Right angle gearboxes are characterized by the fact that the drive shaft and the output shaft are arranged at an angle of 90 degrees. Depending on the gearbox type, the axes can intersect in a plane or cross on two parallel planes, which results in an axis offset.
Right angle gearboxes are realized with different types of gear teeth or a combination of different gearing types. The most popular single-stage gearbox types are bevel and worm.
Because of the high single stage ratios and the low efficiency level, worm gears can achieve a self-locking effect. With worm gears it is also possible to have a hollow shaft as the drive shaft.
Bevel gearboxes come with different types of gearing. Bevel gearboxes with intersecting axes are realized using bevel gearing with straight, helical or spiral teeth. Hypoid gearboxes have helical bevel gearing with which the axes cross with an axis offset. The bandwidth of technically sensible ratios with which the bevel gear stage can be realized is bigger with hypoid gearboxes than with the classical bevel gear teeth.
Bevel gearboxes can also be combined with other gearbox types. A frequent application in this respect is the combination with a planetary gearbox, whereby the planetary gearbox can be connected upstream or downstream. This results in a wide range of overall multiplication factors and wide range of uses in many industrial applications.
The efficiency level of bevel gearboxes is typically lower than that of coaxial spur gearboxes, particularly in comparison to planetary gearboxes. This is because the bevel gear stage generates a high degree of axial force and radial force, which has to be absorbed by appropriate bearings. This increases the power loss, which is particularly notable in the drive stage of the gearbox.
The running noise and the transmittable torques of classic bevel gearboxes are also lower than with single spur gear teeth. Hypoid gearboxes, on the other hand, are extremely noisy and can transmit large amounts of torque, but a considerable amount of bearing load occurs in the bevel gear stage of these gearboxes.
In summarizing, a right angle gearbox is always used when the amount of installation space in the application is limited, or an angular arrangement between the drive and the output is required by the application. They are also used in cases where the input shaft needs to be hollow in order to lead through lines or use clamping sets.
The advantages of right angle gearboxes:
- Use when installation space is limited
- Compact design
- Can be combined with other types of gearbox
- Quiet and high degree of torque when using hypoid gearboxes
- Version with hollow shaft possible
The disadvantages of right angle gearboxes:
- Complex design
- Lower efficiency level than planetary gearbox
- Lower torques in single-stage ratio range