DESC:FORM 2
The Patent Act 1970
(39 of 1970)
&
The Patent Rules, 2005

COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

TITLE OF THE INVENTION
“COMBINED BRAKING SYSTEM FOR A TWO-WHEELED VEHICLE”

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 combined braking system (CBS) for a two-wheeled vehicle. More particularly, the invention is related to a valve assembly of combined braking system for two wheeled motor vehicles, preferably bikes and scooters, wherein the CBS valve assembly eliminates the reverse movement of the piston of the valve and thereby provides an effective and superior combined braking performance.

Background of the Invention

[002] A combined braking system (CBS), also called linked braking system (LBS), is a system for linking front and rear brakes on a motorcycle or scooter. In this system, the rider's action of depressing one of the brake levers applies both front and rear brakes. The amount of each brake applied may be determined by a proportional control valve and this control valve is called as CBS Valve which plays a crucial role in implementation and working of the combined braking system on two wheeled vehicles. Since April 2019, Govt. of India has mandated Combined Braking System (CBS) on all new two-wheelers below 125 cc.

[003] The conventional two wheeler combined braking system with front and rear combination of hydraulic and mechanical brake normally employs use of actuation levers, equalizers, cables, master cylinders, hydraulically operated front wheel brake and mechanically operated rear wheel brake. These features are essentially provided for achieving combined braking function with required time delay in application of front wheel brake when rear wheel brake is applied. The implementation of these systems presuppose existence of sufficient manufacturing and assembly expertise to reliably provide them on any given two wheelers. It also presupposes existence of adequate space on the two wheeler which may not always be the case.

[004] The combined braking systems available in public domain have been implemented with varying level of success. Document No. JP4458791B2 discloses an interlocking braking device capable of accepting two cable based inputs from operating levers and provide one cable output for operating a mechanical rear wheel brake and a hydraulic output for operating a hydraulic front wheel brake. The master cylinder assembly disclosed accommodates in its vicinity multiple levers with complicated profiles which ensures the device’s operability. Another document No. 5138/CHE/2014 describes an interlocking braking system comprising of a distribution device with said distribution device being capable of receiving input from two brake actuators and provide two braking outputs one of which is hydraulic output which operates the front wheel hydraulic brake and the other is mechanical output which operates a cable operated rear wheel mechanical brake. It is known that these prior art systems have a very complicated construction having multiple sub-components that need precise and accurate manufacturing for ensuring reliable combined braking operation. The state of the art is thus replete with systems and devices that need high number of skilled workers for reliably implementing them on any given two wheeled vehicles.

[005] Further, the combined braking systems of the prior art do not disclose the operation of both the disc brakes (front and rear) through the hydraulic lines by the controlled CBS valve assembly. These systems even do not address the issue of reverse movement of the piston of the CBS valve assembly leading to poor combined braking performance. Hence, there exists a long pending unmet need of providing a combined braking system with a CBS valve assembly that eliminates the reverse movement of the piston of the valve leading to effective combined braking performance.

Objectives of the Invention

[006] The main object of the present invention is to provide a combined braking system with CBS valve assembly for a two wheeled motor vehicle.

[007] Another object of the present invention is to provide a combined braking system for a vehicle wherein the CBS valve assembly has a working chamber formed between the primary piston and the closed end seal.

[008] Still another object of the present invention is to provide a combined braking system for a vehicle wherein the CBS valve assembly has a lock screw arranged perpendicularly in the working chamber, and an air vent hole provided in the cover that opens in the rear brake chamber between the secondary piston assembly and its closed end.

[009] The object of the present invention is to provide a combined braking system for a vehicle wherein the CBS valve assembly isolates front and rear hydraulic circuits and also it isolates front master cylinder and front disc brake in combined braking operation.

[0010] Yet, the object of the present invention is to provide a combined braking system for a vehicle wherein the CBS valve assembly is configured and designed to eliminate the reverse movement of the piston of the valve and thereby provides an effective and superior combined braking performance.

[0011] It is yet another objective of the invention to provide a combined braking system that provides the superior braking performance while maintaining the quality of braking as well as keeping the cost of production low.

Brief Description of the Drawings

[0012] This invention is illustrated in the accompanying drawings, throughout which reference numerals / letters indicate corresponding parts in the various figures. The embodiments herein and advantages thereof will be better understood from the following description when read with reference to the following drawings, wherein

[0013] Figure 1 discloses a schematic diagram of a combined braking system (CBS) in accordance with the present invention.

[0014] Figure 2 discloses a cut sectional view of the CBS Valve body as per the present invention.

[0015] Figure 3 discloses enlarged cut sectional of a piston assembly of the CBS Valve in accordance with the present invention.

[0016] Figures 4a and 4b disclose non-operating condition and operating condition, respectively of the CBS Valve assembly as per the first embodiment of the present invention.
[0017] Figures 5a and 5b disclose non-operating condition and operating condition, respectively of the CBS Valve assembly as per the second embodiment of the present invention.

[0018] Figures 6a and 6b disclose non-operating condition and operating condition, respectively of the CBS Valve assembly as per the third embodiment of the present invention.

Detailed Description of the Present Invention

[0019] Referring to Fig. 1, combined braking system (CBS) (500) for a two wheeler comprises of a rear master cylinder assembly (30) mounted on the left end of the handle bar in case of hand operated lever or on the chassis of the vehicle in case of foot operated lever, a front master cylinder assembly (32) mounted on the right end of the handle bar, a rear braking unit (34), a front braking unit (36), a plurality of hydraulic lines (40) and a CBS valve assembly (100). The CBS valve assembly (100) is in hydraulic communication with the front and rear master cylinder assembly (32 and 30) through the hydraulic lines (40c and 40a), respectively and said CBS valve assembly (100) is in hydraulic communication with the front brake (36) and rear brake (34) through the hydraulic lines (40d and 40b), respectively.

[0020] In accordance with the present invention, the CBS valve assembly (100) (refer Fig. 4a) comprises of a CBS a valve body (1), a pair of covers (2), a seal washer (3), a delay spring (4), a piston assembly (45), a primary seal (6) for the front brake circuit, a primary seal (8) for the rear brake circuit, a secondary seal (9) for the front brake circuit, a seal guide plate (10) and a plate locking means (15a, 15b, 15c) for the front brake circuit, a secondary seal (13) for the rear brake circuit, and a seal guide plate (14) for the rear brake circuit. Further, the CBS valve assembly (100) has a pair of outlet ports (20 and 22) for the fluid supply to the front brake unit (36) and the rear brake unit (34), respectively. It also has a pair of supply ports (24 and 26) to receive the hydraulic supply from the front master cylinder (32) and rear master cylinder (30), respectively.

[0021] Referring to Fig. 2, the CBS valve body (1) is configured to have a multi-step cylindrical profiled cavity (C) bored therein. The stepped profile (C1) houses a cover (2) at the end (E1) of the CBS valve body, the profile (C2) houses a fixed piston (11), the profile (C3) houses the primary piston (7) and said piston forms a brake fluid chamber therein, the profile (C4) facilitate the primary piston (7) to communicate with the profile (C6), the profile (C5) houses a secondary seal (9), the profile (C6) houses a plate locking means (15a, 15b, 15c), a secondary piston (5) and a delay spring (4) and the profile (C7) houses a cover (2) at the end (E2) of the CBS valve body (1). Further, the CBS valve body (1) of the CBS valve assembly (100) is configured to have a pair of supply ports (26, 24) and a pair of outlet ports (22, 20) extending out orthogonally from the outer surface of said CBS valve body (1). The supply port (26) hydraulically connects the profiled cavity (C3) with the rear master cylinder (30) via hydraulic line (40a) and the supply port (24) hydraulically connects the profiled cavity (C6) with the front master cylinder (32) via hydraulic line (40c). The outlet port (22) is in hydraulic communication with the rear brake unit (34) via hydraulic line (40b) and the outlet port (20) is in hydraulic communication with the front brake unit (36) via hydraulic line (40d). The supply port (26) is positioned exactly opposite to the respective outlet port (22) and the positioning of the supply port (24) and the outlet port (20) is offset with each other. The supply port (24) is configured to have a replenishing passage (25) communicating with the profiled cavity (C6) and said replenishing passage (25) facilitate to avoid the jerk/impact being generated due to sudden braking / application of the front brake. The said replenishing passage (25) makes an acute angle (a) with the vertical axis (x-x) of the supply port (24) and said angle (a) varies in the range of 30 to 60 degree.

[0022] The piston assembly (45) comprises of a fixed piston (11), a primary piston (7) and a secondary piston (5). The fixed piston (11) has a cylindrical groove (11G) bored therein to receive the shank of the primary piston (7). The primary piston (7) is configured to have a pair of sliding faces (7P1 and 7P2) projecting out from its peripheral surface and a stepped profiled distal end (7T) to get it fitted in the secondary piston (5). The secondary piston (5) is configured to have a hollow cylindrical cavity (5C) bored at its one end to receive the stepped profiled distal end (7T) of the primary piston (7) and it has a pair of sliding face (5P1 and 5P2) on the outer peripheral surface of the cylindrical cavity (5C) of the secondary piston (5).

[0023] The fixed piston (11) is rigidly fitted inside the profiled cavity (C2) and is locked there with the help of an O-ring (12) positioned in a groove provided on the outer peripheral surface of the said fixed piston (11). The open end of the cylindrical groove (11G) of fixed piston (11) has a stepped profile to accommodate the secondary seal (13) therein and said seal (13) is getting locked there with the seal guide plate (14) fitted against the step portion of the profiled cavities (C2 and C3). The shank (7a) of the primary piston (7) is slideably fitted inside the cylindrical groove (11G) of the fixed piston (11) in such a way that the sliding faces (7P1 and 7P2) of the primary piston (7) is getting positioned in the profiled cavity (C3) and the stepped profiled distal end (7T) is getting positioned in the profiled cavity (C6) after passing through the cavities (C4 and C5). The positioning of the primary piston (7) forms the first brake fluid zone (60) between the seal guide plate (14) and the sliding face (7P2) of the primary piston (7) within the profiled cavity (C3). The primary seal (8) is fitted in between the sliding face (7P1) and the sliding face (7P2) of the primary piston so as to seal the leakage / passage of brake fluid in the pocket (70).

[0024] The secondary piston (5) through its hollow cylindrical cavity (5C) is fitted over the stepped profiled distal end (7T) of the primary piston (7) and locked there through a suitable joining means. The said joining means is preferably selected from threaded joint, press-fit joint and combination thereof. Thus, the assembly of primary piston (7) and the secondary piston (5) is configured to move axially within the multi-step cylindrical profiled cavity (C) of the CBS valve body (1). The positioning of the secondary piston (5) forms the replenishing chamber (80) and the second brake fluid zone (50) within the profiled cavity (C6). The replenishing chamber (80) is being formed between the rear side of the sliding face (5P2) of the secondary piston (5) and the seal guide plate (10) and the second brake fluid chamber (50) is formed between the primary seal (6) and the seal washer (3) fitted in the profiled cavity (C7). The primary seal (6) is fitted in between the sliding face (5P1) and the sliding face (5P2) of the secondary piston (5) so as to seal the leakage / passage of brake fluid from the second brake fluid zone (50) to the replenishing chamber (80). The secondary seal (9) is fitted in the profiled cavity (C5) and locked there with the help of seal guide plate (10) and said seal guide plate (10) is retained at its position with the plate locking means (15). The delay spring (4) is concentrically sleeved over the secondary piston (5) and in between the sliding face (5P1) and the seal washer (3) fitted at the end (E2) of the CBS valve body (1). The stepped profiles (C1 and C7) of the CBS valve body at its both ends (E1 and E2) are closed with the covers (2).

[0025] In preferred embodiment of the CBS valve assembly (100) of the present invention (Figs. 4a and 4b), the plate locking means is a plate lock spring (15a) intelligently placed in the replenishing chamber (80) in between the sliding face (5P2) of the secondary piston (5) and the seal guide plate (10). This plate lock spring (15a) maintains the position of the seal guide plate (10) intact with the face of the profiled cavity (C6) thereby restricting the axial movement of the secondary seal (9) from the profiled cavity (C5) in response to the axial movement of the primary piston (7).

[0026] In another embodiment of the CBS valve assembly (100) of the present invention (Figs. 5a and 5b), the plate locking means (15b) comprises of a groove (CG) provided adjacent to the seal guide plate (10) in the annular surface of the profiled cavity (C6) and a ring (R) fitted therein. The ring (R) is fitted in the groove (CG) such that it abuts with the face of the seal guide plate (10). The ring (R) of the plate locking means (15b) maintains the position of the seal guide plate (10) intact with the face of the profiled cavity (C6) thereby restricting the axial movement of the secondary seal (9) from the profiled cavity (C5) in response to the axial movement of the primary piston (7).

[0027] Still in another embodiment of the CBS valve assembly (100) of the present invention (Figs. 6a and 6b), the plate locking means (15c) comprises of a stepped profile groove (SG) bored orthogonally in the CBS valve body (1) adjacent to the seal guide plate (10) communicating with the replenishing chamber (80) and a screw (S) fitted therein with the help of a screw lock ring (16). The screw (S) is fitted in the stepped profile groove (SG) in such way that the shank of the screw (S) projects out in the replenishing chamber and abuts with the face of the seal guide plate (10). The screw (S) fitted in the groove (SG) of the plate locking means (15c) maintains the position of the seal guide plate (10) intact with the face of the profiled cavity (C6) thereby restricting the axial movement of the secondary seal (9) from the profiled cavity (C5) in response to the axial movement of the primary piston (7).

[0028] The CBS valve body (1) of the CBS valve assembly (100) is provided with an air vent hole (VH) which get opened / communicates with the pocket (70). This air vent (VH) facilitate to apply atmospheric pressure on the primary piston (7) and thereby eliminates the locking / jamming of the piston assembly into the pocket (70) during its working. The rear braking unit (34) of the combined braking system (500) of the present invention is mounted on the rear wheel of the vehicle and is selected from a drum brake and disc brake. The front braking unit (36) of the present invention is mounted on the front wheel of a vehicle and is selected from a drum brake and disc brake. Thus, the braking units (34 and 36) of the combined braking system of the present invention are selected from a set of disc-disc brake (both brake units are disc brakes), disc-drum brake (rear brake unit is disc brake and front brake unit is drum brake), drum-drum brake (both brake units are drum brake) and drum-disc brake (rear brake unit is drum brake and front brake unit is disc brake).

[0029] As far as the working of the combined braking system of the present invention is concerned, when the front brake lever (28) is actuated by the rider, the pressurized brake fluid travels from front master cylinder (32) via hydraulic line (40c) to the second brake fluid zone (50) of the CBS valve assembly (100) through the supply port (24) and then passes to the front brake unit (36) through the outlet port (20) via hydraulic line (40d) to apply the front brake without any time delay. In this case, the CBS valve assembly (100) acts as a connector to transfer the pressurized brake fluid from front master cylinder (32) to the front brake unit (36) and there is no movement of the assembly of the primary piston (7) and the secondary piston (5) inside the CBS valve assembly (100). The primary piston (7) rests in the fixed piston (11) leading to the brake release condition when the front brake lever is actuated to apply the front brake.

[0030] When the rear brake lever (38) is actuated, the pressurized brake fluid travels from the rear master cylinder (30) via the hydraulic line (40a) to the first brake fluid zone (60) of the CBS valve assembly (100) through the supply port (26). As the pressurized brake fluid enters in the first brake fluid zone (60) it simultaneously exerts pressure in the hydraulic line (40b) and on the primary piston (7). Thus, the pressurized brake fluid in the first brake fluid zone (60) through the hydraulic line (40b) leads the application of rear brake without any time delay and leads to the axial movement of the assembly of primary piston (7) and the secondary piston (5) compressing the delay spring (4). The delay spring (4) is getting slowly compressed as the load on said delay spring (4) is overcome due to the hydraulic pressure leading to the axial movement of the pistons. In this condition of axial movement of the assembly of primary piston (7) and secondary piston (5), the sliding face (5P2) of the secondary piston (5) blocks the opening of the supply port (24) and makes the pressurized brake fluid to flow through the outlet port (20) to the front brake unit (36) via hydraulic line (40d) to apply the front brake with time delay, thus leading to the combined/synchronized braking of the vehicle.

[0031] When the rear brake lever (38) is released, the primary piston (7) travels back to its original position in the fixed piston (11) alienating the vehicle from braking condition. In this condition, there are likely chances that the sliding face (7P2) of the primary piston gets locked / jammed into the pocket (70). Therefore, to prevent the jam of piston assembly, the CBS valve body (1) is provided with an air vent hole (VH) which get opened / communicates with the pocket (70). This air vent (VH) facilitate to apply atmospheric pressure on the primary piston (7) and thereby eliminates the locking / jamming of the piston assembly into the pocket (70) during its working.

[0032] The unique features of the CBS valve assembly (100) of the combined braking system (500) of the present invention, viz. the working chamber (brake fluid zone) formed between the primary piston and the closed end seal; the plate locking means (15a, 15b, 15c) provided in the replenishing chamber (80), and an air vent hole (VH) provided in the CBS valve body (1) that opens into the pocket (70) are the novel features of the present invention imparting the technical advancement. The novel construction of the CBS valve assembly (100) of the combined braking system (500) disclosed in the present invention provides technical advantages of eliminating reverse movement of the piston of the valve, eliminates the locking / jamming of the piston assembly into the pocket (70) and thereby leading to effective combined braking performance that contributes to technical advancement in the technology domain of combined braking system. Thus, the combined braking system having the unique construction of CBS valve assembly as disclosed and described above is technically superior over the conventional solutions available in the public domain fulfilling the requirement of the inventive step. ,CLAIMS:We Claim

1. A combined braking system (500) for a two wheeled vehicle comprising of
? a rear master cylinder assembly (30) mounted on the left end of the handle bar in case of hand operated lever and on the chassis of the vehicle in case of foot operated lever,
? a front master cylinder assembly (32) mounted on the right end of the handle bar,
? a CBS valve assembly (100),
? a rear braking unit (34) mounted on the rear wheel of a vehicle,
? a front braking unit (36) mounted on the front wheel of a vehicle, and
? a plurality of hydraulic lines (40a, 40b, 40c, 40d)
wherein,
• the CBS valve assembly (100) is configured to comprise a CBS a valve body (1), a piston assembly (45), a delay spring (4), a pair of covers (2), primary seals (6, 8), secondary seals (9, 13), seal guide plates (10, 14) and a plate locking means (15a, 15b, 15c); wherein
- the CBS valve body (1) is configured to have a multi-step cylindrical profiled cavity (C) bored therein;
- the stepped profile (C2) houses a fixed piston (11); the stepped profile (C3) houses the primary piston (7) and said piston (7) forms a brake fluid chamber (60) and a pocket (70) therein; and the stepped profile (C6) houses a plate locking means (15a, 15b, 15c), a secondary piston (5) and a delay spring (4) and said piston (5) forms a brake fluid chamber (50) and the replenishing chamber (80) therein;
- the piston assembly (45) comprises of a fixed piston (11), a primary piston (7) and a secondary piston (5); said fixed piston (11) has a cylindrical groove (11G) bored therein to receive the shank (7a) of the primary piston (7); said primary piston (7) is configured to have a pair of sliding faces (7P1 and 7P2) projecting out from its peripheral surface and a stepped profiled distal end (7T) to get it fitted in the secondary piston (5); and said secondary piston (5) is configured to have a hollow cylindrical cavity (5C) bored at its one end to receive the stepped profiled distal end (7T) of the primary piston (7) and it has a pair of sliding face (5P1 and 5P2) on the outer peripheral surface of said cylindrical cavity (5C) of the secondary piston (5);
- the delay spring (4) is concentrically sleeved over the secondary piston (5) and in between the sliding face (5P1) and a seal washer (3) fitted at an end (E2) of the CBS valve body (1); and
- the plate locking means (15a, 15b, 15c) is positioned in the replenishing chamber (80) to fix the position of the seal guide plate (10) and the secondary seal (9) is fitted in the profiled cavity (C5);
• said CBS valve assembly (100) is in hydraulic communication with the front and rear master cylinder assembly (32 and 30) through the hydraulic lines (40c and 40a), respectively; and
• the front brake unit (36) and rear brake unit (34) are in hydraulic communication with said CBS valve assembly (100) through the hydraulic lines (40d and 40b), respectively.

2. The combined braking system (500) for a two wheeled vehicle as claimed in claim 1, wherein
- the plate locking means of the CBS valve assembly (100) is a plate lock spring (15a) positioned in the replenishing chamber (80); and
- said plate lock spring (15a) is positioned in between the sliding face (5P2) of the secondary piston (5) and the seal guide plate (10).

3. The combined braking system (500) for a two wheeled vehicle as claimed in claim 1, wherein
- the plate locking means (15b) of the CBS valve assembly (100) comprises of a groove (CG) provided adjacent to the seal guide plate (10) in the annular surface of the profiled cavity (C6) and a ring (R) fitted therein; and
- the ring (R) is fitted in the groove (CG) in such a way that it abuts with the face of the seal guide plate (10) to restrict the axial movement of the secondary seal (9) and the seal guide plate (10).

4. The combined braking system (500) for a two wheeled vehicle as claimed in claim 1, wherein
- the plate locking means (15c) of the CBS valve assembly (100) comprises of a stepped profile groove (SG) bored orthogonally in the CBS valve body (1) adjacent to the seal guide plate (10) and communicating with the replenishing chamber (80) and a screw (S) fitted therein; and
- said screw (S) is fitted in the stepped profile groove (SG) with the help of a screw lock ring (16) in such way that the shank of the screw (S) projects out in the replenishing chamber (80) and abuts with the face of the seal guide plate (10) to restrict the axial movement of the secondary seal (9) and the seal guide plate (10).

5. The combined braking system (500) for a two wheeled vehicle as claimed in any of the claims 2, 3 and 4, wherein the CBS valve body (1) of the CBS valve assembly (100) is provided with an air vent hole (VH) and said air vent hole (VH) gets opened into the pocket (70).

6. The combined braking system (500) for a two wheeled vehicle as claimed in claim 5, wherein
- the CBS valve body (1) of the CBS valve assembly (100) is configured to have a pair of supply ports (26, 24) and a pair of outlet ports (22, 20) extending out orthogonally from the outer surface of said CBS valve body (1);
- the supply port (26) hydraulically connects the profiled cavity (C3) with the rear master cylinder (30) via hydraulic line (40a) and the supply port (24) hydraulically connects the profiled cavity (C6) with the front master cylinder (32) via hydraulic line (40c); and
- the outlet port (22) is in hydraulic communication with the rear brake unit (34) via hydraulic line (40b) and the outlet port (20) is in hydraulic communication with the front brake unit (36) via hydraulic line (40d).

7. The combined braking system (500) for a two wheeled vehicle as claimed in claim 6, wherein
- the supply port (26) is positioned exactly opposite to the respective outlet port (22) and positioning of the supply port (24) and the outlet port (20) is offset with each other; and
- the supply port (24) is configured to have a replenishing passage (25) communicating with the profiled cavity (C6).

8. The combined braking system (500) for a two wheeled vehicle as claimed in claim 7, wherein the replenishing passage (25) makes an angle (a) with the vertical axis (x-x) of the supply port (24) and said angle (a) varies in the range of 30 to 60 degree.

9. The combined braking system (500) for a two wheeled vehicle as claimed in claim 6, wherein

- the fixed piston (11) is rigidly fitted inside the profiled cavity (C2) of the CBS valve body (1) and is locked there with the help of an O-ring (12) positioned in a groove provided on the outer peripheral surface of the said fixed piston (11);
- the open end of the cylindrical groove (11G) of fixed piston (11) has a stepped profile and said stepped profile houses the secondary seal (13) therein; and
- said seal (13) is locked there in its position with the seal guide plate (14) fitted against the step portion of the profiled cavities (C2 and C3).

10. The combined braking system (500) for a two wheeled vehicle as claimed in claim 9, wherein
- the shank (7a) of the primary piston (7) is slideably fitted inside the cylindrical groove (11G) of the fixed piston (11) in such a way that the sliding faces (7P1 and 7P2) of the primary piston (7) are positioned in the profiled cavity (C3) and the stepped profiled distal end (7T) is positioned in the profiled cavity (C6) after passing through the cavities (C4 and C5) of the CBS valve body (1);
- the positioning of the primary piston (7) is configured to form the first brake fluid zone (60) between the seal guide plate (14) and the sliding face (7P2) of the primary piston (7) within the profiled cavity (C3); and
- the primary seal (8) is fitted in between the sliding face (7P1) and the sliding face (7P2) of the primary piston so as to seal the leakage of brake fluid in the pocket (70).

11. The combined braking system (500) for a two wheeled vehicle as claimed in claim 10, wherein
- the secondary piston (5) through its hollow cylindrical cavity (5C) is fitted over the stepped profiled distal end (7T) of the primary piston (7) and locked there through a joining means selected from threaded joint, press-fit joint and combination thereof;
- the assembly of primary piston (7) and the secondary piston (5) is configured to move axially within the multi-step cylindrical profiled cavity (C) of the CBS valve body (1);
- the positioning of the secondary piston (5) forms the replenishing chamber (80) between the rear side of the sliding face (5P2) of the secondary piston (5) and the seal guide plate (10); and forms the second brake fluid zone (50) between the primary seal (6) and the seal washer (3) fitted in the profiled cavity (C7);
- the primary seal (6) is fitted in between the sliding face (5P1) and the sliding face (5P2) of the secondary piston (5) so as to seal the leakage of brake fluid from the second brake fluid zone (50) to the replenishing chamber (80); and
- the secondary seal (9) is fitted in the profiled cavity (C5) and locked there with the help of seal guide plate (10) and said seal guide plate (10) is retained at its position with the plate locking means (15a, 15b, 15c).

12. The combined braking system (500) for a two wheeled vehicle as claimed in claim 6, wherein the rear braking unit (34) and the front braking unit (36) of the combined braking system (500) are selected from a disc brake, drum brake and combination thereof.

Dated this 12th day of Sept. 2023

Sahastrarashmi Pund
Head – IPR
Endurance Technologies Ltd.

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