Screw Jack Torque Screen

WHAT THIS SCREEN ANSWERS

Screw jacks combine high axial force with a compact rotary input, but torque and holding behavior depend heavily on geometry and friction. A lead change can alter both required input torque and the tendency to backdrive. This screen exposes those variables rather than treating a nominal jack capacity as proof that the mechanism will lift, hold, or lower as intended.

Enter axial load, screw lead, mean thread diameter, and a friction coefficient appropriate to the known thread, lubrication, and condition. MechPlane derives lead angle and friction angle, then applies a simplified square-thread raising relation. Real acme geometry, collars, bearings, gear reductions, and efficiency losses are not silently blended into a universal answer.

Friction is not a stable design constant. It can change with lubricant, surface finish, corrosion, contamination, wear, temperature, cycle frequency, and vibration. That uncertainty matters most when a design relies on a screw to resist backdriving. A screen can show that friction and lead angle are relevant. It cannot promise self-locking or safe load retention.

Use the result to compare concepts and identify when a brake or independent restraint must be considered. Confirm thread form, collar friction, gearbox efficiency, load path, buckling, mounting, duty, supplier limits, and any lifting or personnel-safety requirement with qualified review. The output is preliminary mechanical context, not approval of a lifting or holding system.