Gears are widely used, many different types. According to the tooth profile curve can be divided into the involute gear, cycloid gear, circular arc gear. According to the shape can be divided into cylindrical gear, bevel gear, non circular gear, worm - gear rack, etc.; in the tooth's surface can be divided into external gear and internal gear;tooth shape can be divided into straight gear, helical gear, herringbone gear, gear curve etc.

Note: the relevant parameters of gear

D: representation of a pointer gear tooth size, use words to explain the modulus ratio: pitch diameter and tooth number, unit usually (mm), modulus is usually used in the metric system, while in English, the same position in thepitch, the number of gear teeth and pitch to diameter ratio in the sense of value, is the reciprocal of the modulus.Unit (teeth per inch).

D: M = D / N size: Pd = N / D

Pitch: a theory of circle, a pair of engaged gears, the pitch will cross cut

Pitch diameter is the diameter of the pitch circle,: D

Pressure line: two gears in the contact, the contact surface is perpendicular to the direction of the load, usuallypositive pressure is passed along the line direction.

PA: this is the two pressure angle of gear pitch circle tangent line clip and pressure angle, the pressure angle of 14.5 degrees and 20 degrees, the 20 pressure angle, in order to prevent the interference situation.

Gears are used to illustrate:

Basic rack (Standard Rack): all the base circle size, profile, the tooth height, crown height and thickness and sizeare in line with standard spur gear rack specifications, in accordance with the standard gear rack cutting out thespecifications called basic rack.

Reference pitch (Standard Pitch Circle) is used to determine the size of base circle gear: each department. As thenumber of teeth x modulus

Standard pitch line (Standard Pitch Line): a particular section of line rack or measured along the line of the tooth thickness, as the pitch of 1/2.

Effect of pitch circle (Action Pitch Circle): a pair of spur gears in the occlusal function, each have a tangent rollingcircle.

Reference pitch (Standard Pitch): according to the selected standard pitch as benchmark, equal to the base rackpitch.

Pitch circle (Pitch Circle): occlusal contact two gear on the line of centers in the left gear track called the pitch circle.

Pitch diameter Pitch Diameter): the pitch circle diameter.

Full depth (Whole Depth): the crown height and root and.

Effective tooth height (Working Depth): a pair of spur gear tooth crown and high. Also called working tooth height.

The high (Addendum): the addendum circle and the circle radius of the poor.

Dedendum (Dedendum): the pitch circle and the bottom of the tooth circle radius difference.

Tooth thickness (Tooth Thickness): along the pitch circle measurement of tooth thickness.

Backlash (Backlash): two teeth bite, the tooth surface and the tooth surface gap.

Chi Kuan (Face Width): the thickness of the gear shaft diameter direction.

Tooth gap (Clearance): two teeth bite, a gear addendum circle gap between the bottom and other gear.

Node (Pitch Point): a pair of gear pitch circle and tangent points.

Base circle (Basic Circle): drawing the involute tooth profile as base circle.

Chi Genyuan (Dedendum Circle): the root circle.

Pitch (Pitch): the corresponding points between the adjacent two teeth arc distance.

Normal pitch (Normal Pitch): the same line of involute gear along a particular section of the measured pitch.