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 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 straight, each point in the tooth profile has the same pressure position and is add up to the inclination position of the tooth profile. This angle is called 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 line parallel to the top type 
of the tooth and having a tooth thickness add up to the width of the tooth groove is called a dividing range (middle line), which really is a reference collection for calculating how big is the rack.
3. The main parameters:
Groove width, high tooth tip, high root elevation, tooth height, tooth thickness, root radius, etc.
4. The choice of parameters:
(1) Whether the gear is beating, the full tooth depth, the normal normal collection, the tooth direction is qualified, the tooth pitch is poor, and the circumferential section mistake is out of tolerance.
(2) If the installation distance following the gears and racks are installed is suitable.
(3) The rack and gear meshing clearance ought to be 0.25* modulus.
(4) Whether the full tooth depth, runout, and common normal line of the rack are certified.
5. Processing methods:
Gear rack and pinion machining technique:
(1) hobbing
(2) gear shaping
(3) shaving
(4) grinding teeth
(5) molars
