GB2166224A

GB2166224A - Brake valve assembly

Info

Publication number: GB2166224A
Application number: GB08526122A
Authority: GB
Inventors: Aloys Schnaker
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1984-10-24
Filing date: 1985-10-23
Publication date: 1986-04-30
Also published as: IT8522515A0; FR2572038A1; IT1200797B; DE3438899A1; GB8526122D0; GB2166224B

Abstract

A parking-brake valve assembly has a release sleeve (18a) provided with a release ring (18) and a latching sleeve (20) axially movably mounted on the brake lever (5). The latching sleeve (20) or the release sleeve (18a) slides in a guideway (23) of the brake valve assembly, and the release sleeve is subjected to the action of springs (12 and 17). At position B, a latching collar (21) on sleeve (20) drops into a trap (25) in the guideway (23). Depressing handle (16) allows the collar (21) to be engaged below a retaining edge (32) of the guideway (23) when the lever is moved to position C. <IMAGE>

Description

SPECIFICATION Brake valve assembly The invention relates to a brake valve assembly, such as a parking-brake valve assembly, for brake systems of commercial vehicles.

A brake valve assembly comprising a valve member actuable in an axial direction and a pivotable actuating lever for actuating the valve member is known (German Patent Specification (Offenlegungsschrift) No. 33 01 774).

Such a brake valve is generally used in a motor vehicle pressure-medium-operated brake system, having a spring-loaded brake arrangement whose energy storing spring is stressed under supply pressure. By venting the spring-loaded brake cylinder, the energy-storing spring can apply the brakes, e.g. for parking. The actuating lever can be latched in its braking (parking) position.

In addition to the braking position described, the actuating lever of the brake valve can also assume a position in which a test position is obtained in which the braking action is limited to only a part of the motor vehicle.

The actuating lever is guided in a kind of guideway or gate and has to be guided in the guideway manually in order to reach the latching position and the test position, so that the edges and stops of the guideway are subjected to considerable stress, resulting in rapid wear.

The present invention resides in a brake valve assembly having at least one valve member which is actuable in an axial direction and having a pivotable lever which is provided with a handle and which is pivotably mounted on a housing of the brake valve for switching the valve member and is pivotable to assume various positions with which corresponding positions of the valve member are associated, a release sleeve being axially displaceably disposed on the lever below the handle and the end of the release sleeve facing the handle carrying a manually operable release ring and its end facing the housing carrying a latching sleeve, the latching sleeve cooperating with recesses in a guideway.

This has the advantage that faulty actuation is reliably avoided. In addition to this, the release ring sliding in the guideway under spring force subjects the guideway to substantially less wear than a lever itself manually guided in the guideway. The lever can move automatically from a test -position to the latching or parking position.

The invention is further described, by way of example, with reference to the accompanying drawings which is a sectional view of the actuating lever and associated parts of a brake valve assembly according to the invention.

A parking-brake valve has a housing 1 in which a double valve (not illustrated) controls communication between a working cylinder and a source of supply pressure or a relief point. A valve stem 2 is mounted axially displaceably in the housing 1 for the purpose of operating the valve and its top end is located opposite an eccentric 3. The eccentric 3 is carried by a shaft 4 which passes through a le ver 5 at right angles to the axis thereof and to the axis of the valve stem 2. In this manner, the eccentric 3 is turned, and the valve stem 2 is actuated, when the lever 5 is pivoted.

The lever 5 is a rod of round cross section hav ing a shoulder 6 and a reduced portion 7 contig uous thereto towards the free end of the lever. The outer end of the reduced portion carries a transverse pin 8 which serves as an upper stop and which also serves as a means for preventing rotation of a tubular member 10 by virtue of a diametrical recess 9 in the member 10. The interior of the tubular member 10 is stepped, so that the tubular member can slide on the reduced portion 7 and on the non-reduced portion of the lever 5. A spring 12 is fitted between the shoulder 6 of the lever 5 and a shoulder 11 in the interior of the tubular member 10 and seeks to urge the tubular member 10 outwardly in such a way that the inner end of its diametrical recess 9 abuts against the transverse pin 8.

A bush 13 is screwed onto the free end of the tubular member 10 and has two shoulders 14 and 15. The shoulders 14 and 15 serve to anchor a handle 16, and an inner end of the bush 13 forms an abutment for a spring 17 whose other end acts upon a release ring 18 by abutting against an internal shoulder 19 thereof.

The release ring 18 is carried by a release sleeve 18a which is screwed to a latching sleeve 20 or is connected thereto in some other manner. A free space 31 is formed between a bottom end 28 of the release sleeve 18a and an internal shoulder 30 of the latching sleeve 20 and is defined in an axial direction by a foot 29 of the tubular member 10. A latching collar 21 is provided at the bottom end of the latching sleeve 20. The top of the housing 1 is covered by a cover 22 in which a kind of gate or guideway 23 is formed. The guideway 23 forms a slideway for the latching sleeve 20 and for the latching collar 21.

When in the travelling or normal position A (shown in full lines), the latching collar 21 abuts against a shoulder 24 of the guideway 23. The double-seat valve (not illustrated) has connected the compressed-air reservoir to the spring-loaded brake cylinder, so that the energy-storing spring is compressed and the brakes are released.

The actuating lever 5 is pivoted from a position A into position B (partly shown by chain dotted lines) in order to actuate the brakes. The latching collar 21 thereby undertakes guidance of the lever in the radial direction of the arc of traverse A-B, and the latching sleeve 20 undertakes lateral guidance of the lever. At the end of the actuating travel, the latching collar 21 drops into a trap 25 until the bottom end 28 of the release sleeve 18a abuts against the foot 29. One end of the trap 25 is formed by a latching edge 26 and its other end is formed by an abutment face 27. When the lever is in this position B, the double-seat valve is switched over in such a way that the supply pressure is shut off and the brake cylinder is connected to a relief point. The energy-storing spring then applies the brakes. The tractor vehicle and a trailer towed thereby are braked.

The release ring 18 has to be raised manually if the lever 5 is to be moved out of position B. The latching collar thereby slides out of the trap 25.

The lever 5 can then be returned to its starting position A.

However, if the lever 5 is to be moved into the test position C from the position B, the handle 16 has to be pressed downwardly in the axial direction of the lever 5, and the lever 5 has to pivot until the latching collar 21 engages below a retaining edge 32 of the guideway 23. Either the spring 17 may be sufficiently strong to keep the internal parts of the device apart (as illustrated) or, alternatively, the device may be constructed in such a way that the spring 17 becomes fully compressed and the tubular member 10 and the latching sleeve 20 are supported directly against one another.

When the lever 5 is in this position, only some of the brakes, namely the trailer brakes, are actuated to test the brake system for safety.

The lever 5 returns automatically from the test position C to the rest position B.

Claims

1. A brake valve assembly having at least one valve member which is actuable in an axial direction and having a pivotable lever which is provided with a handle and which is pivotably mounted on a housing of the brake valve for switching the valve member and is pivotable to assume various positions with which corresponding positions of the valve member are associated, a release sleeve being axially displaceably disposed on the lever below the handle and the end of the release sleeve facing the handle carrying a manually operable release ring and its end facing the housing carrying a latching sleeve, the latching sleeve cooperating with recesses in a guideway.

2. A brake valve assembly as claimed in Claim 1, in which the latching sleeve is subjected to the force of a spring which seeks to urge the latching sleeve inwardly towards the housing.

3. A brake valve assembly as claimed in claim 2, in which the spring is disposed coaxially of, and within, the latching sleeve.

4. A brake valve assembly as claimed in any of claims 1 to 3, in which the end of the latching sleeve facing the guideway carries a latching collar which serves as a latch member and which is guided in the guideway and cooperates with said recesses therein.

5. A brake valve assembly as claimed in any of claims 1 to 4, in which the handle is fastened to a tubular member which is slidably received on said lever and in which the handle and tubular member are urged by a spring outwardly away from the housing.

6. A brake valve assembly as claimed in claim 5, in which the latching sleeve is received partially over the tubular member.

7. A brake valve assembly, constructed and adapted to be operated substantially as herein described with reference to and as illustrated in the accompanying drawing.