DE2303161A1 - LOAD-CONTROLLED COMPRESSION BRAKE DEVICE FOR VEHICLES - Google Patents

Description

Munich, January 19, 1973

TP11-Oe / st - 1088 -

KNOEE - BEEMSE GmbH 8 Munich 40, Moosacher Strasse 80

"Load-dependent controlled pressure medium braking device for vehicles. "

The present invention relates to a load-dependent controlled compressed air brake device for vehicles, in particular Rail vehicles, with a spring-loaded cylinder, whose load-dependent release pressure can be acted upon Piston can be brought into a release position against the force of a storage spring, the release pressure being controlled by a brake control valve with falling output control pressure characteristics in connection with a downstream, dependent the vehicle load is formed automatically controllable load brake valve.

There are load-dependent controlled, a spring-loaded cylinder comprising compressed air brake devices, e.g. from the DOS 16o5 275 »known in which to change the spring-loaded cylinder release pressure According to the vehicle load when braking, a positive build-up from a brake control valve generated pilot pressure fed to a load brake valve and changed from this load-dependent and via a Downstream three pressure valve in a pressure supplied to the spring-loaded cylinder with falling characteristics is converted. To ensure that the spring-loaded cylinder

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released brake to be able to match exactly to its accumulator spring, are in braking devices according to the DOS 16o5 275 has the load brake valve and the three-pressure valve jointly connected to a compressed air source via an adjustable pressure reducing valve. These air brake devices have the major disadvantage that in the event of an involuntary fall of at least one of the two Control pressures, namely the control pressure supplied to the load brake valve and the three-pressure valve, e.g. B. as a result a leak, the spring-loaded cylinder pressure automatically builds up and causes an unintentional release of the braking device. In addition, the three-pressure valve enlarges the structural complexity of the braking device and thus its production costs unnecessarily.

Compressed air brake devices of the type described at the beginning are also known, e.g. from DOS 16o5 278, in which a control pressure generated by the brake control valve is maintained when the brake is released and is reduced when braking. In this way, the brake automatically comes into effect even if the control pressure is unintentionally lowered. at However, these braking devices are the adaptation and the Allocation of the control and release pressures to the tolerances subject, structural conditions of the braking device complicated, since the necessary settings are made by adjusting the interdependent spring forces

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"or pressures take place nmß. Thus there are deviations from the theoretical Setpoint of the braking forces "unavoidable.

The present invention is therefore based on the object to design a pressure medium brake device in a structurally simple manner in such a way that the aforementioned Defects and disadvantages of the known compressed air brake devices are avoided, i.e. in particular that a particularly simple and trouble-free setting and coordination the braking device is possible.

Starting from a pressure medium brake device of the type mentioned at the outset, this object is achieved according to the invention solved in that the brake control valve and the load brake valve are connected to a common compressed air supply network, which is connected to a compressed air source a known, controllable pressure reducing valve is switched upstream. This is just an adjustment to be carried out on the pressure reducing valve »with which the supply network pressure to the exact level of the release pressure of the Berderspeieherzylinders is lowered and adapted, the braking gradation and the load dependency then being automatic at the same time run off from this an output pressure and it is ensured that in the release position of the brake control valve Always exactly the same set regardless of the vehicle load maximum release pressure of the accumulator spring of the spring _-

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Counteracts storage cylinder. Due to the constant replenishment of the compressed air supply network from the compressed air source via the pressure reducing valve, even in the case of braking operations in rapid succession, there is always only a dependency the respective position of the brake control valve and so that the selected braking stage generates the same output control pressures from it. The pressure medium can both be a pneumatic as well as a hydraulic medium.

To with a pressure medium brake device in which the load brake valve two control pistons acting on a balance beam with a pivot point that can be moved depending on the vehicle load includes, an already responsive to slight changes in pressure To achieve control behavior, with failure of any pressure size of the spring-loaded cylinder automatically comes into action, in an embodiment of the invention, the two control pistons on the one hand from the supply network pressure and on the other hand, on the one hand, from the control pressure generated by the brake control valve and, on the other hand, from the pressure medium pressure of the spring-loaded cylinder be acted upon.

In such a load brake valve, it is also possible according to the invention that the two control pistons on the one hand from Pressure medium pressure of the spring-loaded cylinder and on the other hand is acted upon on the one hand by the control pressure generated by the brake control valve and on the other hand by the supply network pressure »

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the pressure medium pressure of the spring-loaded cylinder via the two control pistons in the same pivoting direction act on the balance beam. As a result, with the same length of the balance arm, a finer gradation of the load-dependent spring-loaded cylinder pressure in connection with a even more precise control behavior of the braking device can be achieved, since in this case the support point of the balance beam can be moved along its entire extent.

To pull tabs between the control piston and the balance beam and being able to avoid the articulation points connected therewith can advantageously be the one generated by the brake control valve Apply control pressure to the relevant control piston on the side facing the balance beam, as in this case the control piston forces can be transmitted to the balance beam by means of simple tappets.

Additional advantageous refinements of the invention can be found in further subclaims.

Several exemplary embodiments of the subject of the invention are detailed below with reference to the accompanying drawings described. Show it:

Fig. .'I a pressure-medium brake device according to a first embodiment in schemati forth _sc

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Depiction,

FIG. 2 shows a comparison with the exemplary embodiment according to FIG slightly modified embodiment.

Pig. 3 shows a detailed view of a further exemplary embodiment of a pressure medium brake device and

Fig. 4 for -the pressure medium brake devices according to Figures 1-3 valid pressure diagram.

In Fig. 1, 1 is a spring-loaded cylinder, 2 is an automatically controllable load brake valve, 3 is an electropneumatic Brake control valve and 4 denotes an adjustable pressure reducing valve. The load brake valve 2 has a .Druckluftversorgungsanschluss 5 ι one with the spring-loaded cylinder connected compressed air output 6 and two control inputs 7 and 8. At the control input 7 is a known, not shown, a load-dependent control pressure generating relay valve and to the control input 8 which is already known in its structure from practice. Brake control valve 3 connected.

Both the load brake valve 2 and the brake control valve 3 are connected to a common compressed air supply network 9. closed, which via the pressure reducing valve 4 with a compressed air source in the form of a main reservoir line 10 connected is. By means of the adjustable pressure reducing valve 4

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can the pneumatic pressure p ^. the main reservoir line to any lower pressure p _T. be lowered and replenished in the compressed air supply network.

The automatically controllable load brake valve 2 comprises two control pistons 11 and 12, which ^{are guided axially displaceably sealed in a cylinder housing 1} 13 and 14 and separate two cylinder chambers 15 and 16 or 17 and 18 from one another. Each control piston 11, 12 has a tappet 19 or 20, polygons are able to act on the ends of a balance beam 21, which rests on a movable support point in the form of a roller 22 on the side facing away from the tappets 19, 20. The two control pistons 11 and 12 have the same piston surfaces with respect to the same application side, ie the application side facing the balance beam 21 or the pressure side facing away from the balance beam. The roller 22 is rotatably mounted at the end of the push rod 23 of a slider crank mechanism 24, on whose crank 25 the piston rod of a piston 26 is articulated, which is axially displaceably guided in a cylinder chamber 27 in a sealed manner and on which the load-dependent control pressure supplied via the control input 7 counteracts the force of a return spring 28 acts.

On the side of the roller 22, another tappet29 is supported on the balance beam 21 opposite the tappet 19 of the piston 11 ^ from which 'on his turned away from the balance beam 21

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End of a valve disk 30 carries. The valve disk 30 is received in a sleeve 31 and forms together with a an opening of the sleeve 21 penetrated by the plunger 29 surrounding a valve seat 32 an outlet valve loaded by a spring 33 to the free atmosphere. The spring 33 is supported on the one hand on the valve plate 30 and on the other hand on the Sleeve 31 from. The sleeve 31 has, distributed along its circumference, radial openings 34, which the interior 35 of the sleeve 31 with a space 36 connect, in which in With reference to the drawing of the lower boundary wall 37, the sleeve 31 seals, is axially displaceable. On his outer jacket the sleeve 31 is provided with an Eund on which a spring 39 arranged in the space 36 extends in the direction of of the balance beam 21 is supported. The second abutment of the spring 39 is the upper boundary wall 40 of the space 36 in relation to the drawing. In the boundary wall 40 is a with an axial bore 41 provided rotating part 42 is used, the end of which extends into the space 36 as a valve seat 43 is formed, which together with the valve plate Serving bottom part 44 of the sleeve 31 an inlet valve for the Space 36 forms and in the closed state the space 36 of a space 45 above the space 36 separates. In the illustrated Position of the balance beam 21 both the outlet valve 30,32 and the inlet valve 43,44 take their final position a, in which the interior 35 of the 'sleeve 31 and thus the space 36 from the atmosphere and from the space 45

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is separating. The spring 33 is made stronger than the spring 39, so that the latter cannot open the inlet valve 43, 44 against the force of the spring 33, even with the support of the base plate 44 serving as a valve plate.

About space 45 is via a pipe 46 and the cylinder area 16 and 18 on the side of the control piston 11 and 12 facing away from the balance beam 21 are via a branching one Pipe 47 connected to the compressed air connection 5 while the space 36 by means of a line 48 via the exit 6 with the spring-loaded cylinder 1 and by means of a line 49 branching off from the line 48 with that of the control piston 12 limited cylinder space 17 is connected. The cylinder chamber 15 is connected to the control input via a line 50 8 connected.

The functioning of the pneumatic pressure medium brake device is as follows:

When the braking device is vented, ie with the main tank line 10 vented, the compressed air supply network 9 is also depressurized. Thus there is neither compressed air at the supply input of the brake control valve 3 * nor at the supply input 5 of the load brake valve 2, whereby the cylinder chambers 16 and 18 and the chamber 45 are also depressurized and also from the brake control valve 3 no compressed air into the cylinder chamber 15 via the

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Control terminal 8 can be fed. Under the action of on the sleeve 31 acting compression spring 39 is because of the balance beam 21 no counterforce can be generated, the inlet valve 4-3 »4 ^ - opened, so that the space 36 with the space 45 connected and thus also the spring-loaded cylinder 1 and the cylinder chamber 17 have no pressurized air can. The spring-loaded cylinder 1 thus exercises under the full effect of its accumulator spring its maximum brake actuation force the end. This vented state of the braking device can occur, for example, when the vehicle is parked.

Independently of this, there is a known manner at the control input 7 of the load brake valve 2 from a non-illustrated one Relay valve generated, the vehicle load proportional Bruckmitteidruck, which the piston 26 against the force. the spring 28 holds in a certain equilibrium position. Via the slider-crank mechanism articulated with the piston 26 24 the position of the roller 22 and thus the position of the support point of the balance beam 21 is thus also determined. The lever arms of the balance beam 21 resulting in this way are denoted by a and b. The translation of the slider crank mechanism 24 is chosen so that, depending on the position of the piston 26, the length of the lever arm a can be less than or at most equal to the length of the lever arm b, the maximum vehicle load being a lever arm distribution of a is assigned equal to b.

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If the main reservoir line 10 serving as the compressed air source for the braking device is now filled with compressed air, a pneumatic pressure lower than the main reservoir line pressure Ρχΐ-j- builds up in the compressed air supply network 9 via the pressure reducing valve 4. Assuming that the brake control valve 3 is held in the release position, ie that the maxin .-: - Ie control pressure P _c corresponding to the supply pressure pr is generated at π ei τ: em control output, the cylinder chambers 15 »16 and 18 via the connection 8 and the line 50 or via the connection 5 and the line 47 of the load brake valve 2 with compressed air of the same pressure level, namely the supply network pressure, p · ^. At the same time, there is supply network pressure PL in space 45 of load brake valve 2 via line 46 and connection 5, which also builds up in space J> 6 and thus in spring-loaded cylinder 1 and in cylinder space 17 of load brake valve 2 via the inlet valve 43, 44, which is still open , because due to the pressure on both sides of the Eegel piston 11, the latter cannot exert any force on the balance beam 21 which would cause the inlet valve to close. By means of the controllable pressure reducing valve 4, the pneumatic pressure in the supply network 9 and thus in the spring-loaded cylinder 1 can now be set in such a way that the preload of the storage spring of the spring-loaded cylinder 1 has just been completely overcome and the latter consequently cannot exert a brake actuation force, but also not an excessive one

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There is pressure in the spring-loaded cylinder. This setting is completely independent of the position the roller 22 and thus-the lever arm lengths a and b of the balance beam 21 of the load brake valve 2.

It is assumed that the vehicle is fully loaded and thus the roller 22 serving as a support point for the balance beam 21 is in its middle position, ie that the lever arms a and b of the balance beam 21 are of equal length. If braking is now to take place, the output control pressure p _o is lowered by means of the electrically controlled brake valve 3 in accordance with the desired braking level. As a result, the balance of forces on the control piston 11 is _{disturbed by the reduced pneumatic pressure p p} in the cylinder space 15 and the balance beam 21 is pivoted under the effect of the pressure difference between the cylinder spaces 16 and 15 in a clockwise direction with respect to the drawing. Via the plunger 29 and the spring 33, which is stronger than the spring 39, the sleeve 31 is first moved upwards in relation to the drawing until it rests on the valve seat 43, so that the inlet valve 43, 44 closes. Subsequently, the plunger 29 causes the valve plate 30 connected to it to lift off the valve seat 32, as a result of which the interior 35 of the sleeve 31 _{5 is} vented to the atmosphere via the openings 3 ^ the space 36 and thus the spring-loaded cylinder 1 and the cylinder space 17 until due to the pressure drop in the cylinder chamber 17, which is

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The pressure forces exerted on the control piston 11 and 12 on the balance beam 21 are again the same, that is, until the pneumatic pressure in the cylinder chamber 17 and thus in the spring-loaded cylinder 1 is equal to the control pressure in the cylinder chamber 15 generated by the brake control valve 3. The control pistons 11 and 12 are then no longer able to exert this pivoting torque on the balance beam, so that the outlet valve 30, 32 closes again under the action of the spring 33 and the venting of the spring-loaded cylinder is ended. This then generates a brake actuation force which is formed from the difference between the preload of its storage spring and the load-dependent pneumatic pressure ρ _Λ present in the spring storage cylinder.

If full braking was initiated by means of the brake control valve 3, i.e. the control pressure ρ ^ present in the cylinder chamber 15 was _{reduced to atmospheric pressure p Q} , the pneumatic pressure of the spring-loaded cylinder is also reduced to atmospheric pressure, as can be readily seen from the above, since the exhaust valve 30 is only then , 32 closes again when the pressure in the cylinder chamber 17 is equal to the control pressure u in the cylinder chamber 15. The spring-loaded cylinder 1 thus generates its maximum brake actuation force.

With a vehicle load between no load and full load, the roller 22 is ^s 2 at the control input 7 of the load brake valve

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pending load-dependent control pressure via the piston 26 and the slider crank mechanism 24 displaced from their central position in such a way that the lever arm a of the balance beam 21 assigned to the control piston 11 is smaller than the lever arm b assigned to the control piston 12. As already stated above, does such a lever arrangement have no influence on the brake lever when the brake is released? ' ■ ..; Pneumatic pressure prevailing in the spring-loaded cylinder 1: ρ
Since in this case too, the control piston 11 because of its two

same pressurization on both sides no force on the Balance beam 21 can exercise, the inlet valve 43,44 is below open to the influence of the spring 39 and thus the spring storage cylinder 1 with the supply network pressure "pi applied and completely solved.

Used to initiate braking when the vehicle is under partial load the output control pressure ρ of the brake control valve lowered according to the desired braking level, the pressure difference between the supply comes back on the control piston 11 snetzdruck.p ^ "in the cylinder chamber 16 and the control pressure υ in the cylinder space 15 to the effect, whereby in verherbeschrittener Way, initially the inlet valve 43,44 closed and then the outlet valve 30,32 is opened. As a result, the pneumatic pressure acts in the spring-loaded cylinder 1 and in the Cylinder space 17 until the on the balance beam 21 by means of the control pistons 11 and 12 on both sides of the roller 22

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exerted moments of force are balanced again. However, since the control piston 12 engages the control piston 11 on the longer lever arm b, must in this state of equilibrium that of the difference in the pressures in the cylinder chambers 18 and 17 certain force exerted by the control piston 12 is less than that exerted by the control piston 11 and determined by the difference in the pressures in the cylinder chambers 16 and 15 Force on the balance beam 21. Somi "must be the pneumatic pressure in the cylinder chamber 17 and thus in the spring-loaded cylinder 1 in the Equilibrium state of the balance beam 21 in which both the inlet valve 43, 44 and the outlet valve JO, J2 are closed must be greater than the control pressure ρ in space 15. Open this is the pneumatic pressure in the spring-loaded cylinder 1 with the same braking level and partial load of the vehicle larger than at full load, so that the accumulator spring can have less effect. Even with an emergency stop a certain residual pressure remains in the spring-loaded cylinder 1. The size of this residual pressure or the pressure difference Compared to the full load of the vehicle, the ratio of the lever arm lengths a and b of the balance beam is 1 addicted. The smaller the vehicle load and thus the lever arm length a, the greater it is in the spring-loaded cylinder 1 residual pressure remaining during full braking, so that with the same applied braking level, that of the spring-loaded cylinder 1 exerted brake actuation force is the lower, the smaller the vehicle load.

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4 shows a diagram in which the main _{reservoir line pressure} ρ τττ, the supply network pressure ρ, the output control pressure ρ generated by the brake control valve 7>

and the pneumatic pressure, ρ in the spring-loaded cylinder 1 are shown over the braking stages from release to full braking. The spring-loaded cylinder pressure p ₀ is shown at part load of the vehicle, that is, at a <b. In the full load range, the ρ line coincides with the ρ line. The pressures ps and .D. are shown for a seven-stage brake control valve 3. However, it should be pointed out that instead of a brake control valve with gradually falling characteristics of the output control pressure _p. Of course also a

Brake control valve with a linearly falling characteristic can be used.

Via the pressure reducing valve 4-, the main storage tank line is released 10 compressed air is constantly fed into the compressed air supply network 9. If due to a defect, e.g. of a leak of any 3 pressures p_, "" p, 'p "or ■ ρ to atmospheric pressure, the spring-loaded cylinder occurs immediately in action and the vehicle is automatically braked.

The braking device shown in Figure 2 differs of the embodiment of Fig. 1 only in that that the cylinder space 16 of the load brake valve 2 is also like the cylinder space 17 instead of with the supply network pressure ρ

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is acted upon by spring-loaded cylinder pressure "p .., so that only in the cylinder chamber 18 the control piston supply network pressure Pj is present. The cylinder space 16 is about a Line 51 is connected to the cylinder space 17. Same components are for the sake of simplicity with the same reference numerals as in Fig; 1 provided. In contrast to the exemplary embodiment according to FIG. 1, it acts as a support point for the balance beam 21 serving roller 22, however, when the vehicle is fully loaded, the one shown in dash-dotted lines, the plunger 20 of the control piston 12 opposite position to itself at part load in relation to the drawing to the left longitudinally of the balance beam 21 to move.

The functioning of this braking device is in principle the same as that of the braking device according to FIG. 1, with the diagram according to FIG. 4 is also fully valid. The main advantages of this modified braking device are, however, that, in the load-dependent adjustment of the roller 22, the entire length of the balance beam is used and this can thus be made shorter in favor of a smaller construction of the load brake valve 2 and that also at least in the area of the full load of the vehicle, due to the long, the control piston 11 with the control pressure PS assigned lever arm of the balance beam compared to the lever arm assigned to the control piston 12, an extremely sensitive, even to the slightest pressure

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Fluctuations in the control pressure p _e in the cylinder chamber 15 responsive control characteristics of the load brake valve 2 is achieved.

The electro-pneumatic used in Figures 1 and 2 Brake control valve.3 can of course also by a purely pneumatic brake control valve with decreasing output control characteristics be replaced. In Fig. 3 is a possible, particularly advantageous arrangement of a purely pneumatic Brake control valve shown in connection with the braking device according to the invention in a schematic partial view. The same components are again provided with the same reference numbers as in FIG. 1.

The purely pneumatic brake control valve 53 is connected on the input control side to a pneumatic control line 5 ^ - which has falling control pressure characteristics. The control line 54- can, for example, be a main air control line which can be influenced by a driver's brake valve (not shown) which, when the brake is not actuated, carries a pressure of five atmospheres which, for braking, can be reduced, for example, to a maximum of three atmospheres. Corresponding to the pressure reduction in the control line 54-, the brake control valve 53 cLer also lowers the output control pressure p _e from a supply pressure to atmospheric pressure in a known manner and therefore not described in more detail.

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In the illustrated embodiment, the control line 54 also serves as a compressed air source for a compressed air supply network 9 »which both the brake control valve53 and a load brake valve 2 is supplied with compressed air. In a connection between the control line 5 ^ and the compressed air supply network 9 is an adjustable pressure reducing valve 4 in series a check valve opening towards the pressure reducing valve 56 upstream. The connecting line 55 is connected between the check valve 56 and the pressure reducing valve 4 a supply air reservoir 57 is connected.

The check valve 56 is used when the control line is charged 54 the supply air tank 57 is filled with compressed air, which is then also available on the input side of the pressure reducing valve 4 and its pressure level via the pressure reducing valve according to the setting of the pressure reducing valve 4, the compressed air supply network 9 is reduced. The structure the load-dependent adjustable, hur indicated by dash-dotted lines Load brake valve 2 is the same as in Fig. 1 or Pig. 2 shown. To coordinate the entire braking system just need, as with. the previously described ^ Br em ε facilities, by means of the pressure reducing valve 4, the pneumatic pressure in the supply network 9 can be set in such a way that the spring-loaded cylinder at full output control pressure ρ ^ des Brake control valve 53 is just completely released. When braking, all other influences run again, such as

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Braking gradation and load dependency of the spring accumulator pressure P ₁ ^ automatically from this starting point. The supply air container 57 ensures that the compressed air supply network 9 continues to be supplied with compressed air via the pressure reducing valve 4 even when the pressure in the control line 54 - is reduced.

Although compressed air was always specified as the pressure medium in connection with the illustrated embodiments, it should also be pointed out that the pressure medium can of course also be a hydraulic medium. In the latter case, there are only collecting containers for those on the outlet valve 30, 32 and on the brake control valve 3 and 53, respectively Provide for leaking fluid when braking.

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Claims (1)

Claims 1.J Load-dependently controlled pressure medium brake device for vehicles, in particular rail vehicles, with a spring-loaded cylinder ^ whose piston, which can be acted upon by a load-dependent release pressure, can be brought into a release position against the force of an accumulator spring, the release pressure of a brake control valve with a falling output control pressure characteristic in connection with a looked up in Depending on the vehicle load, automatically controllable load brake valve is formed, characterized in that the brake control valve (3.53) and the load brake valve (2) are connected to a common pressure medium supply network (9), which is connected to a pressure medium source (10.5 ² O) known, controllable pressure reducing valve (4-) is connected upstream. 2. Load-dependent controlled pressure medium brake device according to claim 1, wherein the load brake valve has two on one Includes a balance beam with a pivot point that can be displaced as a function of the vehicle load, characterized in that the two control pistons (11, 12) on the one hand from the supply network pressure and on the other hand once from the one generated by the brake control valve (3j53) Control pressure and on the other hand from the pneumatic pressure of the 409830/0641 - 22 - Spring-loaded cylinder Ci) are acted upon. 5 · Pressure medium braking device controlled according to the load Claim 1, wherein the load brake valve two to one Includes a balance beam with a pivot point that can be displaced as a function of the vehicle load, characterized in that the two control pistons (11, 12) on the one hand from the pressure medium pressure of the spring-loaded cylinder (1) and on the other hand from that of the brake control valve (3 »53) generated control pressure and on the other hand are acted upon by the supply network pressure, the pneumatic pressure of the spring-loaded cylinder (1) via the control piston (11, 12) in the same pivoting direction act on the balance beam (21). 4-. Pressure medium braking device controlled as a function of the load Claim 2 or 3, characterized in that the control pressure generated by the brake control valve (3, 53) affects the relevant The control piston (11) is acted upon on the side facing the balance beam (21). 5- Load-dependent controlled pressure medium braking device according to one of claims 2-4, characterized in that the two control pistons (11, 12) are at least covered the same piston areas on the same admission side exhibit. - 23 409830/0641 6. Load-dependently controlled pressure medium brake device according to one of the preceding claims, characterized in that that the brake control valve (3) as an electro-pneumatic Control valve is formed. 7 «Load-dependent controlled hydraulic brake device according to one of claims 1 - 5 ι in which the brake control valve as a purely pneumatic, controlled by the pressure in a control line with falling pressure characteristics Control valve is designed, characterized in that the pressure reducing valve (4) is in a connecting line (55) between the at the same time as the compressed air medium source serving control line (5 * 0 and the compressed air supply network (9) a check valve (56) which opens towards the pressure reducing valve (9) is connected in series is, with a supply air tank (57) connected between the check valve (56) and the pressure reducing valve (4) is· 409830/0641 Blank page