In a running bearing, only a portion of the rollers are under load at the same time, and the area where these rollers are located is called the bearing's load zone. The load borne by the bearing and the size of the running clearance will affect the load zone. If the load zone is too small, the rollers are prone to slipping during actual operation.

For wind turbine gearboxes, if the main shaft is designed with a double-bearing support solution, then in theory only the torque is transmitted to the gearbox. In this case, after a simple force analysis, it is not difficult to find that the load borne by the planetary carrier support bearing is relatively small, so the bearing area of the bearing is often relatively small, and the roller is prone to slip. In the design of wind turbine gearboxes, the planet carrier support bearings generally use two single-row tapered bearings or two full-fill cylindrical bearings.

The load area can be increased by appropriately preloading the tapered roller bearing or reducing the clearance of the cylindrical roller bearing.