Protective pipe for brake shoe gap adjuster of railway wagon

Abstract

The utility model relates to a protective tube for a brake-shoe gap adjuster of a railway wagon, which comprises a cylinder, a rear-end sealing sleeve and a front-end sealing seat, and a through cavity is arranged in the cylinder, so that a screw of the adjuster can penetrate through the cavity; the rear end sealing sleeve is arranged at the rear end of the cylinder in a sleeving mode, a buckling ring is arranged on the outer wall of the rear end sealing sleeve, and the buckling ring is embedded into a clamping ring groove in an inner hole of the front cover and used for axial fixing and restraining between the rear end sealing sleeve and the front cover; a boss is arranged on the outer wall of the rear end sealing sleeve and inserted into a groove in an inner hole of the front cover so as to fix and restrain the rear end sealing sleeve and the front cover in the circumferential direction. The front end sealing seat is embedded in the front end of the cylinder body and is used for sealing and supporting the screw rod; the sealing parts of the front end and the rear end of the protective pipe are reliable, axial and circumferential positioning structures are arranged, the failure rate of the automatic bidirectional brake shoe clearance adjuster of the railway wagon is reduced, and the maintenance period of the adjuster is prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of plunger rod sealing protection devices, in particular to a protection tube for a brake shoe clearance adjuster of a railway freight car. Background Art

[0002] The bidirectional brake shoe clearance automatic adjuster (brake adjuster for short) of railway freight cars is an important part of the brake system of railway freight cars. It is used to automatically adjust the position of the brake lever after the brake shoe becomes thinner due to wear, so as to ensure that the stroke of the brake cylinder is within the working range and the brake cylinder maintains the specified pressure during braking. The brake shoe braking pressure will not be reduced due to the decrease in air pressure in the brake cylinder caused by the increase in the brake cylinder stroke.

[0003] The bidirectional brake shoe clearance automatic adjuster is mainly composed of a screw, a tie rod, a sleeve, an outer cylinder, a protective tube, etc. The screw and the tie rod are sealed and installed at both ends of the outer cylinder. The internal mechanism can adjust the distance between the screw and the tie rod to adjust the position of the brake lever. During the clearance adjustment process, the screw and the outer cylinder rotate and move axially. In order to ensure that the exposed part of the screw in the front cover of the outer cylinder is not contaminated by dust, a protective tube is set at the end of the front cover.

[0004] In the prior art, since the rear end of the protective tube is fixed in the inner hole of the front cover with a rubber plug and a retaining ring, there is insufficient circumferential positioning, resulting in the front end of the protective tube not being tightly sealed on the screw. Therefore, after the gate regulator is used for a long time, the protective tube is prone to failure of sealing protection. After the accumulation of dust and moisture, the screw and guide nut are stuck and fail, resulting in the gate regulator malfunctioning, shortening the maintenance cycle.

[0005] Therefore, there is an urgent need to develop a protective tube for a brake shoe clearance adjuster that is simple to manufacture and install and can reliably maintain a sealed state for a long time, thereby reducing the failure rate of the bidirectional brake shoe clearance automatic adjuster of railway freight cars and extending the maintenance cycle of the adjuster. Summary of the invention

[0006] In view of at least one of the problems in the above-mentioned prior art, the purpose of the utility model is to provide a protective tube for a railway freight car brake shoe clearance adjuster, which has reliable sealing parts at the front and rear ends and has axial and circumferential positioning structures, thereby reducing the failure rate of the railway freight car's bidirectional brake shoe clearance automatic adjuster and extending the maintenance period of the adjuster.

[0007] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0008] A protective tube for a brake shoe clearance adjuster of a railway freight car, comprising:

[0009] A barrel having a through cavity therein so that a screw of the adjuster can pass through the cavity;

[0010] A rear end sealing sleeve is sleeved on the rear end of the cylinder, a buckle ring is provided on the outer wall of the rear end sealing sleeve, and the buckle ring is embedded in the clamping ring groove in the inner hole of the front cover to axially fix and constrain the rear end sealing sleeve and the front cover; a boss is provided on the outer wall of the rear end sealing sleeve, and the boss is inserted into the groove in the inner hole of the front cover to circumferentially fix and constrain the rear end sealing sleeve and the front cover;

[0011] The front end sealing seat is embedded in the front end of the barrel and is used for sealing and supporting the screw.

[0012] Preferably, the cylinder comprises a first cylinder portion and a second cylinder portion, the inner diameter of the first cylinder portion is larger than the inner diameter of the second cylinder portion, the front end sealing seat is embedded and installed in the first cylinder portion, and the rear end sealing sleeve is sleeved on the end of the second cylinder portion.

[0013] Preferably, an annular flange rib is provided at the front end port of the cylinder, and a plurality of notches are provided at intervals on the flange rib.

[0014] Preferably, a flanging rib groove and a notch platform engaging with the flanging rib and the notch are provided on the outer wall of the outer end of the front end sealing seat.

[0015] Preferably, the outer wall of the rear end of the cylinder is provided with an annular rib and a plurality of semi-spherical protrusions spaced circumferentially.

[0016] Preferably, the annular ribs are provided in two numbers, and all the semi-spherical protrusions are provided between two of the annular ribs.

[0017] Preferably, an annular rib groove and a semi-spherical convex groove which are matched with the annular rib and the semi-spherical convex are provided on the inner wall of the rear end sealing sleeve.

[0018] Preferably, a plurality of annular steps are arranged at intervals on the outer wall of the rear end sealing sleeve.

[0019] Preferably, the plurality of annular steps include a first support ring, a sealing ring, a second support ring, the buckling ring and an end cover ring which are arranged in sequence, and a plurality of sealing rings are provided.

[0020] Preferably, the boss is a semi-cylinder and is disposed on the second supporting ring.

[0021] The utility model adopts the above technical solution, which has the following advantages:

[0022] 1. The utility model provides a protective tube for a brake shoe clearance adjuster for a railway freight car. The flanged ribs and notches arranged at the front end of the cylinder body can reliably position and constrain the front end sealing seat in the axial and circumferential directions to prevent loosening after the front sealing seat is injection-molded. The rear end cylinder of the cylinder body is provided with two annular ribs and a semi-spherical protrusion. After the rear end sealing sleeve is injection-molded, the rear sealing sleeve can be reliably positioned and constrained in the axial and circumferential directions to prevent loosening, and a corrugated surface is formed on the joint surface to enhance the sealing performance therebetween. The front and rear end sealing parts of the protective tube are reliable and have axial and circumferential positioning structures, which reduces the failure rate of the automatic brake shoe clearance adjuster for railway freight cars and prolongs the maintenance period of the adjuster.

[0023] 2. The utility model provides a protective tube for a brake shoe clearance adjuster for a railway freight car. The front and rear ends of the aluminum alloy cylinder are integrally injection-molded with a front sealing seat and a rear sealing sleeve, so that the protective tube of the brake adjuster becomes a single part, which has the advantages of reliable sealing protection, corrosion prevention, reduced dead weight, reduced friction coefficient and wear between the protective tube and the screw, thereby increasing the service life of the brake adjuster.

[0024] 3. The protective tube for the brake shoe gap adjuster of a railway freight car provided by the utility model has an aluminum alloy cylinder body that is integrally formed of a round tube, has a simple manufacturing process, and is easy to realize mass production to reduce costs.

[0025] 4. The utility model provides a protective tube for a railway freight car brake shoe clearance adjuster, and the front sealing seat is made of nylon or polytetrafluoroethylene. The supporting cylindrical surface and the cylindrical surface of the screw are gap-matched, which can greatly reduce friction and wear when the screw rotates or moves axially between the screw and the front sealing seat. A dustproof sealing ring is added in the second annular groove to effectively prevent dust from entering the protective tube with the movement of the screw.

[0026] 5. The protective tube for the brake shoe clearance adjuster of a railway freight car provided by the utility model has an outer cylinder of a rear end sealing sleeve that adopts a support ring, a sealing ring, a buckle ring, and an end cover ring structure, so that the connection positioning, sealing, and supporting functions of the rear end sealing sleeve and the front cover of the brake adjuster are separated to ensure that its installation and operation are convenient and simple, and it is firmly combined with the front cover, reliably sealed, and not easy to be separated due to force.

[0027] 6. The protective tube for the brake shoe clearance adjuster of a railway freight car provided by the utility model adopts an aluminum-plastic composite structure, which can reduce its own weight, greatly reduce the friction and wear of the screw, and thus improve the overall performance and life of the brake adjuster. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The utility model is a front view schematic diagram of a protective tube for a brake shoe clearance adjuster of a railway freight car provided by an embodiment of the utility model.

[0029] Figure 2It is a left side schematic diagram of a protective tube for a railway freight car brake shoe clearance adjuster provided by this embodiment of the utility model.

[0030] Figure 3 This embodiment of the utility model provides Figure 2 Schematic diagram of BB cross section.

[0031] Figure 4 It is an axonometric view of a protective tube for a railway freight car brake shoe clearance adjuster provided in this embodiment of the utility model.

[0032] Figure 5 It is a front view schematic diagram of the cylinder provided in this embodiment of the utility model.

[0033] Figure 6 It is a left side schematic diagram of the cylinder provided in this embodiment of the utility model.

[0034] Figure 7 This embodiment of the utility model provides Figure 5 Schematic diagram of the AA section.

[0035] Figure 8 This embodiment of the utility model provides Figure 5 A top cross-sectional view of .

[0036] Fig. 9 It is an axonometric view of the cylinder provided in this embodiment of the utility model.

[0037] Fig.10 It is a schematic diagram of the assembly of the protection tube and the gate regulator front cover provided by this embodiment of the utility model.

[0038] Fig.11 This embodiment of the utility model provides Fig.10 CC section view.

[0039] Fig.12 It is an axonometric view of the assembly of the protection tube and the gate regulator front cover provided by this embodiment of the utility model.

[0040] Reference numerals in the figures:

[0041] 100 is the front cover, 101 is the end of the front cover, 102 is the clamping ring groove, 103 is the inner hole of the front cover, 104 is the wall of the inner hole of the front cover, 200 is a screw, 300 is a dustproof sealing ring, 1 is a cylinder, 10 is a second cylinder part, 11 is a first cylinder part, 12 is an annular rib, 13 is a semi-spherical convex, 14 is a flanging rib, 15 is a notch, 2 is a rear end sealing sleeve, 21 is a first supporting ring, 22 is a sealing ring, 23 is a second supporting ring, 24 is a buckling ring, 25 is a cover ring, 26 is a boss, 3 is a front end sealing seat, 31 is a third ring, 32 is a second ring, 33 is a first ring, and 34 is a circular annular plane. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the utility model clearer, the technical solution of the utility model will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0043] In the description of the present invention, it should be noted that the terms "upper", "lower", "front", "rear", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the system or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0044] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "assembly", "setting", and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] The utility model provides a protective tube for a railway freight car brake shoe clearance adjuster, the front and rear end sealing parts of which are reliable and have axial and circumferential positioning structures, thereby reducing the failure rate of the railway freight car's bidirectional brake shoe clearance automatic adjuster and extending the adjuster maintenance period.

[0046] Below, the embodiments of the utility model are described in detail with reference to the accompanying drawings.

[0047] Example

[0048] Please refer to Figures 1 to 3 and Fig.11 , a protective tube for a railway freight car brake shoe clearance adjuster provided in this embodiment includes a cylinder 1, a rear end sealing sleeve 2 and a front end sealing seat 3;

[0049] A through cavity is provided in the barrel 1, so that the screw rod 200 of the adjuster can pass through the cavity;

[0050] The rear end sealing sleeve 2 is sleeved on the rear end of the cylinder 1, and a buckle ring 24 is provided on the outer wall of the rear end sealing sleeve 2, and the buckle ring 24 is embedded in the clamping ring groove 102 in the inner hole 103 of the front cover, so as to axially fix and constrain the rear end sealing sleeve 2 and the front cover 100; a boss 26 is provided on the outer wall of the rear end sealing sleeve 2, and the boss 26 is inserted into the groove in the inner hole 103 of the front cover, so as to circumferentially fix and constrain the rear end sealing sleeve 2 and the front cover 100;

[0051] The front end sealing seat 3 is embedded in the front end of the barrel 1 to seal and support the screw 200 .

[0052] In specific applications, the cylinder 1 is an aluminum alloy cylinder, and the rear end sealing sleeve 2 and the front end sealing seat 3 are both made of polymer materials such as nylon or polytetrafluoroethylene, and are sequentially molded at both ends of the aluminum alloy cylinder 1 through an injection molding process, so that the cylinder 1, the rear end sealing sleeve 2 and the front end sealing seat 3 are integrated parts.

[0053] Please refer to Figures 5 to 9 In this embodiment, the cylinder 1 includes a first cylinder portion 11 and a second cylinder portion 10, the inner diameter of the first cylinder portion 11 is larger than the inner diameter of the second cylinder portion 10, the front end sealing seat 3 is embedded and installed in the first cylinder portion 10, and the rear end sealing sleeve 2 is sleeved on the end of the second cylinder portion 10.

[0054] In some applications, the first barrel portion 11 is a large cylindrical barrel, and its outer diameter is also larger than the outer diameter of the second barrel portion 10, forming a step shape.

[0055] In this embodiment, an annular flange rib 14 is provided at the front end port of the cylinder 1, and a plurality of notches 15 are provided at intervals on the flange rib 14. An annular rib 12 and a plurality of semi-spherical protrusions 13 arranged at circumferential intervals are provided on the outer wall of the rear end of the cylinder 1; the annular rib 12 is provided in two pieces, and all the semi-spherical protrusions 13 are arranged between two annular ribs 12.

[0056] In a specific application, the flange rib 14 at the front end of the cylinder 1, the first cylinder portion 11, the second cylinder portion 10, the two pressed annular ribs 12 at the rear end of the cylinder 1 and a plurality of circumferentially arranged semi-spherical protrusions 13 are integrally formed.

[0057] The cylinder 1 is made of aluminum alloy round tubes through multiple stamping processes such as cutting, tube expansion, and pressing. The main body of the cylinder 1 is an integrated thin-walled cylindrical structure with both ends open. The flange rib 14 at the front end is used to strengthen the rigidity of the end of the large cylindrical body;

[0058] The outer wall of the outer end of the front end sealing seat 3 is provided with a flange rib groove and a notch platform engaged with the flange rib and the notch.

[0059] The cylinder 1 is axially fixed with the front sealing seat 3 by the flange rib 14; the plurality of notches 15 arranged at intervals on the flange rib 14 are used to circumferentially fix the front sealing seat 3 so that it cannot rotate circumferentially around the cylinder 1. The first cylinder portion 11 is made by a tube expansion molding process and is naturally transitionally connected to the first cylinder portion 10. The internal space of the first cylinder portion 11 is used to place the front sealing seat 3.

[0060] In this embodiment, an annular rib groove and a semi-spherical protrusion groove which are matched with the annular rib 12 and the semi-spherical protrusion 13 are provided on the inner wall of the rear end sealing sleeve 2 .

[0061] In specific applications, two annular ribs 12 are arranged at intervals in the circumferential direction at the rear of the cylinder 1, which are used to axially fix the rear end sealing sleeve 2. The outer wall surface of the annular ribs 12 is an arc surface. The annular ribs 12 make the connecting surface of the outer circle of the cylinder 1 and the inner wall of the rear end sealing sleeve 2 form a continuous curved surface, which is conducive to forming a reliable sealing state and preventing the sealing from failing due to deformation. Several semi-spherical protrusions 13 arranged circumferentially between the two annular ribs 12 are used to fix and constrain the circumferential movement of the rear end sealing sleeve 2 relative to the cylinder 1, so as to ensure that the rear end sealing sleeve 2 and the cylinder 1 are reliably fixed as a whole and have reliable sealing performance. The cylinder 1 made of aluminum alloy material has the advantages of reducing the dead weight of the protective tube and preventing the cleanliness of the screw 200 from being affected by internal rust and corrosion.

[0062] Please refer to Figures 1 to 9 In this embodiment, the front end seal seat 3 is made of polymer materials such as nylon or polytetrafluoroethylene, and is formed by injection molding at the front end face of the aluminum alloy barrel 1 and the inside of the first barrel part 11. The front end seal seat 3 is in the shape of a hollow cylinder, and its left outer end covers the flange rib 14 and the notch 15 of the barrel 1. A circular ring-shaped plane 34 is formed at the end face, which is used to form axial and circumferential fixed constraints between the front end seal seat 3 and the barrel 1. The outer wall surface of the front end seal seat 3 embedded in the first barrel part 11 is in contact with the inner wall surface of the first barrel part 11; the inner wall of the front end seal seat 3 is sequentially provided with a plurality of circular ring steps, including a first ring 33, a second ring 32 and a third ring 31, and the first ring 33 is used to protect the outer side of the dustproof seal ring 300. The second ring 32 is used to cooperate with the installation of the dustproof seal ring 300. The third ring 31 and the cylindrical surface of the screw 200 form a clearance fit, which is used to support the screw 200 to rotate circumferentially and move left and right axially in the front end seal seat 3. The front sealing seat 3 is made of a polymer material with a low friction coefficient and wear resistance, which can reduce the friction between the protection tube and the screw 200, thereby improving the overall adjustment sensitivity of the gate regulator, reducing the wear of the screw 200, and increasing the overall service life of the gate regulator.

[0063] Please refer to Figures 1 to 9The rear end sealing sleeve 2 is made of polymer materials such as nylon and is formed by injection molding on the outside of the right end cylindrical surface of the aluminum alloy cylinder 1. The inner wall surface 20 of the rear end sealing sleeve 2 is attached to the outer wall surface of the cylinder 1, and the two annular rib grooves and semi-spherical convex grooves on the inner wall match the two annular ribs 12 and semi-spherical convex 13, so that the rear end sealing sleeve 2 as a whole has reliable fixed constraints with the cylinder 1 in the axial, circumferential and radial directions, and has good sealing performance.

[0064] In this embodiment, a plurality of annular steps are arranged at intervals on the outer wall of the rear end sealing sleeve 2, and the plurality of annular steps include a first support ring 21, a sealing ring 22, a second support ring 23, a buckling ring 24 and an end cover ring 15 arranged in sequence, and a plurality of sealing rings 22 are arranged; wherein the boss 26 is a semi-cylinder and is arranged on the second support ring 23.

[0065] In specific applications, annular steps of different cross-sectional shapes are arranged at intervals on the outer wall of the rear sealing sleeve 2. The outer diameters of the first support ring 21 and the second support ring 23 are equal to the inner cylindrical diameter of the front cover inner hole 103, which are used to support the weight of the protective tube as a whole and transfer the main force of the protective tube to the front cover 100. A plurality of sealing rings 22 are arranged between the first support ring 21 and the second support ring 23, which are used to form a reliable seal between the rear sealing sleeve 2 and the front cover inner hole 103. A buckle ring 24 is arranged on the left side of the second support ring 23. After the protective tube is assembled with the front cover 100, the buckle ring 24 is buckled (embedded) in the clamping ring groove 102 of the front cover 100, which is used for axial fixing and restraining between the protective tube and the front cover 100. An end cover ring 25 is arranged at the left end of the rear sealing sleeve 2, which is used to increase the bending strength of the rear sealing sleeve 2 and the front cover 100, and to form a sealing surface with the front cover end 101 of the front cover 100 to increase the sealing performance and prevent the aging of the internal sealant. Two semi-cylindrical bosses 26 are arranged on the outer cylindrical surface of the second support ring 23 . The semi-cylindrical bosses 26 are inserted into corresponding grooves of the front cover 100 to fix and constrain the circumferential direction of the protection tube and the front cover 100 .

[0066] Please refer to Figures 10 to 12, the protective tube for the brake shoe clearance adjuster of the railway freight car of the present embodiment, before assembling the protective tube, first clean the foreign matter in the installation groove 102 and the inner hole 103 of the front cover 100 of the brake adjuster. Assemble the corresponding dustproof seal ring 300 in the groove of the second ring 32 of the front end sealing seat 3 of the protective tube. The rear end sealing sleeve 2 of the protective tube is appropriately heated and softened, and after applying sealant to the grooves formed between the annular steps on its outer cylindrical surface, axial pressure is applied to the end cover ring 25, and it is pressed into the inner hole 103 of the front cover of the brake adjuster front cover 100. The inner hole 103 of the front cover is a cylindrical hole, and the right end of the protective tube is in contact with the inner hole wall 104 of the front cover. At this time, the first support ring 21 and the second support ring 23 of the rear end sealing sleeve 2 are pressed on the inner hole 103 of the front cover 100, and each sealing ring 22 is tilted and deformed to form multiple elastic sealing rings. Under the action of the sealant, a long-term sealing state can be maintained. The buckle ring 24 of the rear sealing sleeve 2 is clamped in the installation groove 102 of the front cover 100 to prevent the rear sealing sleeve 2 from moving in the axial direction. The end cover ring 25 of the rear sealing sleeve 2 is attached to the outer end surface of the front cover end 101 of the front cover 100 to prevent foreign matter from entering. After the protective tube is assembled with the front cover 100, other assembly processes of the gate regulator can be entered.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the utility model.

Claims

1. A protective tube for a railway freight car brake shoe clearance adjuster, It is characterized in that include: A barrel having a through cavity therein so that the screw of the adjuster can pass through the cavity; A rear end sealing sleeve is sleeved on the rear end of the cylinder, a buckle ring is provided on the outer wall of the rear end sealing sleeve, and the buckle ring is embedded in the clamping ring groove in the inner hole of the front cover to axially fix and constrain the rear end sealing sleeve and the front cover; a boss is provided on the outer wall of the rear end sealing sleeve, and the boss is inserted into the groove in the inner hole of the front cover to circumferentially fix and constrain the rear end sealing sleeve and the front cover; The front end sealing seat is embedded in the front end of the barrel and is used for sealing and supporting the screw.

2. The protective tube for the brake shoe clearance adjuster of a railway freight car according to claim 1, It is characterized in that The cylinder includes a first cylinder part and a second cylinder part, the inner diameter of the first cylinder part is larger than the inner diameter of the second cylinder part, the front end sealing seat is embedded and installed in the first cylinder part, and the rear end sealing sleeve is sleeved on the end of the second cylinder part.

3. The protective tube for the brake shoe clearance adjuster of a railway freight car according to claim 1, It is characterized in that An annular flange rib is arranged at the front end of the cylinder, and a plurality of notches are arranged at intervals on the flange rib.

4. The protective tube for the brake shoe clearance adjuster of a railway freight car according to claim 3, It is characterized in that The outer wall of the outer end of the front end sealing seat is provided with a flange rib groove and a notch platform which are engaged with the flange rib and the notch.

5. The protective tube for the brake shoe clearance adjuster of a railway freight car according to claim 1, It is characterized in that The outer wall of the rear end of the cylinder is provided with an annular rib and a plurality of semi-spherical protrusions arranged at intervals in the circumferential direction.

6. The protection tube for the brake shoe clearance adjuster of a railway freight car according to claim 5, It is characterized in that The annular ribs are arranged in two pieces, and all the semi-spherical protrusions are arranged between two of the annular ribs.

7. The protection tube for the brake shoe clearance adjuster of a railway freight car according to claim 5, It is characterized in that An annular rib groove and a semi-spherical convex groove which are matched with the annular rib and the semi-spherical convex are arranged on the inner wall of the rear end sealing sleeve.

8. The protection tube for the brake shoe clearance adjuster of a railway freight car according to claim 1, It is characterized in that A plurality of annular steps are arranged at intervals on the outer wall of the rear end sealing sleeve.

9. The protection tube for the brake shoe clearance adjuster of a railway freight car according to claim 8, It is characterized in that The plurality of annular steps include a first support ring, a sealing ring, a second support ring, the buckling ring and an end cover ring which are arranged in sequence, and a plurality of sealing rings are provided.

10. The protection tube for the brake shoe clearance adjuster of a railway freight car according to claim 9, It is characterized in that The boss is a semi-cylinder and is arranged on the second supporting ring.

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