Free screw jack efficiency calculator. Compute lead angle, friction angle, raising and lowering torque, mechanical advantage and self-locking condition for square, ACME and V-thread screws.
Screw jack efficiency is one of those Machine Design topics where the formula looks simple but has enough details to trip you up. You have the lead angle, the friction angle, the effective friction coefficient that changes with thread profile, and then the self-locking condition which depends on whether phi is greater than lambda. And it all changes depending on whether you use square, ACME or V-threads.
I wanted one place where I could select the thread type, put in geometry and friction and immediately see raising torque, lowering torque, efficiency and whether the screw is self-locking. This comes up in both GATE machine design questions and in actual jacking equipment sizing at work.