Nomenclature of Gears
BY MUHAMMAD ALIF BIN ALIMUDDIN
Pitch
The distance between a face of a tooth to the next
Measured on the reference line
Backlash or tooth clearance
Backlash must exist between gears, as it is essential to allow for thermal expansion lubrication
Bottom clearance or tip and root clearance
Diameter, addendum, dedendum, tooth:
Gear ratio
Gear ratio = number of teeth on DRIVEN gear(output) / number of teeth on DRIVER gear(input)
Gear trains
Have various arrangements of large and small gears in sequence
Idler gear
Used between two others gears, either to make an output gear rotate in the same direction as an input gear, or two link input output gear when there is a distance between them
Mechanical advantage of reduction and multiplication gear systems
Gears are used to gain mechanical advantage or to change the directional of movement. To gain a mechanical advantage when using gears, the number of teeth on either the drive gear or driven gear is varied. For example, if both the drive gear and the driven gear have the identical number of teeth, no mechanical advantage is gained. However, if a drive has 50 teeth and the driven gear has 100 teeth mechanical advantage of 2 is gained. In other words, the amount of power required to turn the drive is reduced by half.