US3412829A

US3412829A - Retarders

Info

Publication number: US3412829A
Application number: US347458A
Authority: US
Inventors: Kenneth A Browne; Thomas H Engle
Original assignee: CHESAPEAKE AND OHIO RAILWAY Co
Current assignee: CHESAPEAKE AND OHIO RAILWAY Co
Priority date: 1964-02-26
Filing date: 1964-02-26
Publication date: 1968-11-26
Anticipated expiration: 1985-11-26

Description

Nov. 26, 1968 K. A. BROWNE ET AL 3,412,829

RETARDERS 4 Sheets-Sheet 1 Filed Feb. 26, 1964 BROWNE INVENTORS KENNETH A. THOMAS H. ENGLE BY I Dgqdl-Z ##M Q M ATTORNEYS 22 FIG.

Nov. 26, 1968 K. A. BROWNE ET AL 3,412,829

RETARDERS 4 Sheets-Sheet 5 Filed Feb. 26, 1964 FIG.?

mm O E m w ERN B S N H I Hhwfl f m H T8 .0 EA T MM A TM W M United States Patent 3,412,829 RETARDERS Kenneth A. Browne, Lakewood, and Thomas H. Engle,

Cleveland, Ohio, assignors to The Chesapeake and Ohio Railway Company, Cleveland, Ohio, a corporation of Virginia Filed Feb. 26, 1964, Ser. No. 347,458 13 Claims. (Cl. 188180) The present invention relates to car retarders for railway cars and the like and more particularly to track apparatus which automatically senses the speed of a railroad car and if the speed is in excess of a predetermined value, reduces its speed, preferably to a predetermined velocity, by the application of a brake mechanism along the track to the wheels of the car.

In the operation of free running track vehicles, it is often desirable and necessary to sense and control the speed of the moving vehicle by equipment located off the vehicle, for example, the speed of railroad cars in gravitytype classification yards, wherein the railroad cars are caused to freely roll down an inclined track and onto branch tracks where the various trains are made up. The cars are stopped on the branch tracks by striking or bumping into the cars already on the tracks and unless their speed is quite slow, damage to the cars and/or their contents may result. Since various cars are of different weight, have different resistance to rolling movement, etc., some means for sensing the speed of the freely rolling cars is usually employed on the inclined track and/ or the branch tracks and when their speed exceeds a predetermined velocity, braking means along the track is applied to them, usually to their wheels, to reduce their speed thereby preventing or attempting to prevent damage to the cars, their contents and/or couplings, etc., due to their striking or bumping cars on the branch tracks at too high a speed.

The principal object of the present invention is to provide a new and improved track apparatus for sensing, and when necessary, reducing the speed of railroad cars, as mentioned above, which apparatus is of a simple, but durable construction, easy to install and maintain, automatic, reliable and economical in operation.

Another object of the invention is to provide a new and improved car retarder of the character referred to which will, within certain limitations, automatically release cars passing therethrough at the predetermined velocity regardless of the weight, rolling resistance and incoming speed of the cars.

Another object of the invention is to provide a new and improved car retarder of the character mentioned which is self-contained and operated solely by the extraction of kinetic energy from the passing railroad cars.

Another object of the invention is the provision of a new and improved car retarder of the character referred to which can be installed in an existing track without any disturbance or modification of the track or at least any material change in the existing track, for example, drilling a few holes in the web portions of the rails.

A further object of the invention is the provision of a new and improved car retarder of the character referred to that will fit between the rails and above the ties of the track.

A further object of the invention is the provision of a new and improved car retarder of the character referred to which will not interfere with the normal track signal systems, etc.

A more specific object of the invention is the provision of a new and improved car retarder of the character referred to having a sensing means located adjacent to one or more of the track rails which is engaged by a wheel or wheels of 'a car moving along the track to provide a signal indicative of the speed of the car, and braking means 3,412,829 Patented Nov. 26, 1968 "ice along the track responsive to said signal for retarding the car, that is, reducing the speed of the car when the speed of the car exceeds a predetermined value.

A further object of the present invention is to provide a new and improved car retarder of the character referred to which provides a visual signal in the event of an operational failure in the apparatus.

The invention resides in certain constructions, combinations and arrangement of parts and further objects and advantages of the invention will be apparent to those skilled in the art to which it relates from the following description of the preferred embodiment described with reference to the accompanying drawings, in which:

FIG. 1 is a fragmentary plan view of a railway track embodying the present invention;

FIG. 2 is a sectional view, with portions in elevation, approximately along line 22 of FIG. 1;

FIG. 3 is a fragmentary sectional view approximately along the line 3-3 of FIG. 2;

FIG. 4 is a sectional view, with portions in elevation, approximately along line 44 of FIG. 1;

FIGS. 5 and 6 are views similar to FIG. 4 but with the parts shown in different operating positions;

FIG. 7 is a schematic illustration of the control system forming a part of the retarder shown in the previous figures;

FIG. 8 is a perspective view of a part of the apparatus embodied in the present invention;

FIG. 9 is a partial side elevational view and a partial vertical longitudinal sectional view of the apparatus shown in FIG. 8;

FIG. 10 is a sectional view, with portions in elevation, approximately along line 10-10 of FIG. 9;

FIG. 11 is an enlarged fragmentary view of a portion of FIG. 2; and

FIG. 12 is a fragmentary sectional view showing a modification of part of the apparatus embodied in the present invention.

The preferred embodiment of the retarder of the present invention is especially adapted for use with conventional railroad tracks and is illustrated or shown in the drawings as applied to such a track comprising a pair of running rails 10, 11 supported on ties 9 in the usual manner. The retarder comprises a pair of elongated built-up brake beams designated generally by the reference characters A, B located at and adjacent to the gauge side of the running rails 10, 11, respectively. The brake beams A, B are supported for limited movement toward and away from said rails and are vertically adjustable with respect to the rails with which they are associated. The brake beams are caused to engage the wheels of a railroad car passing thereby with a retarding force by an operating unit C in response to a sensing means D located along the track which provides a control signal indicative of the speed of a railroad car moving along the track and into and/ or through the retarder. The sensing unit D is connected to the operating unit C by a control means E including operating valves, etc.

The brake beams A, B include suitable

elongated brake shoes

12, 13, respectively, normally positioned close to the rails 10, 11, that is, in the positions shown in FIGS. 1, 2 and 4 in which positions they are adapted to be engaged by and moved away from the respective running rails adjacent to which they are positioned by the wheels W, shown in dot-dash lines in FIGS. 5 and 6, of a car moving into and through the retarder. In order to facilitate entrance of the car wheels between the running rails and the brake beams, the ends of the brake beams including the

shoes

12, 13 are beveled on their sides adjacent to the running or track rails.

In the embodiment shown, the

brake shoes

12, 13 are sageway 82 in a manually operable valve 83 shown diagramatically in FIG. 7 and a conduit 84 leading from the valve 83 to the sump. The conduit 81 has a check valve 85 therein which prevents reverse flow. Hydraulic fluid when exhausted from the cylinder by movement of the piston 75 as hereinafter explained flows from the cylinder 50 through conduit 86, passageway 87 in valve 83, conduit 88, control means E, and conduit 89 to the sump 80. The operation of the control means E and the speed sensing means D will be fully explained hereinafter. For the present, it is suflicient to say that the control means E is selectively operable by the sensing means D to block or permit egress of fluid from the cylinder 50 in accordance with the speed signals provided by the sensing means D.

When the operating parts of the operating unit C are in the position shown in FIG. 4, the spring 70 preferably is compressed, that is, preloaded to a greater or lesser degree, as desired, between the fixed and movable abutments 71 and 72, respectively, and the movable abutment member 72 is against the stop 73 on the end of the tubular member 60. Under these conditions the spring 70' does not exert any force or pressure on the left-hand telescopic assembly and the telescopic assemblies are pushed apart as far as permitted by the

tie bolts

43 and 44, previously referred to, by the action of the low pressure fluid in the closed end of the cylinder 50 against the piston head 75 and the action of the piston head 75 against the movable abutment member 72 through the spacer member 78. In other words, the low pressure fluid in the closed left-hand end of the cylinder 50 acting through the compression spring 70 expands or tends to expand the telescoping assemblies and move or hold, as the case may be, the brake beams A, B to positions adjacent to the running rails 10, 11, respectively. The movement of the brake beams toward the running rails is limited by the adjustable tie means 42 connecting opposite ends of the brake beams, which tie means have been previously mentioned as including the

elongated bolts

43, 44.

When a car approaching the retarder is moving at a speed in excess of a predetermined velocity, the speed sensing means D will send a signal to the control means E to block egress of the hydraulic fluid from cylinder 50. The speed sensing means D senses the speed of the car prior to the leading wheels W of a truck T thereof entering the retarder. As a first pair of wheels W of the truck T of a car enter the retarder from the left, as viewed in FIG. 1, and engage the

brake shoes

12 and 13 of the brake beams A and B, respectively, the left ends of the brake beams A and B will be moved inward toward ach other. Since the right ends of the brake beams A, B cannot move outwardly toward the rails, due to the tie means 42 at their right-hand ends, the telescoping assemblies of the operating unit C will be partially collapsed, i.e., moved toward each other, in order to accommodate the inward movement of the left ends of the brake beams engaged by the wheels W. As the telescoping assemblies collapse, the abutment 71 will move toward the abutment 72 and the spring 70 will be compressed or further compressed as the case might be, and the stop 73 will move away from the abutment 72 to the right transferring the force of the spring 70 to the spacer 78 and in turn the piston 75 and through the fluid trapped in the head end of the cylinder 50 to the left-hand telescopic assembly forcing the brake beams A, B into tight engagement with the wheels W of the car. As the wheels W move through the retarder, the spring 70 will be compressed further and when the wheels W are located at the centerline of the operating unit C of the spring will be under maximum compression, exerting a pressure, for example, from approximately 16,600 lbs. to 17,000 lbs., and the operating unit C will be in the position shown in FIG. 5. It will be understood, however, that the spring 70 etc., can

be constructed to exert any desired force upon the wheels of the car.

The retarder preferably has a length slightly greater greater than twice the distance between the centerlines of the first and second pairs of wheels W and W, respectively, of the truck 88. In this event, when the first pair of wheels W of the truck are located at the centerline of the operating unit C, the second pair of wheels W of a truck will have to enter the retarder and the right ends of the brake beams A, B will be moved inwardly toward each other until the brake beams proper are parallel to the rails 10, 11. This parallel position is maintained until the first pair of wheels W move out of the retarder. Thereafter, as the second pair of wheels W move toward the exit end of the retarder, the operating unit gradually expands under the action of the spring until the wheels pass out of the retarder, that is, move beyond the right ends of the brake beams A, B. The end of the brake beams A and B move outwardly toward the rails 10, 11 until they engage the ends of the tie means 42. If the car is still moving at a velocity in excess of the predetermined value for which the retarder is set, the same sequence of operation will be followed with regard to the wheels of the trailing or other truck of the car.

If the speed sending means D signals the control means E that the speed of a car moving through the retarder has been reduced to the predetermined set velocity while one or more of the car wheels is in the retarder, the control means E will operate to ermit egress of hydraulic fluid from the closed end of the cylinder 50 through the conduit 86. The spring 70 will thereupon move the piston through the movable abutment member 72 and spacer sleeve 78 toward the left, as viewed in FIG. 5. Movement toward the left continues until the spring 70 again is substantially extended, or until the abutment 71 engages the stop 73. The telescoping assemblies of the operating unit C, which are now released from the compression forces of the spring 70, will assume the position shown in FIG. 6. The low pressure fluid in the closed end of the cylinder 50, however, will hold the

brake shoes

12, 13 of the brake beams in engagement with the wheels W of the car, but merely with a slight pressure, that is, a pressure not sufficient to produce any appreciable retardation of the car.

When a car approaching the retarder is moving at a speed below the predetermined velocity, the speed sensing means D will not signal the control means E to close egress of fluid from the cylinder 50. The action and operational sequence of the retarder will be the same as previously described, except that the spring 70 will immediately move the piston 75 through the movable abutment member 72 and spacer sleeve 78 to the left as viewed in FIG. 4, and the operating unit C collapses and assumes the position shown in FIG. 6 when the first pair of wheels W of the truck are located at the centerline of the operating unit C. The low pressure fluid in the cylinder 50, however, will hold the brake members in engagement with the passing wheels of the car, but merely with a slight pressure, that is, a pressure not sufiicient to produce any appreciable retardation.

The sensing means D includes an elongated flexible or collapsible member extending adjacent and parallel to the outside of the rail 10 at the retarder. The top of the member 90 is slightly above the rail 10 and its overall length is such that it extends a short distance ahead and preferably behind the retarder. The member 90 is press fitted within a U-shaped channel 91, which channel has a downwardly extending web portion 92 bolted to the rail 10 by the same bolts which bolt the fish plate used in connecting the retarder to the rail. Spacer rings 93 are interposed between the web portion 92 of the member 91 and fish plates at the side of the rail 10 adjacent to which the member 91 is located and which form part of the mounting means for the retarder for the purpose of properly spacing the tube 90 outwardly with respect to the rail 10. The web portion 92 contains vertically elongated aperout producing a pressure drop across the piston greater than the force or pressure of the spring 120, the piston 107 and the spool valve 114 will remain in their extreme right-hand positions, shown in FIGS. 7 and 10. As previously mentioned, with the spool valve 114 in this position, the

apertures

126 and 128 will remain in communication with each other and egress of fluid from the cylinder 50 of the operating unit C will be permitted with the result that no appreciable braking force on the wheels of the car will be exerted by the retarder. The fluid forced through orifice 130 flows to the sump 80 via conduit 89. From the sump, which is constantly maintained at a low pressure, as previously mentioned, fluid is conducted by conduit 141 to a T passage 143 contained within the rotatable valve member 83 forming part of a valve means 145 and from the passage 143 through the conduit 146 to the passageway 98 in the member 90 the opposite end of which is connected to the end of the aperture 94 at the entrance end of the retarder by a short conduit 146. As best shown in FIG, 10, the member 83 is cylindrical and rotatably received within a cylindrical opening 147 formed within the housing 104. The member 83 normally occupies the position indicated in FIGS. 7 and 10.

When a Wheel W of a car moving at a velocity in excess of the predetermined value, for example, greater than six miles per hour, engages and collapses the member 90 to close the passage 94 therein and the orifice 130 is not large enough to accommodate the entire volume of the entrapped fluid being displaced per unit of time. This will cause a pressure drop across the piston which is greater than the force or pressure of the spring 120 with the result that the piston 107 and the spool valve 114 will be moved to the left, as viewed in FIGS. 7 and 10. When the spool valve 114 is moved to the left communication between

apertures

126 and 128 is blocked and egress of the fluid from the closed end of the cylinder 50 of the operating unit C is prevented. As previously mentioned, blocking the egress of fluid from cylinder 50 of the operating unit C prevents the movement of piston member 75 to the left, as viewed in FIG. 5, upon a wheel entering the retarder with the result that spring 70.will urge the

brake shoes

12 and 13 of the brake beams A and B, respectively, into tight engagement with the wheels W of the car to retard the speed of the same. As soon as the velocity of the car drops below the predetermined value, the volumetric rate of displacement of fluid from member 90 will be less than that required to pass through the orifice 130 in the piston 107 and the pressure drop across the piston 107 will decrease to a value which is less than the biasing force or pressure exerted by the spring 120 and the spring 120 will move the spool valve 114 and the piston 107 to the right. Movement of the spool 114 to the

right places apertures

126 and 128 in communication with each other and permits egress of fluid from cylinder 50. The egress of fluid from cylinder 50 of the operating unit C will enable the spring to move the piston 75 to the left and relieve the braking force on the wheels of the car in a manner hereinbefore described.

If the speed of an approaching car is far in excess of the predetermined safe value, provision is made for bypassing or communicating the entrapped volume of fluid directly to the sump 80 in order to protect the member 90 from excessive back pressures. When a wheel W of a car moving at a velocity greatly in excess of the predetermined value engage and collapse the member 90, the rate of displacement of the entrapped column of fluid will be far greater than that which can be accommodated by the orifice 130. This will result in a large pressure drop across the orifice and the piston 107 and the spool valve 114 will be rapidly moved toward the left until communication is made between the chamber 106 and a plurality of circumferentially spaced openings 156 contained in left end of the sleeve 108, which openings 156 are also in communication with the chamber 111 and in turn the sump 80. When the piston 107 and associated spool valve 114 are moved to an extreme left position, as viewed in FIG. 10, the right end of the spool valve 114 will be positioned at and close the apertures 126 and thus, egress of fluid from the cylinder 50 of the operating unit C will be blocked. As previously described, blocking egress of fluid from cylinder 50 results in the retarder applying a braking force to the Wheels of the car.

Bolted or otherwise secured to the housing 104 is an elongated cylindrical member 158. Slidably received within the member 158 is a diaphragm piston 160. The piston 160 is normally urged to the left, as shown in FIG. 9 of the drawings, by a spring means 162 one end of which is secured to the right side of the piston and the opposite end to a member 164 closing the right-hand end of the member 158. The sump consists of the chamber formed between the piston 160 and the housing 104. The spring 162 provides a slight compressive force for maintaining the sump 80 and the hydraulic system under a low pressure.

To initially fill the entire hydraulic system the cylindrical member 83 of the valve means is manually rotated ninety degrees in a clockwise direction from the position shown in FIGS. 7 and 10. For this purpose the right-hand end of the member 83, as viewed in FIG. 10, contains a slot 170, which is adapted to be engaged with a suitable tool or key for manual rotation. Referring to FIG. 7, manual rotationof the valve ninety degrees in a clockwise direction places T passage 82 in communication with conduit 81 and a supply conduit 172 and blocks conduit 84. Elbow passage 87 will now be in communication with

conduits

86 and 174 and communication with passage 88 will be blocked. T passage 143 will now be in communication with

conduits

146 and 174 and communication with conduit 141 will be blocked. The member 83 contains an additional elbow passage 176 located between the

passages

82 and 87 which is normally blocked off, but now communicates conduit 178 leading from the sump 80 with an air bleed conduit 180.

With the member 83 in the position referred to, hydraulic fluid is pumped by a hand pump 181 from a suitable source 182 through conduit 172, T passage 82, conduit 81, cylinder 50 of the operating unit C, conduit 86, elbow passage 87, conduit 174, T passage 143, conduit 146, bottom passageway 98 in member 90, top passageway 94 in member 90, conduit 97, chamber 106, orifice 130, chamber 111, conduit 89 and into the sump 80. From the sump 80 the fluid is pumped through conduit 178, elbow passage 176 and bleed conduit 180. The conduit 178 is connected with the top of the sump 80 to insure that all the air, which might get into the sump 80 will be bled from the system.

After the filling operation is complete and the hydraulic fluid begins to flow out of the air bleed passage 180, the cylindrical member 144 is manually rotated a few degrees in the counterclockwise direction. Movement of the valve means in this direction a few degrees will blank off the air bleed passage 180 which is of smaller diameter than the other passages in member 83, but will not blank off any of the other passages. The hand pump is now pumped a few more strokes to overfill the system and causes movement of piston within cylinder member 158 to the right. as viewed in FIG. 9. Movement of the piston 160 to the right compresses spring 162 which in turn maintains the hydraulic fluid contained in the system under a low pressure. The member 83 is then rotated counterclockwise to its normal position, as shown in FIGS. 7 and 10.

The initial overfill of hydraulic fluid in the system insures that the retarder will operate efliciently even though the

brake shoes

12, 13 wear and/or if the tie means 42 loosen, since additional fluid is available which can be supplied to the cylinder 50 to move the piston 75 slightly to the right, as viewed in FIG. 4, in order to com- Having described our invention, we claim:

1. In track apparatus for applying a braking force to wheels of a car or the like moving along a pair of spaced running rails in excess of a predetermined speed, an elongated brake means adapted to be supported adjacent to one of the running rails for movement toward and from said rail, a cylinder member closed at one end and operatively supported between said rails, 21 first member operatively connected to said brake beam and projecting into said cylinder member, piston means slidably supported in said cylinder member adjacent to said closed end thereof, abutment means on said first member spaced from said piston means, spring means interposed between said piston means and said abutment means, a fluid reservoir, conduit means connecting said closed ends of said cylinder member with said reservoir, valve means in said conduit means for permitting flow from said cylinder member, means for sensing the speed of a car moving along said rail, and means operatively connecting said valve means and said speed sensing means preventing flow through said valve means when said car is moving in excess of a predetermined speed.

2. In track apparatus for applying a braking force to wheels of a car or the like moving along a pair of spaced running rails in excess of a predetermined speed, spaced elongated brake beams adapted to be supported adjacent to the running rails for movement toward and from said rails, a cylinder member closed at one end interposed between said rails and operatively connected to one of said brake beams, a first member operatively connected to the other of said brake beams and projecting into said cylinder member, piston means slidably supported in said cylinder member adjacent to said closed end thereof, first abutment means on said first member and within said cylinder member adjacent to the side of said piston means opposite said closed end of said cylinder member, second abutment means on said first member spaced from the side of said first abutment means opposite said piston means, spring means interposed between said pistons means and said first abutment means at one end and said second abutment means at the other end, a fluid reservoir, conduit means connecting said closed end of said cylinder member with said fluid reservoir, valve means in said conduit means for controlling flow from said cylinder member, speed sensing means for sensing the speed of a car moving along said rails, and means operatively con necting said valve means and said speed sensing means for preventing flow through said valve means when said car is moving in excess of a predetermined speed.

3. In track apparatus for applying a braking force to wheels of a car or the like moving along .a pair of spaced running rails in excess of a predetermined speed, spaced elongated brake beams adapted to be supported generally parallel with and adjacent to the guage side of the running rails for movement toward and from said rails, a cylinder member closed at one end and operatively connected to one of said brake beams, a first member operatively connected to the other of said brake beams and projecting into said cylinder member, piston means slidably supported in said cylinder member adjacent to said closed end thereof, abutment means on said first member spaced from piston means, spring means interposed between said piston means and said abutment means adopted to yieldably urge said piston means away from said abutment means, a fluid reservoir, normally closed conduit means connecting said closed end of said cylinder member with said fluid reservoir, means for sensing the speed of a car moving along said rails including an elongated member having a collapsible chamber, means supporting said member adjacent to one of said running rails and in a position in which said chamber is collapsed by a wheel of said car moving along said rails, and means operatively connecting said collapsible chamber to said valve means preventing flow through said valve means when said car is moving in excess of a predeterminad speed.

4. In track apparatus for applying a braking force to wheels of a car or the like moving along a pair of spaced running rails in excess of a predetermined speed, spaced elongated brake beams adapted to be supported adjacent to the running rails for movement toward and from said rails, a cylinder member closed at one end interposed between said rails and operatively connected to one of said brake beams, a first member operatively connected to the other of said brake beams and projecting into said cylinder member, piston means slidably supported in said cylinder member adjacent to said closed end thereof, a movable abutment member within said cylinder member at the side of said piston means opposite said closed ends of said cylinder member and movable relative to said cylinder member and said first member, means on said first member between said piston means and said movable abutment member for limiting movement of said movable abutment member relative to said first member toward said piston means, abutment means on said first member spaced from the side of said movable abutment member opposite said piston means, biasing means interposed between said movable abutment member and said abutment means for yieldably urging said movable abutment member away from said abutment means, means slidably connected to and extending between the adjacent ends of said brake beams for limiting movement of said brake beams toward said rail, a fluid reservoir, conduit means connecting said closed end of said cylinder member with said fluid reservoir, valve means in said conduit means for controlling flow from said cylinder member, speed sensing means for sensing the speed of a car moving along said rails, and means operatively connecting said valve means and said speed sensing means for preventing flow through said valve means when said car is moving in excess of a predetermined speed.

5. In track apparatus for applying a braking force to wheels of a car or the like moving along a pair of spaced running rails in excess of a predetermined speed, spaced elongated brake beams adapted to be supported generally parallel with and adjacent to the gauge side of the running rails for movement toward and from said rails, a cylinder member closed at one end and operatively connected to one of said brake beams, a first member operatively connected to the other of said brake beams and projecting into said cylinder member, a piston member slidably supported in said cylinder member adjacent to said closed end thereof, a movable abutment member within said cylinder member at the side of said piston member opposite said closed end of said cylinder and movable relative to said cylinder member and said first member, means for limiting movement of said piston member and said movable abutment member toward one another, adjustable means secured on said first member and being adjustable between said piston member and said movable abutment member and for limiting movement of said movable abutment member relative to said first member toward said piston member, abutment means on said first member spaced from the side of said movable abutment member opposite said piston member, biasing means interposed between said movable abutment member and said abutment means for yieldably urging said movable abutment member away from said abutment means, a fluid reservoir, conduit means connecting said closed end of said cylinder member with said fluid reservoir, valve means in said conduit means for controlling flow of fluid from said cylinder member to said reservoir, speed sensing means for sensing the speed of a car moving along said rails and means operatively connecting said valve means and said speed sensing means for preventing flow through said valve means when said car is moving in excess of a predetermined speed.

6. In track apparatus for applying a braking force to wheels of a car or the like moving along a pair of spaced running rails in excess of a predetermined speed, spaced 17 retarder to release condition upon reduction of said con- 3,237,007 trol signal below said value. 3,240,930

References Cited 5 5, 4 UNITED STATES PATENTS 1,066,602

2,452,720 11/1948 Bodkin 18862 18 2/ 1966 Crawford 246182 3/1966 Porter et a1. 246-182 FOREIGN PATENTS 1/ 1938 Germany. 10/ 1959 Germany.

6/ 1950 Great Britain.

DUANE A. REGER, Primary Examiner.

Claims

10. A SELF-CONTAINED TRACK APPARATUS FOR BRAKING A CAR OR THE LIKE MOVING ALONG A PAIR OF SPACED RUNNING RAILS MOUNTED ON CONVENTIONAL TIES AND ROADBED STRUCTURE COMPRISING BRAKE ELEMENTS FOR APPLYING A BRAKING FORCE TO THE WHEELS OF THE CAR OR THE LIKE, MEANS FOR SUPPORTING SAID APPARATUS BETWEEN THE RUNNING RAILS OF AN EXISTING TRACK STRUCTURE ENTIRELY WITHIN THE RAILS AND ABOVE THE TIES, AND SPEED SENSING MEANS CONTROLLING OPERATION OF SAID BRAKE ELEMENTS AS A FUNCTION OF THE SPEED OF THE CAR OR THE LIKE, THUS CONTINUOUSLY MONITORING THE MOVEMENT OF A CAR OR THE LIKE THROUGH SAID APPARATUS.