A reverse seal system

Abstract

The application discloses a reverse sealing system and relates to the technical field of sealing, which comprises a main sealing ring, an oil baffle and a supporting ring. The main sealing ring is installed on a main shaft and has a sealing part for abutting against an end cover. The sealing part is arranged in a direction inclined to a bearing. The sealing part can make oil liquid have a tendency to flow to the bearing, thereby reducing the probability of oil liquid leakage. The side of the main sealing ring away from the bearing is provided with the oil baffle. The oil baffle has a first oil storage groove for storing the oil liquid leaked from the main sealing ring. The supporting ring has a second oil storage groove. The sidewall of the first oil storage groove can guide the oil liquid into the second oil storage groove. Meanwhile, the supporting ring has an oil discharge hole. An oil discharge pipe is connected to the oil discharge hole to connect a circulating system, so that the oil liquid can be discharged into an oil collecting tank and then be injected into the bearing by an oil pump. While avoiding the oil liquid leakage, the reverse sealing system realizes the circulating lubrication of the oil liquid, improves the lubrication effect and prolongs the service life of a power generation equipment.

Description

Technical Field

[0001] This invention relates to the field of sealing technology, and in particular to a reverse sealing system. Background Technology

[0002] In mechanical equipment, the working quality of bearings directly affects the equipment's lifespan. The main environmental factors contributing to bearing damage include external impurities intruding or insufficient internal lubrication. Therefore, improving bearing sealing performance is crucial for extending their service life. Especially in the wind power industry, with the widespread adoption of integrated semi-direct-drive wind turbine generators, bearings commonly use thin oil lubrication, which has low viscosity and high fluidity, making it prone to leakage. Currently, main bearings in the wind power industry primarily rely on labyrinth seals, supplemented by packing and water seals. However, these sealing structures are prone to aging and wear after long-term exposure to harsh conditions such as wind, sand, temperature differences, and vibration, leading to thin oil leakage. This not only pollutes the environment and increases maintenance costs but may also cause poor lubrication or even bearing damage. Simultaneously, friction between the sealing lip and the bearing can easily trigger high-temperature alarms and bearing damage, further threatening operational safety. Therefore, developing a highly efficient and reliable bearing sealing system that combines external circulation and cooling effects is of significant application value in solving lubrication leakage, reducing frictional temperature rise, and improving bearing reliability. Summary of the Invention

[0003] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a reverse sealing system that can improve sealing and lubrication effects, and solve the problems of high temperature caused by friction in the sealing lip and bearing, as well as spindle wear.

[0004] According to an embodiment of the present invention, a reverse sealing system is installed in a power generation device, the power generation device including a main shaft, bearings, and a fixedly installed end cap, including: The main sealing ring, oil retainer ring, and support ring are provided. The main sealing ring is installed on the main shaft and located on one side of the bearing. The main sealing ring has a sealing part that abuts against the end cover. The sealing part is inclined towards the bearing. The oil retainer ring is installed on the main shaft and located on the side of the main sealing ring away from the bearing. The oil retainer ring has a first oil reservoir. The support ring is fixedly installed on the end cover. The support ring has a second oil reservoir. The first oil reservoir and the second oil reservoir are arranged opposite each other along the radial direction of the main shaft. At the same time, the support ring has an oil drain hole. The circulation system includes an oil collection tank and an oil pump. The oil collection tank is connected to an oil drain hole through an oil drain pipe to collect leaked oil. The oil pump can inject the oil in the oil collection tank into the bearing.

[0005] A reverse sealing system according to an embodiment of the present invention has at least the following beneficial effects: In this embodiment, a main sealing ring is installed on the main shaft. The main sealing ring has a sealing portion that abuts against the end cover. The sealing portion is inclined towards the bearing, which allows the oil to flow towards the bearing, reducing the probability of oil leakage. An oil retainer ring is provided on the side of the main sealing ring away from the bearing. The oil retainer ring has a first oil reservoir for storing oil leaking from the main sealing ring. A support ring has a second oil reservoir. The first and second oil reservoirs are arranged radially opposite each other along the main shaft. The sidewall of the first oil reservoir guides the oil into the second oil reservoir. At the same time, the support ring has an oil drain hole. By connecting an oil drain pipe to the oil drain hole and then to a circulation system, the oil can be drained into an oil collection tank and then re-injected into the bearing by an oil pump. This prevents oil leakage while achieving circulating lubrication, improving lubrication efficiency and extending the service life of the power generation equipment.

[0006] According to some embodiments of the present invention, the oil retainer ring has a guide edge that is inclined along the axial direction of the main shaft and extends in a direction away from both the main shaft and the bearing. The end of the guide edge has a hook that extends in a direction close to the bearing to guide the oil to fall into the second oil reservoir.

[0007] According to some embodiments of the present invention, the width of the second oil reservoir is greater than the width of the first oil reservoir along the axial direction of the main shaft, so as to ensure that the oil in the first oil reservoir can drip into the second oil reservoir.

[0008] According to some embodiments of the present invention, the bottom of the second oil reservoir has an inclined guide surface along the axial direction of the main shaft, and the guide surface extends in a direction away from the bearing and the main shaft to avoid oil accumulation on the side of the second oil reservoir near the main seal ring, and to allow the oil to fall smoothly into the drain hole.

[0009] According to some embodiments of the present invention, the oil baffle ring is composed of multiple first sub-components, and each of the two ends of the first sub-component is provided with a connecting step. The connecting steps of two adjacent first sub-components can be interlocked, which facilitates the installation and fixing of the oil baffle ring.

[0010] According to some embodiments of the present invention, the support ring is composed of a plurality of second sub-components, and each of the two ends of the second sub-component is provided with a positioning pin and a positioning hole, and the second sub-component can be inserted into the positioning hole of another adjacent second sub-component through its positioning pin to realize the installation of the support ring.

[0011] According to some embodiments of the present invention, the second sub-assembly has multiple hollowed-out portions on the side opposite to the main shaft, so that a rib is formed between two adjacent hollowed-out portions, which helps to reduce the use of materials.

[0012] According to some embodiments of the present invention, the end cap is provided with a chamfer on the side near the bearing. The chamfer can prevent oil from accumulating between the sealing part and the end cap, allowing the oil to flow to the bearing and ensuring good lubrication.

[0013] According to some embodiments of the present invention, the end cover is provided with a mounting groove on the side away from the bearing, and a washer is embedded in the mounting groove. The outer periphery of the washer abuts against the inner peripheral wall of the mounting groove and the side wall of the support ring, thereby preventing oil leakage from the end cover and the support ring.

[0014] According to some embodiments of the present invention, a dustproof ring is installed on the side of the support ring away from the bearing. The dustproof ring has a dustproof part that abuts against the outer peripheral wall of the spindle to prevent external dust from entering.

[0015] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 This is a schematic diagram of a reverse sealing system installed in a power generation device according to an embodiment of the present invention; Figure 2 for Figure 1 A magnified view of A in the middle; Figure 3 for Figure 1 A magnified view of B in the middle; Figure 4 This is a cross-sectional view of the end cap in an embodiment of the present invention; Figure 5 This is an isometric view of the first sub-component in an embodiment of the present invention; Figure 6 This is a first isometric view of the second sub-component in an embodiment of the present invention; Figure 7 This is a second isometric view of the second sub-component in an embodiment of the present invention; Figure 8 This is a cross-sectional view of the support ring and dustproof ring in an embodiment of the present invention; Figure 9 This is a cross-sectional view of the dustproof ring in an embodiment of the present invention.

[0017] Figure label: Power generation equipment 100; main shaft 101; end cover 102; chamfer 1021; generator 103; oil collection tank 104; main oil tank 105; mounting part 106; oil drain pipe 107; bearing 108; mounting groove 109; Main sealing ring 110; base 111; gasket 112; dustproof ring 113; dustproof part 114; sealing part 115; limiting platform 116; Oil baffle ring 120; first oil reservoir 121; guide edge 122; hook 123; first sub-assembly 124; connecting step 125; first connecting hole 126; Support ring 130; second oil reservoir 131; oil drain hole 132; guide surface 133; second sub-assembly 134; positioning pin 135; positioning hole 136; second connecting hole 137; hollow part 138; rib part 139; extension part 140; third connecting hole 141; slot 142; fourth connecting hole 143. Detailed Implementation

[0018] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0019] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0020] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0021] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0022] Reference Figures 1 to 3In an embodiment of the present invention, a reverse sealing system is installed in a power generation device 100, particularly a wind power generation device. The power generation device 100 includes a main shaft 101, a bearing 108, a generator 103, and an end cover 102 fixedly installed on the generator 103. The main shaft 101 is pivotally connected to the generator 103. The bearing 108 is located on the outer periphery of the main shaft 101 and installed in the generator 103. The end cover 102 is wrapped around the outer periphery of the main shaft 101. A main sealing ring 110, an oil retaining ring 120, and a support ring 130 are provided between the main shaft 101 and the end cover 102. The main sealing ring 110 is installed on the main shaft 101 and located on one side of the bearing 108. The main sealing ring 110 includes a base 111 and a sealing portion 115 that abuts against the end cover 102. The sealing portion 115 extends from the base 111 toward the end cover 102 and is inclined toward the bearing 108.

[0023] In some embodiments, one sealing portion 115 is provided. In this embodiment, it is preferable to provide multiple sealing portions 115, which are arranged at intervals along the axial direction (hereinafter referred to as the axial direction) of the main shaft 101, which can further improve the sealing effect and reduce the probability of oil leakage from the bearing 108.

[0024] Understandably, the spindle 101 has a mounting portion 106 extending radially outward, and the base 111 is fixedly mounted in the mounting portion 106. By providing an inclined sealing portion 115, the oil tends to flow towards the bearing 108, further reducing the probability of oil leakage. Furthermore, the thickness of the sealing portion 115 gradually decreases from one end connected to the base 111 to the other end, ensuring sufficient sealing strength while effectively reducing the heat generated by friction.

[0025] In some embodiments, the main sealing ring 110 adopts a traditional rotary lip sealing ring (circular spring reverse lip cloth clamping oil seal, reverse lip leaf spring oil seal, etc.).

[0026] It is understood that the oil retainer ring 120 is installed on the main shaft 101 and located on the side of the main seal ring 110 away from the bearing 108. The oil retainer ring 120 has a guide edge 122, which is inclined and extends along the axial direction of the main shaft 101. The guide edge 122 extends in the direction away from both the main shaft 101 and the bearing 108. At the same time, the guide edge 122 forms a first oil reservoir 121. The first oil reservoir 121 is used to store the oil leaking from the main seal ring 110, so as to prevent the oil from leaking to the outside of the power generation equipment 100 and thus reducing the oil volume.

[0027] It is understood that the end of the guide rail 122 has a hook 123, which extends towards the bearing 108, so that the side wall of the hook 123 near the bearing 108 and the side wall of the guide rail 122 near the bearing 108 are arranged in a V-shape. When the oil flows from the first oil reservoir 121 to the second oil reservoir 131, the hook 123 can guide the oil to fall into the second oil reservoir 131 and prevent the oil from flowing away from the bearing 108, thereby preventing the oil from overflowing.

[0028] In some embodiments, the oil baffle ring 120 is provided with a positioning structure protruding axially, and the main sealing ring 110 is provided with a recessed structure on the side near the oil baffle ring 120 that can be inserted into the positioning structure, which can further prevent the main sealing ring 110 from rotating around the main shaft 101. Furthermore, two to four positioning structures are arranged circumferentially along the main shaft 101.

[0029] Reference Figure 5 It is understandable that the oil baffle ring 120 adopts a split structure, consisting of multiple first sub-assemblies 124. Each of the first sub-assemblies 124 has connecting steps 125 at both ends. Within the same first sub-assembly 124, the connecting steps 125 at both ends are located on different sides, forming a Z-shape. This allows the connecting steps 125 of adjacent first sub-assemblies 124 to interlock, ensuring a secure connection and facilitating disassembly and maintenance. Furthermore, the connecting steps 125 have first connecting holes 126, through which bolts can pass and be screwed onto the mounting portion 106 of the spindle 101, away from the outer wall of the bearing 108, thus fixing the first sub-assembly 124 to the spindle 101 and achieving a fixed installation of the oil baffle ring 120.

[0030] Furthermore, the support ring 130 is fixedly installed on the end cap 102. The support ring 130 has a second oil reservoir 131. The first oil reservoir 121 and the second oil reservoir 131 are arranged radially opposite to each other along the main shaft 101, together forming a complete oil guiding channel. Along the axial direction of the main shaft 101, the width of the second oil reservoir 131 is greater than the width of the first oil reservoir 121, to ensure that the oil in the first oil reservoir 121 can drip into the second oil reservoir 131, avoiding oil leakage and reduction.

[0031] It is understandable that when oil seeps out from the main seal 110 and falls into the oil baffle ring 120 (such as...) Figure 3As shown, the first oil reservoir 121 can temporarily store oil. Due to the fluidity of the oil, it can flow downwards along the first oil reservoir 121 surrounding the main shaft 101 and eventually drip into the second oil reservoir 131 under the guidance of the guide edge 122. Since the width of the second oil reservoir 131 is greater than the width of the first oil reservoir 121, and the support ring 130 has an extension 140 extending towards the main shaft 101, which can cover the oil-blocking ring 120, the oil will not exceed the range of the second oil reservoir 131 of the support ring 130, thus ensuring that the oil will not leak out and can be recovered.

[0032] When oil seeps out from the main seal ring 110 and falls into the second oil reservoir 131 of the support ring 130 (e.g.) Figure 2 As shown in the figure, the bottom of the second oil storage tank 131 has an oil drain hole 132, from which oil can be discharged directly. Furthermore, a one-way valve (not shown in the figure) is provided in the oil drain hole 132 to prevent oil from flowing back into the support ring 130, thereby avoiding oil accumulation and overflow.

[0033] The system also includes a circulation system, comprising an oil collection tank 104 and an oil pump (not shown in the figure). The oil pump and its motor are located outside the oil collection tank 104. The oil collection tank 104 is connected to the oil drain hole 132 via an oil drain pipe 107 to collect leaked oil, thereby achieving oil recovery and preventing insufficient lubrication of the bearing 108 due to leakage. In some embodiments, a check valve is provided at the end of the oil drain pipe 107 connected to the oil collection tank 104 to prevent backflow of oil. It is understood that the circulation system also includes a main oil tank 105 and a monitoring device. When the collected oil reaches a set level (measured by a level gauge), the monitoring device will start the oil pump to re-inject the filtered and purified oil into the bearing 108 for lubrication, achieving the recycling of lubricating oil and ensuring continuous lubrication.

[0034] It is understood that the bottom of the second oil reservoir 131 has an inclined guide surface 133. Along the axial direction of the main shaft 101, the guide surface 133 extends in a direction away from the bearing 108 and the main shaft 101 to prevent oil from accumulating on the side of the second oil reservoir 131 near the main sealing ring 110, and to allow the oil to fall smoothly into the drain hole 132. This is beneficial to improving the circulation efficiency of the oil and can prevent the oil from accumulating in the second oil reservoir 131 to avoid oil overflow.

[0035] Reference Figure 6 and Figure 7The support ring 130 is composed of multiple second sub-assemblies 134. Each second sub-assembly 134 has a locating pin 135 and a locating hole 136 at both ends. The locating pin 135 protrudes outwards, allowing the second sub-assembly 134 to be inserted into the locating hole 136 of an adjacent second sub-assembly 134 via its locating pin 135, thus enabling the installation of the support ring 130. Furthermore, each second sub-assembly 134 has multiple second connecting holes 137. Bolts can pass through these second connecting holes 137 and be screwed onto the outer side wall of the end cap 102 away from the bearing 108, thus fixing the second sub-assembly 134 and achieving the fixed installation of the support ring 130.

[0036] In some embodiments, the support ring 130 is made of a single-piece metal casting, which avoids the risk of leakage at the interface from multiple sub-components. However, this makes the support ring 130 difficult to manufacture and difficult to install, which is not conducive to later maintenance.

[0037] In this embodiment, both the second sub-component 134 and the first sub-component 124 use PA+glass fiber material. PA material has a density that is 5-6 times lower than that of metal, which is beneficial for significantly reducing product weight and making it easier to install and maintain.

[0038] To reduce weight and save materials, the second sub-assembly 134 has multiple hollowed-out portions 138 on the side opposite to the main shaft 101, forming ribs 139 between adjacent hollowed-out portions 138. This significantly reduces material usage while ensuring structural strength, thereby saving costs.

[0039] It is understandable that the second sub-assembly 134 located below the main spindle 101 has at least two oil drain holes 132 (e.g., Figure 7 (as shown in the image) to ensure that the oil can be discharged smoothly.

[0040] Furthermore, multiple third connection holes 141 are provided at both ends of the second sub-component 134. The third connection holes 141 enable the two adjacent second sub-components 134 to be connected by pins or bolts, which is beneficial to achieve a tight connection between the two adjacent second sub-components 134, thereby improving the structural strength of the support ring 130 and improving the anti-leakage effect.

[0041] Reference Figure 8 A slot 142 is provided at the end of the extension 140 of the support ring 130 near the spindle 101. A dustproof ring 113 is installed in the slot 142 to prevent external dust from entering the sealing system. A dustproof part 114 is provided at the end of the dustproof ring 113, which maintains close contact with the surface of the spindle 101 to achieve the dustproof function. At the same time, the thickness of the dustproof part 114 gradually decreases along the direction near the spindle 101, ensuring dustproof effect while facilitating installation and reducing frictional resistance.

[0042] Reference Figure 9 The dustproof ring 113 has a limiting platform 116 on the side opposite to the bearing 101. The limiting platform 116 protrudes to increase the contact resistance between the dustproof ring 113 and the inner wall of the slot 142, ensuring its stability during equipment operation and preventing loosening or detachment due to vibration. Furthermore, the extension 140 of the support ring 130 has a fourth connecting hole 143. A bolt can be inserted into the fourth connecting hole 143, and the bolt can abut against the side wall of the dustproof ring 113, thereby improving the installation stability of the dustproof ring 113 and preventing loosening due to vibration. It is understood that the fourth connecting hole 143 is a threaded hole, allowing the bolt to be threaded into it.

[0043] Understandably, as the bolt passes through the first connecting hole 126 and is tightened onto the end cap 102, the support ring 130 moves toward the end cap 102 and the dustproof part 114 in the dustproof ring 113 is dragged on the outer wall of the spindle 101, thereby causing the dustproof part 114 to tilt away from the bearing 108, so as to prevent external dust from accumulating between the dustproof part 114 and the outer wall of the bearing 108, thereby preventing dust intrusion.

[0044] Reference Figure 2 and Figure 4 It is understood that the end cap 102 has a chamfer 1021 on the side near the bearing 108. The chamfer 1021 can effectively prevent oil from accumulating in the gap between the sealing part 115 and the end cap 102. At the same time, the outer side of the end cap 102 is provided with a special mounting groove 109, in which a washer 112 is installed. The washer 112 fits tightly with the side wall of the support ring 130 to form a reliable static seal structure, further preventing oil leakage. In this embodiment, the washer 112 is an O-ring.

[0045] The working process of the reverse sealing system can be divided into several key stages: First, the sealing stage, where the inclined sealing part 115 of the main sealing ring 110 guides the oil to the bearing 108, achieving a preliminary seal; second, the oil blocking stage, where any oil that may leak from the main sealing ring 110 is collected by the first oil reservoir 121 of the oil blocking ring 120; then, the oil draining stage, where the oil flows into the second oil reservoir 131 of the support ring 130 through the guiding structure, and finally enters the oil collection tank 104 through the oil drain hole 132; finally, the circulation stage, where the oil in the oil collection tank 104 is filtered and purified, and then re-injected into the bearing 108 lubrication system by the oil pump, completing the entire circulation process.

[0046] Compared to traditional labyrinth seals and packing seals, the reverse sealing system offers significant advantages. It provides better sealing, longer service life, and lower maintenance costs. Its advantages are particularly pronounced in applications using thin oil lubrication, effectively addressing the problem of thin oil leakage. The system's circulating lubrication design not only saves lubricating oil but also reduces environmental pollution. Simultaneously, the reverse sealing system provides a novel solution for the 108 bearing seal in equipment such as the 103 wind turbine generator set. Its innovative design concept and reliable performance make it widely applicable in new energy equipment, heavy machinery, and other fields. With continuous technological improvement and wider application, this reverse sealing system will make a significant contribution to improving equipment reliability and reducing operation and maintenance costs.

[0047] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A reverse sealing system installed in a power generation device, the power generation device comprising a main shaft, bearings, and a fixedly mounted end cap, characterized in that, include: The system comprises a main sealing ring, an oil retainer ring, and a support ring. The main sealing ring is mounted on the main shaft and located on one side of the bearing. The main sealing ring has a sealing portion that abuts against the end cover and is inclined towards the bearing. The oil retainer ring is mounted on the main shaft and located on the side of the main sealing ring away from the bearing. The oil retainer ring has a first oil reservoir. The support ring is fixedly mounted on the end cover and has a second oil reservoir. The first oil reservoir and the second oil reservoir are radially opposite to each other on the main shaft. The support ring also has an oil drain hole. The bottom of the second oil reservoir has an inclined guide surface that extends axially along the main shaft and in a direction away from both the bearing and the main shaft. The oil retainer ring has a guide edge that is inclined and extends axially along the main shaft and in a direction away from both the main shaft and the bearing. The end of the guide edge has a hook that extends towards the bearing. The circulation system includes an oil collection tank and an oil pump. The oil collection tank is connected to the oil drain hole through an oil drain pipe to collect leaked oil. The oil pump can inject the oil in the oil collection tank into the bearing.

2. The reverse sealing system according to claim 1, characterized in that, Along the axial direction of the main shaft, the width of the second oil reservoir is greater than the width of the first oil reservoir.

3. A reverse sealing system according to claim 1, characterized in that, The oil baffle ring is composed of multiple first sub-components. Each of the two ends of the first sub-component is provided with a connecting step, and the connecting steps of two adjacent first sub-components can be interlocked.

4. A reverse sealing system according to claim 1, characterized in that, The support ring is composed of multiple second sub-components. Each of the two ends of the second sub-component is provided with a positioning pin and a positioning hole. The second sub-component can be inserted into the positioning hole of another adjacent second sub-component through its positioning pin.

5. A reverse sealing system according to claim 4, characterized in that, The second sub-component has multiple hollowed-out sections on the side opposite to the main shaft, forming ribs between adjacent hollowed-out sections.

6. A reverse sealing system according to claim 1, characterized in that, The end cap has a chamfer on the side near the bearing, which can prevent oil from accumulating between the sealing part and the end cap.

7. A reverse sealing system according to claim 1, characterized in that, The end cover has a mounting groove on the side away from the bearing. A washer is embedded in the mounting groove. The outer periphery of the washer abuts against the inner peripheral wall of the mounting groove and the side wall of the support ring, thereby preventing oil leakage between the end cover and the support ring.

8. A reverse sealing system according to claim 1, characterized in that, A dustproof ring is installed on the side of the support ring away from the bearing, and the dustproof ring has a dustproof part that abuts against the outer peripheral wall of the spindle.

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