right and the direction for tightening a conventional right-handed fastening screw.

Screw handedness

While right-handed screws are the most common,some manufacturers offer left-handed screws.The application of the left-handed ball screw is limited,even though most manufacturers offer left-handed and right-handed dimensions and specifications.Lead screws,on the other hand,are commonly available in a variety of designs and sizes with both left and right hand options.So why should you use a left-handed lead or ball screw when you can use a conventional right-handed screw and just reverse the direction of the motor?A common reason is to drive two screws from a single motor -- usually through gears or other transmission components with dual output shafts.

Screw handedness

Screws with both left-hand and right-hand threads are useful in actuators that need to produce opposing motions.Some manufacturers even produce combination left-handed and right-handed screws,in some manufacturers even produce combination left-handed and right-handed screws,in which a single screw shaft has been machined with left-handed threads on one end and right-handed threads on the other end.Thus,when a motor drives the screw in one direction,the two nuts move towards each other.When the motor reverses direction,the nuts move away from each other.This design is especially useful in dual-motion linear actuators.

Dual-motion linear actuator

Some linear actuators include both left-handed and right-handed screws,welded or mechanically joined and driven by a single motor.Each end of the screw has a nut,so the loads move towards or away from each other as the screw rotates.