Gear rack is a 
special gear whose teeth are distributed in the strip.
1. The basic concept:
The rack can be divided into a spur gear rack and a helical gear rack, which are paired with a spur gear and a helical gear, respectively; the tooth profile of the rack is definitely a straight line instead of an involute (planar for the tooth surface) , equal to the indexing circle radius is usually infinite cylindrical gear.
2. The main features:
(1) Since the tooth profile of the rack is direct, each point on the tooth profile has the same pressure position and is equal to the inclination position of the tooth profile. This angle is named the tooth position and the typical value is 20°.
(2) The same pitch and modulus are given on the direct lines parallel to the very best line.
(3) A collection parallel to the very best type of the tooth and having a tooth thickness equal to the width of the tooth groove is named a dividing series (middle line), which really is a reference line for calculating how big is the rack.
3. The main parameters:
Groove width, high tooth tip, high root height, tooth height, tooth thickness, root radius, etc.
4. The decision of parameters:
(1) Whether the gear is beating, the entire tooth depth, the normal normal line, the tooth direction is qualified, the tooth pitch is poor, and the circumferential section mistake has gone out of tolerance.
(2) If the installation distance following the gears and racks are installed is appropriate.
(3) The rack and gear meshing clearance should be 0.25* modulus.
(4) Whether the complete tooth depth, runout, and common normal line of the rack are certified.
5. Processing methods:
Gear rack and pinion machining method:
(1) hobbing
(2) gear shaping
(3) shaving
(4) grinding teeth
(5) molars
