The acme screw jack uses an acme threaded screw that is typically self-locking, meaning it will hold its position without a brake. Ball screw jacks use ball screws to convert rotary motion to linear movement, and require 1/3 the horse power compared to a acme screw jacks. Due to the efficiency of the ball screw, brakes must be used to stop and hold the load screw in position. Brakes are also recommendefor use on any jacks if vibration is present.