Brake system for rail cars

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 on, when Thomas H. Engle's U.S. Pat. No. 5,746,293 issued in May of 1998, the problems discussed in his earlier patents 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 substantially safer and 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'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

30

. 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. No. 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 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

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 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.

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

.

Referring to

FIG. 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 FIG.

3

). Rectangular orifice

100

of lever arm

26

is adapted to receive rectangular protrusion

102

of brake head

24

(see FIG.

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 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

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

.

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 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 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.