Machine Design 2

Module

The ratio of the pitch diameter to the no. of teeth.

Herringbone Gear

The other name of double helical gear.

Addendum Circle

The circle that bounds the outer ends of the gear teeth.

Contact Ratio

The ratio of arc of action to circular pitch

The average number of teeth in contact for mating gears.

The ratio of length of action to the base pitch

Face Width

The length of teeth in the axial direction (gear).

Dedendum

The radial distance from the pitch circle to the root circle (gear).

Whole Depth

Equal to the addendum plus the dedendum

Working Depth

The radial distance between the working- depth circle & the root circle

Idler Gear

The intermediate gear in a gear train arrangement

Flank

The surface of the tooth between the pitch & the root cylinders.

Clearance

The radial distance between the working- depth circle & the root circle.

Angle of Action

The angle through which the gear turns from the particular pair of teeth comes into contact until they go out of contact.

Base Pitch

The distance measured along the base circle from a point on one tooth to the corresponding point on the adjacent tooth.

Annular Gear

In internal spur gear, it is the bigger gear

Bevel Gear

Gears used to connect intersecting shafts, usually but not necessarily at 90 degrees

Helical Gear

Also called twisted spur gears

Sun & Planet Gears

It is used to change rotary motion to reciprocating motion

Chordal Thickness

Also called tooth thickness

Hypoid Gears

Gears used to transmit power between nonintersecting shafts, nearly always at right angles to each other.

Shaft

Rotating member transmitting power

Axle

Stationery member carrying rotating wheels, pulleys, etc.

Line Shaft

One driven by prime mover

Spindles

Short Shafts on Machine

Gib Head

Square or flat and tapered with a head.

Pin Key

May be either straight or tapered (taper of ¼ to 1/16 in/ft). It is usually a drive fit.

Roll Pin

One of several patented methods of keying, is driven or pressed into a hole that is small enough to close the slit, assembled in a radial direction.

Kennedy Keys

Keys that are tapered square keys, with or without gib heads and also called tangential keys

Woodruff Key

Key type that fits into a semicylindrical seat in the shaft,

It is widely used in the automotive and machine tool industries

Feather Key

Key that allows the hub to move along the shaft but prevents rotation on the shaft

Splined Shaft

Reversing torques and repeatedly applied torques are tough on connections