The difference between the space width and the tooth thickness along the pitch circle is _______.

Concept:

Backlash

• It is the difference between the space width and the tooth thickness along the pitch circle.
• Backlash = Space width - Tooth thickness

Additional Information

Addendum: 

• It is the radial distance between pitch circle and the addendum circle.
• The addendum is the height by which a tooth of a gear projects beyond (outside for external, or inside for internal) the standard pitch circle or pitch line.
• In the gear drive, Standard Addendum = 1 module
• But we know that, addendum (a) \(a=\frac{1}{DP}=\frac{CP}{\pi }=0.318~CP\)

Circular pitch: 

• It is the distance measured on the circumference of the pitch circle from a point of one tooth to the corresponding point on the next tooth. It is usually denoted by CP. Mathematically,

• Circular pitch, \(CP = \frac{{\pi d}}{T}\)

Diametral Pitch: 

• It is the ratio of the number of teeth to the pitch circle diameter in millimetres. It is denoted by DP. Mathematically,

• \(DP = \frac{T}{d}= \frac{\pi}{CP}\)

Dedendum:

• It is the radial distance between the pitch circle and the root circle.

Working depth: 

• This is the distance of engagement of two mating teeth and is equal to the sum of the addendums of the mating teeth of two gears.

Whole depth: 

• This is the height of a tooth and is equal to the addendum plus dedendum.

Face width: 

• This is the width of the gear and it is the distance from one end of a tooth to the other end.

Face of a tooth: 

• This is the surface of the tooth between the pitch circle and the outside circle.

Flank of tooth: 

• This is the surface of the tooth between the pitch circle and root circle.

Clearance: 

• This is the radial distance between the top land of a tooth and the bottom land of the mating tooth.