FORM 2
THE Patent Act, 1970
(39 of 1970)
&
The Patent Rules, 2003
COMPLETE SPECIFICATION
(See Section 10 and Rule 13)
Combined brake system for a two wheeler
Endurance Technologies Pvt Ltd R&D, E 93, MIDC Industrial Area, Waluj, Aurangabad, Maharashtra-431136
The following specification describes the invention

Field of the invention
The present invention relates to combined brake system for a two wheeler and more particularly to combined brake system for front hydraulically operated disc brake assembly and rear hydraulically operated drum brake assembly.
Description of the prior art
The term "combined brake system" in connection with motorcycle or a two wheeler is understood to mean a brake system in which, when a when a "hand brake lever" or the "foot brake pedal" is operated, the front wheel brake and the rear wheel brake are applied. Thus, by operating a single actuating device, both brakes are applied. Combinations are also possible wherein one brake lever acts on one wheel and the other brake pedal on both wheels.
One combined brake system for motorcycles is disclosed, for example, in DE3803563 A1. In this brake system, when the foot brake pedal is operated, braking pressure is applied simultaneously to the front wheel brake and the rear wheel brake. Furthermore, an additional front wheel brake is provided to which braking pressure is applied by operating the hand brake lever. The additional front wheel brake can be operated independently of the operation of the foot brake lever. When in combination mode, rear pedal is operated, an additional change in the wheel loading takes place due to simultaneous operation on front wheels. In order to prevent the front wheel from locking up when the foot lever is operated, a brake pressure regulator is provided which accordingly limits the pressure at the front brake.

Normally, the combined braking system involves braking action via hydraulic action or via mechanical linkages. Although mechanical linkages have the merit of being cheaper and simpler in construction and easy to maintain, however, there is much wear and tear involved in its construction. Further, there is no change possible in leverage ratio of input and output forces at brake pedal. Additionally, there are much mechanical losses involved in the usage of mechanical linkages in combined brake system. In systems with hydraulic action, they have the advantage of minimum hydraulic losses, low packaging size as well as wide possibility of variation of hydraulic ratio of brake system. Further, in mechanical brakes, no wear compensation feature is provided and the pedal play has to be adjusted manually.
Majority of two wheelers in the world have drum brakes in the rear wheel. To implement the combined brake system in such vehicles along with taking advantage of hydraulic system, a lot of solutions were provided. For example, in US 3752273, a solution was provided which involved combined brake system with drum brakes in rear wheel. However, majority of such systems involved tandem master cylinder in its construction and were complex in design. Further it involved stepped calipers at front which involved excessive wear and tear and difficult to manufacture.
Hence to obviate the lacunae in the prior art, it is the objective of the present invention to provide a combined brake system for a two wheeler having rear drum brake and hydraulic actuation system which is simple in construction and cost effective to manufacture.
Another objective of the present invention is to provide a combined brake system which involved a single master cylinder and multi pot calipers having less wear and tear.

Brief description of the invention
A drum brake is used in the rear wheel instead of a disc brake for a combined brake system two wheelers. However, the actuation system for operating the drum brake is hydraulic. The rear pedal actuates the wheel cylinder through a distributor that further actuates both the brake shoes, at a time. The rear wheel cylinder is operated through a hydraulic hose or metal brake tubes from the distributor and or a combination of the hydraulic hoses and metal tubes.
Brief description of the drawings
The invention will be described in further detail below, reference being made to the accompanying drawings, in which:
Figure 1 illustrates the prior art.
Figure 2 illustrates the present invention.
Figure 3 illustrates the hydraulic drum brake according to the present invention.
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Detailed description of the invention.
FIG. 1 illustrates a combined brake system for a motorcycle or a two wheeler having two or three pot calipers in front wheel. The figure shows the front wheel (1) and the rear wheel (2) of a motorcycle indicated schematically, a disk brake (3) and (4), respectively, being assigned to each. The brake system assigned to the front wheel (1) has a conventional design, i.e., a three pot brake caliper (5) of the disk brake (3) is connected by a hydraulic line (6) to a master cylinder (7) which can be controlled with a hand brake lever (8).

A distributor (9) is provided immediately after brake master cylinder. The distributor (9) is connected by separate hydraulic lines (19) & (20) to the front (3) and rear (4) brakes. This master cylinder contains a hydraulic control valve (not shown) which forms the regulating device for controlled distribution of the brake force between the two wheels (1 & 2). This device can be only a distributor with pressure control valve or separate regulating valve. With the known combined brake system, it is possible to operate the hydraulic brake system assigned to the front wheel (1) by using the hand lever (8) alone or to operate the hydraulic brake system assigned to both the front wheel (1) and the rear wheel (2) jointly with the foot brake lever (10). In this case, the regulating system formed by the hydraulic control valve produces a controlled distribution of brake force between the two wheels.
Figure 2 and Figure 3 illustrates the general layout of the present invention. For the front brake (3), a multi pot caliper is used with variable bore diameter. It uses either a two or three piston caliper (12) where two pistons are actuated together with individual master cylinder at the front. The third piston is actuated through action of pedal (13) and hydraulic action or force from the distributor (18).
A drum brake (11) is used in the rear wheel (2) instead of a disc brake. However, the actuation system for operating the drum brake (11) is hydraulic. The rear pedal actuates the wheel cylinder (14) through a distributor (18) that further actuates both the brake shoes (15), with a single pivot point (16), at a time. The rear wheel cylinder is operated through a hydraulic hose (16) from the distributor (18) and a banjo bolt (17) or a suitable joint. The front wheel brake is connected through a hose (21) from said distributor (18). The banjo bolt (17) transfers the hydraulic force from the distributor (18) through a set of opposite pistons (not shown) present in said wheel cylinder (14) which further pushes the brakes shoes (15) for effective braking action.

In a second embodiment of a present invention, the hydraulic action on the rear drum brake can also be initiated by action of hand operated lever (not shown) instead of pedal operated lever (13) whereby the hand operated lever actuates the wheel cylinder (14) through a distributor (18) that further actuates both the brake shoes (15), with a single pivot point (16), at a time. Additionally, an auto adjuster (22) is also provided to adjust for the wear compensation of the brake shoes.
While considerable emphasis has been placed herein on the particular features of this invention, it will be appreciated that various modifications can be made, and that many changes can be made in the preferred embodiments without departing from the principles of the invention. These and other modifications in the nature of the invention or the preferred embodiments will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

Claims
We claim:
1. A combined brake system for a two wheeler with a front wheel and a rear
wheel comprising:
a pedal or a hand operated actuation system with a distributor, and multiple
hoses or metal tubes or a combination thereof;
a disc brake on the front wheel of said two wheeler having a multi pot caliper
connected to a hose from said distributor;
a drum brake on the rear wheel of said two wheeler with a banjo bolt
connected to a hose from said distributors.
2. The combined brake system for two wheelers as claimed in claim 1, wherein said drum brake for the rear wheel has a set of brake shoes connected through a single pivot point for its brake shoes.
3. The combined brake system for two wheelers as claimed in claim 1, wherein said brake shoes of said drum brake is actuated by a set of opposite pistons in a wheel cylinder.
4. The combined brake system for two wheelers as claimed in claim 1, wherein said drum brake is provided with an auto adjuster.
5. A two wheeler having said combined brake system as claimed in claim 1.