Fluid-operated supporting arrangement and a conduit breakage safety device

A fluid-operated supporting arrangement has fluid-operated supporting elements connected with a further fluid element by pairs of connecting conduits, and a safety element associated with the further fluid element and arranged so that the connecting conduits of each of the pairs of connecting conduits are open separately into the further fluid element, and the safety element has two pressure-controlled closing members each arranged to close a respective one of the connecting conduits of the respective pair of connecting conduits. A conduit breakage safety device is provided with two separate passages each separately communicating a respective one of two connecting conduits of each of the pairs with a further fluid element, and two pressure-controlled closing members each arranged to close a respective one of the passages.

BACKGROUND OF THE INVENTION 
The present invention relates to a fluid-operated supporting arrangement 
for a travelling mechanism having a plurality of wheels or wheel sets. It 
also generally relates to a safety device for pairs of any conduits. 
Arrangements and devices of the above mentioned general type are known in 
the art. In a known pneumatic or hydraulic supporting arrangement there 
are a plurality of pneumatic or hydraulic supporting elements, such as 
cylinder-and-piston units, which support individual wheels or wheel sets 
and are connected in groups with one another and/or with a pneumatic or 
hydraulic accumulator via pairs of conduits which are provided near the 
supporting element or the accumulator with conduit breakage safety devices 
reacting to breakage of conduits. In conventional constructions, when one 
conduit of a pair of broken, the operational ability of the hydraulic or 
pneumatic mechanism, particularly the travelling mechanism, is maintained 
by the conduit breakage safety device, inasmuch as the broken conduit is 
blocked for preventing further losses of pneumatic or hydraulic medium. 
The remaining, unbroken conduit is sufficient in some cases for the 
operation of the arrangement. One such conduit breakage safety device for 
hydraulic travelling mechanisms is disclosed, for example, in German Pat. 
No. 2,319,611. In this device, two hydraulic cylinders are connected with 
one another by two separate, parallel-arranged conduits which communicate 
with the cylinders with interposition of a three-way valve. One passage of 
the three-way valve leads to the associated cylinder, whereas the two 
other passages lead to the conduits connected in parallel. The safety 
valve includes a common closing member for both conduit passages, which in 
its intermediate position opens both conduit passages and, during breakage 
of one conduit, displaces under the action of the thus produced flow pulse 
for blocking the passage leading to the not-tight conduit. In this safety 
device, the valve-closing member displaces when the flow to one conduit 
passage is stronger than that to the other conduit passage. Thereby, the 
displacement of the closing member increases the resistance of the flow to 
one conduit passage, and reduces the resistance of the flow to the other 
conduit passage. As a result of this, vibrations which take place during 
the travel and insignificantly different flow forces to both conduit 
passages can be increased, and therefore undesirable chatter vibrations of 
the connecting parts can take place. This reduces the operational safety 
of the conduit breakage safety device. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide a 
fluid-operated supporting arrangement and a conduit breakage safety device 
for pairs of conduits, which avoid the disadvantages of the prior art. 
More particularly, it is an object of the present invention to provide a 
fluid-operated supporting arrangement and a conduit breakage safety device 
which guarantee an especially reliable blocking of the broken conduit. 
In keeping with these objects, and with others which will become apparent 
hereinafter, one feature of the present invention resides, briefly stated, 
in a fluid-operated supporting arrangement and/or a safety device in which 
conduit of each pair opens separately from the other conduit of the same 
pair into an associated fluid element such an associated fluid-operated 
supporting element or an accumulator, and is closable there by its own 
closing member which, advantageously, forms a pressurecontrol means. 
In such a construction, displacement of a closing member associated with 
one conduit of a pair does not produce any direct action upon the closing 
member of the other conduit of the same pair. Moreover, the pressure 
control makes it possible to maintain the closing member below critical 
pressure fluctuations which, when overcome, require blocking of a conduit. 
The inventive construction also provides for considerably improved 
reproducibility of conditions of the conduit breakage safety device. 
In accordance with another advantageous feature of the present invention, 
the closing member or a piston actuating the closing member for each 
conduit is displaceably arranged in a cylinder chamber, wherein one 
subchamber associated with one actuating face (front face) of the piston 
communicates with the associated conduit, whereas the other subchamber 
associated with the other actuating face (rear face) of the piston is 
connectable with the other conduit. The pressure of a conduit to be 
secured by a piston acts upon the front side of this piston and loads the 
rear side of the piston against the pressure of the other conduit. Since 
in the conduits of the pair of conduits practically identical pressure 
conditions prevail during normal operation, the pistons are subjected at 
both their actuating faces to practically identical or fixed and 
identically maintained conditions of opposite pressures. Any significant 
deviations of the pressure conditions take place first during breakage of 
one of the conduits, or in other words the piston displaces in its closing 
position when the pressure in a conduit secured by the piston considerably 
falls as a result of the conduit breaking. 
When a travelling mechanism or vehicle runs on surface waves, individual 
wheels or wheel sets of one group perform upward movements whereas the 
wheelsor wheel sets of the other groups perform downward movements. Great 
pressure-medium quantities are conveyed from one supporting element to 
another supporting element, and in some cases to a pressure-medium 
accumulator serving for spring-suspension purposes. These pressure-medium 
streams are connected with different pressures in the supporting elements 
or in the accumulator and the conduits. For preventing blocking of 
conduits during acceptable pressure variations, the pistons can be loaded, 
for example by spring means, to its open position and/or formed as 
differential pistons whose smaller actuating face is loaded by a reference 
pressure, for example by a pressure from the other conduit. 
In accordance with still another especially advantageous feature of the 
present invention, for travelling mechanisms as well as for other 
arrangements, the inventive safety device has a housing with separate 
passages having a connecting passage for a consumer, particularly a 
supporting element or an accumulator, and a connecting passage to a 
conduit connected with the first-mentioned connecting passage, and a 
piston-actuated closing member with a piston displaceable in a cylinder 
chamber whose one end communicates with a reference pressure source and 
whose other end is connected with the associated conduit in closed and 
open positions of the closing member. 
Still a further advantageous feature of the present invention is that the 
piston itself is formed as a closing member and arranged in a cylinder 
chamber which opens into a communication path between the above-mentioned 
passages. In this construction, the safety device can be provided with a 
relatively small number of bore holes in its housing. 
It is especially advantageous for this purpose when the passages for each 
conduit of the pair are located at an angle relative to one another, 
preferably normal to one another, and the cylinder chamber forms an 
extension of the passage in the housing. 
The cylinder chamber may be formed as an opening which extends from one 
housing side and closed at this side, wherein the opening is formed as an 
extension of the passage with formation of a shoulder, and the other 
passage opens radially or laterally into this opening. The piston arranged 
in this cylinder chamber abuts in its end position against the shoulder 
and closes an inlet of the second-mentioned passage. In another end 
position spaced from the shoulder, the piston opens the inlet of the 
second-mentioned passage. 
The pistons can have any practically suitable form, and their dimensions 
must be sufficient to overlap in the closing position the inlet of the 
passage which opens into the abovementioned opening. 
The novel features which are considered characteristic for the invention 
are set forth in particular in the appended claims. The invention itself, 
however, both as to its construction and its method of operation, together 
with additional objects and advantages thereof, will be best understood 
from the following description of specific embodiments when read in 
connection with the accompanying drawing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A vehicle shown in FIG. 1 has wheels 2 and 3 arranged one behind the other. 
The wheels 2 and 3 are suspended in a vertically adjustable manner on the 
vehicle 1 with the aid of links 4 and 5 of suitable construction. The 
links 4 and 5 are pivotally connected with one another and with the 
vehicle 1 by a member 6. Each link 4 and 5, and the associated wheel 2 or 
3, is supported by a respective one of supporting elements 7 and 8 on the 
vehicle 1. 
Each of the supporting elements 7 and 8 has a piston 9 and a cylinder 10 in 
which the piston 9 displaces. The cylinders 10 are connected with one 
another by conduits 11 and 12, for equalization purposes. The conduits 11 
and 12 can be connected via conduits 13 and 14 with further supporting 
elements or with a not shown accumulator for pressure medium. 
When the vehicle 1 runs over a surface wave, for example the wheel 2 
displaces in an upwards direction. The piston 9 of the supporting element 
8 displaces the pressure medium from the associated cylinder 10 into the 
cylinder of the other supporting element 7, and thereby causes a downward 
movement of the wheel 3 relative to the vehicle 1. By this equalization, a 
uniform distribution of the supporting load of the vehicle 1 takes place 
during the operation of the arrangement. 
For the case when one of the conduits 11 or 12 is broken, a conduit 
breakage safety device 16 is arranged on the cylinders 10. It blocks in 
the respective cases the broken conduit 11 or 12 so that the supporting 
elements 7 and 8 communicate with one another only via the other conduit, 
12 or 11. 
The conduit breakage safety device 16 is shown in FIGS. 2 and 3 and has a 
square housing 17 in which parallel openings 18 extend from its one side. 
The openings 18 open in coaxial passages 19. Between the openings 18 and 
the passages 19 a constriction 20 is provided so as to form, between the 
constriction 20 and the openings 18, an annular shoulder 21. 
Transverse passages 22 extend from one housing side radially to the 
openings 18 and open in the vicinity of the annular shoulders 21 into the 
openings 18. 
As considered in FIG. 2, the upper portion of the left opening 18 is 
connected via a bore hole 23 with the right constriction 20. In the same 
manner, the upper region of the right opening 18 is connected via a bore 
hole 23' with the left constriction 20. The openings 18 are closed at the 
outer side of the housing by threaded closures 35. 
Cup-shaped pistons 45 are displaceably arranged in the openings 18. The 
cup-shaped openings of the pistons face toward the annular shoulders 21 
and receive helical springs 22. The springs 22 abut against the annular 
shoulders 21 and urge displacements of the pistons 45 against abutment 
pins 47 associated with the threaded closures 35. 
The pistons 45 can be displaced against the pressure of the springs 46 
until they abut against the annular shoulders 21. In this case, inlets of 
the transverse passages 22 in the openings 18 will be closed. The inlets 
of the bore holes 23 and 23' in the openings 18 remain open, even in the 
position in which the pistons 45 abut against the abutment pins 47. 
The conduit breakage safety device 16 shown in FIGS. 2 and 3 operates in 
the following manner: 
The transverse passages 22 serve as connecting conduits to the cylinders 10 
of one supporting element 7 or 8 in FIG. 1, on which the conduit breakage 
safety device is arranged. Each of the conduits 11 or 12 is connected with 
a respective one of the passages 19 and 20, so that each conduit 
communicates in the upper end position of the pistons 45 with the 
associated supporting element 7 or 8. The pressure acting on the 
constrictions is present also as a reference pressure in subchamber 58 of 
the openings 18, the subchamber 58 located at the piston side facing 
toward the threaded closures 35. This takes place because the subchambers 
58 are connected via the bore holes 23 and 23' with the respective 
restrictions 20 so that the pressure equilibrium, regardless of the 
throttling losses, is provided between the left restriction 20 and the 
right subchamber 58, as well as between the right restriction 20 and the 
left subchamber 58. 
When the conduits connected with the passages 19 are intact, the state of 
equilibrium during flow of the pressure medium prevails in the 
above-mentioned passages and constrictions 20, inasmuch as the 
communicating conduits as well as their connecting paths from the passages 
19 to the passages 22 have identical geometries. 
Identical pressures act upon the front and rear sides of the pistons 45, 
and the springs 46 can hold the pistons 45 in the upper end position shown 
in FIG. 2. 
When the pressure, for example in the left passage in FIG. 2, drops because 
of breakage of the associated conduit, the respective piston 45 displaces 
toward a subchamber 57 associated with the respective restriction 20 of a 
respective opening 18. Thereby, the inlet of the respective transverse 
passage 22 in the respective opening 18 is closed, and the communication 
from the left passage 19 to the left transverse passage 22 is blocked. 
The displacement of the left piston 45 takes place when its rear side is 
loaded by pressure in the right restriction 20 which communicates with an 
intact conduit, since the above-mentioned constriction 20 is in 
communication via the bore hole 23 with the subchamber 58 of the left 
opening 18. 
As a result of this, in the event of conduit breakage of one of the 
conduits 11 and 12, the defective conduit is blocked, whereas the conduit 
which remains unbroken serves for communication of the coupled supporting 
elements 7 and 8 with one another. 
It will be understood that each of the elements described above, or two or 
more together, may also find a useful application in other types of 
constructions differing from the types described above. 
While the invention has been illustrated and described as embodied in a 
fluid-operated supporting arrangement and a conduit breakage safety 
device, it is not intended to be limited to the details shown, since 
various modifications and structural changes may be made without departing 
in any way from the spirit of the present invention. 
Without further analysis, the foregoing will so fully reveal the gist of 
the present invention that others can, by applying current knowledge, 
readily adapt it for various applications without omitting features that, 
from the standpoint of prior art, fairly constitute essential 
characteristics of the generic or specific aspects of this invention. 
What is claimed as new and desired to be protected by Letters Patent is set 
forth in the appended claims. 
In the modified embodiment of the invention according to FIG. 4 a second 
fluid element 7a is a hydraulicly or pneumaticly operated fluid element 
with a piston 9a urged by a spring 9b and a safety element 16a acting 
principally as the safety element 16. 
In the modified embodiment of the invention according to FIG. 5 the 
connecting conduits 11 and 12 of one pair of fluid supporting elements 7 
and 8 are connected to a safety element 16a associated to a hydraulic or 
pneumatic accumulator 7a corresponding to the accumulator according to 
FIG. 4. 
In place of the piston 9a and the spring 9b may be arranged a gas filled 
compressible hollow body for example a ballshaped body acting like the 
piston 9a and the spring 9b. 
Alternatively such shock absorbating elements may be arranged in the 
supporting elements 7 or 8 respectively.