GB2078881A

GB2078881A - Railway vehicle braking system

Info

Publication number: GB2078881A
Application number: GB8020237A
Authority: GB
Original assignee: STANDARD RAILWAY WAGON
Current assignee: STANDARD RAILWAY WAGON
Priority date: 1980-06-20
Filing date: 1980-06-20
Publication date: 1982-01-13
Also published as: GB2078881B

Abstract

A braking system for railway vehicles of simplified construction having fewer parts than known systems includes a crossbar (40, 40') suspended from the vehicle body on each side of an axle, e.g. by tie-rods (42, 42'). A friction brake pad (46, 46'), is mounted at each end of each crossbar for engagement with a wheel rim. One crossbar (40') is linked to a first cranked lever (54) which is also connected to the vehicle and to a second lever (30). The second lever is connected to the other crossbar (40) and to a brake application rod (26). Movement of rod (26) causes the crossbars (40, 40') to move closer together to apply the brakes. The brake force applied by each crossbar is equalised by choice of the dimensions between the pivot points of the mechanism. <IMAGE>

Description

SPECIFICATION Railway vehicle braking system This invention relates to a railway vehicle braking system and more particularly but not exciusively to a braking system for a railway vehicle of the kind in which the wheel carrying axles are mounted on the vehicle chassis.

In order to simplify the traditional massive mechanical brake linkage fitted to railway wagons and also to create sufficient space under the wagon to enable the wagon contents to be emptied from underneath, a braking system has been proposed as is described in our British Patent Specification No. 22506/76 (Serial No. ). The system as disclosed in the above-mentioned specification operates very effectively and moreover occupies considerably less space than earlier forms of braking system. Nevertheless the system comprises a significantly large number of linkages which have to be fitted individually to the underside of the wagon - a somewhat difficult and time consuming task. Moreover it has also been found that the brake blocks tend to wear unevenly.This latter problem would appear to be due to the brake shoes remaining in the same position irrespective of whether the wagon is loaded or not. In the loaded condition, where greater braking forces are required the wheels are displaced upwardly, relative to the brakes so that when the brakes are applied the lower part of the brake blocks comes into contact with the wheel rim before the upper part.

The present invention has been made from a consideration of these problems.

According to the invention there is provided a railway vehicle braking system adapted to operate on the wheels of a single axle, said system comprising a pair of friction material pads movable into and out of contact with each wheel on said axle, each pad of one pair being mounted adjacent one end of a separate crossbar, the pads of the other pair being mounted adjacent the other ends of the crossbars, said crossbars being suspended from the vehicle and connected together intermediate the ends thereof by a first lever pivotally connected to one crossbar and also to the vehicle and a second lever pivotally connected to the second crossbar, to the first lever and to a brake application rod whereby movement of the rod in one direction causes the pads to move towards the wheels for braking and movement of the rod in the other direction causes the pads to move away from the wheels.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a side elevation of a braking system; and Figure 2 is an end elevation, partly in section, of the braking system of Figure 1.

Referring to the drawings the braking system comprises a carrying bracket 10 adapted to be fitted to the underside of a vehicle such as a railway wagon 12. An air cylinder 14 is mounted on the bracket. The piston rod 16 of the air cylinder is pivotally connected adjacent one end 18 of a lever 20. The lever 20 is pivotally connected at 24 to a projecting plate 22 on the bracket 10. A horizontally disposed brake rod 26 is connected at one end 28 to the lever. The other end of the brake rod is located between the upper ends of a pair of spaced apart actuating levers 30 and held in place by a pin 32 which extends between the levers 30 and through the rod 26. The length of the brake rod 26 can be altered to take up slack in the brake system by known means such as a "turn buckle" 34.Additional slack caused by wear of the blocks is automatically taken up by pin 28 rotating anti-clockwise about axle 24 without any change in attitude of lever 20.

The lower ends of the pair of actuating levers are connected by a pin 36 to one end of a link 38 the other end of which is connected to a crossbar 40 which extends across the wagon parallel to the wheel axle 41. Each end of the crossbar is suspended from the wagon by hangers 42 and brake shoes 44 equipped with brake blocks 46 of friction material are journalled on the extreme ends of the crossbar.

Means (not shown) are provided for resiliently holding the brake shoes on the crossbar.

A second similar assembly of crossbar, brake shoes and pads (identified by the reference numerals 38' to 46') is provided on the other side of the axle 41. The link 38' of this second assembly is connected by pin 50 to a yoke 52 formed at the lower end of a cranked lever 54. The upper end of the cranked lever 54 is connected by pin 55 to a yoke 56 on the bracket 10, the axis of the pin 56 being parallel to and substantially vertically above the axle 41. As can be seen in Figure 1 lever 56 has a projecting part 58 which is arranged to extend over the axle to connect with lever 30 by a pin 60 positioned between pins 32 and 36 so as to give the desired clamping force on the wheel.

The brake system just described operates as follows: To apply the brakes air from a source (not shown) is admitted to the cylinder 14 which thereby moves rod 16. The lever 20 is rotated anti-clockwise about axle 24 (as viewed in Figure 1) to pull the brake rod 26 to the left. Lever 30 is rotated anti-clockwise about pin 60 and at the same time moved as a whole towards the left thus causing lever 54 to be rotated clockwise about pin 55.

The aforesaid movement of lever 30 pulls link 38 to the right and hence also pulls crossbar 40 to the right thus applying brake blocks 46 to the wheels 43. The movement of lever 54 causes movement of crossbar 40' to the left so that at the same time brake blocks 46' are also applied to the wheels. The resilient mounting of the brake shoes on the crossbars enables them to conform to the rim of the wheel, the position of which relative to the brake system will be different depending on whether the wagon is loaded or not.

When air pressure in cylinder 14 is reduced a return spring in the cylinder causes the parts of the system to return to their rest position and the brakes are released.

Generally it is desired that the braking force applied by the brakes on one crossbar should be the same as that applied by the brakes on the other crossbar. To achieve that the arrangement of levers 30 and 54 and their points of connection to each other and to the other parts of the system must be determined. It is, therefore, preferred that the distance between pins 32 and 36 should be close to the distance between pins 55 and 50. Further it is preferred that pins 36 and 50 should be equidistant from the axle 41. The position of pin 60 (as stated above) is positioned between pins 32 and 36. In addition the distance between pin 32 and pin 60 approaches the distance between pins 55 and 60.

It is a requirement of many railway wagons that they be equipped with a hand brake. It has been found that a hand brake can be fitted to the present braking system in a very simple manner as will now be described.

A downwardly projecting part 62 on the bracket 10 rotatably supports a rod 64 which extends across the wagon parallel to crossbars 40 and 40'. A cam lever 66 is fixed to the rod 64 so as to engage the lever 20 and apply the brakes when hand brake lever 68 also fixed to the rod 64 is rotated clockwise (as viewed in Figure 1).

It will be evident from the foregoing that the brake system has many advantages. The fitting of many of the parts of the system on bracket 10 enables those parts to be assembled on a bench and then the bracket fixed to the underside of the wagon. This represents a considerable advantage over former systems, the parts of which had to be fixed individually to the underside of the wagon.

It will also be evident that the system is very simple in that it includes fewer levers and points of connection than prior art systems. Thus in addition to the cost savings achieved, the system occupies very little space under the wagon, this being very important if openings or the like are required under the wagon for unloading. In this connection it is to be understood that the crossbars do not have to be straight but may be cranked intermediate the ends thereof so as to provide additional space underthe centre of the wagon.

CLAIMS (Filed on 22/6/81) 1. A railway vehicle braking system adapted to operate on the wheels of a single axle, said system comprising a pair of friction material pads movable into, and out of, contact with each wheel on said axle, each paid in the pair being mounted adjacent one end of a separate crossbar, the pads of the other pair being mounted adjacent the other pair being mounted adjacent the other ends of the crossbars, said crossbars being suspended from the vehicle and connected together intermediate the ends thereof by a first lever pivotally connected to one crossbar and also to the vehicle and a second lever pivotally connected to the second crossbar, to the first lever and to a brake application rod whereby movement of the rod in one direction causes the pads to move towards the wheels for braking and movement of the rod in the other direction causes the pads to move away from the wheels.

2. A railway vehicle braking system as claimed in Claim 1, wherein each crossbar is suspended from the vehicle adjacent the ends thereof.

3. A railway vehicle braking system as claimed in Claim 1, or Claim 2, wherein the first lever is a cranked lever and is connected to the second lever intermediate the ends of the first lever, the arranges ment and first and second levers being such as to extend across the axle.

4. A railway vehicle braking system as claimed in any preceding claim wherein the second lever comprises a pair of levers arranged parallel to each other.

5. A railway vehicle braking system as claimed in Claim 4, wherein the pair of levers receives the brake application rod therebetween.

6. A railway vehicle braking system as claimed in Claim 4 or Claim 5, wherein the pair of levers receives the first lever therebetween.

7. A railway vehicle braking system as claimed in any preceding claim, wherein the first lever is connected to a crossbar by a first link.

8. A railway vehicle braking system as claimed in any preceding claim, wherein the second lever is connected to the second crossbar by a second link.

9. A railway vehicle braking system as claimed in any preceding claim wherein a hand brake is connected to the brake application rod.

10. A railway vehicle braking system as claimed in any preceding claim wherein fluid pressure actuated means is provided for moving the brake application rod.

11. A railway vehicle braking system as claimed in Claims 7 and 8 or either of Claims 9 and 10 as appendent to Claim 7 and 8 wherein the point of connection between the first lever and first link is substantially the same distance from the axle as the point of connection between the second lever and second link.

12. A railway vehicle braking system as claimed in Claims 7 and 8 or any of Claims 9 to 11 as appendent to Claims 7 and 8 wherein the distance between the point of connection of the first lever to the vehicle and the point of connection of the first lever to the first link is substantially the same as the distance between the point of connection of the second lever to the brake application rod and the point of connection of the second lever to the second link.

13. A railway vehicle braking system as claimed in Claims 7 and 8 or any of Claims 9 to 12 as appendent to Claims 7 and 8, wherein the distance between the point of connection of the first lever to: the vehicle and the point of connection of the first and second levers is substantially the same as the distance between the said point of connection between the first and second levers and the point of connection of the second lever and second link.

14. A railway vehicle braking system substantially as described herein with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. same as that applied by the brakes on the other crossbar. To achieve that the arrangement of levers 30 and 54 and their points of connection to each other and to the other parts of the system must be determined. It is, therefore, preferred that the distance between pins 32 and 36 should be close to the distance between pins 55 and 50. Further it is preferred that pins 36 and 50 should be equidistant from the axle 41. The position of pin 60 (as stated above) is positioned between pins 32 and 36. In addition the distance between pin 32 and pin 60 approaches the distance between pins 55 and 60. It is a requirement of many railway wagons that they be equipped with a hand brake. It has been found that a hand brake can be fitted to the present braking system in a very simple manner as will now be described. A downwardly projecting part 62 on the bracket 10 rotatably supports a rod 64 which extends across the wagon parallel to crossbars 40 and 40'. A cam lever 66 is fixed to the rod 64 so as to engage the lever 20 and apply the brakes when hand brake lever 68 also fixed to the rod 64 is rotated clockwise (as viewed in Figure 1). It will be evident from the foregoing that the brake system has many advantages. The fitting of many of the parts of the system on bracket 10 enables those parts to be assembled on a bench and then the bracket fixed to the underside of the wagon. This represents a considerable advantage over former systems, the parts of which had to be fixed individually to the underside of the wagon. It will also be evident that the system is very simple in that it includes fewer levers and points of connection than prior art systems. Thus in addition to the cost savings achieved, the system occupies very little space under the wagon, this being very important if openings or the like are required under the wagon for unloading. In this connection it is to be understood that the crossbars do not have to be straight but may be cranked intermediate the ends thereof so as to provide additional space underthe centre of the wagon. CLAIMS (Filed on 22/6/81)

1. A railway vehicle braking system adapted to operate on the wheels of a single axle, said system comprising a pair of friction material pads movable into, and out of, contact with each wheel on said axle, each paid in the pair being mounted adjacent one end of a separate crossbar, the pads of the other pair being mounted adjacent the other pair being mounted adjacent the other ends of the crossbars, said crossbars being suspended from the vehicle and connected together intermediate the ends thereof by a first lever pivotally connected to one crossbar and also to the vehicle and a second lever pivotally connected to the second crossbar, to the first lever and to a brake application rod whereby movement of the rod in one direction causes the pads to move towards the wheels for braking and movement of the rod in the other direction causes the pads to move away from the wheels.