Background Art The rail network in North America is the largest in the world, operating with the high axle loads customarily used with heavy freight hauling railways. However, as is disclosed in United States patent 5,767,973 of Hans J. Naumann,"... the rail network in the North America is... characterized by an inordinately high number of railroad accidents and derailments; these incidents occur at a substantially higher rate in North America than anywhere else in the world." Applicant believes that one of the causes of this problem is a failure to properly operate and maintain the braking systems on rail cars. Such lack of proper operation and maintenance is often due to the complexity of such systems, difficulty of access to the components in such systems, and the lack of readily apparent visual indicators warning of system status.

It is an object of this invention to provide a brake system which is substantially safer and more reliable than prior art brake systems.

Disclosure of invention In accordance this invention, there is provided a brake system for rail cars comprised of an intensifier, a spool valve connected to said intensifier, a pump connected to said spool valve, a first cylinder connected to said spool valve, and a second cylinder connected to said spool valve.

Brief description of the drawings The claimed invention will be described by reference to the specification and to the following drawings, in which like numerals refer to like elements, and in which: Figure 1 is a schematic view of one preferred brake apparatus of the invention mounted on a railway truck, Figure 2 is a schematic view of the brake apparatus of Figure 1, showing the position of its components vis-a-vis the railway truck, Figure 2A is a schematic of a hydraulic circuit involving a spool valve of the brake apparatus, Figure 3 is a partial side view of the brake apparatus of Figure 2, Figure 4 is a schematic view of a pin block which may be used in conjunction with the apparatus of Figure 1 ; Figure 5 is a perspective view of a brake lever and clevis which may be used in conjunction with the pin block of Figure 4, and Figure 6 is a perspective view of a brake head.

Best Mode for Carrying Out the Invention Figure 1 is a perspective view of a railway truck 10 onto which a brake system is mounted. In the embodiment depicted, the brake system is comprised of hydraulic fluid reservoir 13, air master cylinder 14, fluid master cylinder 16, spool valve 17, first hydraulic cylinder 18, second hydraulic cylinder 20, hand pump 22, brake head 24, brake lever 26, and pin block 28.

The hand pump 22 is but one preferred independent means of providing a separate source of brake force, commonly used for parking cars when no air pressure is available at cylinder 14. One may use other means, manually and/or automatically operated, for applying force to the brakes. It is preferred that these other means include an air or hydraulic cylinder powered by one or more suitable activation means, which may be manual or automatic.

In one embodiment, not shown, the hand pump 22 is replaced with an air or hydraulic cylinder powered by an alternate or remotely applied force. Thus, by way of illustration, a series of railroad cars make have a multiplicity of brake systems, each with a pump 22 centrally operated and controlled from one location.

In the embodiment depicted in Figure 1, the brake system is mounted onto a railway truck 10. A railway truck supports one end of a rail car and generally is comprised of bolster 30, side frame 32, side frame 34, wheel assembly 36, wheel assembly 38, and suspension springs 40. Railway trucks and their associated braking systems are well known to those skilled in the art.

In another embodiment, not shown, the reservoir 13, the intensifier (comprised of elements 14 and 16), the spool valve 17, and the pump 22 can be mounted on the associated railway car and hydraulically connected to the remaining components on the railway truck 10. In yet another embodiment, the reservoir 13 can be mounted on bolster 13. It does not matter where these components are located as long as they are operatively connected to each other.

Figure 2 also is a perspective view of railway truck 10 onto which the components of the preferred brake system 12 are mounted. Referring to Figure 2, air from an air reservoir (not shown) is fed to air master cylinder 14 and hydraulic master cylinder 16, which collectively act as an intensifier. In general, an air line (not shown) is connected from one railway car to another; whenever the pressure in such air line drops, air is fed from an air reservoir (not shown) to the line 42 to provide the desired air pressure to the system.

Under stable conditions, a constant pressure is applied via line 42 to elements 14 and 16. When the brakes 44,46,48, and 50 are off, the air pressure in line 42 is atmospheric pressure, generally about 14.7 pounds per square inch. When the brakes 44,46,48, and 50 are to be applied, a switch (not shown) is activated which reduces the pressure in the air line connecting the railway cars. The reduced pressure state causes the air reservoir (not shown) to feed air into line 42, thereby increasing the pressure in such line to a predetermined value, depending upon the size of the railway truck, often from about 40 to about 70 pounds per square inch.

Air master cylinder 14 and hydraulic master cylinder 16 collectively act as an intensifier, whose function is to convert the increased air pressure within line 42 to hydraulic pressure; many such intensifiers comprise only one integral element. These intensifier units are often referred to as"boosters"or"air powered hydraulic pumps"or"air powered hydraulic systems"or"air powered hydraulic intensifiers."They are well known in the art and are described, e. g., in United States patents 5,782,158,5,772,289,5,724,852,5,634,778, 5,375,814,5,303,643,5,290,140,5,271,881,5,242,358,4,993,226, 4,784,579,4,773,222, 4,582,278,4,011,724, and the like. One such intensifier, which is referred to as a pneumatic/hydraulic pressure intensifier, is disclosed in United States patent 5,746,293.

It is preferred that the intensifier, which comprises air cylinder 14 and hydraulic cylinder 16, be capable of converting from about 50 to about 75 pounds per square inch of air pressure into an output hydraulic pressure of from about 500 to about 2,000 pounds per square inch. The ratio of the hydraulic pressure produced by the intensifier to the input air pressure should preferably be from about 5/1 to about 25/1 and, in one embodiment, is from about 8/1 to 17/1.

For the sake of simplicity of representation, applicant has depicted the intensifier used in his device as being comprised of two separate units, air cylinder 14 and hydraulic cylinder 16. As is well known to those skilled in the art, the commercially available intensifier units are often sold as one integral package whose elements provide several different functions.

These commercially available intensifiers, as long as they provide the degree of pressure amplification required, may be used in the device of this invention.

In one embodiment, hydraulic cylinder 16 is an air cylinder.

Referring to Figure 2, the hydraulic fluid under amplified pressure is fed via line 52 to spool valve 17. A spool valve is a slide-type hydraulic valve in which the movable part is a "spool."These valves, and their use in brake systems, are well known and are described, e. g., in United States patents 5,882,089,5,836,845,5,711,584,5,624,164,5,547,264, 5,442,916,5,417,480,5,328,002,5,323,688,5,188,002,5,141,293, 5,123,712, and the like.

Hydraulic logic circuits for controlling spool valves, and their outputs, are well known. One such logic circuit is disclosed in United States patent 4,201,277 of Bruno Meier et al. In this patent, hydraulic activators are provided with a relief valve which serves to permit communication between a disengaging cylinder chamber and a work cylinder chamber. The open position of the relief valve occurs when the release apparatus for the rotatable friction brake member is closed. The closed position of the relief valve occurs after the rotating brake is released. Other hydraulic logic circuits for controlling spool valves are disclosed, e. g., in United States patents 5,218,997,4,811,650,4,812,789,4,154,261, and the like. Furthermore, the spool valves can be replaced, in part or whole, by other hydraulic control valves performing the same function.

Referring again to Figure 2, it will be seen that spool valve 17 is hydraulically connected to both hydraulic cylinder 16 (via line 52), and to hand pump 22 (via line 54).

Spool valve 17 has outputs 56,58,60, and 62. For the sake of simplicity of representation, the circuit logic involving spool valve 17 is schematically illustrated in Figure 2A.

Referring to Figure 2A, it will be seen that spool valve 17 is capable of feeding hydraulic fluid via lines 56 and 58 to hydraulic cylinders 18 and 20, respectively. Such fluid flow will cause these hydraulic cylinders to move in a manner such that they will activate the brakes.

The fluid flow through lines 56 and 58 can be caused by means of fluid from hydraulic cylinder 16, which is caused to flow because of air pressure in air cylinder 14. This fluid flow occurs when the service brake is applied by the engineer; and it flows through both of lines 56 and 58 to cylinders 18 and 20.

The activation of hand pump 22 will also cause fluid flow through lines 56 and 58 and the resultant movement of cylinders 18 and 20.

When the pressure applied by the hand pump 22 is equal to the pressure applied through line 52, then the spool within spool valve 17 will not move, and no fluid will flow to either cylinder 18 or cylinder 20.

If no service brake is applied by the engineer, then no fluid will flow through line 52.

In that case, fluid flowing though line 54 because of the use of hand pump 22 will cause the spool to move within valve 17 and the resultant movement of cylinders 18 and 20.

If, however, the service brake is applied by the engineer, the system is designed in such manner that the pressure exerted through line 52 upon the spool will always be greater than the pressure exerted upon the spool through line 54. Thus, when the service brake is applied and the hand brake is not applied, such pressure will cause the movement of cylinders 18 and 20. When both the service brake is applied and the hand brake is applied, cylinders 18 and 20 will still move because of the greater pressure from line 52. Furthermore, a pressure sensor disposed within line 52 at point 60 will sense the increased the pressure in such line and cause a pressure controller 62 to open a valve in line 54 located at point 64 and to release pressure back into pump 22.

The schematic of Figure 2A provides one means for releasing the pressure in line 54 when the pressure in line 52 exceeds a certain specified value. It is only one of many possible means of achieving this end, all of which are within the scope of this invention.

In the preferred embodiment depicted in Figure 2A, an isolation valve 66 is disposed within line 58, and an isolation valve 68 is disposed within line 56.

When the pressure at point 60 exceeds a certain specified value, then isolation valves 66 and 68 allow high pressure fluid to flow back into the system. However, until and unless the pressure at point 60 exceeds such as specified value, the system will only allow forward flow in lines 56 and 58 unless and until the pressure in the cylinders 18 and 20 is manually released back into the system by means of a release valve (not shown). When such forward flow has achieved the objective of moving the cylinders 18 and 20 to the desired extent, isolation valves 66 and 68 will close and not allow flow in either direction until and unless it senses the pressure in line 52 has exceeded the aforementioned specified level.

The hydraulic cylinders 18 and 20 are disposed above the bolster 30, thus being removed to some degree from the risk of contact with moving debris from the wheels of the truck. The bolster 30 moves up and down on springs 40. The hydraulic cylinders 18 and 20 are sufficiently spaced that, even at the maximum height of bolster 30, it will not contact either of such cylinders. In general, when the truck 10 is motionless, the hydraulic cylinders 18 and 20 are at least about 2 inches above the bolster 30 when the truck is unloaded.

Attachment pins 70,72,74, and 76 are adapted to engage the slack adjusters 78,80, 82, and 84. These slack adjusters are shown in greater detail in Figure 3.

Figure 3 is a side view of the side frame 32 (see Figure 2). The side frame on the other side of the truck, side frame 34, will have a similar configuration.

Cylinder 18 is connected to lever arm 26 at point 86. The structure of lever arm 26 is shown in greater detail in Figure 5. Referring to Figure 5, a clevis 90, attached to cylinder 18 and equipped with orifices 92 and 94, is aligned with orifice 96 of lever arm 26 and is removably attached thereto by means of a pin 98 (see Figure 3). Rectangular orifice 100 of lever arm 26 is adapted to receive rectangular protrusion 102 of brake head 24 (see Figure 6).

The rectangular protrusion 102 is comprised of an orifice 104 adapted to be aligned with the orifices 106 and 108 of lever arm 26 (see Figure 5); and, when so aligned, the lever arm 26 may be removably attached to the brake head 24 by means of a pin.

Lever arm 26 is also comprised of an orifice 110 which is adapted to receive rod 112 of pin block 28.

The connection of lever arm 26 to the hydraulic cylinder 18, the brake head 24, and the pin block 28 is similar to the connection of lever arm 27, the free rod end of hydraulic cylinder 18, the brake head 25, and the pin block 29.

These connections allow brake heads 24 and 25 to self align to the wheels 37,39,41, and 43 (see Figure 2). This phenomenon allows brake pads 44 and 46 to rotate into positions wherein they are in full contact with the wheels.

Many other designs may be used that will accomplish the same function.

Furthermore, spring force or other means (not shown) can be introduced at the various connection points to accommodate tolerances and to balance forces or moments to maintain the shoe 46 in proper relation to the wheel 37.

Referring again to Figure 3, it will be seen that slack adjusters 78 and 80 are connected to hydraulic cylinder 18, one for limiting movement in one direction, the other for limiting movement in the other direction. These slack adjusters are well known in the railway art and are described, e. g., in United States patents 5,813,771,5,615,755,5,253,736, 5,246,081,5,197,373,5,067,872,4,973,206,4,683,991,4,676,346, 4,662,485, 4,646,882,4,530,422,4,498,711,4,497,392,4,457,407,4,420,066, and the like.

The levers, slack adjusters, and cylinders are supported by and forces reacted into the side frames. An alternate means could have these elements supported by the bolster and/or by another structure.

It is to be understood that the aforementioned description is illustrative only and that changes can be made in the apparatus, in the ingredients and their proportions, and in the sequence of combinations and process steps, as well as in other aspects of the invention discussed herein, without departing from the scope of the invention as defined in the following claims.

In one embodiment, the air powered fluid system, instead of producing a hydraulic flow at an increased pressure in response to an air flow at a lesser pressure, produces a fluid flow at an increased pressure in response to the an air flow at a lesser pressure..

The spool valve referred to in this specification acts as a manifold, directing fluid flow to certain locations in response to certain conditions. Other manifolds may also be used, and other valves than spool valves may also be used.

The hydraulic cylinders referred to in this specification are but one means of providing linear movement in response to the flow of fluid under pressure. Other devices, such as other movable cylinders, also may be used.