What is the meaning of pitch bearings?

pitch bearings, also known as blade bearings, are a component of modern wind turbines that connect the rotor hub and rotor blades. The bearings allow the required oscillations to control the load and power of the wind turbine. The pitch system brings the blades to the desired position by adjusting the aerodynamic angle of attack. Pitch systems are also used for emergency interruption of turbine systems.

• What are the design features of pitch bearings?

• What is the difference between yaw bearing and pitch bearing?

• What are the working characteristics of pitch bearings?

What are the design features of pitch bearings?

Most large rolling bearings are used as pitch bearings. Bearings withstand high bending moments, radial and axial loads in both directions. Therefore, the rolling elements of state-of-the-art wind turbines are ball bearings, which are used in double rows with four points of contact. This means that each raceway carries two points, and a total of four points. Other possible options are different arrangements of rolling elements or multi-row cylindrical roller bearings. The pitch bearings of modern wind turbines can be up to 4 meters in diameter.

Lubricants can only be changed with a lot of time and cost. Also, since the hub of the pitch bearing is constantly rotating, the used lubricant must be left in place. Therefore, pitch bearings in wind turbines are usually lubricated with grease. Bearings experience various operating conditions during operation. Therefore, the operating conditions of the grease are very difficult throughout the turbine time. The industrial greases used to date have very different compositions and do not always achieve the expected wear resistance.

What is the difference between yaw bearing and pitch bearing?

①The function of the pitch system is to adjust the pitch of the blades and change the angle of attack of the airflow to the blades when the wind speed is too high or too low, thereby changing the aerodynamic torque obtained by the wind turbine and keeping the power output stable. The yaw system mainly has two functions, one is to make the wind wheel track the wind direction; the other is to automatically untie the cable when the cable drawn out of the engine room is entangled due to the yaw.

②The yaw and pitch bearings have to bear a large overturning moment, and some of them are exposed, and are easily damaged by dust, water mist, freezing and other pollution. Therefore, surface anti-corrosion treatment that meets the entire service life should be carried out. Equally important is the sealing technology that prevents the leakage of grease inside the bearing and the intrusion of foreign impurities.

What are the working characteristics of pitch bearings?

The pitch bearing has to withstand the impact load generated by the uncertain wind force, and has the characteristics of intermittent operation, frequent start and stop, large transmission torque and high transmission ratio. Therefore, the yaw bearing requires a small clearance; compared with the yaw bearing, the pitch bearing bears a larger shock load and the vibration transmitted by the blade is also large, so zero clearance or small negative clearance is required to reduce Fretting wear on small rolling surfaces.

LYXQL Slewing Bearing Co., Ltd. has various pitch bearings that can provide the increasing of products, and make them more effective, reliable, and consistent.