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yaw bearing. In order to achieve that, an adjustment mechanism is necessary, which enables the technicians to adjust the contact pressure of each individual gliding element in a controllable and secure way. The most common solution is the utilization of bottom bearing plates equipped with large opening, which accommodate the adjustable gliding bearing systems. These adjustable gliding bearings comprise a gliding unit (i.e. gliding pad) and an adjustable pressure distribution plate. In between the gliding pad and the pressure plate several spring (pre-tension) elements are located. The vertical position of the pressure plates is usually controlled by an adjustment screw. This adjustment screw presses against the pressure plate while being retained by a counter-pressure support plate, fixed on the bearing assembly with strong bolts. In this way it is possible to apply various levels of contact pressure among the different gliding pads and therefore to ensure that each gliding component of the yaw bearing arrangement is performing as anticipated.
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contain a number of gliding elements (radial or axial or a combination). These sub-elements can be individually removed and repaired, re-fit or replaced. In this way the yaw bearing can be serviced without the need of dis-assembly of the whole gliding yaw bearing (e.g., in case of a roller yaw bearing, dis-assembly of the whole wind turbine). This rep-arability offered by the segmented design of the gliding yaw bearing is one of the most important advantages of this system against the roller yaw bearing solution.
423:(often present in such high friction slow moving systems), lubrication is often introduced. This solution generally solves the gliding issues, but introduces more components to the systems and increases the general complication (e.g., difficult maintenance procedures for removal of used lubricant). Some wind turbine manufacturers now use self lubricating gliding elements instead of a central lubrication system. These gliding elements are manufactured from low friction materials or
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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
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When the wind turbine nacelle is positioned on the tower and the yaw bearing assembly is completed it is necessary to adjust the pressure on the individual gliding pads of the bearing. This is necessary in order to avoid un-even wear of the gliding pads and excessive loading on some sectors of the
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able to partially or fully lift the nacelle-rotor assembly while the gliding yaw bearing is still in place. In this way and by providing a small clearance between the gliding elements and the gliding disk, it is possible to exchange the sliding elements without dismantling the gliding yaw bearing.
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The only remaining issue is the replacement of the gliding elements of the gliding yaw bearing surface, which is not segmented. This is usually the top axial surface of the gliding bearing, which constantly supports the weight of the whole nacelle-rotor assembly. For the gliding elements of this
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of the wind turbine, it should be possible to replace worn out yaw bearing gliding elements or other components of the yaw system. To allow for replace-ability of worn out components, the yaw systems are designed in segments. Usually one or more gliding planes comprise several sub-elements that
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Principally, the simplest way to accomplish the yaw bearing tasks with gliding elements is with two gliding planes for the axial loads (top and bottom) and a radial gliding surface for the radial loads. Consequently, the gliding yaw bearing comprises three general surfaces covered with multiple
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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
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face of the disk, while the arrangement of the gliding pads and their exact number and location vary strongly among the existing designs. To assemble the gliding yaw bearings, their cages split in several segments that are assembled together during wind turbine installation or
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To solve this problem, yaw systems incorporate pre-tensioned gliding bearings. These bearings have gliding pads that are pressed via pressure elements against the gliding disk to stabilize the nacelle against undesirable movement. The pressure elements can be simple steel
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bearing, which serves as a rotatable connection of the wind turbine nacelle and the tower. Contrary to the old windmill concept, the modern yaw bearings support the nacelle also from the to thus restraining the nacelle from being rotated by the Y-axis due to the
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but do not allow individual adjustment of the axial and radial gliding elements. This function importantly minimizes the axial and radial "play" of the gliding bearing due to manufacturing tolerances as well as due to wear of the gliding pads during operation.
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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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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.
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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
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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.
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Gliding Yaw
Bearing: Dry or lubricated gliding bearing with plurality of axial and radial gliding pads being in friction contact with a large diameter steel disk, usually combined with the gear-rim as a single
386:) distributed around the three contact surfaces to provide a proper guiding system for the radial and axial movement with relatively low friction coefficient. Such systems are economical and very
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In all gliding bearings wear is an issue of concern, as well as lubrication. Conventional gliding yaw bearings incorporate gliding elements manufactured out of polymer plastics such as
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403:, etc. The use of pneumatic or hydraulic pre-tension elements allows active control of the yaw bearing pre-tension, which provides yaw brake function.
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combines the solutions old windmills used. This system comprises multiple removable radial gliding pads in combination with an axial roller bearing.
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induced by the upper half of the rotor sweep disk and the X-axis due to the torque of the drive train (i.e. rotor, shaft, generator, etc. ).
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of these "primitive" windmills were surprisingly similar to the ones on modern wind turbines. The nacelles rotated by means of wind driven
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and were carefully leveled to create a flat surface where the nacelle gliding ring could glide. The gliding blocks, despite the
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reduction means. These wooden blocks were fixed in wooden slots, carved in the wooden bearing substructure, by means of
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known as fantails, or by animal power, and were mounted on the windmill towers by means of an axial gliding bearing.
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Despite the fact that the gliding yaw bearings and their components are designed and constructed to last the
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Detailed view of a typical pre-tension system for an azimuth (yaw) gliding bearing of a modern wind turbine.
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during the wind turbine operation, and provide smooth rotation characteristics for the orientation of the
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Schematic representation of a historical hybrid yaw bearing with axial rollers and radial gliding pads.
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Schematic representation of a typical gliding yaw bearing configuration of a modern wind turbine.
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Schematic representation of a typical roller yaw bearing configuration of a modern wind turbine.
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teeth to form a gliding-disk/gear-rim. The teeth may be located at the inner or the outer
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gliding surface to be replaced, the nacelle-rotor assembly must be lifted by an external
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Schematic representation of a historical gliding pad and lock configuration next to...
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431:(Teflon)) that allow reliable operation of dry (non-lubricated) gliding yaw systems.
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The roller yaw bearing is a common technical yaw bearing solution followed by many
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In its simplest form, the gliding yaw bearing uses pads (usually made out of
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Schematic representation of the components of a modern gliding yaw bearing.
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a schematic of a similar configuration found on a modern wind turbine.
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gliding pads. These gliding pads come in sliding contact with a
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Wind Energy
Handbook, T. Burton , John Wiley & Sons, Ltd,
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resistant and extremely long lasting. It should last for the
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Wind Power Plants, R. Gasch and J. Twele, Solarpraxis,
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to capture wind coming from different directions. The
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is the most crucial and cost intensive component of a
46:. Unsourced material may be challenged and removed.
239:, or even lined with copper (or brass) sheet as a
185:of the 18th century began implementing rotatable
174:of the wind turbine) while being cost effective.
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162:under all weather conditions. It has also to be
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419:(PA). To reduce friction, wear, and avoid
283:The main categories of yaw bearings are:
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106:Learn how and when to remove this message
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556:Molenbouw, A. Sipman, Zutphen, 2002,
516:Molenbouw, A. Sipman, Zutphen, 2002,
345:The gliding yaw bearing is a combined
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366:disk, which is usually equipped with
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122:Schematic representation of the main
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291:bearing (usually four-point bearing)
130:is located between the wind turbine
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31:needs additional citations for
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401:hydraulic pre-tension elements
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903:Blade element momentum theory
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235:gliding surface covered with
893:2020s in wind power research
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913:Energy return on investment
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314:wind turbine manufacturers
287:Roller Yaw Bearing: Large
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970:Wind power forecasting
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614:Airborne wind energy
407:Wear and lubrication
40:improve this article
1035:Additional portals:
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676:Lists of wind farms
489:Wind turbine design
325:Gliding yaw bearing
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461:Bearing Adjustment
421:stick-slip effects
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38:Please help
33:verification
30:
372:cylindrical
253:lubrication
191:yaw systems
140:yaw bearing
96:August 2009
945:Laddermill
898:Betz's law
843:including
776:Yaw system
668:Wind farms
619:By country
606:Wind power
598:Wind power
495:References
484:Wind power
425:composites
237:animal fat
195:yaw drives
144:yaw system
134:and tower.
128:yaw system
66:newspapers
417:polyamide
415:(POM) or
183:Windmills
164:corrosion
1059:Category
1013:Category
886:Concepts
852:Goldwind
816:Software
769:Darrieus
764:Savonius
729:Floating
714:Airborne
656:panemone
651:Windmill
639:Turbines
634:Offshore
478:See also
384:polymers
289:diameter
241:friction
187:nacelles
1025:Commons
862:Senvion
839:GE Wind
834:Enercon
781:bearing
734:Nacelle
624:History
427:(e.t.g
397:springs
356:moments
295:element
178:History
160:nacelle
156:moments
132:nacelle
80:scholar
1044:Energy
877:Vestas
872:Suzlon
857:Nordex
744:QBlade
724:Design
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351:radial
249:wedges
233:convex
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749:Small
454:jacks
450:crane
364:steel
347:axial
279:Types
245:nails
152:loads
87:JSTOR
73:books
935:HVDC
923:grid
558:ISBN
548:ISBN
538:ISBN
518:ISBN
368:gear
349:and
263:The
168:wear
166:and
154:and
138:The
59:news
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247:or
42:by
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