GB1592539A - Compressed air brake systems - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO COMPRESSED AIR BRAKE SYSTEMS (71) We, ROBERT BOSCH GMBH, a German company of Postfach 50, 7 Stuttgart 1, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to compressed air brake systems for vehicles.

A problem common to all vehicles is that of providing security against theft, and commercial vehicles having a compressed air brake system are not yet customarily provided with a simple anti-theft device, so that tractor vehicle-trailer vehicle combinations are frequently being stolen, particularly when they are loaded with valuable freight.

In the case of vehicles having an hydraulic brake system, it is already known to main hydraulic brake pressure in a wheel brake cylinder by means of a valve which is fixable so as to be secure against unauthorised tampering. However, a device of this type is not operationally reliable, since no hydraulic valve is sufficiently fluid-tight to prevent a decrease in the hydraulic pressure and to prevent the brake pressure in the wheel cylinder from dropping to an extent where the vehicle can be driven away or can roll away.

According to the present invention there is provided a compressed air brake system for commercial vehicles, having a compressed air supply, a control valve and at least one spring-loaded brake cylinder whose energystoring spring is stressed by compressed air and rendered inoperative when the control valve is in its position for releasing the brake and, when the control valve is in its position for applying the brake, the said energystoring spring is relieved of stress and actuates the brake upon removal of the action of the compressed air, in which a compressed air line leading to the spring-loaded brake cylinder is provided with means whereby communication between the spring-loaded cylinder and a relief point can be established in a manner at least resistant against unauthorised tampering.

A compressed air brake system embodying the present invention can have the advantage that a commercial vehicle cannot be readily driven away by unauthorised persons. The energy-storing spring has applied the brake, and, in addition to providing compressed air, possibly only by starting the engine, the control valve, or a separate parking control valve, also has to be moved from its fixed, tamper-resistant position, in which it is preferably locked with a lock and key, in order to release the brake applied by the energy-storing spring. Thus, in order to release the brake, an ignition key is required for switching on the means for producing the compressed air, as well as the key for releasing the control valve or separate parking valve from its fixed position. It is unlikely that unauthorised persons can fulfil all these pre-requisites for driving away a commercial vehicle.

The invention will be further described by way of example, with reference to the accompanying drawing, which illustrates two embodiments of the invention.

A brake system on a tractor vehicle has a compressor I which supplies compressed air to two reservoirs 5 and 6, a secondary load 7 and a trailer vehicle air supply line 8 by way of a pressure regulator 2, an anti-frosting pump 3 and a 4-circuit protective valve assembly 4. Two tractor vehicle service brake circuits I and II are associated respectively with the two reservoirs 5 and 6 and can supply compressed air to a front wheel brake cylinder 10 and a rear wheel brake cylinder 11 by way of a foot-operated two-circuit brake valve 9. Compressed air lines 12 and 13 of the two brake circuits I and II are connected to a trailer vehicle brake control valve 14 to which is also connected a third line 15 which leads from a spring-loaded brake circuit having a manually operable parking brake valve 16 and two springloaded brake cylinders 17 and 18. The spring-loaded brake circuit is supplied with compressed air from the trailer vehicle air supply line 8 by way of a non-return valve 19.

A compressed air line coupling head 20 is located at the end of thc trailer vehicle compressed air supply linc 8 and, down strcam of the trailer vehicle brake control valve 14, a linc 21 leads to a trailer vehicle brake line coupling head 22. Furthermore. a branch line 23 leads from the trailer vehicle compressed air supply line coupling head 20 to the trailer vehicle brake control valve 14.

Finally, a brake line 24 leads from the holed brake valve unit 16 to the spring-load cr brake cylinders 17 and 18.

The manually operable parking brake valve 16 has a housing 27 which carries an actuating lever 34. The housing 27 has a compressed air line inlet connection 3 1 for the compressed air line, a connection 32 fir the brake line 24, and an atmospheric air connection 33 (acting as a relief point). When the vehicle is ready to travel, the parking brake valve 16 maintains communication between the compressed air line and the brake line 24 and, when the parking brake valve 16 is in its illustrated braking position.

communication with the compressed air line is shut off and the brake line 24 communicates with the atmospheric air.

The housing 27 is provided with a projection point 35, and a second projection point 36 is provided on the actuating lever 34.

When the valve 16 is in its illustrated position, the two projection points 35 and 36 are lockable in their mutual positions by means of a lock 38 which is lockable by a key 37, so that unauthoriscd persons cannot move the lever 34.

Alternatively or additionally as is shown by a connection line 39 (shown by a broken line), it is al o possible to connect the spring loaded cylinders to a special control valve 40.

The control valve 40 has a relief point 41 and is assembled with, or connected to, a cylinder lock 42 and is lockable by means of a key 43.

The control valve 40 is arranged at a point in the driver's cab which is readily accessible from the drivcr's seat. Preferably, the line connection 39 is a flexible line made from plastics material.

The system described above operates as follows: When the vehicle, parked in a theftresistant manner, is to be driven away, the ignition system has to be actuated by means of an ignition key and the engine of the vehicle has to be started. The compressor of the compressed air brake system supplies compressed air to the system. llowever, this compressed air cannot stress the energystoring springs in the spring-loaded brake cylinders 17 and 18 and cannot release the brake, since the manually operated parking brake valve 16 or the control valve 40 allows compressed air to flow to the atmosphere.

A pressure can build up in the springloaded brake cylinders 17 and 18 only when the driver has unlocked the valve 16 or 40 by means of the key 37 or 43 and has brought the valve into a different switching position in which communication with the atmospheric air (relief point 33 or 41) has been interrupted. The energy-storing springs are then compressed and the brakes are released.

When the vehicle is to be parked in a theft proof manner after a journey, the valve 16 or 40 is brought into the position for venting the compressed air line and is locked in this position in a theft-resistant manner.

WHAT WE CLAIM IS: 1. A compressed air brake system for commercial vehicles. having a compressed air supply, a control valve and at least one spring-loaded brake cylinder whose energystoring spring is stressed by compressed air and rendered inoperative when the control valve is in its position for releasing the brake and, when the control valve is in its position for applying the brake, the said energystoring spring is relieved of stress and actuates the brake upon removal of the action of the compressed air, in which a compressed air line leading to the spring-loaded brake cylinder is provided with means whereby communication between the spring-loaded cylinder and a relief point can be established in a manner at least resistant against unauthorised tampering.

2. A compressed air brake system as claimed in claim 1, in which the said means are provided on the control valve which is in the form of a manually operable parking brake valve and which is lockable in a tamper-resistant manner when in its braking position.

3. A compressed air brake system as claimed in claim 1, in which the said means are provided on a separate control valve which is assembled with, or coupled to, a lock, preferably a cylinder lock.

4. A compressed air brake system as claimed in claim 3, in which the separate control valve is adapted so that it can be arranged in the driver's cab at a location which is readily accessible from the driver's seat, and in which a compressed air line, connecting the control valve to the springloaded brake cylinder is a flexible line made of plastics material.

5. A compressed air brake system for commercial vehicles, constructed and arranged and adapted to operate substantially as hereinbefore particularly described with reference to and as illustrated in the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. located at the end of thc trailer vehicle compressed air supply linc 8 and, down strcam of the trailer vehicle brake control valve 14, a linc 21 leads to a trailer vehicle brake line coupling head 22. Furthermore. a branch line 23 leads from the trailer vehicle compressed air supply line coupling head 20 to the trailer vehicle brake control valve 14. Finally, a brake line 24 leads from the holed brake valve unit 16 to the spring-load cr brake cylinders 17 and 18. The manually operable parking brake valve 16 has a housing 27 which carries an actuating lever 34. The housing 27 has a compressed air line inlet connection 3 1 for the compressed air line, a connection 32 fir the brake line 24, and an atmospheric air connection 33 (acting as a relief point). When the vehicle is ready to travel, the parking brake valve 16 maintains communication between the compressed air line and the brake line 24 and, when the parking brake valve 16 is in its illustrated braking position. communication with the compressed air line is shut off and the brake line 24 communicates with the atmospheric air. The housing 27 is provided with a projection point 35, and a second projection point 36 is provided on the actuating lever 34. When the valve 16 is in its illustrated position, the two projection points 35 and 36 are lockable in their mutual positions by means of a lock 38 which is lockable by a key 37, so that unauthoriscd persons cannot move the lever 34. Alternatively or additionally as is shown by a connection line 39 (shown by a broken line), it is al o possible to connect the spring loaded cylinders to a special control valve 40. The control valve 40 has a relief point 41 and is assembled with, or connected to, a cylinder lock 42 and is lockable by means of a key 43. The control valve 40 is arranged at a point in the driver's cab which is readily accessible from the drivcr's seat. Preferably, the line connection 39 is a flexible line made from plastics material. The system described above operates as follows: When the vehicle, parked in a theftresistant manner, is to be driven away, the ignition system has to be actuated by means of an ignition key and the engine of the vehicle has to be started. The compressor of the compressed air brake system supplies compressed air to the system. llowever, this compressed air cannot stress the energystoring springs in the spring-loaded brake cylinders 17 and 18 and cannot release the brake, since the manually operated parking brake valve 16 or the control valve 40 allows compressed air to flow to the atmosphere. A pressure can build up in the springloaded brake cylinders 17 and 18 only when the driver has unlocked the valve 16 or 40 by means of the key 37 or 43 and has brought the valve into a different switching position in which communication with the atmospheric air (relief point 33 or 41) has been interrupted. The energy-storing springs are then compressed and the brakes are released. When the vehicle is to be parked in a theft proof manner after a journey, the valve 16 or 40 is brought into the position for venting the compressed air line and is locked in this position in a theft-resistant manner. WHAT WE CLAIM IS:

1. A compressed air brake system for commercial vehicles. having a compressed air supply, a control valve and at least one spring-loaded brake cylinder whose energystoring spring is stressed by compressed air and rendered inoperative when the control valve is in its position for releasing the brake and, when the control valve is in its position for applying the brake, the said energystoring spring is relieved of stress and actuates the brake upon removal of the action of the compressed air, in which a compressed air line leading to the spring-loaded brake cylinder is provided with means whereby communication between the spring-loaded cylinder and a relief point can be established in a manner at least resistant against unauthorised tampering.

2. A compressed air brake system as claimed in claim 1, in which the said means are provided on the control valve which is in the form of a manually operable parking brake valve and which is lockable in a tamper-resistant manner when in its braking position.

3. A compressed air brake system as claimed in claim 1, in which the said means are provided on a separate control valve which is assembled with, or coupled to, a lock, preferably a cylinder lock.

4. A compressed air brake system as claimed in claim 3, in which the separate control valve is adapted so that it can be arranged in the driver's cab at a location which is readily accessible from the driver's seat, and in which a compressed air line, connecting the control valve to the springloaded brake cylinder is a flexible line made of plastics material.

5. A compressed air brake system for commercial vehicles, constructed and arranged and adapted to operate substantially as hereinbefore particularly described with reference to and as illustrated in the accompanying drawing.