Second, the planet gear bearings need to play an active part in Helical Gearbox torque transfer. Planetary systems split the torque input from sunlight gear amongst the planet gears, which transfer torque to a world carrier linked to the gearbox output. The bearings that support the planets on the carrier have to bear the full brunt of that torque transfer.
Or, in extreme cases, they could select angular contact or tapered roller bearings, both which are made to withstand axial loads.
In planetary gearboxes, however, it’s a lot more difficult to design around these axial forces for just two related reasons. Initial, there is typically hardly any area in a planetary gearbox to include the kind of bulky bearings that may tolerate high axial forces.
The presence of axial forces makes things completely different for the bearings that support helical gears. But it’s important to make a distinction between fixed-axis and planetary gearboxes. In fixed-axis gearboxes, the additional axial forces total little more than an inconvenience. Gearbox designers will most likely upsize the bearings to accommodate the additional forces.
Since they don’t need to withstand any axial forces, spur gear bearings play just a supporting part in the functioning of the gearbox. The bearings simply need to support the rotating equipment shafts, but they do not play an active part in torque transfer.
Helical Gears Place Higher Demand on Bearings