Pronunciation: [skɹˈuː d͡ʒˈak] (IPA) 
The spelling of "screw jack" follows the traditional pronunciations of each individual word. "Screw" is spelled as it sounds, with the "s" and "rew" sounds making up the entire word. "Jack" is also spelled phonetically with the "j" and "ack" sounds. In IPA, "screw" would be transcribed as /skru/, and "jack" as /dʒæk/. When combined, these two words create the compound word "screw jack", which is pronounced as /skru ʤæk/.
A screw jack is a mechanical device designed to provide a mechanical advantage in lifting heavy loads. It consists of a threaded screw mechanism, a handle or lever for rotating the screw, and a base or housing to support the load. The screw jack operates on a principle of converting rotational motion into linear motion, allowing for easy lifting or lowering of heavy objects.
The screw jack typically consists of a threaded screw shaft with a male thread and a matching female thread in the housing. The screw is turned using the handle or lever, which causes the screw to move linearly within the housing. As the screw moves, it engages with a load-bearing block or plate, causing it to rise or descend depending on the direction of rotation.
The mechanical advantage of a screw jack lies in the screw thread's pitch, which affects the distance the load moves vertically with each revolution of the handle. This allows for a relatively small amount of force applied to the handle to generate a larger force for lifting or lowering the load. Screw jacks are commonly used in automotive, construction, and industrial applications where heavy loads need to be raised or adjusted.
Overall, a screw jack is a simple yet effective device that uses a screw mechanism to convert rotational force into linear motion, providing a mechanical advantage for lifting heavy loads.
A contrivance for raising great weights through short lifts by means of a screw, or by a combination of toothed wheels.
Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874.
The word "screw jack" can be broken down into two parts: "screw" and "jack".
The term "screw" originated from the Old French word "escroe" in the 14th century, which referred to a cylindrical coil or twist. It further evolved from the Latin word "scrofa" meaning a sow’s corkscrew-shaped tail. Over time, the term "screw" began to be used to describe a device or mechanism with a helical structure, used for holding or fastening things together.
The word "jack" has its roots in Middle English, derived from the Old French word "jaque" which means a servant, specifically referring to a man-at-arms. By the 16th century, "jack" began to be used as a generic term for a mechanical device that could raise heavy objects.
