The square threads are named after their square geometry. In this paper selection of two different types of screw threads namely Square and Acme threads. The objectives of this paper is to critically analyze and compare between ACME and SQUARE threads from stress and strain perspective in order to improve the performance from safety and durability point of view for developments in the field of thread design. Improvement in Design of car jack is really important to make the tool more efficient and user friendly with high safety features.

The correct use of jacks can prevent the accidents and injuries. Every year near about 160 injuries are associated with car jacks. A car jack is an important device in vehicle to change flat tire in our journey. Many users are familiar with manually operated car jack which still included as standard equipment in cars. A power screw is designed to translate radial motion to linear motion. A screw jack is a device used to lift the vehicle above the ground level in order to ease repairs.

Acme threads autodesk inventor 2015