DE2437849A1 - ACTUATING DEVICE FOR A VEHICLE BRAKE - Google Patents

Description

Actuating device for a vehicle brake

The invention relates to an actuating device for a vehicle brake.

Trucks and other heavy vehicles are usually equipped with service or deceleration braking systems for normal braking which are usually pneumatically operated from a main pressure source. It is usual, Provide auxiliary brake actuation devices with which the brakes operate in the event of a failure of the system pressure and if the Service or deceleration brakes cannot be actuated, are kept in the applied state. The auxiliary brake actuators can also be used to apply the brakes when parking.

In an emergency it can happen that the vehicle stops in a place where the malfunctioning pressure system is not can be repaired. For this reason it is advisable to the manual override devices with devices with which the brakes can be released so that the vehicle can be towed to a repair shop.

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According to an earlier proposal, an actuating device for a vehicle brake has one operating in a cylinder and on its inner wall surface guided piston, an elastic device, the piston from an end wall of the cylinder urges away forward toward a brake applied position, the piston normally is retained by the application of the elastic biasing force counteracting fluid pressure, continues to a hollow member of predominantly longitudinal extent, which is rotatably mounted in the said end wall and extends from this extends forward and has an internally threaded part, and a corresponding mating thread, stop member cooperating with the threaded part of the elongated hollow member against which the piston rests can be brought to limit the piston advance, the piston by relative rotation between the stop member and the hollow member is retractable from the brake tensioning position against the resilient biasing force.

In such conventional brake actuators an axial extension is connected in one piece with the piston, one of the rearwardly protruding part of the other, penetrates the front end wall of the cylinder to come to rest on a brake tendon. The one to the rear The protruding part of the end wall is of considerable length and serves to support and guide the piston extension. In such brake actuation devices, difficulties arise from the length of the front wall part in that than the piston stroke is shortened by the end wall part, or that the actuating device to achieve a Required piston stroke must be excessively long, whereby the installation of the actuating device at limited Space becomes difficult.

The invention is based on the object of an actuating device for a vehicle brake that does not adhere to the disadvantages mentioned.

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An actuating device solving the object of the invention is characterized according to the invention in that the piston is slidably guided on the outer surface of the hollow member and on the inner wall surface of the cylinder and on the Outer surface of the hollow member engages at spaced apart locations in the axial and radial directions.

The invention is illustrated below with reference to a schematic drawing showing a section in the longitudinal direction through the Actuating device shows explained with further details.

The actuating device has a cylinder 1 in which a brake actuation unit for auxiliary or emergency braking works, as well as a cylinder 2 for receiving a brake actuation unit for service or deceleration braking. Both brake actuators act on common brake tendon 3 »by its movement the Brake is tightened and released.

The brake actuation unit for the service braking includes a membrane 4 which is attached to its outer circumference and rests against a head 5 of the brake tendon 3. When the service brake is applied, pressure flow is over a Inlet 6 initiated and acts on the back of the diaphragm 4 to adjust the brake tendon to the left.

The brake actuation unit for auxiliary or emergency braking includes a piston that is slidably supported in the cylinder 1 7, which is urged forward by a helical compression spring 8 in the direction of a brake tensioning position. The helical compression spring 8 is supported on the piston 7 and on an end or end wall 9 of the cylinder. The piston is usually held in the position shown by Druckflud, which is from a (not shown) main source via a Inlet 10 can be fed.

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The piston 7 has a forwardly extending hollow Piston rod 11 which penetrates a wall 12 separating the cylinder 1 from the cylinder and is sealed in this is supported. A rearwardly extending hollow piston member 13 is slidable on a hollow brake release member 14 out of predominant longitudinal extent. The brake release member 14 is in an opening 15 in the end wall 9 rotatably mounted and through the interaction of an enlarged head 14A and a spring ring 16 with the The outer edge of the opening 15 is secured against greater axial displacement.

The hollow brake release member 14 has an internally threaded one provided part 14B, which is connected to a corresponding Counter-threaded stop member 17 is connected, which is connected to the front with the hollow brake release member 14 axially aligned hollow piston rod 11 penetrates. On his front end, the stop member has a head 17A which is formed on a rear end of the piston rod, radially inwardly directed puddle 18 can be brought to bear.

During operation, the brake actuation unit can be actuated for auxiliary or emergency braking through pressure loss in the system or with manual valve control through cancellation of the pressure supplied via the inlet 10, for example, to carry out holding braking when parking will.

In the event of a pressure failure, the piston 7 moves to the left under the biasing force of the spring 8, the front end of the Piston rod 11 comes to rest on membrane 4 and adjusts the brake tensioning member 3 to tension the brake. The adjustment of the piston 7 in the brake tensioning direction is limited by approaching the head 17A of the stop member on the flange 18 of the piston rod.

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The hollow brake release member is used to release the brake, for example when the vehicle is to be taken to a workshop 14 turned with a wrench, for example. As a result of the frictional engagement between the head 17A and the flange 18, the brake release member 14 rotates relative to the stop member 17, which in the hollow brake release member is screwed in and the piston 7 out of its brake clamping position withdraws. When the brake is released, the piston 7 »of the helical compression spring 8, the end wall 9 »the brake release member 14 and the stop member 17 dismantle the existing assembly for maintenance purposes by after removing a spring ring 19 holding the end wall 9, the end wall 9 is removed from the cylinder 1.

The invention is not restricted to the above exemplary embodiment, but rather within the framework of this basic idea can be modified in many ways. For example, the piston rod 11 can be articulated on the piston 7, to difficulties with the concentric arrangement due to the support of the piston in the cylinder 1, on the hollow Brake release member 14 and in the partition wall 12 to avoid.

The above-described actuating device has the advantage that the piston 7 is stable and in operation on the hollow brake release member 14 and is guided on the cylinder wall that the assembly with the piston 7 despite the high biasing force the spring 8 can be easily and safely removed from the actuating device, and that the walls 9 and 12, since they are essentially perforated plates, have a simple structure and reduce manufacturing costs can be executed the same with each other.

/ Claims

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Claims (2)

1A-45 289 PATENT CLAIMS 1. Actuator for a vehicle brake, with a piston working in a cylinder and guided on its inner wall surface, an elastic device, which urges the piston forward away from an end wall of the cylinder in the direction of a brake applied position, wherein the piston is normally held back by applying the elastic biasing force counteracting fluid pressure is, furthermore, with a hollow member of predominantly longitudinal extent, which is in said end wall is rotatably mounted and extends from this forward and has an internally threaded part, and with a corresponding mating thread with the threaded portion of the elongated hollow member cooperating stop member on which the piston for Abutment can be brought to limit the piston advance, the piston by relative rotation between the stop member and the hollow member can be withdrawn from the braking position against the elastic biasing force, thereby characterized in that the piston (7) is slidably guided on the outer surface of the hollow member (14) and on the inner wall surface of the cylinder (1) and on the Outer surface of the hollow member (14) at locations spaced apart from one another in the axial and radial directions attacks. 2. Actuating device according to claim 1, characterized characterized in that the end wall (9) with the Cylinder (1) is removably connected. 509811/0703