Rack machining

Definition: Flat or straight rods with a series of equidistant teeth.

The rack is also divided into straight rack and helical rack, which are used in pairs with straight and helical cylindrical gears respectively. The rack's tooth profile is straight rather than involute (plane for tooth surface), which corresponds to infinite cylindrical gear with indexing radius.

Main characteristics of rack

(1) Because the rack profile is straight line, all points on the tooth profile have the same pressure angle, which is equal to the inclination angle of the tooth profile. This angle is called the tooth angle, and the standard value is 20 degrees.

(2) Any straight line parallel to the top line has the same pitch and modulus.

(3) The straight line parallel to the top line of the tooth and the thickness of the tooth equals the width of the alveolar is called the indexing line (midline), which is the baseline for calculating the size of the rack.

Main parameters of rack

Wide alveolar width, high top, high root, high tooth height, tooth thickness, radius of root circle, etc.