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Yaw bearing
The yaw bearing is the most crucial and cost intensive component of a yaw system found on modern horizontal axis wind turbines. The yaw bearing must cope with enormous static and dynamic loads and moments during the wind turbine operation, and provide smooth rotation characteristics for the orientation of the nacelle under all weather conditions. It has also to be corrosion and wear resistant and extremely long lasting. It should last for the service life of the wind turbine) while being cost effective.
Windmills of the 18th century began implementing rotatable nacelles to capture wind coming from different directions. The yaw systems of these "primitive" windmills were surprisingly similar to the ones on modern wind turbines. The nacelles rotated by means of wind driven yaw drives known as fantails, or by animal power, and were mounted on the windmill towers by means of an axial gliding bearing.
These gliding bearings consisted of multiple gliding blocks fixed on the windmill tower structure. These blocks maintained sliding contact with a gliding ring on the nacelle. The gliding blocks were wooden cube-like pieces with convex gliding surface covered with animal fat, or even lined with copper (or brass) sheet as a friction reduction means. These wooden blocks were fixed in wooden slots, carved in the wooden bearing substructure, by means of nails or wedges and were carefully leveled to create a flat surface where the nacelle gliding ring could glide. The gliding blocks, despite the lubrication would wear quite often and would have to be exchanged. This operation was relatively simple due to the wedge-based connection between substructure and gliding blocks. The gliding blocks were further locked via movable locking devices which, in a different form, remain as a technical solution in modern gliding yaw bearings.
The gliding ring of the windmill nacelle was made from multiple wooden parts and, despite the old construction techniques, was usually quite level, allowing the nacelle to rotate smoothly around the tower axis.
The hybrid yaw bearing system combines the solutions old windmills used. This system comprises multiple removable radial gliding pads in combination with an axial roller bearing.
The main categories of yaw bearings are:
The roller yaw bearing is a common technical yaw bearing solution followed by many wind turbine manufacturers as it offers low turning friction and smooth rotation of the nacelle. The low turning friction permits the implementation of slightly smaller yaw drives (compared to the gliding bearing solution), but on the other hand requires a yaw braking system.
Some manufacturers use a plurality of smaller yaw drives (usually six) to facilitate easy replacement. Such a configuration with plurality of yaw drives often offers the possibility of active yaw braking using differential torque from the yaw drives. In this case half of the yaw drives apply a small amount of torque for clockwise rotation and the other half apply torque in the opposite direction and then activate the internal magnetic brakes of the electric motor. In this way the pinion-gear rim backlash is eliminated and the nacelle is fixed in place.
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Yaw bearing AI simulator
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Yaw bearing
The yaw bearing is the most crucial and cost intensive component of a yaw system found on modern horizontal axis wind turbines. The yaw bearing must cope with enormous static and dynamic loads and moments during the wind turbine operation, and provide smooth rotation characteristics for the orientation of the nacelle under all weather conditions. It has also to be corrosion and wear resistant and extremely long lasting. It should last for the service life of the wind turbine) while being cost effective.
Windmills of the 18th century began implementing rotatable nacelles to capture wind coming from different directions. The yaw systems of these "primitive" windmills were surprisingly similar to the ones on modern wind turbines. The nacelles rotated by means of wind driven yaw drives known as fantails, or by animal power, and were mounted on the windmill towers by means of an axial gliding bearing.
These gliding bearings consisted of multiple gliding blocks fixed on the windmill tower structure. These blocks maintained sliding contact with a gliding ring on the nacelle. The gliding blocks were wooden cube-like pieces with convex gliding surface covered with animal fat, or even lined with copper (or brass) sheet as a friction reduction means. These wooden blocks were fixed in wooden slots, carved in the wooden bearing substructure, by means of nails or wedges and were carefully leveled to create a flat surface where the nacelle gliding ring could glide. The gliding blocks, despite the lubrication would wear quite often and would have to be exchanged. This operation was relatively simple due to the wedge-based connection between substructure and gliding blocks. The gliding blocks were further locked via movable locking devices which, in a different form, remain as a technical solution in modern gliding yaw bearings.
The gliding ring of the windmill nacelle was made from multiple wooden parts and, despite the old construction techniques, was usually quite level, allowing the nacelle to rotate smoothly around the tower axis.
The hybrid yaw bearing system combines the solutions old windmills used. This system comprises multiple removable radial gliding pads in combination with an axial roller bearing.
The main categories of yaw bearings are:
The roller yaw bearing is a common technical yaw bearing solution followed by many wind turbine manufacturers as it offers low turning friction and smooth rotation of the nacelle. The low turning friction permits the implementation of slightly smaller yaw drives (compared to the gliding bearing solution), but on the other hand requires a yaw braking system.
Some manufacturers use a plurality of smaller yaw drives (usually six) to facilitate easy replacement. Such a configuration with plurality of yaw drives often offers the possibility of active yaw braking using differential torque from the yaw drives. In this case half of the yaw drives apply a small amount of torque for clockwise rotation and the other half apply torque in the opposite direction and then activate the internal magnetic brakes of the electric motor. In this way the pinion-gear rim backlash is eliminated and the nacelle is fixed in place.