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Gears and sprockets are both splined wheels used in machinery, but gears are toothed wheels designed to mesh with other gears and transmit motion, while sprockets directly engage and move a flexible element. Gears are generally preferable in most scenarios, while sprockets are common in bicycles, conveyor belts, and film projection reels. Gears can use networks to build strength and accuracy, while sprockets need to work independently. If a tooth breaks off a gear, there is little likelihood that the machine itself will fail, while if a single tooth on one of the sprockets breaks off, it increases the chance that the chain will be thrown off.
The biggest difference between a pinion and a gear is how each works functionally. Both tend to be splined wheels used in machinery, and their basic appearance is often very similar, but how they work and what they do, exactly, tends to be very different. In general, a gear is a toothed wheel designed to mesh with other gears and transmit motion to them, which in turn can cause motion elsewhere. A sprocket, in contrast, is a sprocket designed to directly engage and move an indented or perforated flexible element, such as a chain or belt. Consequently, the applications of each are different. Sprockets are most common when a moving belt or chain is contained, as commonly found in bicycles, conveyor belts, and film projection reels. Gears are generally preferable in all other scenarios, cars and heavy machinery included. Not only are gears universally more useful, they’re also less likely to need repair or reassembly.
Basic functionality
Both cogs and gears are used to transmit power within machines or to move objects by interlocking. However, a cogwheel usually interacts directly with a part of the machinery in question, while gears can and often push against each other first, then use that collective motion to influence a larger mechanical process. Another way of expressing this is that sprockets need to work independently, but gears can use networks to build strength and accuracy. The difference is usually most noticeable when you look closely at the grooves or teeth of each.
In the case of a gear wheel, the teeth are constructed to fit precisely into the perforations or slots of the items the tool is designed to move. As a result, the possibilities for design variations tend to be somewhat limited. Gears, on the other hand, mesh directly with each other and thus lend themselves to a wide variety of applications. For example, the teeth of a gear might be on the outside of the wheel or on the inside circumference; another type, called a worm gear, is not a wheel at all but a threaded rod.
Impact of damage
Another important difference between a pinion and a gear is what happens if one of the two is damaged. The two sprockets that carry the chain on a bicycle, for example, also drive the chain in a straight line, and if a single tooth on one of the sprockets breaks off, it increases the chance that the chain will be thrown off. A broken chain will generally incapacitate the entire bike. If a tooth breaks off a gear, on the other hand, assuming the broken tooth falls out of the workings of the machine, there is little likelihood that the machine itself will fail as a result, even though it may experience a reduction in efficiency. In most cases, the load from the damaged gear can shift to another without causing much strain.
Common uses for sprockets
In addition to bicycles, sprockets are also commonly found on tracked vehicles such as tanks and bulldozers, and in movie cameras and movie projectors. In each, the rotation of the sprocket moves a flexible device, such as a chain, belt, or photographic film strip. Where the flex is a continuous ring, such as in bicycles and tracked vehicles, the many segments that make up the ring make it more vulnerable to wear. In some cases this requires more maintenance, and it also means that the sprockets are typically located on the outside of appliances, or at least behind relatively easily accessible panels.
Situations where gears are best
Gears are found in the internal workings of many if not most machines. They are an integral part of automobile engines, for example, where they work by transmitting power from the engine to the drive wheels. Some gear arrangements, such as worm drives, can limit power transmission to one direction without additional devices such as brakes. Precision gears also drive many watches.
The functional differences between a pinion and a gear combined with the overall superiority of the gear over the pinion usually lead designers to choose gears when they can. A commonly cited example is rear-wheel drive cars and trucks, which use a rigid drive shaft to transmit power from the engine to the driven wheels. Bicycle-type chain drives were popular with some early automotive vehicles, but their popularity waned with time; the last chain car was produced in the 1960s.
