1. Pièce de métal en forme de tronc de cône taraudée en spirale sur le pourtour qu'on fait entrer dans le bois ou le métal (vis Parker) en tournant.
2. Vis sans fin : sorte d'hélice utilisée pour faire monter l'eau d'un puits, d'une rivière, élever du sable, etc.
Sinonimi: screw propeller
ETYM Old Eng. scrue, Old Fren. escroue, escroe, female screw, French écrou, Latin scrobis a ditch, trench, in Late Lat., the hole made by swine in rooting; cf. Dutch schroef a screw, German schraube, Icel. skrűfa.
1. A fastener with a tapered threaded shank and a slotted head.
2. A simple machine of the inclined-plane type consisting of a spirally threaded cylindrical rod that engages with a similarly threaded hole.
3. A device with several angled blades that rotates to push against water or air; SYN. screw propeller.
In construction, cylindrical or tapering piece of metal or plastic (or formerly wood) with a helical groove cut into it. Each turn of a screw moves it forward or backward by a distance equal to the pitch (the spacing between neighboring threads).
Its mechanical advantage equals 2 r/P, where P is the pitch and r is the radius of the thread. Thus the mechanical advantage of a tapering wood screw, for example, increases as it is rotated into the wood.
The thread is comparable to an inclined plane (wedge) wrapped around a cylinder or cone.