DE102017127900B3 - Level control device for a strut of a motor vehicle - Google Patents

Abstract

Level control device (1) for a spring strut (2) of a motor vehicle (3), comprising at least the following components: - a rotationally fixed adjusting spindle (4) with a spindle axis (5); - an adjusting nut (6) by means of which the adjusting spindle (4) a main support unit (7) for the adjusting nut (6) for receiving axial forces (16) in an axial main direction (8), - a main bearing (9) which is located between the adjusting nut (6). 6) and the main support unit (7) is arranged to permit a low-friction relative rotation between the adjusting nut (6) and the main support unit (7), - a biasing member (10, 28) which the Verstellmutter (6) with a predetermined biasing force (11) presses against the main bearing (9), - a slide unit (12, 30), which is designed to receive axial forces (16) in an axial opposite direction (13) and for low-friction relative rotation between the adjusting nut (6). and the biasing member (10, 28), the opposite direction (13) being opposite to the main direction (8), characterized in that the biasing member (10) is disposed between the main bearing (9) and the main support unit (7).

Description

The invention relates to a level control device for a strut of a motor vehicle according to the preamble of claim 1, a strut with such a level control device, and a motor vehicle with such a strut.

Level control devices for a strut of a motor vehicle are known from the prior art. The task of the level control device is to set the vehicle height, ie the ground clearance. For many applications, it has proven useful to provide a central rotationally fixed adjusting spindle, on which along its spindle axis a corresponding adjusting nut is axially movable. For example, such a spindle drive is designed as a ball screw. The adjusting nut is supported rotatably about the spindle axis axially in a spring strut housing, to which support a main bearing, for example, an angular contact ball bearing, is provided. When used in a motor vehicle, the entire weight of the motor vehicle or its specific weight proportion for the suspension strut is located on this main bearing. In such a main state of the strut, the set position, so the centering of the main bearing to the spindle axis, ensured. In other conditions in which the weight of the motor vehicle is lifted to the main bearing, for example, in the delivery state or replacement or temporary removal in a repair or maintenance on the motor vehicle, the location of the main bearing must still be ensured. For this purpose, a biasing bearing is provided in the prior art, which is arranged relative to the main bearing on the opposite side of the adjusting nut. By means of the preload bearing, usually with the use of a compensating element, a minimum preload force on the main bearing is permanently kept to its position assurance. The disadvantage here is that in all operating conditions in addition to the main bearing a friction caused by the preload bearing is overcome. The high friction power must be reduced as a rule by using a complex axial roller bearing.

The DE 10 2014 203 861 A1 shows a generic type actuator assembly for a level adjustment in a motor vehicle, wherein at least two separate actuators are included and each for obtaining a linear motion component having actuator movement rotatably driven element, and a common drive motor is present, which is coupled via drive connections with the elements of both actuators is.

The DE 10 2016 213 424 A1 shows a suspension element, with a screw drive, which comprises a threaded spindle and a spindle nut which is mounted by means of a thrust bearing in a housing, wherein the axial bearing is designed as a rolling bearing, roll their rolling elements directly on the spindle nut.

On this basis, the present invention has the object, at least partially overcome the known from the prior art disadvantages. The features of the invention will become apparent from the independent claims, to which advantageous embodiments are indicated in the dependent claims. The features of the claims may be combined in any technically meaningful manner, and to this end, the explanations of the following description and features of the figures may be used, which include additional embodiments of the invention.

• - eine rotationsfeste Verstellspindel mit einer Spindelachse;
• - eine Verstellmutter, mittels welcher die Verstellspindel relativ zu der Verstellmutter axial verfahrbar ist;
• - eine Hauptstützeinheit für die Verstellmutter zur Aufnahme von Axialkräften in einer axialen Hauptrichtung;
• - ein Hauptlager, welches zwischen der Verstellmutter und der Hauptstützeinheit angeordnet ist, um ein reibungsarmes relatives Verdrehen zwischen der Verstellmutter und der Hauptstützeinheit zu ermöglichen;
• - ein Vorspannelement, welches die Verstellmutter mit einer vorbestimmten Vorspannkraft gegen das Hauptlager presst;
• - eine Gleiteinheit, welche zur Aufnahme von Axialkräften in einer axialen Gegenrichtung und für ein reibungsarmes relatives Verdrehen zwischen der Verstellmutter und dem Vorspannelement (10, 28) eingerichtet ist, wobei die Gegenrichtung der Hauptrichtung entgegengesetzt ausgerichtet ist.

The invention relates to a level control device for a strut of a motor vehicle, comprising at least the following components:

• - A rotationally fixed adjusting spindle with a spindle axis;
• - An adjusting nut, by means of which the adjusting spindle is axially movable relative to the adjusting nut;
• - A main support unit for the adjusting nut for receiving axial forces in an axial main direction;
• a main bearing, which is arranged between the adjusting nut and the main support unit to allow a low-friction relative rotation between the adjusting nut and the main support unit;
• - A biasing member which presses the adjusting nut with a predetermined biasing force against the main bearing;
• a sliding unit adapted to receive axial forces in an axially opposite direction and for a low-friction relative rotation between the adjusting nut and the biasing element (US Pat. 10 . 28 ), the opposite direction being opposite to the main direction.

The leveling device is mainly characterized in that the biasing element between the main bearing and the main support unit is arranged.

In the following, reference will be made to this spindle axis if the axial direction, radial direction or direction is explicitly different Reverse direction and corresponding terms are used.

The level control device according to the invention fulfills the tasks described above for setting a desired underfloor distance by means of a shock absorber. For this purpose, a rotationally fixed adjusting spindle is provided, which is axially movable by means of the adjusting nut, which is rotatable about the spindle axis of the adjusting spindle, as a result of a rotation of the adjusting nut relative to the adjusting spindle according to the thread pitch. Alternatively, the adjusting spindle is rotationally fixed and fixed axially and the adjusting nut moves axially and takes a corresponding strut casing with. The adjusting nut is axially supported by means of a main bearing on a main support unit of a spring housing. The main support unit is directly or indirectly either on the supported element, such as the chassis of a motor vehicle, or the corresponding element whose level, ie axial distance to the chassis to be adjusted, for example, a vehicle, supported or formed thereof.

The biasing element according to the invention now acts in marked contrast to the previously known solutions not in the main direction of the main bearing to press the main bearing against the main support unit. Rather, the biasing element between the main support unit and the main bearing is arranged and acts in the opposite direction to the main direction. As a result, the main bearing is pressed with the adjusting nut against a sliding unit which is adapted to receive axial forces in the opposite direction. By the adjusting nut is pressed against the sliding unit, the main bearing is clamped between the biasing member and the adjusting nut supported on the sliding unit. However, this happens only in such a state in which the axial forces are lower in the axial main direction than the biasing force or in total with the weight of the damped suspended element, such as a vehicle. For example, such a condition exists when the shock absorber is delivered to the fitter for installation in a motor vehicle.

This structure has the advantage that it is possible to dispense with a compensation element, because an adjustment of the distance by means of the biasing element is adjustable. A complex preload bearing, for example in the sliding unit, can be omitted, and the invention proposed biasing element is the only biasing element for the opposite direction. It is also provided no biasing element in the main direction. Rather, the sliding unit takes over in cooperation with the biasing member the task of biasing the main bearing in other states than the main state.

According to an advantageous embodiment of the level control device, the main support unit and the sliding unit are integrally formed by a common spring strut housing or one or both of these components is supported as a separate element in the common spring strut housing.

In this preferred embodiment, the main support unit and / or the sliding unit are formed or comprised of a common strut housing, so that the spring strut housing forms a clamp. Preferably, the spring strut housing is designed in two parts or in several parts, so that the level control device is easy to assemble. Alternatively or additionally, the main support unit is designed as a separate element which can be mounted in the spring strut housing. Likewise, alternatively or additionally, the sliding unit is designed as a separate element which can be mounted in the spring strut housing, preferably a different housing half of the spring strut housing than that of the main support unit.

• - zumindest eine Tellerfeder;
• - zumindest eine Wellfeder; und
• - zumindest eine Spiralfeder.

According to an advantageous embodiment of the level regulating device, the biasing element comprises at least one, preferably only one, of the following elements:

• - at least one plate spring;
• - At least one wave spring; and
• - At least one coil spring.

According to one of these advantageous embodiments, the biasing element is designed as a spring, preferably a steel spring. While a coil spring is particularly cost-effective, a plate spring or corrugated spring is particularly advantageous because in this way a very high spring force can be generated in an axially small space. A plate spring is particularly advantageous because in this case a force transmission is adjustable by means of the lever spacing of the antagonistic force application points. In a particularly preferred embodiment, the biasing member is designed with a degressive spring characteristic, so that the biasing force increases less with increasing compression or even in the brought to block state (main state) is less than in the maximum rebound state (predetermined load limit reached).

According to an advantageous embodiment of the level control device, the adjusting nut is axially spaced from an axial force in the main direction above a predetermined load limit of the sliding unit and pressed upon reaching the predetermined load limit of the biasing member axially against the sliding unit.

In this particularly advantageous embodiment, a predetermined load limit for an axial force in the main direction is provided, wherein the adjusting nut is spaced at an axial force above this load limit of the sliding unit, so that there is no contact friction. Upon reaching this load limit, however, the adjusting nut is pressed axially against the sliding unit, so that a minimum preload force is ensured on the main bearing. This load limit is adapted to the specific load of the relevant strut, for example, the specific proportion of vehicle weight. Thus, in a normal driving condition (main condition), the adjusting nut would be jammed by the sliding unit and pressed against the sliding unit alone in the other states, for example when the strut is removed. As a result, it is possible to design the sliding unit cost-effective, wherein the coefficient of friction compared to a rolling bearing is significantly higher and / or the sliding unit already at a few relative rotations under load, so at contact at least under biasing force, comes to a maximum of the lifetime. The maximum lifetime under this load assumption or the number of load changes can be reduced by a factor of 10 ³ [1,000] compared to the design of a conventional preload bearing. It should be noted that the predetermined load limit is usually well above an empty load condition described above, so that, for example, a multiple removal and installation of a strut over a lifetime of, for example, 150,000 km to 300,000 km even with improper use of the removed strut or the expansion and installation of the shock absorber is ensured.

According to an advantageous embodiment of the level control device, the main bearing comprises a main support side first bearing element and a nut side second bearing element, wherein only the first bearing element is guided both when applying an axial force in the main direction above the load limit and each load condition below the load limit radially, preferably centered to the spindle axis is.

In this preferred embodiment, the main bearing is radially guided in all load states, preferably centered by means of the spring housing and / or preferably to the spindle axis. The main support side first bearing element is, for example, a bearing ring of a rolling bearing, for example, an angular contact ball bearing or a Wälzkegellagers, and the radial guide surface is sleeve-like, and preferably has a low coefficient of friction. The mother-side second bearing element of the main bearing, for example according to an (antagonistic) bearing ring of a rolling bearing, is preferably guided solely on the main support side first bearing element, wherein the relative position between the two bearing elements in the main state by means of the acting weight and in other states, for example upon reaching the predetermined load limit, is ensured by means of the biasing force applied by the biasing element.

According to an advantageous embodiment of the level control device, the biasing element is loaded when the load limit is exceeded such that the biasing element is brought to block, and the biasing element forms in block brought on a flat bearing surface for the main bearing.

• - ein Schraubenfederelement mit nur einer Windung, sodass kein Windungsabschnitt überlappt, oder
• - eine Wellfeder, deren Wellen glatt auflegbar sind, beispielsweise mittels einer radialen Dehnung der Wellfeder oder mittels Aussparung im Material für Dehnungen in radialer Richtung und/oder in Umfangsrichtung, oder
• - eine Tellerfeder beziehungsweise eine Membranfeder welche auf Block gebracht einen Anstellwinkel von 0° in der Ebene senkrecht zum Federweg, bevorzugt senkrecht zu der Spindelachse, der Tellerfeder aufweist.

In this advantageous embodiment, the biasing element in the main state, ie, for example, when the predetermined load limit is exceeded, switched off. That is, the biasing member does not provide an available spring travel because the biasing member is brought to block. Here, the biasing member preferably forms a plane bearing surface for the main bearing, so that the largest possible contact surface and thus the lowest possible surface pressure on the main bearing or the respective bearing element are present. For this purpose, the biasing element is preferred either

• a helical spring element with only one turn, so that no turn section overlaps, or
• - A corrugated spring whose waves are smoothly placed, for example by means of a radial expansion of the corrugated spring or by means of recess in the material for strains in the radial direction and / or in the circumferential direction, or
• - A plate spring or a diaphragm spring which brought to block an angle of attack of 0 ° in the plane perpendicular to the spring travel, preferably perpendicular to the spindle axis, the plate spring.

On a conventionally necessary shim or the like can be dispensed with in the illustrated embodiments of the invention. Any tolerances in the assembly chain are usually irrelevant to the function of the shock absorber. The conventionally used shim was necessary to ensure sufficient preload for the main bearing. In the main state, the bias is ensured by the weight. In other states, the inventively proposed biasing element acts.

According to a further aspect, the invention relates to a shock absorber for a motor vehicle, comprising a spring strut housing and a Level control device according to one embodiment as described above.

According to this advantageous embodiment, the suspension strut is equipped with the previously described leveling device, so that, for example, the underbody height of a motor vehicle is adjustable. The friction of such a shock absorber is significantly reduced in the main state and represent the structure considerably cheaper, because it can be dispensed with a complex rolling bearing and / or a sheave together with associated quality assurance step. Such a level control device can be used, for example, for off-road sports cars (SUV, English: Sport Utility Vehicle), but also in smaller vehicles.

According to a further aspect, the invention relates to a motor vehicle with a plurality of wheels, wherein at least one of the wheels is damped by means of a strut according to one embodiment as described above in the direction of gravity.

According to this aspect of the invention, a motor vehicle is provided with at least one such strut, preferably in a passenger car at least at two steerable wheels.

According to an advantageous embodiment of the motor vehicle, the motor vehicle comprises at least one strut with a level control device, in which the adjusting nut is axially spaced by a thrust unit of axial force in the main direction above a predetermined load limit and pressed upon reaching the predetermined load limit of the biasing member axially against the sliding unit is, wherein the load limit is smaller than a stored for the means of the associated strut vehicle specific weight fraction of the motor vehicle.

In this advantageous embodiment, the adjusting nut in the main state of the shock absorber is axially spaced from the sliding unit, and the biasing member loaded to block. When the strut in question is removed, the adjusting nut is pressed against the sliding unit. Then there is a contact friction between the adjusting nut and the sliding unit. Thus, it is permanently ensured that the main bearing is securely positioned and preferably centered, but at the same time in most states, the adjusting nut alone has to overcome the low friction of the main bearing. Particularly preferably, the biasing element is brought to block in the main state and is then turned off, so has a reduced as a result of a degressive spring characteristic biasing force.

• 1: eine Niveaureguliervorrichtung mit konventioneller Vorspannung;
• 2: eine Niveaureguliervorrichtung mit Tellerfeder im ausgefederten Zustand;
• 3: die Niveaureguliervorrichtung von 2 im Hauptzustand; und
• 4: ein Kraftfahrzeug mit Federbeinen.

The above-described invention will be explained in detail in the background of the relevant technical background with reference to the accompanying drawings, which show preferred embodiments. The invention is not limited by the purely schematic drawings in any way, it being noted that the drawings are not dimensionally accurate and are not suitable for the definition of size ratios. It is shown in

• 1 a level control device with conventional bias voltage;
• 2 : a leveling device with plate spring in the rebounded state;
• 3 : the leveling device of 2 in the main state; and
• 4 : a motor vehicle with struts.

Ordinal numbers used in the preceding and following description, unless explicitly stated to the contrary, are for the purpose of distinctness only and do not represent any order or ranking of the designated components.

In 1 is an example of a level control device 1 in the section shown in section, as they are for a strut 2 of a motor vehicle 3 can be used (see. 4 ). To the spindle axis 5 are at least the adjusting spindle 4 and the relatively axially movable adjusting nut 6 arranged rotationally symmetrical. The spindle system is exemplified as a ball screw. Here is a spring leg housing 15 provided in which the adjusting nut 6 is included. Either the strut housing moves 15 axially with the adjusting nut 6 with or the strut casing 15 is fixed and the adjusting spindle 4 moves to it axially. In an application in a motor vehicle 3 (see 4 ) is the spring leg housing 15 itself either sprung and / or damped against, for example, a chassis of a motor vehicle 3 supported or firmly connected to such a chassis. A conventional main spring and / or a conventional main damper (not shown) are in series with the leveling device 1 connected. The main direction 8th is gravity 19 opposite direction. In the main state, the vehicle weight at least partially on the strut 2 and it results in an axial force 16 in the main direction 8th , It is the main state with an axial force 16 in the main direction 8th represented by means of the main bearing 9 is absorbable such that the axial force 16 in the strut casing 15 over the main support unit 7 can be introduced and at the same time the adjusting nut 6 relative to the strut housing 15 (and the adjusting spindle 4 ) is rotatable. Resulting from such a rotation an axial relative movement between the adjusting spindle 4 and strut casing 15 , The main support unit 7 is a component of the multi-part spring housing 15 and forms a support surface in the plane perpendicular to the spindle axis 5 and a cylindrical centering surface as a lateral surface relative to the spindle axis 5 , As a result, the main bearing on the one hand axially to initiate the axial force 16 in the main direction 8th supported and on the other to the spindle axis 5 centered. The main camp 9 is as an angular contact ball bearing with a main support side first bearing element 17 and a nut side second bearing element 27 , which are designed as bearing rings executed. The axial force 16 in the main direction 8th This ensures a radial preload. However, in the case when the strut is from a motor vehicle 3 is removed for maintenance. For such a condition is a conventional biasing element 28 provided, which via a conventional sliding unit 30 permanently a conventional preload force 29 in the main direction 8th applies. In the main state thus acts on the main camp 9 not just the axial force 16 resulting from a major load, such as gravity 19 but also the conventional preload force 29 , Conventionally, in addition an axial compensation element for adjusting the conventional biasing force due to manufacturing tolerances and mounting tolerances is used, for example, a disc-shaped element (shim) with a set according to need thickness in the main direction 8th , Furthermore, the conventional sliding unit is located 30 permanently on the adjusting nut 6 on, whereby a relatively complicated Axialwälzlager is necessary to keep the friction sufficiently low.

In 2 is a leveling device 1 shown, which in large part with the level control device 1 to 1 at least functionally identical. In detail, the structure of the multi-part designed spring housing 15 different and it is instead of an angular contact ball bearing as a main bearing 9 a Wälzkegellager is provided. Concerning the basic contexts and component description, the previous paragraph is referred to the 1 and the general description. An essential difference to the conventional embodiment of a leveling device 1 lies in the way the preload on the main bearing 9 is ensured, so that at least the first bearing element 17 remains centered in all states. The biasing element 10 is between the main camp 9 and the main support unit 7 arranged, and designed as a plate spring or diaphragm spring. The illustrated state is a state in which the axial force 16 in the main direction 8th less than the sum of axial force 16 and preload force 11 in the opposite direction 13 in that a predetermined load limit has been undershot. As a result, the biasing element 10 rebounds and presses the adjusting nut 6 in the opposite direction 13 against the sliding unit 12 , As a result, one acts for a desired preload force 11 sufficient axial force 16 to the main camp 9 , Here is the main support unit 7 executed such that the first bearing element 17 in every condition even with very low preload force 11 remains centered. Because the state shown is not the main state and / or in the state shown, a twisting of the adjusting nut 6 is acceptable with an increased friction in terms of wear and / or applied actuating forces, a low-cost and easy-to-install sliding unit is used, for example, a dry sliding bearing. In addition, can be dispensed with a shim, because by means of a reserve in the spring travel of the biasing member 10 a corresponding tolerance can be bridged.

In 3 is the leveling device 1 according to 2 shown in the main state. The axial force 16 in the main direction 8th is so great that the antagonistic forces in the opposite direction 13 are overcome, so the predetermined load limit is exceeded. The load limit is in the illustrated state, preferably the main state, so far exceeded that the biasing element 10 brought to block and a plane contact surface 18 forms. Resulting from the maximum deflection of the preload element 10 is the adjusting nut 6 from the sliding unit 12 by means of the slide bearing clearance 31 from the strut casing 15 on the slide unit side. So there is no friction and only the main bearing 10 provides a small to be overcome friction during rotation of the adjusting nut 6 , A geometric tolerance compensation is preferably not necessary because the tolerances in the main direction 8th within the spring travel of the biasing element 10 are compensable. The preload force 11 acts in the opposite direction 13 and not summing up with the axial force 16 in the main direction. In a particularly preferred embodiment, the biasing element 10 designed with a degressive spring characteristic, so that the preload force 11 Increases less strongly with increasing compression or even in the brought to block state (main state) is less than in the maximum rebounded state (predetermined load limit is exceeded).

In 4 is a motor vehicle 3 shown schematically, in front of a driver's cab 24 a left (steerable) front wheel 20 and a right (steerable) front wheel 21 , as well as behind the driver's cab 24 a left rear wheel 22 and a right rear wheel 23 each by means of a strut 2 , for example as in 2 and in 3 are shown, stored. The front wheels 20 and 21 are by means of a handlebar 26 steerable, and are driven by a drive unit, not shown. The rear wheels 22 and 23 are parallel to the longitudinal axis 25 hung rigidly hung.

With the level control device according to the invention, the construction of the spindle system in the spring strut housing is simplified, low-friction and cost-effective executable.

LIST OF REFERENCE NUMBERS

1

Niveaureguliervorrichtung

2

strut

3

motor vehicle

4

adjusting spindle

5

spindle axis

6

adjusting nut

7

Main support unit

8th

main direction

9

main bearing

10

biasing member

11

preload force

12

slide

13

opposite direction

14

preload bearings

15

Strut housings

16

Axial force

17

first bearing element

18

plane contact surface

19

gravity

20

left front wheel

21

right front wheel

22

left rear wheel

23

right rear wheel

24

cab

25

longitudinal axis

26

handlebars

27

second bearing element

28

conventional biasing element

29

conventional preload force

30

conventional sliding unit

31

plain bearing distance

Claims (9)

Level control device (1) for a suspension strut (2) of a motor vehicle (3), comprising at least the following components: - a rotationally fixed adjusting spindle (4) with a spindle axis (5); - An adjusting nut (6), by means of which the adjusting spindle (4) relative to the adjusting nut (6) is axially movable; - A main support unit (7) for the adjusting nut (6) for receiving axial forces (16) in an axial main direction (8); - A main bearing (9) which is arranged between the adjusting nut (6) and the main support unit (7) to allow a low-friction relative rotation between the adjusting nut (6) and the main support unit (7); - A biasing member (10, 28) which presses the adjusting nut (6) with a predetermined biasing force (11) against the main bearing (9); - A slide unit (12, 30) which is adapted to receive axial forces (16) in an axial opposite direction (13) and for a low-friction relative rotation between the adjusting nut (6) and the biasing member (10, 28), wherein the opposite direction (13) of the main direction (8) is oppositely oriented, characterized in that the biasing member (10) between the main bearing (9) and the main support unit (7) is arranged. Level control device (1) according to Claim 1 wherein the main support unit (7) and the slide unit (12) are integrally formed by a common spring strut housing (15) or one or both of these components are supported as a separate element in the common spring strut housing (15). Level control device (1) according to Claim 1 or 2 wherein the biasing element (10) comprises at least one, preferably only one, of the following elements: - at least one plate spring; - At least one wave spring; and - at least one coil spring. A level control device (1) according to any one of the preceding claims, wherein the adjusting nut (6) is axially spaced from the slide unit (12) when a thrust force (16) is applied in the main direction (8) above a predetermined load limit and when the predetermined load limit is reached by the biasing element (10) is pressed axially against the sliding unit (12). Level control device (1) according to Claim 4 wherein the main bearing (9) comprises a main support side first bearing element (17) and a nut side second bearing element (27), wherein only the first bearing element (17) both on application of an axial force (16) in the main direction (8) above the load limit as well is radially guided at each load state until reaching the predetermined load limit and centered to the spindle axis (5). Level control device (1) according to Claim 4 or 5 wherein the biasing member (10) is loaded when the load limit is exceeded so that the biasing member (10) is brought to block, and the biasing member (10) forms a plane contact surface (18) for the main bearing (9) in the block , Suspension strut (2) for a motor vehicle (3), comprising a suspension housing (15) and a leveling device (1) according to one of the Claims 2 to 6 , Motor vehicle (3), comprising a plurality of wheels (20, 21, 22, 23), wherein at least one of the wheels (20, 21, 22, 23) by means of a strut (2) according to Claim 7 is stored damped in the direction of gravity (19). Motor vehicle (3) according to Claim 8 comprising at least one spring strut (2) comprising a level regulating device (1) Claim 4 , wherein the load limit is smaller than a specific own weight portion of the motor vehicle (3) for the vehicle wheel (20, 21, 22, 23) mounted by means of the associated shock absorber (2).

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