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A ratchet consists of a round gear or a linear rack with teeth, and a pivoting, spring-loaded finger called a pawl (or click, in clocks and watches [1] [2]) that engages the teeth. The teeth are uniform but are usually asymmetrical, with each tooth having a moderate slope on one edge and a much steeper slope on the other edge.
In watches, the "drive" wheel is the one that winds up the spring, and the Geneva wheel with four or five spokes and one closed slot prevents overwinding (and also complete unwinding) of the spring. This so-called Geneva stop or "Geneva stop work" was the invention of 17th or 18th century watchmakers.
First or great wheel attached and ratcheted to the main spring, or cable, barrel. The ratchet allows the main spring or cable barrel to be wound without turning the wheel. In horology jargon the pawl of the ratchet is called "the click". The first wheel turns the pinion of the center wheel. Center or second wheel which turns once
The simplest freewheel device consists of two saw-toothed, spring-loaded discs pressing against each other axially with the toothed sides together, like a ratchet but with the usual stationary part also rotating. Rotating in one direction, the saw teeth of the drive disc lock with the teeth of the driven disc, making it rotate at the same speed.
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Bicycle parts. List of bicycle parts by alphabetic order: Axle: as in the generic definition, a rod that serves to attach a wheel to a bicycle and provides support for bearings on which the wheel rotates. Also sometimes used to describe suspension components, for example a swing arm pivot axle
The BSA design had a splined freewheel unit (BSA part No.8-1913) which attached to the hub shell (BSA part No.8-701) and carried four sprockets. [3] Shimano made their first freehub in 1978 in both the Dura-Ace, and 600 (later known as Ultegra) models. It was a significant improvement.
Since the 1870s, in an improved version the pendulum drove a ratchet wheel via a pawl on the pendulum rod, and the ratchet wheel drove the rest of the clock train to indicate the time. The pendulum was not impelled on every swing or even at a set interval of time—it was only impelled when its arc of swing had decayed below a certain level.