What is a Screw Jack?

 

A screw jack is a device used to completely or partially lift a vehicle or other object off the ground. Depending on the size, these devices can be used to lift the corners of the vehicle or lift the vehicle a few feet into the air to allow the operator to access the underside of the vehicle. Screw jacks are found in many machine shops, auto repair facilities, and in the auto racing industry. Additionally, many vehicles have screw jacks included in the spare tire kit, which makes it easier for drivers to repair flat tires. Very large screw jack systems are even used to lift the house to repair or replace the foundation.

These devices are usually made of light steel, lead or stainless steel. It comes in two basic varieties: Caesar Jack and Worm Jack. Another type of jack design based on the hydraulic principle is mainly used in manufacturing and industrial facilities and does not work like a screw jack.

The scissor screw jack is the most basic model and is commonly used to repair flat tires. They have a scissor-shaped design operated by a large lead screw. The bottom of the jack lies on the ground and the top fits under the bodywork. Insert the screw in the centre of the scissor system and turn it clockwise to raise the jack and lift the car. After replacing the tires, lower the vehicle to the ground by turning the screw counterclockwise.

Worm jacks have a very large screw-shaped body. At the top is a lifting platform used to support vehicles, houses or other objects. When the jack is actuated in a ratchet motion, the lifting platform is raised to body level in the form of a screw. Worm jacks generally offer a higher level of precision and consistency than scissor jacks, and can also lift heavier loads. This device is also called "machine screw jack".

Scissor bolt jacks can only lift a relatively small amount of weight, but they offer a number of advantages. It is inexpensive and easy to use, so almost anyone can successfully lift a vehicle to change tires or perform minor repairs. It's also small and light enough to carry along with spare tires in your car trunk.