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This is known as a right-handed (RH) thread, because it follows the right-hand grip rule. Threads oriented in the opposite direction are known as left-handed (LH). By common convention, right-handedness is the default handedness for screw threads. Therefore, most threaded parts and fasteners have right-handed threads.
Left-handed screw threads are also used in some other applications: Where the rotation of a shaft would cause a conventional right-handed nut to loosen rather than to tighten due to fretting induced precession. Examples include: The left hand pedal on a bicycle. [21] [23] The left-hand screw holding a circular saw blade or a bench grinder wheel on.
Chirality, however, is observer-independent: no matter how one looks at a right-hand screw thread, it remains different from a left-hand screw thread. Therefore, a symmetric object has sinistral and dextral directions arbitrarily defined by the position of the observer, while an asymmetric object that shows chirality may have sinistral and ...
Most screws are tightened by clockwise rotation, which is called a right-hand thread. [4] [5] Screws with a left-hand thread are used in exceptional cases, such as where the screw will be subject to counterclockwise torque, which would tend to loosen a right-hand screw. For this reason, the left-side pedal of a bicycle has a left-hand thread. [6]
To apply the right-hand rule, place one's loosely clenched right hand above the object with the thumb pointing in the direction one wants the screw, nut, bolt, or cap ultimately to move, and the curl of the fingers, from the palm to the tips, will indicate in which way one needs to turn the screw, nut, bolt or cap to achieve the desired result.
This can cause threaded parts to either tighten or loosen under a load, depending on the direction of rotation, typically with a force that can far exceed the typical torque of a wrench. For example, this is a common problem in bicycle pedals, thus on nearly all bikes built after the 1930s, the left-side pedal is equipped with left-hand ...
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Left Hand Brewing Company, a brewery located in Longmont, Colorado; Left-hand path and right-hand path, terms describing the two different/opposing belief systems; Left hand screw thread, screws threaded in the opposite direction of the more common right hand threads; LeftHand StoreVirtual, Hewlett-Packard storage products for computing, see HP ...