FR2878922A1 - COMBINED SERVICE BRAKE AND SPRING BRAKE ASSEMBLY WITH HYDRAULIC ACTIVE LINK. - Google Patents

Abstract

The invention relates to a combined service brake and accumulator spring brake installation (1) for motor vehicles comprising: a service brake device (2) arranged directly on a brake mechanism close to the wheel or to the wheel. axle and having a service brake cylinder (4) in which is guided a service brake piston (6) which can be pneumatically powered and which actuates the brake mechanism by a service brake piston rod (8).

Description

COMBINED SERVICE BRAKE AND BRAKE SYSTEM

  HYDRAULIC COUPLING ACCUMULATOR SPRING

  The invention starts from a combined service brake and accumulator spring brake system for motor vehicles, in particular for commercial motor vehicles.

  In order to actuate brakes in commercial motor vehicles, a combined pneumatic cylinder of service brake and accumulator spring brake is used. A combined cylinder of this type is, in a series arrangement, a combination of a service brake cylinder for actuating the service brake and an accumulator spring brake cylinder for actuating the emergency brake. and the accumulator spring brake. A mechanical release device integrated in the combined cylinder in the region of the accumulator spring brake cylinder makes it possible, when the compressed air is missing or when the accumulator spring piston is out, that is to say is in the position brake, loosen the wheel brake.

  The tightened construction conditions on pneumatic suspension axles of modern commercial motor vehicles but also the great mechanical stresses occurring in operation make it necessary to ensure that combined cylinders of this kind take up as little space as possible and are light. A short combined cylinder of this kind is known, for example, from EP 0 452 621 B1.

  The object of the invention is to improve a combined service brake and accumulator spring brake system of the type mentioned above which is more suitable when the construction conditions are tightened on the motor vehicle. 30 35

  Advantage of the invention The invention is based on the idea of separating certain modules from a combined service brake and accumulator spring brake actuated strictly speaking in a purely pneumatic manner and arranged at a distance from a mechanism brake close to a wheel or axle to save space. But to continue to ensure the advantageous functionality of a combined cylinder or the active connection of the service brake and the accumulator spring brake, the modules separated from each other are coupled to each other by a link active hydraulic. The incompressibility properties of the hydraulic fluid allow safe transmission of hydraulic signals.

  According to a first aspect, the subject of the invention is a combined service brake and accumulator spring brake system for motor vehicles, in particular for commercial motor vehicles, comprising: a) a service brake device arranged directly on a brake mechanism close to the wheel or axle and having a service brake cylinder in which is guided a service brake piston which can be pneumatically powered and which actuates the brake mechanism by a piston rod of service brake, (b) an accumulator spring brake device which is arranged at a distance from the brake mechanism close to the wheel or axle and which has an accumulator spring brake cylinder in which is guided by pneumatic pressure in an accumulator spring brake chamber, an accumulator spring brake piston being tensionable against the elastic force of an accumulator spring, there is no active hydraulic connection between the accumulator spring brake piston and the service brake piston, so that actuation caused by the supply of air or the venting of the spring brake chamber accumulator piston of the accumulator spring brake, causes actuation of the service brake piston.

  This aspect is therefore based on the consideration of only putting the service brake device on the brake mechanism close to a wheel or axle and putting the accumulator spring brake device away from it and providing for an active hydraulic connection between the two devices, in order to be able to maintain locked the pneumatic service brake device even for a long period of time by means of the parking brake device being in the brake clamping position. Because the service brake cylinder in position close to the wheel or axle is shorter and lighter than a combined cylinder, space and weight are gained on the axle or on the wheel. to brake. This also sounds favorably, due to the lower unsprung charges, on the dynamic properties of the vehicle.

  Preferably: the hydraulic active link comprises at least a) a first hydraulic piston cooperating with a first hydraulic chamber under pressure, b) a second hydraulic piston cooperating with a second hydraulic chamber under pressure, as well as c) a pressure line between the first hydraulic pressure chamber and the second hydraulic pressure chamber, wherein d) the first hydraulic piston and the first hydraulic pressure chamber are associated with the accumulator spring brake device and e) the second hydraulic piston and the second hydraulic chamber under pressure are associated with the service brake device.

  the first hydraulic piston is in connection with the accumulator spring brake piston.

  the second hydraulic piston comprises a hydraulic membrane.

  the first hydraulic pressure chamber is constituted in the accumulator spring brake cylinder and the second hydraulic pressure chamber in the service brake cylinder.

  the second hydraulic piston is subjected, on the one hand, to the hydraulic pressure prevailing in the pressure conduit and, on the other hand, to the pneumatic pressure of a pneumatic service brake chamber which controls the brake piston on duty.

  the second hydraulic piston is constituted so as to abut on the service brake piston.

  The invention also relates to a combined service brake and accumulator spring brake system for motor vehicles, particularly for commercial motor vehicles, comprising: a) a service brake cylinder which is remote from a mechanism brake wheel close to 10 a wheel or axle and in which is guided a pneumatically serviceable service brake piston which is in connection with a first hydraulic piston cooperating with a first hydraulic chamber under pressure, b) a cylinder spring-loaded accumulator which is remote from the brake mechanism close to a wheel or axle and in which is guided an accumulator spring brake piston which can be tensioned by the pneumatic pressure of an accumulator spring brake chamber against the elastic force of an accumulator spring, the piston by which the service brake piston can be moved in the direction of the brake, a piston t hydraulic pressure between the first hydraulic pressure chamber and a second hydraulic pressure chamber in a cylinder-piston drive close to a wheel or axle having a second hydraulic piston that actuates the brake mechanism close to a wheel or an axle by a piston rod.

  According to this aspect of the invention, the pneumatically actuated combined cylinder constituted by the accumulator spring brake cylinder and the service brake cylinder is thus disposed at a distance from the brake mechanism close to a wheel or a hub and controls by an active hydraulic connection a hydraulic cylinder-piston drive close to a wheel or axle which actuates again the brake mechanism close to a wheel or an axle. Such a cylinder-piston drive is constructed c) also generally in a shorter and easier manner than a pneumatic combined cylinder.

Preferably.

  the brake mechanism close to a wheel or an axle is formed by a disk brake.

  The combined pneumatically actuated cylinder consisting of the accumulator spring brake cylinder and the service brake cylinder is thus disposed away from the brake mechanism close to the wheel or axle and controlled by an active hydraulic connection. , a hydraulic cylinder-piston drive close to a wheel or an axle, drive which actuates again the brake mechanism close to a wheel or an axle. A cylinder-piston drive of this type is, in general, also shorter and lighter than a pneumatic combined cylinder.

  The invention also relates to a combined service brake and accumulator spring brake system for motor vehicles, particularly for commercial motor vehicles, comprising: a) a service brake cylinder which is remote from a mechanism close to a wheel or axle and in which is guided a pneumatically powered service brake piston which is connected to a first hydraulic piston cooperating with a first hydraulic chamber under pressure, b) a cylinder to an accumulator spring which is remote from the brake mechanism close to a wheel or axle and in which is guided an accumulator spring brake piston which can be tensioned by the pneumatic pressure of an accumulator spring brake chamber; against the spring force of an accumulator spring, the piston through which the service brake piston can be moved in the direction of brake engagement, t hydraulic pressure between the first hydraulic pressure chamber and at least a second hydraulic pressure chamber of a hydraulically actuated brake mechanism and attached to a wheel or axle.

  In this case, all the pneumatically actuated combined cylinder consists of the accumulator spring brake cylinder and the service brake cylinder and is also spaced from the brake mechanism close to a wheel or axle. But by the active hydraulic connection, the hydraulic brake mechanism is actuated directly, that is to say that the second chamber under hydraulic pressure is an integral part of the hydraulic brake mechanism and is formed, for example, by the pressure chamber hydraulic in the context of a hydraulic disc brake. This embodiment requires the least space in the area of wheels or axles.

Preferably.

  - the hydraulically actuated brake mechanism is a hydraulic disc brake.

  - the service brake cylinder and the accumulator spring brake cylinder are arranged coaxially and form a construction unit.

  the first hydraulically actuated piston is coaxially connected to the service brake pistons by a piston rod.

  the accumulator spring brake piston is constituted to abut the service piston by means of an accumulator spring brake piston rod.

  - The hydraulic pressure line communicates with a hydraulic tank.

  Exemplary embodiments of the invention are shown in the drawings and explained in more detail in the description which follows. In the drawings: FIG. 1 is a schematic cross-sectional view of a combined accumulator spring brake system according to a first aspect of the invention; Figure 2 is a schematic cross-sectional view of a combined accumulator spring brake system according to another aspect of the invention; Figure 3 is a schematic cross-sectional view of a combined accumulator spring brake system according to another aspect of the invention.

  Description of the embodiments

  1 represents a combined installation 1 of service brake and accumulator spring brake according to a first aspect of the invention which comprises a service brake device 2 arranged directly on a brake mechanism not shown for scale reasons , close to a wheel or an axle. This installation comprises a service brake cylinder 4 in which is guided a service brake piston 6 which can be pneumatically supplied and actuating the brake mechanism by a rod 8 of service brake piston. The brake mechanism is, for example, a disk brake which is tightened or loosened in a purely mechanical manner, that is to say exclusively by means of a linear movement, illustrated by the arrow in FIG. 1, of the piston rod 8 of the service brake.

  In addition, the combined installation 1 of the service brake and the accumulator spring brake comprises an accumulator spring brake device 10 disposed at a distance from the brake mechanism close to a wheel or axle and having a cylinder 12 of accumulator spring brake in which is guided an accumulator spring brake piston 18 can be moved by pneumatic pressure in an accumulator spring brake chamber 10 against the elastic force of a spring 16 accumulator. The piston 18 comprises, for example, a membrane 20 stretched in a side wall of the spring brake cylinder 12 and movable axially, which membrane is reinforced in the middle by a piston disc 22. The atmosphere or the air supply of the accumulator spring brake chamber 14 is effected by means of a pneumatic connection 24. In addition, the accumulator spring 16 is supported, on the one hand, on the side remote from the accumulator spring brake chamber 14, the accumulator spring brake piston 18 and, on the other hand, on a front wall. of the spring brake cylinder 12.

  There is, between the accumulator spring brake piston 18 and the service brake piston 6, an active hydraulic connection, so that a linear movement caused by an air supply or by venting the accumulator spring brake chamber 14 of the accumulator spring brake piston 18 causes a linear movement of the service brake piston 6 in the tightening and loosening direction. Although the service brake device 2 is mounted on the brake mechanism close to a wheel or axle, the accumulator spring brake device 10 is remote therefrom. A coupling of the two devices 2, 10 is given by the hydraulic active link. This comprises at least a first hydraulic piston 28 cooperating with a first chamber 26 under hydraulic pressure, a second hydraulic piston 32 cooperating with a second chamber 30 under hydraulic pressure, and a pressure conduit 34 between the first chamber 26 under hydraulic pressure and the second chamber 30 under hydraulic pressure. The hydraulic pressure conduit 34 again communicates with a hydraulic reservoir 36 which stores an incompressible hydraulic fluid and which, if necessary, injects it into the pressure conduit 34.

  The first hydraulic piston 28 is guided linearly in a hydraulic cylinder 38 in one piece with the spring brake cylinder 12 accumulator and is axially connected axially by a spring brake rod 40 accumulator with the coaxial brake piston 18 to accumulator spring. The piston rod 40 of accumulator spring brake passes in particular with sealing in a passage opening of a front wall, facing the piston 18 accumulator spring brake, the hydraulic cylinder 38 whose front wall remote from the piston 18 brake The accumulator spring comprises another passage opening into which the pressure conduit 34 opens.

  The accumulator spring brake device 10 is a passive brake, that is to say that an air supply of the accumulator spring brake chamber 14 causes the accumulator spring brake to be released by displacement of the brake piston 18 with accumulator spring and first hydraulic piston 28 against the action of the spring 16 accumulator in Figure 1 to the right, while the clamping is caused by venting the chamber 14 spring brake accumulator, the spring 16 accumulator thus pushing the piston 18 spring brake accumulator and the first piston 28 hydraulic to the left in Figure 1.

  The second hydraulically actuated piston 32 is associated with the service brake device 2 and comprises, for example, an axially movable membrane 42 having a central piston disk 44 which constitutes, between it and a front wall of the service brake cylinder 4 in which opens the pressure conduit 34, the second chamber 30 under hydraulic pressure. Between the second piston 32 actuated hydraulically and the piston 6 of the service brake which preferably also comprises a membrane 46 movable axially piston disc 48 central piston, extends a chamber 50 of service brake which can be supplied with air and venting by means of a pneumatic connector 52. The second hydraulic piston 32 is then supplied, on the one hand, by the hydraulic pressure in the pressure conduit 34 and, on the other hand, by the pneumatic pressure in the service brake chamber 50. As is apparent from Figure 1, the second piston 32 hydraulic abuts on the piston 6 of the service brake and drives. In addition, the service brake piston 6 is placed in the release position by a return spring 54 when there is no pressure either in the service brake chamber 50 or in the second hydraulic pressure chamber 30. .

  The operating mode of the combined installation 1 of service brake and accumulator spring brake according to the first aspect of the invention is from this the following: from the situation shown in Figure 1 in which both the spring brake accumulator that the service brake are loosened, the service brake chamber 50 is, to tighten the service brake, supplied with air by the pneumatic connection 52, so that, on the one hand, the piston 6 of the The operating brake is pushed in Figure 1 to the left in the clamping position and that, secondly, the second hydraulic piston 32 is pushed to the right on the front wall of the cylinder 4 operating brake. The operating brake piston rod 8 thus serves the disc brake. In addition, the hydraulic force produced in the pressure conduit 34 by the second hydraulic piston 32 and transmitted to the first hydraulic piston 32 by means of the pressure conduit 34 contributes to the fact that the accumulator spring brake piston 18 is kept in the released position. against the action of the spring 16 accumulator.

  On the other hand, a venting of the service brake chamber 50 while the accumulator spring brake is released causes the service brake piston 6 to be pushed back by the return spring 54 into the release position, c that is to say to the right in FIG. 1, and abuts on the second hydraulic piston 32 which then applies to the front wall of the service brake cylinder 4.

  To maintain the service brake for a long time in the clamping position, that is to say when the pneumatic pressure in the chamber 50 of the service brake has lowered after a certain time, or when the brake chamber 50 service has been vented by the pneumatic connector 52, it is now necessary to apply the accumulator spring brake. For this purpose, the accumulator spring brake chamber 14 is vented by the pneumatic connection 24, so that the accumulator spring 16 of the accumulator spring brake piston 18 is forced together with the first hydraulic piston 28 towards the The displacement of the first hydraulic piston 28 causes the first chamber 26 to shrink under hydraulic pressure, so that hydraulic fluid is discharged through the pressure conduit 34 into the second chamber 30 under hydraulic pressure. The higher hydraulic pressure pushes the second hydraulic piston 32 together with the service brake piston 6 to the left in FIG. 1 and holds it in the clamping position.

  According to the service brake, another aspect of the invention is shown in FIG. 2, the combined installation of and the accumulator spring brake comprises a cylinder 4a of distance from a mechanism of an axle and in which the service brake is arranged. the brake close to a wheel is guided a piston 6a of or a service brake can be pneumatically supplied and communicating with a first piston 28a hydraulic a first chamber 26a under pressure a cylinder 12a spring brake distance from the axle mechanism and wherein is elastic, a piston 18a can be moved by a spring 16a accumulator by pneumatic pressure in a chamber spring brake chamber 14a, piston through which the service brake piston 6a can be moved in the direction of the brake application, a led 34a of hydraulic pressure between the first chamber 26a under hydraulic pressure and the second chamber 30a under hydraulic pressure, in a drive 5 A piston cylinder close to a wheel or axle having the second hydraulic piston 32 which actuates, by a piston rod 58a, the brake mechanism close to a wheel or axle formed, for example, by a disc brake.

  According to this aspect of the invention, the service brake cylinder 4a and the accumulator spring brake cylinder 12a, arranged coaxially with the hydraulic cooperating one behind, close brake accumulator which is arranged at a wheel or at a wheel. guided against the accumulator spring brake force the other, form a combined cylinder 60a which is disposed remote from the brake mechanism close to a wheel or axle and which controls, by a hydraulic active link , the hydraulic piston-cylinder drive 56a close to a wheel or axle, which again activates the disk brake attached to a wheel or axle.

  The rod 40a of the accumulator spring brake piston 18a passes sealed into a passage opening formed in a partition 62a between the accumulator spring brake cylinder 12a and the service brake cylinder 4a and can, by its front surface, come abut on the service brake piston 6a which comprises a membrane 46a, stretched on the side wall of the axially movable and axially movable brake cylinder 4a, and a central piston disc 48a. In a known manner, the accumulator spring brake piston 18a can be further counteracted by the action of the accumulator spring 16a by supplying air to the accumulator spring brake chamber 14a by means of the coupling 24a tire in the release position. In addition, by air supply, performed by means of the pneumatic coupling 52a, the service brake chamber 50a which extends between the partition 62a and the service brake piston 6a, the latter can be set against the action of the return spring 54a in the clamping position. The first hydraulic piston 28a arranged coaxially at the end of the service brake piston rod 8a then reduces the volume of the first hydraulic pressure chamber 26a which forms part of the service brake cylinder 4a and which is arranged on the front side opposite the partition 62, and into which penetrates the rod 8a service brake piston. It is integrated in the spring brake piston rod 40a accumulator a mechanical release device 64a by which the accumulator spring brake can be released in case of need or relief if the pressure runs out.

  From this, the operating mode of the installation of the combination of service brake and accumulator spring brake according to the second aspect of the invention is as follows: from the situation shown in FIG. 2, in which both the accumulator spring brake and the service brake are loosened, the service brake chamber 50a is supplied with air to press the service brake by the pneumatic coupling 52a, so that, on the one hand, the piston 6a of The service brake is remote from the partition 62a, while the first hydraulic piston 28a is displaced to the left in FIG. 2. The displacement of the first hydraulic piston 28a causes the first chamber 26a to shrink under hydraulic pressure, so that Hydraulic fluid is discharged through the pressure conduit 34 into the second chamber 30a under hydraulic pressure of the piston-cylinder drive 56a. The higher hydraulic pressure therein pushes the second hydraulic piston 32a of the piston-cylinder drive 56a to the left in FIG. 2 so that the disc brake is tightened.

  On the other hand, an atmosphere of the chamber 50a of the service brake causes the service brake piston 6a to be put by the return spring 54a in the unclamped position, that is to say is moved towards the right in Figure 2, and abuts on the front surface of the spring brake piston rod 40a accumulator up to the partition 62a.

  To maintain the service brake for a long time in the clamping position, that is to say when the pneumatic pressure in the service brake chamber 50a has decreased after a certain time or when the service brake chamber 50a has been vented by the pneumatic coupling 52a, it is now necessary that the accumulator spring brake is tightened. For this purpose, the accumulator spring brake chamber 14a is vented by the pneumatic connector 24a, so that the accumulator spring 16a pushes the accumulator spring brake piston 18a to the left in FIG. piston rod 40a of spring brake piston accumulator. The service brake piston 6a, as well as the first hydraulic piston 28a which is coupled thereto by the service brake piston rod 8a, follows this movement, causing the first chamber 28a to shrink under hydraulic pressure, so that hydraulic fluid is discharged through the discharge conduit 34 into the second form 30a under hydraulic pressure of the piston-cylinder drive 56a. The larger hydraulic pressure therein pushes the second piston 32a hydraulic to the left in Figure 2 in the tightening direction. As long as the spring pressure is not compensated by the air supply of the accumulator spring brake chamber 14a, the second hydraulic piston 32a is held in the clamping position by the series circuit consisting of the accumulator spring 16a, the piston rod 40a of the accumulator spring brake, the piston rod 8a of the service brake and the hydraulic liquid column in the pressure line 34a.

  The combined installation of the service brake and the accumulator spring brake according to a third aspect of the invention differs from that of FIG. 2 only in that instead of a piston-piston drive 56a which actuates a purely mechanical brake mechanism, there is now a hydraulically actuated brake mechanism 66b which is connected directly to the pressure conduit 34. The second chamber 30b under hydraulic pressure is thus an integral part of the hydraulic brake mechanism 66b, so that an additional cylinder-piston drive is no longer necessary. the same to that elements corresponds of the mode of previous, and the modules having being function same reference signs, being equipped with the b distinguished only by the complementary letter. In all three embodiments, the service brake device 2, 2a, 2b can be operated independently of the accumulator spring brake device 10, 10a, 10b and vice versa.

  Enumeration of reference signs 1, la, lb Service brake or spring brake installation 2, 2a, 2b Service brake 4, 4a, 4b Service brake cylinder 6, 6a, 6b Brake piston service 8, 8a, 8b Service brake piston rod 10, 10a, 10b Brake spring device 12, 12a, 12b Brake cylinder with accumulator spring 14, 14a, 14b Brake chamber with accumulator spring 16, 16a, 16b Battery spring 18, 18a, 18b Spring brake piston accumulator Diaphragm 22 Piston disk 24, 24a, 24b Pneumatic connection 26, 26a, 26b First hydraulic pressure chamber 28, 28a, 28b First hydraulic piston 30, 30a, 30b Second hydraulic pressure chamber 32, 32a Second hydraulic piston 34, 34a, 34b Pressure pipe 36, 36a, 36b Hydraulic reservoir 38, 38a, 38b Hydraulic cylinder 40, 40a, 40b Brake piston rod with accumulator spring 42 Diaphragm 44 Disc piston 46, 46a, 46b Membr ae 48, 48a, 48b Piston disk 50, 50a, 50b Service brake chamber 52, 52a, 52b Pneumatic connection 54, 54a, 54b Return spring 56a Cylinder drive on piston 58a Piston rod 60a, 60b Combination cylinder 62a, 62b Partition 64a, 64b Releasing device 66b Hydraulic brake mechanism 15 20 25 30 35

Claims (15)

  1. Installation (1) combined service brake and accumulator spring brake for motor vehicles, especially for commercial motor vehicles, characterized in that it comprises: a) a service brake device (2) disposed directly on a brake mechanism close to the wheel or axle and having a service brake cylinder (4) in which a service brake piston (6) which is pneumatically powered and which actuates the brake mechanism is guided by a service brake piston rod (8), b) an accumulator spring brake device (10) which is disposed remote from the brake mechanism close to the wheel or axle and which has a cylinder (12). ) an accumulator spring brake which is guided by a pneumatic pressure in a chamber (14) of accumulator spring brake, an accumulator spring brake piston (18) being tensionable against the elastic force of a spring (16) battery (c) an active hydraulic connection between the accumulator spring brake piston (18) and the service brake piston (6) so that actuation caused by the supply of air or the atmosphere of the chamber (14) of the accumulator spring brake of the piston (18) of the accumulator spring brake causes actuation of the service brake piston (6).   2. Combined installation of service brake and accumulator spring brake according to claim 1, characterized in that the active hydraulic connection 5 comprises at least a) a first piston (28) hydraulic cooperating with a first chamber (26) hydraulic under pressure, b) a second hydraulic piston (32) cooperating with a second hydraulic chamber (30) under pressure, and c) a pressure line (34) between the first hydraulic pressure chamber (26) and the second chamber (30). ) hydraulic fluid under pressure, wherein d) the first hydraulic piston (28) and the first hydraulic pressure chamber (26) are associated with the accumulator spring brake device (10) and e) the second hydraulic piston (32) and the second hydraulic pressure chamber (30) are associated with the service brake device (2).   3. Combined service brake and accumulator spring brake system according to claim 2, characterized in that the first hydraulic piston (28) is connected to the accumulator spring brake piston (18).   4. Combined service brake and accumulator spring brake system according to claim 2 or 3, characterized in that the second hydraulic piston (32) comprises a hydraulic diaphragm (42).   5. Combined service brake and accumulator spring brake system according to claim 4, characterized in that the first hydraulic pressure chamber (26) is formed in the accumulator spring brake cylinder (12) and the second chamber (30) hydraulic pressure under the cylinder (4) of the service brake.   6. Combined installation of service brake and accumulator spring brake according to one of claims 2 to 5, characterized in that the second piston (32) is hydraulically subjected, on the one hand, to the hydraulic pressure prevailing in the pressure conduit (34) and, secondly, the pneumatic pressure of a pneumatic service brake chamber (50) which controls the service brake piston (6).   7. Combined service brake and accumulator spring brake system according to claim 6, characterized in that the second hydraulic piston (32) is designed to abut on the service brake piston (6).   8. Combined installation of the service brake and the accumulator spring brake for motor vehicles, in particular for commercial motor vehicles, characterized in that it comprises: a) a service brake cylinder (4a) which is remote from a brake mechanism close to a wheel or axle and in which is guided a pneumatically powered service brake piston (6a) which is connected to a first hydraulic piston (28a) cooperating with a first hydraulic chamber (26a) under pressure, b) a cylinder (12a) with an accumulator spring which is remote from the brake mechanism close to a wheel or axle and in which a piston (18a) of An accumulator spring brake that can be tensioned by the pneumatic pressure of an accumulator spring brake chamber (14a) against the spring force of a spring (16a) accumulator, piston (18a) by which the service brake piston (6a) e can be moved in the direction of the brake clamping, c) a hydraulic pressure line (34) between the first hydraulic pressure chamber (26a) and a second hydraulic pressure chamber (30a) in a cylinder-shaped drive (56a). piston close to a wheel or axle having a second hydraulic piston (32a) which actuates the brake mechanism close to a wheel or axle by a piston rod (58a).   9. Combined service brake and accumulator spring brake system according to one of the preceding claims, characterized in that the brake mechanism close to a wheel or axle is formed by a disk brake.   10. Combined service brake and accumulator brake system (lb) for motor vehicles, particularly for commercial motor vehicles, comprising: a) a service brake cylinder (4b) which is remote from a mechanism brake system close to a wheel or axle and in which is guided a pneumatically powered service brake piston (6b) which is connected with a first hydraulic piston (28b) cooperating with a first chamber (26b) hydraulic fluid under pressure, b) a cylinder (12b) with an accumulator spring which is remote from the brake mechanism close to a wheel or axle and in which is guided a piston (18b) of accumulator spring brake which can be tensioned by the pneumatic pressure of an accumulator spring brake chamber (14b) against the spring force of a spring (16b) accumulator, piston (18b) through which the service brake piston (6b) can to be moved in the direction (c) a hydraulic pressure line (34) between the first hydraulic pressure chamber (26b) and at least one second hydraulic pressure chamber (30b) of a hydraulically actuated and hydraulically actuated brake mechanism (66b) to a wheel or an axle.   Combined service brake and accumulator spring brake system according to claim 10, characterized in that the hydraulically actuated brake mechanism is a hydraulic disc brake (66b).   12. Combined service brake and accumulator spring brake system according to one of claims 8 to 11, characterized in that the service brake cylinder (4a; 4b) and the brake cylinder (12a; accumulator spring are arranged coaxially and form a building unit.   Combined service brake and accumulator spring brake system according to one of Claims 8 to 12, characterized in that the hydraulically actuated first piston (28a; 28b) is coaxially connected to the brake pistons (6a; 6b). in service by a piston rod (8a; 8b).   10 15 20 14. Combined service brake and accumulator spring brake system according to one of Claims 8 to 13, characterized in that the accumulator spring brake piston (18a; 18b) is constructed to abut the operating piston (6a; 6b) via a piston rod (40a; 40b) of accumulator spring brake piston.   Combined installation of service brake and accumulator spring brake according to one of the preceding claims, characterized in that the hydraulic pressure conduit (34; 34a; 34b) communicates with a hydraulic reservoir (36; 36a; 36b). .