Shaft head main oil pump for steam turbine

Abstract

The spindle head main oil pump comprises a pump shell and an impeller, the interior of the pump shell is hollow, a cavity is formed in the pump shell, and the pump shell is provided with an oil inlet and an oil outlet which communicate with the cavity; the impeller is rotatably arranged in the cavity, the rotating axis of the impeller extends in the front-back direction, and the outer peripheral walls of the front side and the rear side of the impeller are both sleeved with floating sealing pieces connected with the corresponding positions of the inner peripheral wall of the cavity in a sealed mode. The floating sealing piece comprises an outer sealing ring arranged on the peripheral wall of the impeller in a sleeving mode and an inner sealing ring located between the outer sealing ring and the impeller, the hardness of the inner sealing ring is smaller than that of the outer sealing ring, and a gap can be formed between the inner sealing ring and the outer sealing ring so that an oil film can be formed. The inner sealing ring and the outer sealing ring which are different in hardness are matched, so that the abrasion resistance and the service life of the floating sealing element can be improved; and when the impeller rotates at a high speed, the oil film can form a circle of dynamic pressure ring, so that the floating sealing element obtains a better sealing effect.

Description

Technical Field

[0001] The present application relates to the technical field of oil pumps, and in particular to a shaft head main oil pump for a steam turbine. Background Art

[0002] The shaft head main oil pump is the main oil pump of the turbine shaft head. It is mainly used to transport the lubricating oil in the turbine forced lubrication system and provide regulating and lubricating oil for the normal operation of the turbine unit.

[0003] In order to ensure the normal operation of the steam turbine, oil leakage needs to be avoided. Currently, sealing rings are usually set on the front and rear sides of the impeller. Although this improves the oil leakage situation to a certain extent, the sealing rings are easily worn out during long-term operation, affecting the sealing performance. Summary of the Invention

[0004] Based on this, it is necessary to provide a shaft head main oil pump for a steam turbine with improved wear resistance and sealing performance.

[0005] The present application provides a shaft head main oil pump for a steam turbine, comprising a pump casing and an impeller, wherein the interior of the pump casing is hollow to form a chamber, and the pump casing has an oil inlet and an oil outlet communicated with the chamber; the impeller is rotatably arranged in the chamber, and the rotation axis of the impeller extends along the front-to-back direction, and the outer peripheral walls at the front and rear ends of the impeller are both provided with floating seals that are sealed and connected to the corresponding positions of the inner peripheral wall of the chamber, and the floating seal comprises an outer sealing ring mounted on the outer peripheral wall of the impeller and an inner sealing ring located between the outer sealing ring and the impeller, the hardness of the inner sealing ring is less than that of the outer sealing ring, and a gap can be formed between the inner sealing ring and the outer sealing ring for forming an oil film.

[0006] In one embodiment, the inner sealing ring is a sealing body made of Babbitt alloy, the outer sealing ring is a sealing body made of cast steel, and the impeller is made of stainless steel.

[0007] In one embodiment, the material of the Babbitt alloy is a bearing bush.

[0008] In one embodiment, a flange is provided on the outer peripheral wall of the outer sealing ring, and an installation opening for inserting the flange is provided on the inner peripheral wall of the chamber at a position corresponding to the flange. Thus, the flange and the installation opening cooperate to achieve circumferential positioning of the outer sealing ring and the inner peripheral wall of the pump housing, thereby enabling the outer seal to be more easily assembled on the pump housing.

[0009] In one embodiment, the outer circumferential wall of the inner sealing ring is provided with a first protrusion, and the inner circumferential wall of the outer sealing ring is provided with a first recess that matches the first protrusion. Thus, the cooperation between the first protrusion and the first recess can achieve circumferential positioning of the inner and outer sealing rings.

[0010] In one embodiment, the outer sealing ring located on the front side is defined as a front sealing ring, and the inner sealing ring located on the front side is defined as a front sealing portion. The inner peripheral wall of the front sealing ring is provided with a second convex portion extending inward, the first concave portion is located behind the second convex portion, and the front end of the front sealing portion is against the second convex portion.

[0011] In one embodiment, the inner sealing ring located at the rear side is defined as a rear sealing portion, and the first protrusions are provided at both the front and rear ends of the rear sealing portion, and each of the first protrusions corresponds to one of the first recesses.

[0012] In one embodiment, the pump casing is provided with an installation channel for installing the pump shaft, the pump shaft is coaxially arranged with the impeller and connected to the impeller, and a floating oil retaining ring is sleeved between the outer peripheral wall of the pump shaft and the inner peripheral wall of the installation channel, the floating oil retaining ring includes an outer oil retaining ring sleeved on the periphery of the pump shaft and an inner oil retaining ring located between the pump shaft and the outer oil retaining ring, the material of the inner oil retaining ring is Babbitt alloy, and the material of the outer oil retaining ring is cast steel.

[0013] In this way, in the floating oil retaining ring, the outer oil retaining ring is made of cast steel, which improves the pressure resistance and wear resistance, while the inner oil retaining ring is made of Babbitt alloy. In the environment of lubricating oil, the inner oil retaining ring is soft, which increases the wear resistance. Therefore, the floating sealing ring improves the wear resistance and extends the service life through the combination of cast steel and Babbitt alloy.

[0014] In one embodiment, the outer oil retaining ring is installed on the peripheral wall of the installation channel through a connecting piece, a third protrusion is provided on the outer peripheral wall of the inner oil retaining ring, and a third recess adapted to the third protrusion is provided on the inner peripheral wall of the outer oil retaining ring.

[0015] In one embodiment, a gap is formed between the outer and inner oil slings to form an oil film. This oil film forms a dynamic pressure ring when the pump shaft rotates at high speed. This dynamic pressure ring seals the high-pressure and low-pressure areas of the main oil pump, thereby achieving a better sealing effect for the floating oil sling.

[0016] Compared to the prior art, the inner sealing ring of the floating seal in the shaft head main oil pump provided by this application contacts the impeller. The inner sealing ring has a lower hardness than the outer sealing ring. This results in better sealing performance and, in the presence of lubricating oil, higher wear resistance. The outer sealing ring, on the other hand, can withstand higher pressure and wear. Therefore, the use of inner and outer sealing rings of varying hardness improves the wear resistance and service life of the floating seal. Furthermore, an oil film forms in the gap between the inner and outer sealing rings. When the impeller rotates at high speed, this oil film forms a dynamic pressure ring, which seals the high-pressure and low-pressure areas in the main oil pump, thereby achieving a better sealing effect for the floating seal. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the following briefly introduces the drawings required for use in the embodiments or the conventional technology descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 A perspective view of a main oil pump of a shaft head according to an embodiment of the present application;

[0019] Figure 2 for Figure 1 Cross-sectional view along direction BB;

[0020] Figure 3 for Figure 2 A partial enlarged view of point I in the middle;

[0021] Figure 4 for Figure 2 A partial enlarged view of position II in the middle;

[0022] Figure 5 for Figure 1 Cross-sectional view along the AA direction.

[0023] Figure markings: 1. Pump casing; 10. Chamber; 101. Oil inlet channel; 102. Oil outlet channel; 103. Mounting port; 11. Pump cover; 12. Bottom casing; 13. Mounting channel; 131. Groove; 2. Impeller; 3. Floating seal; 31. Front sealing ring; 311. Second convex portion; 32. Front sealing portion; 33. Rear sealing ring; 34. Rear sealing portion; 351. Flange; 352. First convex portion; 353. First concave portion; 7. Pump shaft; 8. Floating oil retaining ring; 81. Outer oil retaining ring; 811. Protrusion; 812. Third concave portion; 82. Inner oil retaining ring; 821. Third convex portion; 91. Connector; 92. Bolt; 93. Gasket; 94. Spring washer. DETAILED DESCRIPTION

[0024] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0025] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it may be directly on the other component or there may also be a central component. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may be a central component at the same time. The terms "vertical", "horizontal", "up", "down", "left", "right", "side", "top", "bottom" and similar expressions used in the specification of this application are only used to describe the various example structural parts and elements of this application, but these terms are used here for the purpose of convenience of explanation and are determined based on the example orientations shown in the accompanying drawings, and do not represent the only implementation method. Since the embodiments disclosed in the application can be set in different directions, these terms indicating directions are only for illustration and should not be regarded as limitations. For example, "up" and "down" are not necessarily limited to directions opposite to or consistent with the direction of gravity.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0027] In this application, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it can mean that the first feature is directly in contact with the second feature, or the first feature and the second feature are indirectly in contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it can mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is higher in level than the second feature. When a first feature is "below," "below," or "below" a second feature, it can mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is lower in level than the second feature.

[0028] It should be noted that "axial arrangement" means that the overall arrangement direction is along the axial direction, including but not limited to axial extension, and may form an angle with the axial direction.

[0029] Unless otherwise defined, all technical and scientific terms used in the specification of this application have the same meaning as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in the specification of this application includes any and all combinations of one or more of the relevant listed items.

[0030] like Figures 1 to 5 As shown, the present application discloses a shaft head main oil pump for a steam turbine. The shaft head main oil pump is installed on the base of the steam turbine. The shaft head main oil pump comprises a pump casing 1 and an impeller 2. The interior of the pump casing 1 is hollow to form a chamber 10, and the pump casing 1 has an oil inlet channel 101 and an oil outlet channel 102 connected to the chamber 10. Figure 1 and Figure 2 As shown, the oil inlet channel 101 and the oil outlet channel 102 are both located at the bottom of the pump housing 1. Specifically, the pump housing 1 includes a pump cover 11 and a bottom housing 12 connected in sequence from top to bottom. The pump cover 11 and the bottom housing 12 are connected by bolts 92, and spring washers 94 are provided at the bolts 92. In this embodiment, there are multiple bolts 92, and they are arranged at intervals along the circumference of the pump cover 11. In addition, a gasket 93 is provided between the pump cover 11 and the bottom housing 12. The presence of the gasket 93 avoids a rigid connection between the pump cover 11 and the bottom housing 12. The above-mentioned oil inlet channel 101 and the oil outlet channel 102 are both located on the bottom housing 12.

[0031] like Figure 2 As shown, the impeller 2 is rotatably disposed within the chamber 10, with its rotational axis extending in the fore-aft direction. Floating seals 3 are sleeved around the outer circumferences at both the front and rear ends of the impeller 2, sealingly connected to corresponding locations on the inner circumference of the chamber 10. In this embodiment, two floating seals 3 are provided, spaced apart in the fore-aft direction.

[0032] The floating seal 3 comprises an outer sealing ring and an inner sealing ring. The outer sealing ring is sleeved onto the outer circumferential wall of the impeller 2, while the inner sealing ring is positioned between the outer sealing ring and the impeller 2. The inner sealing ring is in contact with the outer circumferential wall of the impeller 2, while the outer sealing ring is positioned close to the inner circumferential wall of the chamber 10. In this embodiment, the hardness of the inner sealing ring is lower than that of the outer sealing ring, and a gap is formed between the inner and outer sealing rings to form an oil film. In other words, the oil film is located between the inner and outer sealing rings.

[0033] It is understood that the inner seal ring of the floating seal 3, which contacts the impeller 2, has a lower hardness than the outer seal ring. This results in superior sealing performance and, in the presence of lubricating oil, high wear resistance. The outer seal ring, on the other hand, can withstand high pressure and wear. Therefore, the combination of inner and outer seal rings of varying hardness improves the wear resistance and service life of the floating seal 3. Furthermore, after the turbine's main oil pump stabilizes, an oil film forms between the inner and outer seal rings. This oil film, when the impeller 2 rotates at high speed, forms a dynamic pressure ring, which seals the high-pressure and low-pressure areas of the main oil pump, thereby achieving even better sealing for the floating seal 3.

[0034] In this embodiment, the inner sealing ring is a seal made of babbitt alloy, the outer sealing ring is a seal made of cast steel, and the impeller 2 is made of stainless steel. As will be appreciated, the stainless steel impeller 2 ensures its strength and a certain degree of hardness, thereby preventing the impeller 2 from breaking during operation and causing the steam turbine unit to stop operating, as would be the case with an aluminum alloy. Furthermore, this prevents the impeller 2 from being too hard and causing it to collide with the outer sealing ring, thereby extending the service life of the impeller 2 and ensuring operational reliability. The outer sealing ring is made of cast steel, which improves its compressive and wear resistance, while the inner sealing ring is made of babbitt alloy, which is softer in the presence of lubricating oil, thus increasing its wear resistance. Therefore, the combination of cast steel and babbitt alloy improves the wear resistance and service life of the floating sealing ring.

[0035] Specifically, the material of the Babbitt alloy is a bearing bush.

[0036] It should be noted that the compositions of the above-mentioned cast steel, stainless steel and babbitt alloy are the same as those in the prior art and will not be described in detail in this application.

[0037] In this embodiment, a flange 351 is protruding from the outer circumferential wall of the outer sealing ring, and an installation opening 103 for inserting the flange 351 is formed on the inner circumferential wall of the chamber 10 at a position corresponding to the flange 351. Thus, the cooperation between the flange 351 and the installation opening 103 can achieve circumferential positioning of the outer sealing ring and the inner circumferential wall of the pump housing 1, allowing the outer seal to be better assembled on the pump housing 1.

[0038] In one embodiment, the flange 351 may be an annular flange extending along the circumference of the outer sealing ring, or at least two flanges 351 may be formed on the outer peripheral wall of the outer sealing ring and spaced apart along the circumference of the outer sealing ring.

[0039] The flange 351 may be formed at a position close to the center of the outer peripheral wall of the outer sealing ring, or may be formed at a position off-center of the outer peripheral wall of the outer sealing ring.

[0040] like Figure 2 and Figure 3 As shown, a first convex portion 352 is provided on the outer circumferential wall of the inner sealing ring, and a first concave portion 353 is provided on the inner circumferential wall of the outer sealing ring to match the first convex portion 352. In this way, the circumferential positioning of the inner and outer sealing rings can be achieved through the cooperation of the first convex portion 352 and the first concave portion 353.

[0041] In one embodiment, the first protrusion 352 may be an annular protrusion extending along the circumference of the inner sealing ring, or at least two first protrusions 352 may be formed on the outer peripheral wall of the inner sealing ring and spaced apart along the circumference of the inner sealing ring.

[0042] In this embodiment, if Figure 2 and Figure 3 As shown, the outer sealing ring located on the front side is defined as a front sealing ring 31, and the front side of the inner peripheral wall of the front sealing ring 31 is provided with a second protrusion 311 extending inward, and the first recess 353 is located behind the second protrusion 311, and the inner sealing ring located on the front side is defined as a front sealing portion 32, and the front end of the front sealing portion 32 is against the second protrusion 311.

[0043] It can be understood that the presence of the second protrusion 311 limits the front sealing portion 32 from moving forward, further enabling the front sealing portion 32 to be more reliably constrained on the front sealing ring 31 .

[0044] In one embodiment, the second protrusion 311 may extend along the circumference of the front sealing ring 31 and be annular. Alternatively, at least two second protrusions 311 may be formed on the inner circumferential wall of the front sealing ring 31 and spaced apart along the circumference of the front sealing ring 31 .

[0045] Further, such as Figure 2 and Figure 3 As shown, the outer sealing ring at the rear side is defined as the rear sealing ring 33, and the inner sealing ring at the rear side is defined as the rear sealing portion 34. The rear sealing portion 34 has two first protrusions 352, which are spaced apart along the front-to-back direction. Each first protrusion 352 corresponds to a first recess 353, that is, two first recesses 353 are provided on the rear sealing ring 33. In this way, the rear sealing portion 34 can be more reliably constrained on the rear sealing ring 33.

[0046] The two first protrusions 352 may be located near the middle of the rear sealing portion 34 or at other positions. In this embodiment, the two first protrusions 352 are located at the front and rear ends of the rear sealing portion 34 respectively.

[0047] In addition, if Figure 2 and Figure 4As shown, the pump housing 1 is provided with a mounting channel 13 for mounting the pump shaft 7. The pump shaft 7 is coaxially arranged with the impeller 2 and connected to the impeller 2. A floating oil retaining ring 8 is sleeved between the outer peripheral wall of the pump shaft 7 and the inner peripheral wall of the mounting channel 13. The floating oil retaining ring 8 includes an outer oil retaining ring 81 sleeved on the outer periphery of the pump shaft 7 and an inner oil retaining ring 82 located between the pump shaft 7 and the outer oil retaining ring 81. The material of the inner oil retaining ring 82 is babbitt alloy, and the material of the outer oil retaining ring 81 is cast steel.

[0048] It can be understood that in the floating oil retaining ring 8, the outer oil retaining ring 81 is made of cast steel, which improves the pressure resistance and wear resistance, while the inner oil retaining ring 82 is made of Babbitt alloy. In the environment of lubricating oil, the inner oil retaining ring 82 is soft, which increases the wear resistance. Therefore, the floating sealing ring improves the wear resistance and extends the service life through the combination of cast steel and Babbitt alloy.

[0049] like Figure 2 As shown, a gap is formed between the outer oil slinger 81 and the inner oil slinger 82 to form an oil film. As a result, when the pump shaft 7 rotates at high speed, the oil film forms a circle of dynamic pressure ring, which seals the high-pressure and low-pressure areas in the main oil pump, thereby achieving a better sealing effect for the floating oil slinger.

[0050] In this embodiment, if Figure 2 and Figure 3 As shown, the outer oil retaining ring 81 is mounted on the peripheral wall of the mounting channel 13 via a connector 91. Specifically, an outwardly extending protrusion 811 is formed on the outer peripheral wall of the outer oil retaining ring 81. The inner peripheral wall of the mounting channel 13 has a groove 131 corresponding to the protrusion 811, and the connector 91 is disposed on the protrusion 811 and connected to the corresponding groove wall of the groove 131. In this way, the outer oil retaining ring 81 is securely connected to the mounting channel 13. The connector 91 is a cylindrical pin or screw, etc.

[0051] Furthermore, the protrusion 811 may be formed near the middle of the outer oil retaining ring 81 or may be arranged at a position deviated from the center.

[0052] In order to realize the constraint between the inner oil retaining ring 82 and the outer oil retaining ring 81, as shown in FIG. Figure 3 As shown, a third convex portion 821 is provided on the outer circumferential wall of the inner oil retaining ring 82, and a third concave portion 812 is provided on the inner circumferential wall of the outer oil retaining ring 81 to match the third convex portion 821. The third convex portion 821 can be one or at least two. In this embodiment, there are two third convex portions 821, which are spaced apart along the length of the pump shaft 7, and each third convex portion 821 corresponds to a third concave portion 812. In this embodiment, a third convex portion 821 is provided at both the front and rear ends of the inner oil retaining ring 82.

[0053] The third protrusion 821 may extend along the circumference of the inner oil sling ring 82 and be annular. Alternatively, at least two third protrusions 821 may be arranged at intervals along the circumference of the inner oil sling ring 82 .

[0054] In this embodiment, the longitudinal cross-sections of the first protrusion 352 and the third protrusion 821 are both triangular in shape.

[0055] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0056] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of patent protection for the present application shall be determined by the appended claims.

Claims

1. A main oil pump for a steam turbine, characterized in that: The invention comprises a pump casing (1) and an impeller (2), wherein the interior of the pump casing (1) is hollow and forms a chamber (10), and the pump casing (1) has an oil inlet channel (101) and an oil outlet channel (102) communicated with the chamber (10); the impeller (2) is rotatably arranged in the chamber (10), and the rotation axis of the impeller (2) extends along the front-back direction, and the outer peripheral walls at the front and rear ends of the impeller (2) are both provided with floating seals (3) sealedly connected to corresponding positions of the inner peripheral wall of the chamber (10), and the floating seals (3) include an outer sealing ring sleeved on the outer peripheral wall of the impeller (2) and an inner sealing ring located between the outer sealing ring and the impeller (2), the hardness of the inner sealing ring is less than that of the outer sealing ring, and a gap can be formed between the inner sealing ring and the outer sealing ring for forming an oil film.

2. The main oil pump of the shaft head according to claim 1, characterized in that: The inner sealing ring is a sealing body made of Babbitt alloy, the outer sealing ring is a sealing body made of cast steel, and the material of the impeller (2) is stainless steel.

3. The main oil pump of the shaft head according to claim 2, characterized in that: The material of the Babbitt alloy is a bearing bush.

4. The main oil pump of the shaft head according to claim 1, characterized in that: A flange (351) is protruding from the outer peripheral wall of the outer sealing ring, and an installation opening (103) for inserting the flange (351) is provided on the inner peripheral wall of the chamber (10) at a position corresponding to the flange (351).

5. The main oil pump of the shaft head according to claim 4, characterized in that: A first convex portion (352) is provided on the outer peripheral wall of the inner sealing ring, and a first concave portion (353) adapted to the first convex portion (352) is provided on the inner peripheral wall of the outer sealing ring.

6. The main oil pump of the shaft head according to claim 5, characterized in that: The outer sealing ring located at the front side is defined as a front sealing ring (31), and the inner sealing ring located at the front side is defined as a front sealing portion (32). The inner peripheral wall of the front sealing ring (31) is provided with a second convex portion (311) extending inward, the first concave portion (353) is located behind the second convex portion (311), and the front end of the front sealing portion (32) is against the second convex portion (311).

7. The main oil pump of the shaft head according to claim 5, characterized in that: The inner sealing ring located at the rear side is defined as a rear sealing portion (34), and the front and rear ends of the rear sealing portion (34) are both provided with the first convex portions (352), and each of the first convex portions (352) corresponds to a first concave portion (353).

8. The main oil pump of the shaft head according to any one of claims 1 to 7, characterized in that: The pump housing (1) is provided with a mounting channel (13) for mounting a pump shaft (7). The pump shaft (7) is coaxially arranged with the impeller (2) and connected to the impeller (2). A floating oil retaining ring (8) is sleeved between the outer peripheral wall of the pump shaft (7) and the inner peripheral wall of the mounting channel (13). The floating oil retaining ring (8) includes an outer oil retaining ring (81) sleeved on the outer periphery of the pump shaft (7) and an inner oil retaining ring (82) located between the pump shaft (7) and the outer oil retaining ring (81). The material of the inner oil retaining ring (82) is Babbitt alloy, and the material of the outer oil retaining ring (81) is cast steel.

9. The main oil pump of the shaft head according to claim 8, characterized in that: The outer oil retaining ring (81) is mounted on the peripheral wall of the mounting channel (13) via a connecting piece (91); a third convex portion (821) is provided on the outer peripheral wall of the inner oil retaining ring (82); and a third concave portion (812) adapted to the third convex portion (821) is provided on the inner peripheral wall of the outer oil retaining ring (81).

10. The main oil pump of the shaft head according to claim 8, characterized in that: A gap can be formed between the outer oil retaining ring (81) and the inner oil retaining ring (82) to form an oil film.

Images