Gear rack is a special gear whose teeth are distributed on the strip.
1. The basic concept:
The rack can be split into a spur gear rack and a helical gear rack, which are paired with a spur gear and a helical gear, respectively; the tooth account of the rack is certainly a straight line rather than an involute (planar for the tooth surface) , equivalent to the indexing circle radius can be infinite cylindrical gear.
2. The main features:
(1) Since the tooth profile of the rack is right, each point on the tooth profile gets the same pressure position and is equal to the inclination position of the 
tooth profile. This angle is named the tooth position and the standard value is 20°.
(2) The same pitch and modulus are provided on the straight lines parallel to the top line.
(3) A range parallel to the top type of the tooth and having a tooth thickness equal to the width of the tooth groove is called a dividing collection (middle line), which is a reference range for calculating the size of the rack.
3. The main parameters:
Groove width, high tooth suggestion, high root height, tooth elevation, tooth thickness, root radius, etc.
4. The choice of parameters:
(1) Whether the gear is beating, the entire tooth depth, the normal normal range, the tooth direction is qualified, the tooth pitch is poor, and the circumferential section error is out of tolerance.
(2) Whether the installation distance after the gears and racks are installed is suitable.
(3) The rack and gear meshing clearance ought to be 0.25* modulus.
(4) Whether the complete tooth depth, runout, and common normal type of the rack are qualified.
5. Processing methods:
Gear rack and pinion machining technique:
(1) hobbing
(2) gear shaping
(3) shaving
(4) grinding teeth
(5) molars
