The variable pitch gear box is an important part of the fan variable pitch system, its main function is to increase the torque of the variable pitch motor on the variable pitch bearing, drive the blade to change the blade pitch Angle at different wind speeds, so that the blade is in the best state of absorbing wind energy, and can drive the blade feathering brake when the wind speed exceeds the cutting wind speed, so as to ensure the machine to run efficiently and smoothly.
The variable gear box transmission mechanism is composed of multiple planetary gear trains, usually 3 stages, and the planetary transmission form is NGW type.
Tapered roller bearings carry mainly radial-axial combined loads with the radial load as main one. The axial carrying capacity depends on the raceway angle of the outer rings, the bigger the angle is, the more the carrying capacity will be. This type of bearings belong to the type of separate ones, which are classified as single row, double row and multiple row tapered roller bearings as per the arrangement of the rolling bodies.
The single row tapered roller bearings can only carry the axial force of one direction. So two sets of bearings must be used together. Double row and four row bearings can carry radial-axial combined loads with the radial loads as main on and can carry axial load of two directions.
