A screw jack has a screw thread, 7.5 cm mean diameter and 1.5 cm pitch. The load on the jack revolves with the screw. The coefficient of friction at the screw threads is 0.05. (1) Find the tangential force to be applied to the jack at 36 cm radius so as to lift a load of 600 N. (2) State whether the jack is self- locking. If it is, find the torque necessary to lower the load. If not, find the torque which must be applied to keep the load from descending.

A screw jack has a screw thread, 7.5 cm mean diameter and 1.5 cm pitch. The load on the jack revolves with the screw. The coefficient of friction at the screw threads is 0.05. (1) Find the tangential force to be applied to the jack at 36 cm radius so as to lift a load of 600 N. (2) State whether the jack is self- locking. If it is, find the torque necessary to lower the load. If not, find the torque which must be applied to keep the load from descending.

International Edition---engineering Mechanics: Statics, 4th Edition

4th Edition

ISBN:9781305501607

Author:Andrew Pytel And Jaan Kiusalaas

Publisher:Andrew Pytel And Jaan Kiusalaas

Chapter7: Dry Friction

Section: Chapter Questions

Problem 7.57P: The square-threaded screw with a pitch of 10 mm and a mean radius of 18 mm drives a gear that has a...

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