Abstract:
A brake system for rail cars is disclosed. The brake system includes a first source for providing a braking force to a first and a second braking apparatus, a second source for providing a separate force to the first and a second braking apparatus, and a manifold for simultaneously delivering a braking force from either the first source or the second source to the first and second braking apparatus. The manifold includes a positionable valve operable under the influence of pressure differentials applied thereto by the first source and the second source and wherein the position of the valve controls which braking force will be applied to the first and second braking apparatus. The brake system further includes a controller arranged in operable combination with the first source and the second source for inhibiting a braking force from the second source being directed to the first and the second force to the first and the second braking apparatus.

Description:
This application is a continuation of application Ser. No. 09/345,022, filed Jul. 2, 1999. 
    
    
     FIELD OF THE INVENTION 
     A brake system for rail cars comprising an intensifier, a spool valve, a pump, and at least two hydraulic or air cylinders. 
     BACKGROUND OF THE INVENTION 
     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. For many years there has been a trend in North America to use heavier and heavier freight cars. This trend has required designers of brake systems to attempt to pack more and more brake performance into a smaller and smaller space. 
     In a paper presented at the September, 1971 Annual Meeting of the Air Brake Association (1971). Thomas H. Engle, Senior Project Engineer of the New York Air Brake Company (of Starbuck Avenue, Watertown, N.Y.) disclosed that “About four years ago, our Company decided that in the long run the best solution for this squeeze would be a hydro-pneumatic braking system which included both hand and power braking, and which would use a mechanical lock on the handbrake so as to hold a car, on which handbrakes had been applied, even in the absence of hydraulic pressure.” 
     In 1972, U.S. Pat. No. 3,707,309 was issued to Mr. Engle. This patent claimed a fluid operated brake system for a railway car which comprised a hydraulic hand brake control unit which had to be manually activated and deactivated. Failure to deactivate the control unit at the appropriate time causes the brakes to maintain contact with the wheels, thus increasing wear and tear upon the system and leading to premature failure. 
     By no later Mar. 16, 1976, when U.S. Pat. No. 3,944,286 issued to Thomas H. Engle, there existed, according to such patent, “ . . . railway regulations which require a crewman to move or confirm all parking brakes to an ‘OFF’ position . . .  ” The patent disclosed that “The prior art systems . . . may create problems in use since it is frequently the case that the parking brake has not been fully unlocked and released by a crewman before an attempt is made to move the car. Obviously, this can cause numerous delays to locate the stuck brakes, undue brake wear if some movement does occur and similar deleterious effects.” The solution to this problem presented in this patent was to provide a brake system which first required a crewman to release the parking brake of a particular car. The patentees disclosed that “If, however, the crewman has failed to even partially release the parking brake of a particular car, the booster 70 will be ineffective to release either the brake or the brake locking mechanism.” 
     Some twenty-three years later, when Thomas H. Engles&#39;s U.S. Pat. No. 5,746,293 issued in May of 1998, the problems discussed in his earlier patent had not been solved. Thus, as is disclosed at lines 50-55 of column 1 of this 1998 Engle patent, “ . . . these hand brakes have been a source of problems. This is particularly the case when such hand brakes are not released when a train consist is ready to move over the tracks . . .  ” 
     About the same time that U.S. Pat. No. 5,746,293 issued to Mr. Engle, U.S. Pat. No. 5,767,973 issued to Hans J. Naumann. This latter patent disclosed that “ . . . 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 more reliable than prior art brake systems. 
     It is another object of this invention to provide a brake system which allows ready visual access to determine whether the brakes are disengaged. 
     It is yet another object of this invention to provide a brake system which can readily be attached to conventional railway trucks. 
     It is yet another object of this invention to provide a brake system which can readily be removed from conventional railway trucks for service. 
     It is yet another object of this invention to provide a brake system which automatically disengages a hand brake upon application of a train&#39;s service brake. 
     It is yet another object of this invention to provide a brake system which is relatively lightweight, small, and inexpensive. 
     It is yet another object of this invention to provide a brake system which can be used with a railway truck and a railway car. 
     It is yet another object of this invention to provide a brake system which will require substantially less maintenance than prior art braking systems, less time to do such maintenance, and less expense to do such maintenance. 
     SUMMARY OF THE 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: 
     FIG. 1 is a schematic view of one preferred brake apparatus of the invention mounted on a railway truck, 
     FIG. 2 is a schematic view of the brake apparatus of FIG. 1, showing the position of its components vis-a-vis the railway truck, 
     FIG. 2A is a schematic of a hydraulic circuit involving a spool valve of the brake apparatus, 
     FIG. 3 is a partial side view of the brake apparatus of FIG. 2, 
     FIG. 4 is a schematic view of a pin block which may be used in conjunction with the apparatus of FIG. 1; 
     FIG. 5 is a perspective view of a brake lever and clevis which may be used in conjunction with the pin block of FIG. 4, and 
     FIG. 6 is a perspective view of a brake head. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 is a perspective view of a railway truck  10  onto which, in the preferred embodiment depicted, 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 . 
     As will be appreciated by those skilled in the art, 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, in general, 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 FIG. 1, the brake system is mounted onto a railway truck  10 . As is known to those skilled in the art, 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 and are described, e.g., in U.S. Pat. Nos. 5,040,466, 4,981,082, 4,907,514, 4,844,554, 4,838,174, 4,766,818, 4,679,506, 4,669,391, 4,630,715, 4,428,301, and the like. The disclosure of each of these United States patents is hereby incorporated by reference into this specification. 
     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 . As will apparent to those skilled in the art, it does not matter where these components are located as long as they are operatively connected to each other. 
     FIG. 2 also is a perspective view of railway truck  10  onto which the components of the preferred brake system  12  are mounted. Referring to FIG. 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 below a predetermined value, 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. 
     In the preferred embodiment depicted, 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 U.S. Pat. Nos. 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. The disclosure of each of these United States patents is hereby incorporated by reference into this specification. 
     One such intensifier, which is referred to as a pneumatic/hydraulic pressure intensifier, is disclosed in U.S. Pat. No. 5,746,293, the entire disclosure of which is hereby incorporated by reference into this specification. 
     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 again to FIG. 2, the hydraulic fluid under amplified pressure is fed via line  52  to spool valve  17 . As is known to those skilled in the art, 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 U.S. Pat. Nos. 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. The disclosure of each of these United States patents is hereby incorporated by reference into this specification. 
     Hydraulic logic circuits for controlling spool valves, and their outputs, are well known. One such logic circuit is disclosed in U.S. Pat. No. 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. The entire disclosure of this patent is hereby incorporated by reference into this specification. 
     Other hydraulic logic circuits for controlling spool valves are disclosed, e.g., in U.S. Pat. Nos. 5,218,997, 4,811,650, 4,812,789, 4,154,261, and the like. The disclosure of each of these United States patents is hereby incorporated by reference into this specification. Furthermore, the spool valves can be replaced, in part or whole, by other hydraulic control valves performing the same function. 
     Referring again to FIG. 2, it will be seen that spool valve  17  is hydraulically conneced 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 FIG.  2 A. 
     Referring to FIG. 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, as will be discussed in more detail later in this specification. 
     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 . As is discussed elsewhere in this specification, 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 he engineer, the system is designed in such a 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 operably disposed within line  52  at point  60  will sense the increased the pressure in such line and cause a pressure controller  62  to operably open a valve in line  64  located schematically at point  64  and to release pressure back into pump  22 . 
     The schematic of FIG. 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 FIG. 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 or predetermined value or level, then isolation valves  66  and  68  allow high pressure fluid to flow back into the system. However, until and unless the pressure art point  60  exceeds such a predetermined or specified value or level, 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  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. 
     Referring again to FIG. 2, it will be seen that 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. As will be apparent to those skilled in the art, 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. 
     Referring again to FIG. 2, 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 FIG.  3 . 
     FIG. 3 is a side view of the side frame  32  (see FIG.  2 ). It will be appreciated the side frame on the other side of the truck, side frame  34 , will have a similar configuration. 
     Referring to FIG. 3, it will be seen that cylinder  18  is connected to lever arm  26  at point  86 . The structure of lever arm  26  is shown in greater detail in FIG.  5 . 
     Returning to FIG. 5, a clevis  90 , attached to cylinder  18  and equipped with orifices  92  and  94 , is aligned with orifice  96  defined by lever arm  26  and is removably attached thereto by means of a pin  98  (see FIG.  3 ). Lever arm  26  furthermore defines an orifice  100 , preferably having a rectangular margin, and which is adapted to receive a rectangular protrusion  102  of brake head  24  (see FIG.  6 ). The rectangular protrusion  102  on brake head  24  defines an orifice  104  adapted to be aligned with the orifices  106  and  108  of lever arm  26  (see FIG.  5 ); and, when so aligned, the lever arm  26  may be removably attached to the brake head  24  by means of a pin. 
     Referring again to FIG. 5, lever arm  26  further defines 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 . 
     As will be apparent to those skilled in the art, these connections allow brake heads  24  and  25  to self align to the wheels  37 ,  39 ,  41 , and  43  (see FIG.  2 ). This phenomenon allows brake pads  44  and  46  to rotate into positions wherein they are in full contact with the wheels. 
     It will be apparent that 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 FIG. 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 U.S. Pat. Nos. 5,813,771, 5,615,755, 5,476,269, 5,465,816, 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 entire description of each of these United States patents is hereby incorporated by reference into this specification. 
     Furthermore, in the preferred embodiments depicted, the levers, slack adjusters, and cylinders are supported by and forces reacted into the side frames. An alternative 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 term fluid, as used in this specification, is intended to encompass both air and liquid material. 
     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.