DESC:Field of the invention

[0001] The present invention relates to a pneumatic braking system. More particularly, the present invention relates to a mechanism for a pneumatic braking system for preventing compounding effect which may prevent damages/failures/abnormalities caused during compounding braking.

Background of the invention

[0002] Generally, a pneumatic braking system is used in heavy vehicles, such as trucks, buses, trailers and the like. The pneumatic braking system includes a service brake and a parking brake. For applying parking brake, air from a parking side portion is released through a hand brake valve to atmosphere, and the brake is mechanically applied under force of a power spring. If at the same instance, driver applies service brakes, then additional force is exerted on a pushrod. This phenomenon is called as compounding braking. Compounding braking damage the brake components.

[0003] The compounding braking puts a high amount of stress on slack adjusters and further parts associated in braking system, thereby causing damage to the pneumatic brake system parts or brake abnormalities / failure. Whenever parking brakes are applied, there is a tremendous force applied to all of the brake components in the pneumatic brake system. In addition, if a heavy service brake is applied at the same time, the force of the air application is added to the previous force of the parking brakes. These forces together are referred as compounding, that can damage brake components, such as a slack adjuster, an S-cam, a brake chamber, a mounting bolt, a brake shoe roller, a shoes and brake drums and the like. At present, an external valve is being used as anti-compounding along with relay valve or quick release valve having added feature to avoid compounding braking called as anti-compounding relay valve or anti compounding quick release valve. This adds to cost.

[0004] Therefore, there is a need to provide a mechanism for a pneumatic braking system for preventing compounding effect, which can overcome at least some of the above mentioned drawbacks of the prior art.

Objects of the invention

[0005] Object of the present invention is to provide a mechanism for a pneumatic braking system for preventing compounding effect.

[0006] Another object of the present invention is to provide a mechanism for a pneumatic braking system, which can eliminate the need of an external anti compounding valve or similar product for said purpose in the pneumatic braking system thereby reducing extra cost of construction.

[0007] Further object of the present invention is to provide a mechanism for a pneumatic braking system, which can prevent damage to the components of the pneumatic braking system during compounding.

[0008] Another object of the present invention is to provide a mechanism for a pneumatic braking system, which can increase life of components in the pneumatic braking system

[0009] Still another object of the present invention is to provide a mechanism for a pneumatic braking system, which can improve life of a power spring.

[0010] Further object of the present invention is to provide a mechanism for a pneumatic braking system, which is economical to manufacture.

[0011] One more object of the present invention is to provide a mechanism for a pneumatic braking system, which is easy to manufacture and is robust in construction.

[0012] Further object of the present invention is to provide a mechanism for a pneumatic braking system facilitates in saving cost of servicing, which occurs due to compounding braking.

Summary of the invention
[0013] According to the present invention there is to provide a mechanism for a pneumatic braking system for preventing compounding effect. The pneumatic braking system includes a service brake actuator, a parking brake actuator and a first pushrod. The first push rod connecting braking elements with the service brake actuator. Upon applying service brake, the service brake actuator pushes the first pushrod for applying brakes. A second push rod is connecting the parking brake actuator with the first pushrod. The mechanism includes a passage with an opening and an exhaust configured in the second push rod. Further, the opening releases air from the service brake actuator to the atmosphere in case of compounding braking. Alternatively, the passage is arranged over the second push rod.

[0014] Also, the passage comprises a valve arranged between the opening and the exhaust for permitting the air flow in the opening toward the exhaust. The valve is a unidirectional valve or a gasket

Brief Description of drawings

[0015] The advantages and features of the present invention will become better understood with reference to the following detailed description taken in conjunction with the accompanying drawings, wherein like elements are identified with like symbols, and in which:

[0016] Figure 1 shows a sectional view of a mechanism for a pneumatic braking system in accordance with the present invention.

Detail description of the invention
[0017] An embodiment of this invention, illustrating its features, will now be described in detail. The words "comprising," "having," "containing," and "including," and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items.

[0018] The terms “first,” “second,” and the like, herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another, and the terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.

[0019] The disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms.

[0020] The present invention is to provide a mechanism for a pneumatic braking system for preventing compounding effect. The mechanism can eliminate the need of an external anti compounding valve in the pneumatic brake system thereby reducing extra cost of construction. The mechanism can prevent damage to the components of the pneumatic brake system during compounding. The mechanism can increase the life of brake components in the pneumatic brake system. Further, the mechanism can improve life of a power spring. Furthermore, the mechanism actuator is economical to manufacture. Moreover, the mechanism is easy to manufacture and is robust in construction. Also, the mechanism facilitates in saving cost of servicing, which occurs due to compounding braking.

[0021] Referring now to figure 1, an actuator 100 of an air braking system in accordance with the present invention is illustrated. Specifically, the actuator 100 is an anti-compounding air brake actuator. The actuator 100 includes an enclosure 10, a service brake actuator 50a and a parking brake actuator 50b. Further, the actuator 100 is divided in two portions, the service brake actuator 50a, the parking brake actuator 50b enclosed by the enclosure 10. The service brake actuator 50a includes a first diaphragm 12 and a first pushrod 16. The first diaphragm 12 is connected to the first pushrod 16 and the first pushrod 16 is connected to a braking elements responsible for applying brakes. In case of disc brakes, the braking elements include brakes pads and the brake disc.

[0022] Further, the service brake actuator 50a is activated when a driver driving the vehicle operates a foot brake, which is a normal operation. Upon applying the foot brake, the air in the pneumatic braking system is supplied to the service brake actuator 50a thereby actuating the first diaphragm 12. The first diaphragm 12 pushes the first pushrod 16 outwards for applying brakes.

[0023] Pressurized air is always filled on the parking brake actuator 50b in normal non-operating condition. The parking brake actuator 50b has a second diaphragm 14 and a second pushrod 18. The second pushrod 18 is connected to the first pushrod 16. Therefore, the first pushrod 16 and the second pushrod 18 move together only when a parking brake is applied.

[0024] Further, when the parking brake is applied, the air filled in parking brake actuator 50b is released to atmosphere. When the pressure is released from the parking brake actuator 50b, the spring 24 pushes on a piston (not shown) which is connected with the second pushrod 18, which in turn pushes on a first piston (not shown) and the first pushrod16 for activating the brakes. The second pushrod 18 enters the service brake actuator 50a while pushing the first pushrod 16 for applying the brakes.

[0025] Therefore, for applying service brakes, the air is filled on the service brake actuator 50a and for applying parking brakes, the air is released from the parking brake actuator 50b.

[0026] When the parking brake is applied, the air from the parking brake actuator 50b is released and the second pushrod 18 is pushed by the spring 24 and hence the first pushrod 16 is pushed for applying brakes. Simultaneously, if the service brake is applied, the air starts filling in the service brake actuator 50a pushing the first pushrod 16 outward. This situation is referred as compounding braking. Compounding braking may damage brake components, such as a slack adjuster, an s-cam, a brake chamber, a mounting bolt, a brake shoe roller, a shoes and brake drums and the like.

[0027] To avoid this condition, the present invention provide a mechanism 200 for a pneumatic braking system for preventing compounding effect in accordance with the present invention. Referring again to figure 1, the mechanism 200 includes a passage 210 having an opening 220 and an exhaust 222. In the present embodiment, the mechanism 200 is configured in the second pushrod 18. The passage 210 connects the opening 220 and the exhaust 222, for passing air from the opening 220 to atmosphere through the exhaust 222.

[0028] Specifically, the opening 220 is configured on the second pushrod 18, in such a way that when the parking brakes is applied, the opening 220 enters the service brake actuator 50a and the exhaust 222 remains in the parking brake actuator 50b. When the service brake is applied while the parking brake is already being applied, the second pushrod 18 travels in the service brake actuator 50a along with the opening 220. The air that is filled on the service brake actuator 50a is carried by the opening 220 and then released through the exhaust 222 to the parking brake actuator 50b, which further releases the air out to the atmosphere. This effectively eliminates or reduces service brake pressure and avoids compounding braking.

[0029] In yet another embodiment, the passage 210 includes a valve 226. The valve 226 enables air flow from the opening 220 toward the exhaust 222 and prevent air flow from the exhaust 222 towards the opening 220, which prevents accidental braking. The valve 226 may be arranged between the opening 220 and the exhaust 222. In the present embodiment, the valve 226 is a gasket arranged on the exhaust 222. In alternate embodiments, the valve 226 is a unidirectional flow control valve.

[0030] Therefore, the mechanism 200 of the present invention eliminates the need of an external anti compounding valve in the pneumatic brake system thereby reducing extra cost of construction. The mechanism 200 prevents damage to the components of the pneumatic brake system during compounding. The mechanism 200 increases the life of brake components in the pneumatic brake system. Further, the mechanism 200 improves the life of a power spring. Furthermore, the mechanism 200 is economical to manufacture. Moreover, the mechanism 200 is easy to manufacture and is robust in construction. Also the mechanism 200 facilitates in saving cost of servicing, which occurs due to compounding braking.

[0031] The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the spirit or scope of the present invention.

,CLAIMS:We Claim:

1. A mechanism for a pneumatic braking system for preventing compounding effect, the pneumatic braking system includes a service brake actuator, a parking brake actuator, a first push rod connecting braking elements with the service brake actuator, upon applying service brake, the service brake actuator pushes the first push rod for applying brakes, a second push rod connecting the parking brake actuator with the first push road, the mechanism comprising:
a passage with an opening and an exhaust configured in the second push rod, the opening releases air from the service brake actuator to the atmosphere in case of compounding braking.

2. The mechanism as claimed in claim 1, wherein the passage comprises a valve arranged between the opening and the exhaust for permitting the air flow in the opening toward the exhaust.

3. The mechanism as claimed in claim 2, wherein the valve is a unidirectional valve.

4. The mechanism as claimed in claim 2, wherein the valve is a gasket arranged on the exhaust.

5. The mechanism as claimed in claim 1, wherein the passage is arranged over the second push rod.