28-08-2017, 04:41 PM
A gear or gear is a rotating machine part having cut teeth, or gears, which engage with another gear to transmit torque. Geared devices can change the speed, torque, and direction of a power source. The gears almost always produce a change in torque, creating a mechanical advantage, through their gear ratio, and therefore can be considered a simple machine. The teeth of the two gear gears have the same shape. Two or more gear gears, working in a sequence, are called a gear train or a transmission. A gear can be engaged with a linear toothed part, called a rack, thus producing translation instead of rotation.
The gears in a transmission are analogous to the wheels in a cross system of belt pulleys. An advantage of the gears is that the teeth of a gear prevent slippage. When two gears engage, if one gear is larger than the other, a mechanical advantage occurs, with the rotational speeds and the pairs of the two gears differing in proportion to their diameters.
In transmissions with multiple gear ratios - such as bicycles, motorcycles and cars - the term "gear" as in "first gear" refers to a gear ratio rather than a real physical gear. The term describes similar devices, even when the transmission ratio is continuous rather than discrete, or when the device does not actually contain gears, such as in a continuously variable transmission.
The gears in a transmission are analogous to the wheels in a cross system of belt pulleys. An advantage of the gears is that the teeth of a gear prevent slippage. When two gears engage, if one gear is larger than the other, a mechanical advantage occurs, with the rotational speeds and the pairs of the two gears differing in proportion to their diameters.
In transmissions with multiple gear ratios - such as bicycles, motorcycles and cars - the term "gear" as in "first gear" refers to a gear ratio rather than a real physical gear. The term describes similar devices, even when the transmission ratio is continuous rather than discrete, or when the device does not actually contain gears, such as in a continuously variable transmission.