Gear bearings absorb axial and radial forces, as well as bending moments, which makes them a functionally critical and defining component. Properties such as precision, dynamics and load-bearing capacity are also defined by the specific bearing solution. Nabtesco cycloidal gears feature an integrated robust main bearing that allows them to absorb 250 % higher bending moments than conventional planetary gears of a comparable size.
Cycloidal gears with robust main bearing
Two angular ball bearings of identical size are used in a mirror-image arrangement. By design, the bearings in cycloidal gears have a much larger diameter than those in planetary gears. This provides plenty of space for numerous rolling elements. It’s a simple formula: the more rolling elements, the more powerful the bearing. An O-arrangement is used for adjustment, due to the higher allowable moment compared with an X-arrangement.
Angular ball bearings are especially effective in dynamic applications, due to the even load distribution on the rolling elements in variable bending moment situations during gear rotation. The result is minimal friction and wear. That guarantees not only optimal performance, but also a long service life.
The gearbox as a load-bearing machine element
The robust main bearing makes Nabtesco cycloidal gears a load-bearing element in the machine or robot. It eliminates the need for external bearings, which has definite advantages: reduced engineering expense, faster assembly and lower costs. Especially in applications where overall length is crucial, there is no alternative to the high load-bearing capacity of cycloidal gears, because the elimination of external bearings allows a shorter design. This is advantageous, for example, in pallet-loading applications, which can then use every centimetre in height for vertical stroke.
Incidentally: For robot manufacturers, the integrated main bearing is one of the main reasons for choosing Nabtesco cycloidal gears. The ability to absorb exceptionally high bending moments eliminates the need for extra bearing support of robot arms. This allows a more compact robot design with maximum precision, dynamics, load capacity and rigidity.
Main bearing without inner race
The main bearing is integrated in all standard cycloidal gears from Nabtesco. The RV-N, Neco® and Neco®HT series do not require an inner race. Instead, the inner bearing surface is ground. This results in a bearing with higher rigidity.
All bearings are assembled and preloaded by Nabtesco. The trick is to find the right balance between a rigid bearing and the lowest possible basic friction moment. This is facilitated by Nabtesco’s extensive expertise in the field of bearing technology, which has been developed and perfected over a period of several decades.
Benefits of a robust main bearing:
- Absorption of high bending moments
- Gearbox is a load-bearing machine element
- External bearings are not necessary
- More compact design
- Reduced engineering expense
- Faster assembly
- Lower costs