GB1600896A

GB1600896A - Actuating device for hand brake valves

Info

Publication number: GB1600896A
Application number: GB10465/78A
Authority: GB
Original assignee: Wabco Fahrzeugbremsen GmbH
Current assignee: Wabco Fahrzeugbremsen GmbH
Priority date: 1977-03-24
Filing date: 1978-03-16
Publication date: 1981-10-21
Also published as: DE2712945B1; FR2385022B1; FR2385022A1; DE2712945C2; IT7867650A0

Description

(54) ACTUATING DEVICE FOR HAND BRAKE VALVES (71) We, WABCO FAHRZEUGBREMSEN GmbH (Formerly Wabco Westinghouse GmbH), a German Company of Am Lindener Hafen 21, 3000 Hanover 91, 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 invention relates to an actuating device for hand brake valves in pressure medium braking systems, in particular in motor vehicle braking systems.

Hand brake valves have been developed for actuating, in a motor vehicle, the parking and secondary brake system which are preferably equipped with spring-loaded brake cylinders, the latter system being actuable in a precisely graduated manner, and also for simultaneously actuating a trailer brake system when a trailer is in use.

A hand brake valve of this type has become known through German Utility Model Specification 19 84 921 and the actuating device of this known valve (illustrated in Figure 1 of the accompanying drawings) consists of a switching lever I connected with a rotatable cap of the valve, with a stop 2 attached to it. Two detents 3 and 4 are arranged on the valve housing and a stop recess 5 is located behind the detent 4, the lever I being tensioned by a spring 6 which keeps the stop 2 in a position switched by extending the lever 1 into the stop recess 5.

In order to be able to explain in a comprehensible manner the disadvantages of this actuating device, the individual switching positions of the device and the effects obtained with them during driving will now be described, as far as is necessary, with the aid of Figure 1.

In the driving position, the stop 2 bears against the detent 3. In order to actuate, in a graduated manner, the secondary brake system, the lever I is displaced in the direction of the detent 4, and, in the full braking position, the stop 2 bears against the detent 4 as shown in Fig. 1. When the trailer is in use, the brake system of the trailer is also actuated in graduated manner. If the lever 1 is released, the said lever automatically moves back into the driving position, that is, with the stop 2 against the detent 3.

In the parking brake position of the vehicle the stop 2 is brought over and beyond the full braking position, that is, past the detent 4, into the stop recess 5 by extension of the lever, and the vehicle then cannot accidentally roll forward, as a result of braking force of the spring-loaded braking cylinder arranged on the rear axle.

When the trailer is used, two different arrangements are possible, in the said parking brake position, for simultaneous parking braking of the trailer. In the first arrangement, the trailer is co-braked only as far as the detent 4, that is, only as far as the maximal secondary braking position and is then automatically released again in the parking braking position of the hauling vehicle: that is, in this arrangement, in the parking braking position, the vehicle and the trailer are held only by the spring-loaded brakes of the rear axle of the motor vehicle.

In the second arrangement, the brake system of the trailer remains braked when the stop 2 is positioned in the recess 5: that is, in the case, the vehicle and the trailer are held both by the spring brakes of the rear axle of the motor vehicle and also by the trailer brakes.

In the first case, the trailer can be moved after disengagement but in the second case this is not achieved until the trailer brakes have first been mechanically released.

It is legally laid down that the parking brake force of spring-loaded brakes acting only on the rear wheels of the motor vehicle must hold the vehicle and trailer without cooperation of the trailer brakes at a gradient of 12% when parked. It is, accordingly, necessary that for the parking brake position in which both the rear axle of the motor vehicle and the trailer are braked, an additional switching position, a so-called testing position, should be provided on the hand brake valve for purposes of testing these legal requirements. Normally, this testing position is behind the locking position for the parking brake and in the opposite direction to the driving position and, from time to time, the driver must move the hand lever into this testing position in order to ensure that the spring-loaded brakes are working efficiently.

Both of the braking arrangements utilizing the Fig.l design of actuating device have the disadvantage that the lever 1 accidentally can be moved over the detent 4, which can be recognised as a transition point, into the stop recess 5, as a result of a swift movement caused by panic. This causes uncontrollable over-braking and, in addition, in the arrangement without braking for the trailer can lead to "buckling" of the vehicle and trailer.

Further disadvantages arise if, as a result of jamming, the lever 1 does not lock automatically into the parking position and the parked vehicle begins to move by itself.

This happens if the automatic slide-return of the lever into the driving position, which is desired after secondary braking, takes place where it is not required. The reverse is also possible that is, as a result ofjamming of the lever it can be very difficult to pull the lever back out of the parking position.

The present invention provides an actuating device for a hand brake valve for a braking system, including a switching member movable in a guideway for actuating the brake valve, the guideway having two portions offset one from the other and that part of the switching member within the guideway being formed with two cams offset one from the other, the switching member having two orientations in each of which a respective one of the cams serves to guide the switching member in a respective one of the portions of the guideway.

In one form of device, in accordance with the invention and suitable for either a vehicle or vehicle and trailer combination, the switching member is movable, in one of its orientations and in the respective portion of the guideway, from a driving position to a full secondary braking position to actuate a secondary brake system of the vehicle, being thereafter movable into the other orientation to actuate a parking brake system of the vehicle and is then movable in that other orientation and in the respective portion of the guideway to test the parking braking action of the vehicle or combination.

In an embodiment of the invention, described herein, the two portions of the guideway are disposed, relative to the switching member, at different levels and the two cams are similarly disposed and are offset at 90 from each other. In this embodiment, as a result of the clear distinction between the tasks assigned to the actuating device as a result of the design of the cams offset at 90 , accidental movement of the switching member into the parking braking position, and the dangers caused by undesired switching of this type, can be eliminated and the risk of accidents occurring under certain conditions can be reduced or even removed.

In the following, the construction and operation of a hand actuating device according to the invention are described in more detail, by way of example, with the aid of Figures 2 to 6 of the accompanying drawings, of which: Figure 2 shows a section through the actuating device according to the invention, Figure 3 shows the lever and cam arrangement in the driving position, Figure 4 shows the lever and cam arrangement in the secondary brake position, Figure 5 shows the lever and cam arrangement in the parking position, Figure 6 shows the lever and cam arrangement in the testing postion.

The actuating device substantially consists, according to Figure 2, of a switching housing 8 and a switching lever 12 comprising a handle 9, a cam member 10 and a connecting rod 11, the lever being securely fixed by its connecting rod 11 to a roller member 13 which is rotatably mounted in the switching housing 8 and the lower side of which is designed as an actuating cam for control of the hand brake valve. For the purpose of guiding the switching lever 12, the cover 14 of the switching housing 8 is designed with a radial guideway 15. The connection of the connecting rod 11 to the cam member 10 is formed by a pin 16 (or, alternatively and not illustrated, by a screw connection) which at the same time limits rotational movement of the cam member about its longitudinal axis.In the vicinity of the guideway 15, the cam member 10 is provided with two cams 17, 18 offset relative to each other by 90 and disposed one above the other lengthwise of the lever 12 as seen in Fig. 2. When the lever 12 is switched, the lower cam 17 is guided in the main portion of the guideway 15 while an indention 19 in the guideway 15 acts as a detent for the upper cam 18 or, following rotation of the cam member 10 through 90 about its longitudinal axis, as a guide for the upper cam. The handle 9 is screwed to the upper portion of the cam member 10.

The effect of moving the lever 12 along the guideway 15 will now be described. In the driving position, the lever 12 is at the end of the guideway remote from the indentation 19, as shown in Fig. 3. In the region of actuation for a secondary brake (that is movement of the lever 12 along the guideway over an angle of about 68 from the Fig. 3 postion) , the lower cam 17, nearest to the point of rotation of the switching lever 12, undertakes guiding in the main portion of the guideway 15. In the position of full secondary braking (figure 4) the offset cam 18, by bearing on the upper indentation 19 of the guideway 15, prevents actuation into the spring brake testing postion (figure 6), which position can only be initiated when switching of the lever 12 into the indentation 19 has taken place as will now be described.

By turning the cam member 10 into the parking position (figure 5), that is, by turning the switching lever 12 through 90 , the lower cam 17 rests against the guideway 15 and prevents backward movement of the switching lever 12 into the driving position (figure 3). The lever is thus locked firmly, for parking brake-action by the spring-loaded brakes on the vehicle rear axle and, depending on the arrangement employed, possibly by trailer brakes also.However, at the same time, the switching lever is now free to be moved into the spring-loaded brake testing position (figure 6) located at an angle of about 80 from the driving position of Fig. 3, being guided in this movement by the upper cam 18, and it is not possible for backward movement out of this position (figure 3) to occur without the lever being turned back through 90 .

WHAT WE CLAIM IS: 1. An actuating device for a hand brake valve for a braking system, including a switching member movable in a guideway for actuating the brake valve, the guideway having two portions offset one from the other and that part of the switching member within the guideway being formed with two cams offset one from the other, the switching member having two orientations in each of which a respective one of the cams serves to guide the switching member in a respective one of the portions of the guideway.

2. A device according to claim l, for a braking system for a vehicle or vehicle and trailer combination, in which the switching member is movable, in one of its orientations and in the respective portion of the guideway. from a driving position to a full secondary braking position to actuate a secondary brake system of the vehicle, being thereafter movable into the other orientation to actuate a parking brake system of the vehicle and is then movable in that other orientation and in the respective portion of the guideway to test the parking braking action of the vehicle or combination.

3. A device according to claim I or claim 2, in which the two portions of the guideway are disposed, relative to the switching mem ber, at different levels and the two cams are similarly disposed and are offset at 90 from each other.

4. A device according to claim 2, in which, in the full secondary braking position or in the parking braking position the nonguiding cam rests against a portion of the guideway.

5. A device according to claim 4, in which. in the full braking position the nonguiding cam rests against a portion of the guideway to prevent movement of the switching member into the testing position.

6. A device according to claim 4 or claim 5, in which in the parking braking position, the non-guiding cam rests against a portion of the guideway to prevent movement of the switching member into the driving position.

7. A device according to any one or the preceding claims in which the switching member consists of an actuating rod, a cam member carrying the cams and a handle.

8. A device according to claim 7, in which the actuating rod is connected with the cam member by means of a pin.

9. A device according to claim 8, in which there is a screw connection between the cam member and the handle.

10. A device according to claim 8 or claim 9, in which the connection between the cam member and the actuating rod limits rotational movement of the cam member to 90'.

11. An actuating device for a hand brake valve for a braking system, substantially as described herein with reference to, and as illustrated by, Figs. 2 to 6 of the accompanying drawings.

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. spring brake testing postion (figure 6), which position can only be initiated when switching of the lever 12 into the indentation 19 has taken place as will now be described. By turning the cam member 10 into the parking position (figure 5), that is, by turning the switching lever 12 through 90 , the lower cam 17 rests against the guideway 15 and prevents backward movement of the switching lever 12 into the driving position (figure 3). The lever is thus locked firmly, for parking brake-action by the spring-loaded brakes on the vehicle rear axle and, depending on the arrangement employed, possibly by trailer brakes also.However, at the same time, the switching lever is now free to be moved into the spring-loaded brake testing position (figure 6) located at an angle of about 80 from the driving position of Fig. 3, being guided in this movement by the upper cam 18, and it is not possible for backward movement out of this position (figure 3) to occur without the lever being turned back through 90 . WHAT WE CLAIM IS:

1. An actuating device for a hand brake valve for a braking system, including a switching member movable in a guideway for actuating the brake valve, the guideway having two portions offset one from the other and that part of the switching member within the guideway being formed with two cams offset one from the other, the switching member having two orientations in each of which a respective one of the cams serves to guide the switching member in a respective one of the portions of the guideway.