Description:FORM 2
The Patent Act 1970
(39 of 1970)
and
The Patent Rules, 2005

COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

TITLE OF THE INVENTION
“COMPACT SHOCK ABSORBER FOR A MOTORBIKE”

Endurance Technologies Limited
E-92, M.I.D.C. Industrial Area, Waluj,
Aurangabad – 431136, Maharashtra, India

The following specification particularly describes and ascertains the nature of this invention and the manner in which it is to be performed.

Field of Invention

[001] The present invention is related to a shock absorber for a motorbike. More particularly, the present invention is related to a shock absorber having an intelligent construction of rod guide and oil seal making the shock absorber compact, eliminating the components and adaptable in motorbikes having the space constraint beneath the seat.

Background of the Invention

[002] In order to have a safe and comfortable ride, shock absorbers are generally employed in motorbikes to absorb the energy of the impact caused by the irregularity on the road surface and soften the subsequent oscillations. The shock absorbers are mainly of two types based on its construction viz. twin tube shock absorbers which have double-wall oil storage tubes, and mono tube shock absorbers which have single-wall oil storage tube.

[003] The mono-tube shock absorber has a gas chamber and an oil chamber. A separation (or free) piston acts as a partitioning member for the oil chamber and gas chamber. The mono-tube shock absorbers are generally mounted at an angle with the vertical and said angle may range up to 40°. The inclined mounting of the shock absorbers necessitates the maintenance of the pressure in the oil chamber which is assisted by the gas chamber. However, the inclination angle of the shock absorber depends upon the seat height of the motorbike from the ground. The lesser is the seat height of the motorbike, the higher is the inclination angle of the shock absorber from the vertical. The kid’s motorbikes having electric / engine propulsion is the typical example of the motorbikes having lesser seat height and a big constraint of space beneath the seat for mounting the shock absorber. In such motorbikes, the mounting angle of the shock absorbers is much higher, even more than 40O but less that 90O.

[004] In the electric / engine powered mini / kid’s motorbikes, the seat height from the ground generally ranges from 430 to 700 mm leading to the space constraint for mounting the shock absorbers. Therefore, in such motorbikes higher inclination angle of the shock absorber from the vertical imposes design challenges for the efficient shock absorber being very less packaging space beneath the seat and higher chances of emulsification of the damping fluid at low mounting conditions from the ground. To address these technical challenges, there is a long pending unmet need to provide a compact shock absorber for electric / engine powered kid’s motorbikes that efficiently works at par and is mountable in the available space beneath the seat and thus addressing the issue of space constraint and inclination angle.

Objectives of the Present Invention

[005] The main object of the present invention is to provide a compact shock absorber for electric / engine powered kids’ motorbikes.

[006] Another object of the present invention is to provide a compact shock absorber for electric / engine powered kids’ motorbikes wherein said shock absorber is configured to have an intelligent construction of rod guide and oil seal making the shock absorber compact, eliminating the components and adaptable in motorbikes having the space constraint beneath the seat.
[007] Another object of the present invention is to provide a compact shock absorber for electric / engine powered kids’ motorbikes having the seat height ranging from 430 to 700 mm.

[008] Another objective of the present invention is to provide a compact shock absorber for motorbikes that addresses the issue of stroke and length limitation and impart at par operational efficiency.

[009] Still the objective of the present invention is to provide a compact shock absorber configured to have a means for recharging the gas so as to eliminate the small amplitude high frequency vibrations / undulations.

[0010] Yet another objective of the present invention is to provide a compact shock absorber which require less assembly cycle time and is cost effective.

Description of Drawings

[0011] This invention is illustrated in the accompanying drawings, throughout which like reference letters / numerals indicate the corresponding parts in the various figures. The embodiment herein and the advantages thereof will be better understood from the following description when read in conjunction with the following drawings, wherein

[0012] Figure 1 discloses an isometric view of the compact shock absorber for motorbikes in accordance with the present invention.

[0013] Figure 2 discloses an exploded view of the compact shock absorber as per the present invention.

[0014] Figure 3 discloses an enlarged view and cut-sectional view of the piston rod assembly of the shock absorber in accordance with the present invention.

[0015] Figure 4 shows an enlarged view and cut-sectional view of the outer tube assembly of the shock absorber as per the present invention.

[0016] Figures 5a, 5b and 5c present cut-sectional views of the oil seal, rod guide and bottom cap, respectively of the shock absorber of the present invention.

[0017] Figure 6 discloses front and side cut-sectional views of the compact shock absorber in accordance with the present invention.

[0018] Figure 7 shows the compact shock absorber of the present invention mounted on the motorbike.

Detailed Description of the Present Invention

[0019] The invention will now be described in detail with reference to the accompanying drawings which must not be viewed as restricting the scope and ambit of the invention. Referring to Figs. 1 and 2, the compact shock absorber (500) of the present invention comprises of a piston rod assembly (50), an outer tube assembly (100), a spring (20), an adjuster (25) and a spring locator (15).
[0020] Referring to Fig. 3, the piston rod assembly (50) further comprises of a tube ring (10), a bump stop (65), a bump stop washer (65W), a piston rod (45), an oil seal (70), a cap seal washer (W), a rod guide (75), a rod guide bush (72), a rebound bumper (80), a support plate (85), a piston (90), a piston band (90B), a piston support plate (90P) and a nut (90N).

[0021] Referring to Fig. 3, the piston rod (45) of the piston rod assembly (50) is configured to have cylindrical stepped profile throughout its length forming three portions viz. a proximal portion (45P1), a center portion (45P2) and a distal portion (45P3). The proximal portion (45P1) of the piston rod (45) has a pointed tapered end and said tapered end of the proximal portion (45P1) is connected with the tube ring (10) by suitable fastening means preferably selected from welding. The center portion (45P2) of the piston rod has a diameter greater than the diameter of the proximal portion (45P1). The distal portion (45P3) has a diameter smaller than the diameter of the center portion (45P2) and is formed at the end of the center portion (45P2). Thus, the diameter of the stepped portions of the piston rod (45) is in the order 45P2 > 45P1> 45P3 and the axial length of the stepped portions of the piston rod (45) is in the order 45P2 > 45P3 > 45P1. The ratio of the axial length of the stepped portions is 2.20L > L > 0.25L; wherein L is the axial length of distal portion (45P3).

[0022] The oil seal (70) in accordance with the present invention (refer Figs. 3 and 5a) comprises of an elastomeric body portion (70A), a uniquely profiled reinforcing metal insert (70M) and a reinforcement ring (70R). The oil seal (70) is formed by over-molding the elastomeric material around the metal insert (70M). The said oil seal (70) forms a unique profile having a first seal lip (70L1), a second seal lip (70L2), a third seal lip (70L3), a base portion (70B) and a seal wing (70W).
[0023] The first seal lip (70L1) converges away from the inner edge of reinforcing metal insert (70M). The second seal lip (70L2) also converges away from inner edge of reinforcing metal insert (70M) but in a direction opposite to that of first seal lip (70L1). The third seal lip (70L3) further converges away from the reinforcement ring (70R) but in the same direction as that of second seal lip (70L2). The reinforcement ring (70R) is placed in a recess formed around the third seal lip (70L3). The oil seal (70) is profiled in such way that it forms an inverted frustum shaped annular recess (70R1) between the base portion (70B) and the first seal lip (70L1) but above the reinforcement mental insert (70M) of the oil seal (70); and forms a frustum shaped annular recess (70R2) between the seal wing (70W) and the inner periphery of the second seal lip (70L2) but below the reinforcement metal insert (70M). Thus, both the recesses (70R1 and 70R2) of the seal (70) are formed opposite to each other but facing towards the reinforcement metal insert (70M).

[0024] The reinforcement ring (70R) is positioned in a recess formed around the third seal lip (70L3) of the seal (70) in order to apply radial load on the seal lip (70L3) thereby enhancing the sealing effect on the piston rod (45). The said seal lips (70L1, 70L2 and 70L3) are formed in a manner so as to allow the passage of the piston rod (45) by deforming over the piston rod (45) enhancing the gripping and sealing effect. This uniquely profiled construction of the seal (70) seals the interface with the piston rod (45) and the inner surface of the outer tube (40) as well eliminating the requirement of O-rings, a pair of back up rings, dust scrapper and a circlip in this shock absorber of the present invention.

[0025] The rod guide (75) in accordance with the present invention (refer Figs. 3 and 5b) is made from metal preferably selected from Aluminum and is configured to have a cylindrical body with extended wing profile (75W) at the lower side (75L) of the said rod guide (75) forming an inverted frustum shaped cavity (75R) at its inner side. The inner diameter of the rod guide (75) guides the piston rod (45) therethrough and outer peripheral surface of the cylindrical body and extended wing of the rod guide (75) guides the outer tube thereon. Further, the said rod guide (75) is configured to have an oil passage (75P) bored therein connecting the oil chamber (40OC) with the inverted frustum shaped cavity (75R). The geometrical axis (A-A) of the oil passage (75P) is at an angle a with respect to the vertical axis (X-X) of the piston rod (45) and said angle a is in the range of 8° to 15O the vertical axis (X-X) of the piston rod (45).

[0026] The piston (90) as disclosed in Fig. 3, has a cylindrical body and it is mounted on the distal portion (45P3) of the piston rod (45). The cylindrical body of the piston (90) is configured to have at least two longitudinal orifices (90O1 and 90O2) and serrations over the outer peripheral surface. The longitudinal orifices (90O1 and 90O2) are provided for passage of oil in the oil chamber during the operation of the shock absorber. The piston band (90B) is fixed over the serrations of the said piston (90) to avoid the leakage of oil from the peripheral surface of the piston and thereby maintain the oil pressure in the oil chamber.

[0027] Referring to Fig. 4, the outer tube assembly (100) comprises of an outer tube (40), a separation piston (90SP), a piston arresting clip (90C), a bottom cap (30) and a gas filling screw (55). The outer tube (40) of the outer tube assembly (100) is a hollow cylindrical tube having a top end (40T) and a bottom end (40B). The outer tube (40) is configured to have an outer step profile (40BS) formed at the bottom end (40B) and an inner step profile (40TS) formed at the top end (40T).
[0028] Referring to Fig. 5c, the bottom cap (30) is configured to have a stepped profile cavity (30C), at least two lugs (30L) and a stepped profiled gas charging port (30CP). The said cavity (30C) include a first step (30C1) and a second step (30C2). The said gas charging port (30CP) is provided at an angle ß with respect to the vertical axis of the bottom cap (30). The said angle ß is preferably 45° to the vertical axis of the bottom cap (30). Further, the bottom cap (30) has a throughout opening (30H) for mounting the shock absorber on the vehicle.

[0029] The piston rod assembly (50) is formed by welding the tube ring (10) with the piston rod (45) around proximal portion (45P1) of the said piston rod (45). The washer (65W) is placed at the step formed at the proximal portion (45P1) of the piston rod (45). During the welding of the tube ring (10) with the piston rod (45), the washer (65W) also gets welded. The bump stop (65) is mounted below the said washer (65W) over the top end of the center portion (45P2) of the piston rod (45). The piston (90) is fitted on the distal portion (45P3) of the piston rod (45) and locked into its position by the nut (90N). A support plate (90P) is placed between the nut (90N) and the piston (90). A set of shims (90SH1 and 90SH2) are placed above and below the piston (90). Further, the first set of shims (90SH1) partially covers the orifices (90O1 and 90O2) while the second set of shims (90SH2) fully covers the orifices (90O1 and 90O2).

[0030] The rod guide (75) and oil seal (70) are mounted towards the bottom end of the center portion (45P2) of the piston rod (45) with the help of a bush (72) and cap seal washer (W) in such a way that the seal wing (70W) of the seal (70) abuts over the extended wing profile (75W) of the rod guide (75) forming an oil pocket (P) by meshing the inverted frustum shaped annular recess (75R) of the rod guide (75) with the frustum shaped annular recess (70R2) of the oil seal (70). While forming the oil pocket (P), the extended wing profile (75W) of the rod guide (75) intelligently overlaps over the third lip portion (70L3) of the oil seal (70) in the inverted frustum shaped annular recess (75R) of the rod guide (75). This novel and inventive construction of the oil seal (70) and the rod guide (75) not only facilitate to achieve the greater suspension stroke within the limited space but also makes the seal (70) to seal the interface with the piston rod (45) and the inner surface of the outer tube (40) thereby eliminating the requirement of O-rings, a pair of back up rings, dust scrapper and a circlip. The bush (72) is fitted over the piston rod (45) within the annular space between the body of the rod guide (75) and the piston rod (45) and the cap seal washer (W) is fitted over the piston rod (45) on the flat polymeric surface (70B) of the seal (70). A support plate (85) is mounted over the distal portion (45P3) of the piston rod (45) and above the first set of shims (90SH1). A rebound bumper (80) is positioned in between the support plate (85) and the rod guide (75).

[0031] The outer tube (40) of the outer tube assembly (100) is joined with the bottom cap (30) with the help of threads provided on the outer surface of the bottom end (40B) of the outer tube (40) and the matching threads provided on the inner surface of the first cavity (30C1) of the bottom cap (30). However, the outer tube (40) can be joined to the bottom cap (30) using any known method such as welding, press-fitting, fastening, etc.

[0032] A separation piston (90SP) is placed inside the outer tube (40) in such a way that it forms two chambers namely an oil chamber (40OC) above it and a gas chamber (40GC) below it and the said separation piston (90SP) acts as a wall between these two chambers. The separation piston (90SP) is locked inside the outer tube (40) with the help a piston arresting clip (90C) positioned in a groove provided between the inner surface of the outer tube (40) and outer surface of the separation piston (90SP). An O-Ring (12O1) is placed in a groove provided on the outer surface of the separation piston (90SP) and interfacing the inner surface of the outer tube (40) so as to seal the leakage of oil, if any, from the oil chamber (40OC). The O-Ring (12O2) is placed in a groove provided in the bottom cap (30) interfacing the outer surface of the outer tube (40) so as to seal the leakage of gas, if any, from the gas chamber (40GC).

[0033] The gas filling screw (55) is fitted in the gas charging port (30CP) of the bottom cap (30) through the threaded joinery. The said gas filling screw (55) includes a stepped cavity (55C) and an air hose valve (55V) fitted within the said gas filling screw (55). The said stepped cavity (55C) receives a screw (50S). An O-Ring (50O1) is placed in between the said screw (50S) and the stepped cavity (55C) and an O-Ring (50O2) is placed in between the gas filling screw (55) and the stepped profile cavity (30C) of the bottom cap (30).

[0034] Referring to Fig. 6, the piston rod (45) along with the piston rod assembly (50) passes through the top open end (40T) of the outer tube (40) of the outer tube assembly (100). The cap seal washer (W) of the piston rod assembly (50) closes the top open end (40T) of the outer tube (40) of the outer tube assembly (100) and said top end (40T) is crimped over the cap seal washer (W) so that the rod guide (75) is positioned and locked within the inner step profile (40TS) of the outer tube (40). The adjuster (25) is rotatably placed over the lugs (30L) of the bottom cap (30) and the spring locator (15) is fitted over the bump stop washer (65W) of the piston rod assembly (50). The lugs (30L) are provided on the upper peripheral surface of the bottom cap (30) for adjusting the preload. The spring (20) is positioned in between the spring locator (15) and the adjuster (25). Further to this, a pair of rubber bush (30RB) is fitted inside the thorough opening (30H) of the bottom cap (30). A pair of steel bush (30SB) is fitted inside the pair of said rubber bush (30RB). A rubber bush (10R) is fitted inside the tube ring (10) and a steel bush (10S) is then fitted inside the said rubber bush (10R). The compact shock absorber (500) of the present invention assembled in this fashion is then mounted on the vehicle by fixing the tube ring (10) with the swing arm (1) of the vehicle and the bottom cap (30) with the vehicle frame (2). The mounting of this compact shock absorber is at an angle ranging from 15 to 20 degree with the horizontal.

[0035] As far as the working of the compact shock absorber of the present invention is concerned, when the vehicle fitted with mini shock absorber (500) is subjected to the road surface irregularity, the spring (20) positioned between the spring locator (15) and the spring adjuster (25) is compressed pushing the piston (90) to travel downward inside the oil chamber. At this time the damping oil from the oil chamber (40OC) in the region below the piston (90) starts to flow through the orifices (90O1 and 90O2) in the oil chamber being formed between the rod guide (75) and the piston (90). The first set of shims (90SH1) deflects during this stage to allow the passage for damping oil present in the oil chamber (40OC).

[0036] When the spring (20) is about to get fully compressed, the bump stop (65) comes into contact with the cap seal washer (W) fitted at the top end (40T) of outer tube (40) and absorbs the residual energy through its own compression so as to avoid the bottoming effect in the fully compressed condition of the spring (20). This prevents the shock absorber (500) from getting damaged due to hard metal to metal contact when the spring (20) gets fully compressed. The adjuster (25) can be rotated with the help of a tool by putting it in the annular collar of the adjuster to adjust the preload on the spring as desired by the rider depending on the road conditions causing the profiled surface to move up or down.

[0037] When the vehicle has moved past the irregularity of the road surface and runs on the smooth road surface, the main spring (20) starts getting decompressed and releases its stored energy making the piston (90) to move up at its original position. At this point, the damping oil in the oil pocket between the piston (90) and the rod guide (75) starts flowing back through the orifices (90O1 and 90O2) to the oil chamber (40OC) below the piston (90). During this, the damping fluid in the region within the outer tube (40) formed between the piston (90) and the guide (75), deflects the second set of shims (90SH2) and flows back into the oil chamber (40OC) formed between the piston (90) and the separation piston (90SP). Further, the damping fluid present in the oil pocket (P) flows back to oil chamber (40OC) via the oil passage (75P) of the rod guide (75) and the orifices (90O1 and 90O2) of the piston (90).

[0038] When the spring (20) is decompressing, the pressurized gas filled in the gas chamber (40GC) of outer tube (40) below the separation piston (90SP) exerts a force on the damping fluid in the oil chamber (40OC) above the separation piston (40) so as to keep the oil chamber (40OC) pressurized to cater small amplitude high frequency undulations and thereby prevents the formation of damping fluid foam within the shock absorber (500) of the present invention.

[0039] The compact shock absorber (500) of the present invention eliminates the use of an O-Ring, a pair of backup ring, a dirt scrapper and a circlip in comparison to a conventional mono tube shock absorber. Further, the unique arrangement of the oil seal (70) and the rod guide (75) helps in removing the dead metal forming a compact and efficient seal assembly having less packaging space requirement.

[0040] The compact shock absorber (500) in accordance with the disclosed embodiment provides the following technical advantages that contributes to the advancement of technology:
- It provides freedom to mount the shock absorber at any mounting condition.
- It provides a compact shock absorber adapted to be used with two wheelers having seat height limitations.
- Eliminates the requirement of O-rings, a pair of back up rings, dust scrapper and a circlip in this shock absorber of the present invention.
- It provides means for recharging the gas thus the small amplitude high frequency undulations.
- It provides means for adjusting the spring pre-load.
- It reduces the assembly cycle time thus reducing the overall effective cost of the shock absorber assembly.

[0041] It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiment herein has been described in terms of preferred embodiment, those skilled in the art will recognize that the embodiment herein can be practiced with modification within the spirit and scope of the invention as described herein. , Claims:We Claim

1. A compact shock absorber (500) for a motorbike comprising of a piston rod assembly (50), an outer tube assembly (100), a spring (20), an adjuster (25) and a spring locator (15); wherein
? the piston rod assembly (50) is configured to comprise of a tube ring (10), a bump stop (65), a bump stop washer (65W), a piston rod (45), an oil seal (70), a cap seal washer (W), a rod guide (75), a rod guide bush (72), a rebound bumper (80), a support plate (85), a piston (90), a piston band (90B), a piston support plate (90P) and a nut (90N); wherein
- the piston rod (45) is configured to have cylindrical stepped profile throughout its length forming a proximal portion (45P1), a center portion (45P2) and a distal portion (45P3); and the diameter of the stepped portions of said piston rod (45) is in the order 45P2 > 45P1> 45P3;
- the oil seal (70) is configured to have a uniquely profiled reinforcing metal insert (70M) and an elastomeric body portion (70A) over-molded around said metal insert (70M) forming a first seal lip (70L1), a second seal lip (70L2), a third seal lip (70L3), a base portion (70B) and a seal wing (70W);
- the rod guide (75) is configured to have a cylindrical body with extended wing profile (75W) at the lower side (75L) of said rod guide (75) forming an inverted frustum shaped cavity (75R) at its inner side; and
- said rod guide (75) and oil seal (70) are mounted towards the bottom end of the center portion (45P2) of the piston rod (45) with the help of the bush (72) and the cap seal washer (W) in such a way that the extended wing profile (75W) of the rod guide (75) overlaps over the third lip portion (70L3) of the oil seal (70) and the seal wing (70W) of the seal (70) abuts over the extended wing profile (75W) of the rod guide (75) forming an oil pocket (P);
? the outer tube assembly (100) is configured to comprise an outer tube (40), a separation piston (90SP), a piston arresting clip (90C), a bottom cap (30) and a gas filling screw (55); wherein
- the outer tube (40) is a hollow cylindrical tube having a top end (40T) and a bottom end (40B) and said outer tube (40) is configured to have an outer step profile (40BS) formed at the bottom end (40B) and an inner step profile (40TS) formed at the top end (40T); and
- said outer tube (40) is joined with the bottom cap (30) through the threaded joinery and said bottom cap (30) is configured to have a stepped profile cavity (30C), at least two lugs (30L) and a stepped profiled gas charging port (30CP); and said stepped profile cavity (30C) has a first step (30C1) and a second step (30C2);
? said piston rod assembly (50) passes through the top open end (40T) of the outer tube (40) of the outer tube assembly (100) and is fitted therein in such a way that the cap seal washer (W) of the piston rod assembly (50) closes the top open end (40T) of the outer tube (40) of the outer tube assembly (100) and said top end (40T) is crimped over the cap seal washer (W) so that the rod guide (75) is positioned and locked within the inner step profile (40TS) of the outer tube (40).

2. The compact shock absorber (500) for a motorbike as claimed in claim 1, wherein
- the proximal portion (45P1) of the piston rod (45) is configured to have a pointed tapered end and said tapered end of the proximal portion (45P1) is connected with the tube ring (10) by a fastening means selected from welding;
- the axial length of the stepped portions (45P1, 45P2 and 45P3) of the piston rod (45) is in the order 45P2 > 45P3 > 45P1; and
- the ratio of the axial length of said stepped portions (45P1, 45P2 and 45P3) is 2.20L > L > 0.25L, where L is the axial length of distal portion (45P3).

3. The compact shock absorber (500) for a motorbike as claimed in claim 1, wherein
- the first seal lip (70L1) of the oil seal (70) converges away from the inner edge of reinforcing metal insert (70M);
- the second seal lip (70L2) converges away from inner edge of reinforcing metal insert (70M) but in a direction opposite to that of first seal lip (70L1);
- the third seal lip (70L3) converges away from the reinforcement ring (70R) but in the same direction as that of second seal lip (70L2); and
- said reinforcement ring (70R) is positioned in a recess formed around the third seal lip (70L3) of the seal (70) in order to apply radial load on the seal lip (70L3) thereby enhancing the sealing effect on the piston rod (45).

4. The compact shock absorber (500) for a motorbike as claimed in claim 3, wherein the oil seal (70) is profiled to form
- an inverted frustum shaped annular recess (70R1) between the base portion (70B) and the first seal lip (70L1) but above the reinforcement mental insert (70M) of the oil seal (70);
- a frustum shaped annular recess (70R2) between the seal wing (70W) and the inner periphery of the second seal lip (70L2) but below the reinforcement metal insert (70M); and
- both the recesses (70R1 and 70R2) of the seal (70) are formed opposite to each other but facing towards the reinforcement metal insert (70M).

5. The compact shock absorber (500) for a motorbike as claimed in claim 1, wherein
- the rod guide (75) is configured to have an oil passage (75P) bored therein connecting the oil chamber (40OC) with the inverted frustum shaped cavity (75R);
- the geometrical axis (A-A) of said oil passage (75P) is at an angle a with respect to the vertical axis (X-X) of the piston rod (45); and
- said angle a is in the range of 8° to 15O with respect to the vertical axis (X-X) of the piston rod (45).

6. The compact shock absorber (500) for a motorbike as claimed in claim 1, wherein
- the piston (90) has a cylindrical body and said cylindrical body of the piston (90) is configured to have at least two longitudinal orifices (90O1 and 90O2) and serrations over the outer peripheral surface; and the piston band (90B) is fixed over the serrations of the said piston (90) to avoid the leakage of oil from the peripheral surface of the piston and thereby maintain the oil pressure in the oil chamber; and
- said piston (90) is fitted on the distal portion (45P3) of the piston rod (45) and locked into its position by the nut (90N) in such way that a support plate (90P) is placed between the nut (90N) and the piston (90), the first set of shims (90SH1) partially covers the orifices (90O1 and 90O2) and the second set of shims (90SH2) fully covers the orifices (90O1 and 90O2).

7. The compact shock absorber (500) for a motorbike as claimed in claim 6, wherein
- the bush (72) is fitted over the piston rod (45) within the annular space between the body of the rod guide (75); and
- the piston rod (45) and the cap seal washer (W) is fitted over the piston rod (45) on the flat polymeric surface (70B) of the seal (70).

8. The compact shock absorber (500) for a motorbike as claimed in claim 1, wherein the bottom cap (30) is configured to have
- a gas charging port (30CP) provided at an angle ß with respect to the vertical axis of the bottom cap (30), and said angle ß is 45° with respect to the vertical axis of the bottom cap (30);
- a throughout opening (30H) for mounting the shock absorber on the vehicle; and
- lugs (30L) on its upper peripheral surface for adjusting the preload.

9. The compact shock absorber (500) for a motorbike as claimed in claim 8, wherein
- the adjuster (25) is rotatably placed over the lugs (30L) of the bottom cap (30) and the spring locator (15) is fitted over the bump stop washer (65W) of the piston rod assembly (50);
- the spring (20) is positioned in between the spring locator (15) and the adjuster (25);
- a pair of rubber bush (30RB) is fitted inside the thorough opening (30H) of the bottom cap (30) and a pair of steel bush (30SB) is fitted inside the pair of said rubber bush (30RB).

10. The compact shock absorber (500) for a motorbike as claimed in claim 1, wherein
- the separation piston (90SP) is placed inside the outer tube (40) in such a way that it forms two chambers namely an oil chamber (40OC) above it and a gas chamber (40GC) below it and the said separation piston (90SP) acts as a wall between these two chambers;
- said separation piston (90SP) is locked inside the outer tube (40) with the help a piston arresting clip (90C) positioned in a groove provided between the inner surface of the outer tube (40) and outer surface of the separation piston (90SP);
- the O-Ring (12O1) is placed in a groove provided on the outer surface of the separation piston (90SP) and interfacing the inner surface of the outer tube (40) so as to seal the leakage of oil, if any, from the oil chamber (40OC); and
- the O-Ring (12O2) is placed in a groove provided in the bottom cap (30) interfacing the outer surface of the outer tube (40) so as to seal the leakage of gas, if any, from the gas chamber (40GC).

11. The compact shock absorber (500) for a motorbike as claimed in any of the claims 2, 4, 5, 7, 9 and 10, wherein
- the compact shock absorber (500) is mounted on the vehicle by fixing the tube ring (10) with a swing arm (1) of the vehicle and the bottom cap (30) with the vehicle frame (2); and
- said mounting of the compact shock absorber is at an angle ranging from 15 to 20 degree with the horizontal.

Dated this 23rd day of August 2023

Sahastrarashmi Pund
Head – IPR
Endurance Technologies Ltd.

To,
The Controller of Patents,
The Patent Office, at Mumbai.