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Robertson screwdrivers are easy to use one-handed, because the tapered socket tends to retain the screw, even if it is shaken. [3]: 85–86 They also allow the use of angled screwdrivers and trim-head screws. The socket-headed Robertson screws are self-centering and reduce cam out. They also stop a power tool when set, and can be more easily ...
Self-tapping screws can be divided into two classes: [3] those that displace material (especially plastic and thin metal sheets) without removing it, known as "thread-forming" self-tapping screws, and self-tappers with sharp cutting surfaces that remove the material as they are inserted, termed "thread-cutting" self-tapping screws.
The Acme thread was developed in 1894 as a profile well suited to power screws that has various advantages over the square thread, [note 1] which had been the form of choice until then. It is easier to cut with either single-point threading or die than the square thread is (because the latter's shape requires tool bit or die tooth geometry that ...
The screw pump is the oldest positive displacement pump. [1] The first records of a water screw, or screw pump, date back to Hellenistic Egypt before the 3rd century BC. [1] [3] The Egyptian screw, used to lift water from the Nile, was composed of tubes wound round a cylinder; as the entire unit rotates, water is lifted within the spiral tube to the higher elevation.
Large load capacity screw piles may have various components such as flat half helices, Bisalloy cutting tips and helices, cap plates or rebar interfaces for connection to various concrete or steel structures. Most industries use screw piling experts due to the cost efficiencies and, increasingly, the reduced environmental impact.
Animation showing the operation of a screw. As the screw shaft rotates, the nut moves linearly along the shaft. This is a type called a lead screw. A machine used in schools to demonstrate the action of a screw, from 1912. It consists of a threaded shaft through a threaded hole in a stationary mount.
A ball screw involves significantly more parts and surface interactions than many similar systems. While a basic lead screw is composed of only a solid shaft and a solid nut with simple mating geometries, a ball screw requires precisely-formed curved contours and multi-part assemblies to facilitate the action of the bearing balls.
The Dzus fasteners (gold coloured circular objects) fastening the cowling panels of the 1930s Hawker Hind. The Dzus fastener, also known as a turnlock fastener or quick-action panel fastener, [1] is a type of proprietary quarter-turn spiral cam lock fastener often used to secure skin panels on aircraft and other high-performance vehicles.