1. Types and characteristics of cylindrical gears

Spur gear

1) The two axes of the large and small gears are parallel to each other

2) During external meshing transmission, the rotation directions of the two gears are opposite; During internal meshing transmission, both gears rotate in the same direction

3) The tooth shape can be made into normal teeth, short teeth, and can be modified

4) The gear tooth length direction line is inclined to the gear axis by an angle

5) Meshing transmission is more stable and transmits greater force than straight cylindrical gear transmission

6) Difficulty in manufacturing spur gears Helical gears

Gear and rack

1) The gear that meshes with the rack can be a spur or helical gear and has the characteristics of a spur or helical gear

2) Rack and pinion transmission is to change rotation into linear movement or to change movement into rotation

3) The rack is formed when the gear diameter is infinite

2. Types and characteristics of bevel gears

Straight bevel gear

1) The two axes of the large and small gears intersect at the apex of the cone

2) When the pitch cone angle of the large gear is equal to 90 °, it becomes a planar generating gear; When it is greater than 90 °, it becomes an internal meshing bevel gear

Helical bevel gear

1) The tooth line is oblique, tangent to a circle, and does not intersect the cone top

2) The screw angles of the large and small gears are equal, but the directions are opposite

3) Smoother than straight bevel gear transmission

Spiral bevel gear

1) Smooth transmission, large transmission force, suitable for off speed transmission

2) The screw angles of the large and small gears are equal, but the directions are opposite

3) The axes of two gears intersect at the apex of the cone

4) Spiral bevel gears are further divided into circular arc teeth, extended epicycloid teeth, and quasi involute teeth

3. Types and Characteristics of Worms and Worm Gears

Archimedean worm

1) The tooth shape on the axial section of the worm is straight

2) Easy to manufacture

Linear worm

1) The tooth shape on the normal section of the worm screw is a straight line

2) The worm is the best made of the three types, and is the most common

Involute worm

The tooth shape on the plane parallel to the worm axis and tangent to the base cylinder is linear

Arc worm and worm gear

1) High efficiency, good oil film formation

2) Large bearing capacity

3) Complex manufacturing and assembly

4) Also known as spherical worm gear pair

5) The tooth type is further divided into the original type and the modified plow. The purpose of the modification is to facilitate the formation of an oil film in the transmission of the worm and worm gears