Gear

1) Gear
shaft
pinion
ToothProfile
teeth per minute: n*N
If a gear having N teeth rotates at n revolutions per minute, the product N*n has the dimension "teeth per minute". This product must be the same for both members of a mating pair.
the pitch point
helical gear
Helical gears have certain advantages; eg. when connecting paralle shafts they have a higher load-carrying than spur gears with the same tooth numbers and cut with the same cutter. Helical gears can be also be used to connect nonparalled ,non-intersecting shafts at any angle to one another. Ninety degrees is the most common angle at which such gears are used.
spur gear
A gear having tooth elements that are straight and paralle to its axis is known as a spur gear. A spur pair can be used to conect parallel shafts only. Paralle shafts, however, can also conected by gears of another type, and a spur gear can be mated with a gear of a dfferent type.
bevel gear
worm
Worm gears provide the simplest means of obtaining large ratios in a single pair. They are usually less efficient than parallel shaft gears, however, because of a additional sliding movement along the teeth. Because of ther similarity, the efficiency of a worm and gear denpends on the same factors as the efficiency of screw.
engagement
mate
bushing
V-Belt
Chain drive