Bevel gearboxes can be realized using bevel gears with straight, helical or spiral teeth. The axes of bevel gearboxes usually intersect at an angle of 90 degrees, whereby other angles are also basically possible. The direction of rotation of the drive shaft and the output shaft can be the same or opposing, depending on the installation situation of the bevel gears.
The simplest type of bevel gearbox has a bevel gear stage with straight or helical teeth. This type of gearing is cheaper to manufacture. However, since only small profile coverage can be realized with gearwheels with straight or helical teeth, this bevel gearbox runs quietly and has less transmittable torque than other bevel gear teeth. When bevel gearboxes are used in combination with planetary gearboxes, the bevel gear stage is usually realized with a ratio of 1:1 in order to maximize the transmittable torques.
Another version of bevel gearboxes results from the use of spiral gearing. Bevel gears with spiral teeth can be in the form of spiral bevel gears or hypoid bevel gears. Spiral bevel gears have a high degree of total coverage, but are already more expensive to manufacture than bevel gears with straight or helical teeth because of their design.
The advantage of spiral bevel gears is that both the quietness and the transmittable torque can be increased. High speeds are also possible with this type of gear teeth. Bevel gearing generates high axial and radial loads during operation, which can only be absorbed at one side because of the intersecting axes. Particularly when it is used as a rapidly rotating drive stage in multi-stage gearboxes, special attention must be paid to the service life of the bearing. Also, unlike worm gearboxes, self-locking cannot be realized in bevel gearboxes. When a right angle gearbox is needed, bevel gearboxes can be used as a low-cost alternative to hypoid gearboxes.
The advantages of bevel gearboxes:
- Ideal for limited installation space
- Compact design
- Can be combined with other types of gearbox
- Fast speeds when spiral bevel gears are used
- Lower cost
The disadvantages of bevel gearboxes:
- Complex design
- Lower efficiency level than planetary gearbox
- Lower torques in single-stage transmission ratio range