The duty cycle, the length of the screw, the magnitude of the load, and the efficiency of the screw jack unit all have a direct influence on the amount of heat generated within the screw jack. Since most of the power input is used to overcome friction, a large amount of heat is generated in the worm gear set in both ball screw and machine screw jacks, and in the lifting screw of machine screw jacks. Long lifts can cause serious overheating. High duty S-Series screw jacks have oil lubricated cubic gearbox housing specifically designed to dissipate heat more efficiently with increased surface area and mass, allowing increased duty capabilities.