Main features of the rack
(1) Since the tooth profile of the rack is straight, each point on the tooth profile has the same pressure angle and is equal to the inclination angle of the tooth profile. This angle is called the tooth angle and the standard value is 20°.
(2) The same pitch and modulus are available on any line parallel to the top line.
(3) A line parallel to the top line of the tooth and having a tooth thickness equal to the width of the tooth groove is called a dividing line (middle line), which is a reference line for calculating the size of the rack.