CN221256492U - Electric push rod for automobile tail plate - Google Patents

Abstract

The utility model relates to the technical field of automobile tail plates, and discloses an electric push rod for an automobile tail plate, which comprises an outer pipe and an inner pipe, wherein a reduction gearbox shell is arranged on the outer pipe, a motor is arranged on the reduction gearbox shell, the reduction gearbox shell is connected with the motor through a planetary reducer, an output shaft on the planetary reducer is meshed with a screw rod through a linkage gear shaft, a first thrust bearing is sleeved on the periphery of a large shaft sleeve, a second thrust bearing is sleeved on the periphery of a small shaft sleeve, wear-resistant sleeves are respectively embedded on two sides of the reduction gearbox shell, and inner holes for hinged connection with equipment are arranged in the wear-resistant sleeves; the wear-resistant sleeve is arranged on two sides of the reduction gearbox shell to reduce the installation distance, the wear-resistant sleeve utilizes the inner hole for equipment hinging, the reduction gearbox shell is reduced in size by adopting a mode of matching a planetary reducer with a linkage gear shaft, and the length of the inner tube is reduced by means of the first thrust bearing and the second thrust bearing which bear thrust force of the inner tube and the third deep groove ball shaft which bears tensile force in a distinguishing mode.

Description

Electric push rod for automobile tail plate

Technical Field

The utility model relates to the technical field of automobile tail boards, in particular to an electric push rod for an automobile tail board.

Background

Along with the development of logistics industry in China, the demand for installing tail boards on vehicles is continuously increasing.

Most of the existing automobile tail boards adopt hydraulic systems, and have the problems of difficult maintenance, running, overflowing, dripping, leaking, low-temperature freezing and the like.

Under the great trend of gradually strengthening 'oil change' of human environmental awareness, an electric push rod is gradually replacing a hydraulic push rod on mobile equipment; one of the difficulties of using an electric push rod instead of a hydraulic cylinder is: the electric push rod has large volume, long push rod length, long installation distance and the like.

Disclosure of utility model

The utility model aims to provide an electric push rod for an automobile tail plate, and aims to solve the problems of large size, overlong push rod and long installation distance of the electric push rod in the prior art.

The utility model is realized in such a way that an electric push rod for an automobile tail plate comprises an outer pipe and an inner pipe, wherein the inner end of the inner pipe is arranged in the outer pipe, the outer end of the inner pipe is connected with a connector, the connector is exposed out of the outer pipe, a reduction gearbox shell is arranged on the outer pipe, a motor is arranged on the reduction gearbox shell, the reduction gearbox shell is connected with the motor through a planetary reducer, an output shaft on the planetary reducer is meshed with a screw rod through a linkage gear shaft, the upper end and the lower end of the linkage gear shaft are respectively arranged in the reduction gearbox shell through a first deep groove ball bearing, and the output shaft on the planetary reducer is fixed in the reduction gearbox shell through a second deep groove ball shaft;

The screw rod is positioned in the outer tube, the bottom end of the screw rod is arranged in the bottom of the reduction gearbox shell through a third deep groove ball shaft, a first shaft shoulder of the screw rod is downwards abutted to a fourth deep groove ball bearing, the fourth deep groove ball bearing is sleeved on the screw rod, a second shaft shoulder of the screw rod and the bottom of the fourth deep groove ball shaft are downwards abutted to a large shaft sleeve respectively, the large shaft sleeve is sleeved on the screw rod, a first thrust bearing is sleeved on the periphery of the large shaft sleeve, the bottom of the first thrust bearing is abutted to the reduction gearbox shell, a spline nut is connected to the periphery of the screw rod in a threaded manner, the top of the spline nut is upwards abutted to a small shaft sleeve, a second thrust bearing is sleeved on the periphery of the small shaft sleeve, the top of the second thrust bearing is abutted to the reduction gearbox shell, the screw rod is meshed with a gear shaft through a driven gear, and the driven gear is abutted to the bottom of the spline nut through a compression nut;

Along fourth deep groove ball bearing top-down's direction, fourth deep groove ball bearing, big axle sleeve, little axle sleeve, spline nut, driven gear, gland nut and third deep groove ball axle arrange in proper order, will through the bearing retainer ring fourth deep groove ball bearing installs on the reducing gear box shell, the wear-resisting cover has been embedded respectively on the both sides of reducing gear box shell, be equipped with the hole that is used for articulated connection with equipment in the wear-resisting cover.

Further, the reduction gearbox shell is arranged in the direction from bottom to top, the reduction gearbox shell, the planetary reducer and the motor are arranged in sequence, and the planetary reducer and the motor are respectively arranged horizontally and oppositely with the outer tube.

Further, the motor is a band-type brake motor.

Further, large fillets are arranged at two ends of the reduction gearbox shell.

Further, the thrust bearing range of the second thrust bearing is smaller than that of the first thrust bearing.

Further, the bottom of outer tube is installed on the reducing gear box shell, install the end cover on the top of outer tube, along the inside wall top-down of outer tube is fixedly connected with first travel switch, second travel switch, the third travel switch of response inner tube mobile position respectively, first travel switch is upper limit switch, the second travel switch is zero position limit switch, the third travel switch is lower limit switch.

Further, the internally mounted of end cover has first pendulum ring and waterproof sealing circle, second pendulum ring, dustproof sealing circle, follows the top direction of end cover, first pendulum ring, waterproof sealing circle, second pendulum ring and dustproof sealing circle are prevented to overlap in proper order and are established on the periphery of inner tube.

Furthermore, the first anti-swing ring and the second anti-swing ring are circular rings with gaps.

Further, a screw rod nut is arranged on the screw rod, the screw rod nut and the screw rod are ball screw pairs, one end of the screw rod nut is connected with a rotation stopping ring and a locking nut through threads, the periphery of the rotation stopping ring is movably embedded in the inner side wall of the outer tube, and the other end of the screw rod nut is fixedly connected with the inner tube through threads.

Further, a third anti-swing ring, a gasket and a fixing nut are arranged at the top of the screw rod, the gasket is pressed on the top of the screw rod through the fixing nut by the third anti-swing ring, and the third anti-swing ring is located between the screw rod and the inner tube.

Compared with the prior art, the electric push rod for the automobile tail plate reduces the installation distance by arranging the wear-resistant sleeves on two sides of the reduction gearbox shell, the wear-resistant sleeves utilize the inner holes for equipment hinging, the reduction gearbox shell is reduced in size by adopting a mode that the planetary reducer is matched with the linkage gear shaft, the length of the inner tube is reduced by the first thrust bearing and the second thrust bearing which bear thrust force of the inner tube and the third deep groove ball shaft which bears tensile force in a distinguishing mode, and the problems of large size, overlong push rod and long installation distance of the electric push rod are solved.

Drawings

Fig. 1 is a schematic structural view of an electric putter for an automobile tailgate according to the utility model;

FIG. 2 is a schematic view of a cut-away structure of a reduction gearbox housing provided by the utility model;

FIG. 3 is a schematic perspective view of an outer tube in section provided by the present utility model;

FIG. 4 is a schematic cross-sectional view of an outer tube and a rotation stop ring provided by the utility model;

FIG. 5 is a schematic view of the cut-away structure of the inner tube provided by the present utility model;

FIG. 6 is a schematic diagram of the first anti-wobble ring and the second anti-wobble ring according to the present utility model;

Fig. 7 is a schematic diagram of a cut-away structure of an electric putter for an automobile tailgate according to the utility model.

In the figure: the motor 10, the planetary reducer 20, the reduction gearbox housing 30, the outer tube 40, the inner tube 50, the connector 60, the screw rod 70, the output shaft 21, the linkage gear shaft 31, the first deep groove ball bearing 32, the second deep groove ball bearing 33, the third deep groove ball bearing 34, the fourth deep groove ball bearing 35, the first thrust bearing 36, the second thrust bearing 37, the bearing retainer ring 38, the wear sleeve 39, the inner hole 310, the large round angle 311, the end cover 41, the first travel switch 42, the second travel switch 43, the third travel switch 44, the first anti-sway ring 45, the waterproof seal ring 46, the second anti-sway ring 47, the dustproof seal 48, the first shaft shoulder 71, the second shaft shoulder 72, the large shaft sleeve 73, the spline nut 74, the small shaft sleeve 75, the driven gear 76, the compression nut 77, the screw nut 78, the rotation stop ring 79, the lock nut 710, the third anti-sway ring 711, the spacer 712, and the fixing nut 713.

Detailed Description

The present utility model will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present utility model more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the utility model.

The implementation of the present utility model will be described in detail below with reference to specific embodiments.

The same or similar reference numerals in the drawings of the present embodiment correspond to the same or similar components; in the description of the present utility model, it should be understood that, if there is an azimuth or positional relationship indicated by terms such as "upper", "lower", "left", "right", etc., based on the azimuth or positional relationship shown in the drawings, it is only for convenience of describing the present utility model and simplifying the description, but it is not indicated or implied that the apparatus or element referred to must have a specific azimuth, be constructed and operated in a specific azimuth, and thus terms describing the positional relationship in the drawings are merely illustrative and should not be construed as limiting the present utility model, and specific meanings of the terms described above may be understood by those of ordinary skill in the art according to specific circumstances.

Referring to fig. 1-7, a preferred embodiment of the present utility model is provided.

The electric push rod for the automobile tail plate comprises an outer pipe 40 and an inner pipe 50, wherein the inner end of the inner pipe 50 is installed in the outer pipe 40, a connector 60 is connected to the outer end of the inner pipe 50, the connector 60 is exposed out of the outer pipe 40, a reduction gearbox shell 30 is installed on the outer pipe 40, a motor 10 is arranged on the reduction gearbox shell 30, the reduction gearbox shell 30 is connected with the motor 10 through a planetary reducer 20, an output shaft 21 on the planetary reducer 20 is meshed with a screw rod 70 through a linkage gear shaft 31, the upper end and the lower end of the linkage gear shaft 31 are installed in the reduction gearbox shell 30 through first deep groove ball bearings 32 respectively, and the output shaft 21 on the planetary reducer 20 is fixed in the reduction gearbox shell 30 through second deep groove ball shafts 33;

The screw rod 70 is positioned in the outer tube 40, the bottom end of the screw rod 70 is mounted in the bottom of the reduction gearbox shell 30 through the third deep groove ball shaft 34, a first shaft shoulder 71 of the screw rod 70 is downward abutted against a fourth deep groove ball bearing 35, the fourth deep groove ball bearing 35 is sleeved on the screw rod 70, a second shaft shoulder 72 of the screw rod 70 and the bottom of the fourth deep groove ball shaft are downward abutted against a large shaft sleeve 73 respectively, the large shaft sleeve 73 is sleeved on the screw rod 70, a first thrust bearing 36 is sleeved on the periphery of the large shaft sleeve 73, the bottom of the first thrust bearing 36 is abutted against the reduction gearbox shell 30, a spline nut 74 is in threaded connection with the periphery of the screw rod 70, the top of the spline nut 74 is upward abutted against a small shaft sleeve 75, a second thrust bearing 37 is sleeved on the periphery of the small shaft sleeve 75, the screw rod 70 is meshed with the linkage gear shaft 31 through a driven gear 76, and the driven gear 76 is abutted against the bottom of the spline nut 74 through the compression nut 77;

Along the direction from top to bottom of the fourth deep groove ball bearing 35, the large shaft sleeve 73, the small shaft sleeve 75, the spline nut 74, the driven gear 76, the compression nut 77 and the third deep groove ball shaft 34 are sequentially arranged, the fourth deep groove ball bearing 35 is mounted on the reduction gearbox shell 30 through the bearing retainer ring 38, the wear-resistant sleeves 39 are respectively embedded on two sides of the reduction gearbox shell 30, and inner holes 310 used for being hinged with equipment are arranged in the wear-resistant sleeves 39.

The planetary reducer 20 has a characteristic of a small volume and a large reduction ratio; the outer casing of the planetary reducer 20 is fixedly connected to the reduction gearbox casing 30, and the output shaft 21 of the planetary reducer 20 is meshed with the screw rod 70 through the linkage gear shaft 31, so that the rotation motion of the planetary reducer 20 is transmitted to the screw rod 70 through the linkage gear shaft 31 in a speed reduction manner to perform low-speed rotation.

The first shaft shoulder 71 of the screw rod 70 presses down the fourth deep groove ball bearing 35, the lower end of the fourth deep groove ball bearing 35 presses the large shaft sleeve 73, the second shaft shoulder 72 of the screw rod 70 presses down the large shaft sleeve 73, the large shaft sleeve 73 presses down the first thrust bearing 36, and the lower end of the first thrust bearing 36 presses on the reduction gearbox shell 30, so that the downward pressure of the screw rod 70 is transmitted to the reduction gearbox shell 30 through the first thrust bearing 36;

The spline nut 74 is fixedly connected with the screw rod 70 through threads, the spline nut 74 presses the small shaft sleeve 75 upwards, the small shaft sleeve 75 presses the second thrust bearing 37 upwards, the upper end of the second thrust bearing 37 abuts against the gearbox casing 30, and accordingly upward tensile force of the screw rod 70 is transmitted to the gearbox casing 30 through the second thrust bearing 37.

Because the pressure that the electric putter needs to bear in the operating mode is far more than the pulling force, so the thrust bearing of selecting second thrust bearing 37 when designing is less than first thrust bearing 36 in scope, makes second thrust bearing 37 thickness size reduce like this to can reduce the installation distance of push rod.

The driven gear 76 is pressed upward against the lower end of the spline nut 74 by the compression nut 77; the outer ring of the fourth deep groove ball bearing 35 is fixedly mounted on the retainer ring 38, the lower part of the retainer ring 38 cannot move downward by being pressed against the second deep groove ball bearing 35, and the upper part of the retainer ring 38 cannot move upward by being pressed by the outer tube 40, thereby increasing the bearing capacity of the inner tube 50.

The above-mentioned electric putter for automobile tailboard reduces the installation distance through setting up wear-resisting cover 39 on the both sides of reducing gearbox shell 30, and wear-resisting cover 39 utilizes hole 310 to be used for the articulated of equipment, reduces the volume of reducing gearbox shell 30 through adopting planetary reducer 20 and linkage gear shaft 31 complex mode, reduces inner tube 50 length through the first thrust bearing 36 and the second thrust bearing 37 that inner tube 50 bore thrust and with the third deep groove ball axle 34 difference selection that bore tensile, has solved the problem that electric putter is bulky, the push rod overlength, the installation distance is long.

In this embodiment, the reduction gearbox 30, the planetary reducer 20 and the motor 10 are sequentially arranged in a bottom-up direction, and the planetary reducer 20 and the motor 10 are horizontally and oppositely arranged with the outer tube 40, respectively. In this way, the volume of the entire electric putter and the mounting arrangement can be reduced.

In this embodiment, the motor 10 is a band-type brake motor 10. Therefore, under the condition that the motor 10 is not electrified, the rotating shaft of the motor 10 can be locked with the shell of the motor 10, and the push rod braking function is realized by designing an outage band-type brake through the motor 10.

In this embodiment, large fillets 311 are provided at both ends of the reduction gearbox housing 30. Thus, the electric push rod can be prevented from interfering with other parts of the tail plate when rotating.

In the present embodiment, the thrust receiving range of the second thrust bearing 37 is smaller than that of the first thrust bearing 36.

Since the pressure to be borne by the inner tube 50 is much greater than the tensile force in the working condition, the thrust bearing range of the second thrust bearing 37 is selected to be smaller than that of the first thrust bearing 36 in design, so that the thickness dimension of the second thrust bearing 37 is reduced, and the installation distance of the inner tube 50 can be reduced.

In this embodiment, the bottom of the outer tube 40 is mounted on the reduction gearbox shell 30, the top of the outer tube 40 is mounted with an end cover 41, and a first travel switch 42, a second travel switch 43, and a third travel switch 44 for sensing the moving position of the inner tube 50 are respectively and fixedly connected from top to bottom along the inner side wall of the outer tube 40, wherein the first travel switch 42 is an upper limit switch, the second travel switch 43 is a zero limit switch, and the third travel switch 44 is a lower limit switch. The inner tube 50 is provided with a sensing block protruding above to trigger the first travel switch 42, the second travel switch 43 or the third travel switch 44, and the sensing block is arranged between the inner tube 50 and the external appearance. Thus, the tail plate can be controlled to run to a preset position through a plurality of travel switches in the electric push rod and then stop, so that whether the electric push rod moves to the potential energy is clearly known.

The first travel switch 42 is triggered when the inner tube 50 drives the sensing block to operate to an upper limit state, and the third travel switch 44 is triggered when the inner tube 50 drives the sensing block to operate to a lower limit state, so that the electronic limit function of the limit position is achieved;

The second travel switch 43 is a zero limit switch, and the system is reset to zero when the inner tube 50 drives the induction block to run; the electric push rod is responsible for completing the movement of the tail plate from the ground to the carriage in the equal-height process, and a response feedback signal is usually used for controlling the electric push rod to stop in time when the tail plate touches the ground and reaches the carriage contour;

Under normal conditions, the inner tube 50 drives the sensing block to return to zero after passing through the second travel switch 43, at this moment, the fixed distance of extension or retraction of the inner tube 50 receives a feedback signal that the tail plate touches the ground or reaches the contour of the carriage, when the fixed distance is exceeded and the feedback signal is not received yet, the system controls the electric push rod to stop moving and give an alarm and send out a corresponding error code, at this moment, the feedback signal or the zero position can prove that one of the feedback signal or the zero position is broken, and only when the two breaks down simultaneously, the electric push rod can move to a state beyond the set length, thereby causing dangerous accidents, and the function is regarded as a double protection function.

Similarly, when the tail plate moves to the upper limit or the lower limit, the distance from the second travel switch 43 is fixed, and when the inner tube 50 drives the sensing block to move to reach the fixed distance after the second travel switch 43 is zeroed, the feedback signal systems of the first travel switch 42 and the third travel switch 44 do not receive the operation of the inner tube 50, alarm and send out corresponding error codes; only if the second travel switch 43 and one of the limit switches are failed, the electric push rod can lose the electronic limit function so as to be damaged, and the electronic limit switch is a double protection function of electronic limit in the limit position.

In this embodiment, the first anti-swing ring 45, the waterproof sealing ring 46, the second anti-swing ring 47 and the dustproof sealing ring 48 are installed inside the end cover 41, and the first anti-swing ring 45, the waterproof sealing ring 46, the second anti-swing ring 47 and the dustproof sealing ring 48 are sequentially sleeved on the outer periphery of the inner tube 50 along the top direction of the end cover 41. In this way, the tightness within the outer tube 40 can be increased and the stability of the inner tube 50 in operating the telescoping can be increased.

In this embodiment, the first anti-swing ring 45 and the second anti-swing ring 47 are both circular rings with notches. In this way, the first anti-sway ring 45 and the second anti-sway ring 47 can be installed in the end cap 41 without axial fixation.

In this embodiment, the screw rod 70 is provided with a screw rod nut 78, the screw rod nut 78 and the screw rod 70 are a pair of ball screw rods 70, one end of the screw rod nut 78 is connected with a rotation stopping ring 79 and a locking nut 710 through threads, the periphery of the rotation stopping ring 79 is movably embedded in the inner side wall of the outer tube 40, and the other end of the screw rod nut 78 is fixedly connected with the inner tube 50 through threads.

When the screw rod 70 rotates and the screw rod nut 78 cannot rotate, the screw rod nut 78 moves linearly along the axial direction, and the rotation stop ring 79 cannot rotate but can move linearly back and forth along the inner side wall of the outer tube 40 due to the matching of the outer shape of the rotation stop ring 79 with the inner shape of the outer tube 40;

Since the screw nut 78 and the rotation stop ring 79 are fixed together and cannot rotate, the screw nut 78 carries the inner tube 50 to do telescopic linear operation when the screw 70 rotates; the use of the ball screw 70 pair converts rotational motion into linear motion with high efficiency.

In this embodiment, a third anti-swing ring 711, a spacer 712 and a fixing nut 713 are disposed on the top of the screw rod 70, the spacer 712 is pressed on the top of the screw rod 70 by the third anti-swing ring 711 through the fixing nut 713, and the third anti-swing ring 711 is located between the screw rod 70 and the inner tube 50. The third anti-sway bar 711 is interposed between the lead screw 70 and the inner pipe 50 and functions to prevent the end of the lead screw 70 from bending and swaying.

The foregoing description of the preferred embodiments of the utility model is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the utility model.

Claims (10)

1. The electric push rod for the automobile tail plate is characterized by comprising an outer pipe and an inner pipe, wherein the inner end of the inner pipe is arranged in the outer pipe, a connector is connected to the outer end of the inner pipe, the connector is exposed out of the outer pipe, a reduction gearbox shell is arranged on the outer pipe, a motor is arranged on the reduction gearbox shell, the reduction gearbox shell is connected with the motor through a planetary reducer, an output shaft on the planetary reducer is meshed with a screw rod through a linkage gear shaft, the upper end and the lower end of the linkage gear shaft are respectively arranged in the reduction gearbox shell through first deep groove ball bearings, and the output shaft on the planetary reducer is fixed in the reduction gearbox shell through second deep groove ball shafts;

The screw rod is positioned in the outer tube, the bottom end of the screw rod is arranged in the bottom of the reduction gearbox shell through a third deep groove ball shaft, a first shaft shoulder of the screw rod is downwards abutted to a fourth deep groove ball bearing, the fourth deep groove ball bearing is sleeved on the screw rod, a second shaft shoulder of the screw rod and the bottom of the fourth deep groove ball shaft are downwards abutted to a large shaft sleeve respectively, the large shaft sleeve is sleeved on the screw rod, a first thrust bearing is sleeved on the periphery of the large shaft sleeve, the bottom of the first thrust bearing is abutted to the reduction gearbox shell, a spline nut is connected to the periphery of the screw rod in a threaded manner, the top of the spline nut is upwards abutted to a small shaft sleeve, a second thrust bearing is sleeved on the periphery of the small shaft sleeve, the top of the second thrust bearing is abutted to the reduction gearbox shell, the screw rod is meshed with a gear shaft through a driven gear, and the driven gear is abutted to the bottom of the spline nut through a compression nut;

Along fourth deep groove ball bearing top-down's direction, fourth deep groove ball bearing, big axle sleeve, little axle sleeve, spline nut, driven gear, gland nut and third deep groove ball axle arrange in proper order, will through the bearing retainer ring fourth deep groove ball bearing installs on the reducing gear box shell, the wear-resisting cover has been embedded respectively on the both sides of reducing gear box shell, be equipped with the hole that is used for articulated connection with equipment in the wear-resisting cover.

2. The electric putter for an automobile tailgate according to claim 1 wherein the reduction gearbox housing and the planetary reducer and the motor are sequentially arranged in a bottom-up direction, the planetary reducer and the motor being respectively arranged horizontally opposite to the outer tube.

3. An electric putter for an automotive tailgate according to claim 2 wherein said motor is a band-type brake motor.

4. The electric putter for an automobile tailgate according to claim 3 wherein said reduction gearbox housing is provided with large fillets at both ends thereof.

5. The electric putter for an automotive tailgate according to claim 4 wherein said second thrust bearing is thrust-bearing less than said first thrust bearing.

6. The electric putter for automobile tailgate according to any one of claims 1 to 5 wherein the bottom of the outer tube is mounted on a reduction gearbox housing, an end cover is mounted on the top of the outer tube, a first travel switch, a second travel switch, a third travel switch for sensing the movement position of the inner tube are respectively fixedly connected from top to bottom along the inner side wall of the outer tube, the first travel switch is an upper limit switch, the second travel switch is a zero limit switch, and the third travel switch is a lower limit switch.

7. The electric putter for an automobile tailgate according to claim 6 wherein the end cap has first and second anti-sway rings, a waterproof seal ring, and a dustproof seal ring mounted therein, the first, waterproof, second, and dustproof seal rings being sequentially sleeved on the outer circumference of the inner tube along the top direction of the end cap.

8. The electric putter for an automobile tailgate according to claim 7 wherein said first and second anti-sway collars each employ a ring having a notch.

9. The electric putter for automobile tailgate according to any one of claims 1 to 5 wherein a screw nut is provided on the screw, the screw nut and the screw being a ball screw pair, one end of the screw nut being connected to a rotation stop ring and a lock nut by screw threads, the outer circumference of the rotation stop ring being movably embedded in the inner side wall of the outer tube, the other end of the screw nut being fixedly connected to the inner tube by screw threads.

10. The electric putter for an automobile tailgate according to claim 9 wherein the top of the screw is provided with a third anti-sway ring, a washer, a fixing nut, the third anti-sway ring pressing the washer against the top of the screw through the fixing nut, the third anti-sway ring being located between the screw and the inner tube.