GB1600730A - Braking systems - Google Patents

Description

(54) BRAKING SYSTEMS (71) We, PROCOR (UK) LIMITED, a Company organised and existing under the laws of the State of Delaware, United States of America, of Horbury Wagon Works, Horbury, Wakefield, West Yorkshire WF4 5QH, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to braking systems for rail freight wagons.

There are two basic types of braking systems which have been used for rail freight wagons. The first system has clasp brakes, which are operated from a large cylinder in the middle of the wagon and act through levers and rods on brake blocks which operate on the wheel tread. A slack adjuster is situated in the rigging to allow for block and wheel wear. The second system has disc brakes, where disc plates are attached to the wagon wheels and disc pads are actuated through calipers and a combined air cylinder and slack adjuster unit.The disc brake system is a more recent development and a large proportion of wagons built over the last few years have been fited with one disc per axle giving a substantial space advantage because all the brake gear is confined to the outboard ends of the wagon and no brake beams are used, allowing for hoppers to come very close to the axles.

In recent years service problems have developed with disc brakes in certain operating conditions. The' result is that on 60 m.p.h.

operation and 254on axle loads it is usually necessary to fit two discs per axle on new vehicles. substantially increasing the building costs.

Over the years new brake blocks have been developed to replace cast iron blocks for conventional clasp brakes. Cast iron is quick wearing. produces metallic dust and can be a fire hazard due to heat or sparking.

Most of the new blocks are the high friction composition (h.f.c.) type with a mean (or60 m.p.h.) coefficient of friction approximately twice that of cast iron. although the static coefficient of friction (used for handbrake design) is about the same as for cast iron. The main problems with h.f.c. blocks leading to non-acceptance by certain operators are little in-service experience in the U.K. and their different performance characteristics whereby they may not perform well in mixed traffic, i.e. in the same train as vehicles fitted with cast iron blocks. They do, however, overcome most of the disadvantages of cast iron blocks and should have reasonable market penetration.

It is an object of the invention to provide a clasp brake system in a freight wagon giving a space saving advantage comparable to that obtained with the conventional disc brake system.

According to the present invention, there is provided a rail freight wagon with a brake system comprising, for each axle, a pair of brake beams pivotally suspended for move ment towards and away from the opposite sides thereof, wheel brake gear including a pair of brake blocks at each and of the axle carried by the brake beams and for engaged ment with the wheel tread and further including a lever assembly at each end of the axle for effecting movement of the brake beams relatively toward and away from each other, and a power actuating means for generating a braking force, said power actuating means being operatively associated with said lever assemblies whereby said generated braking force effects movement of the brake beams relatively toward each other to cause the brake blocks to apply a braking pressure to the wheels.

Preferably, each lever assembly is an Hlever assembly comprising two depending levers interconnected intermediate their ends by a cross-link and connected at their lower ends to respective brake beams, the upper end of one of said levers being connected to the actuating means.

The power actuating means may comprise a fluid pressure operated piston and cylinder device and a rotary slack adjuster.

The wagon may have two fixed axles or two double axle bogies.

The invention will now be further described by way of example only, with refer ence to the accompanying drawings, in which: Fig. I is a part section of a two axle rail freight wagon with a clasp brake system according to the invention; Fig. 2 is a part plan view corresponding to Fig. 1: Fig. 3 is a section of a bogie of a rail freight wagon with a clasp brake system according to the invention; Fig. 4 is a plan view of the bogie shown in Fig. 3; Fig. 5 is another section of the bogie of Fig. 3 showing the handbrake mechanism; and Fig. 6 is a corresponding plan view.

Figs. 1 and 2 show the LH end portion of a two axle rail freight wagon with a chassis 1, LH buffer gear 2. the LH axle 3 and a wheel 4 at one end of the axle 3. The wagon braking system comprises a pair of brake beams for each axle, an H-lever assembly for each wheel, a power actuator unit operatively connected to each H-lever assembly, and a handbrake at the LH end only of the wagon. The following detailed description of that part of the braking system associated with the axle 3 and the wheel 4 will thus suffice for a full understanding of the wagon braking system.

The axle 3 is flanked by brake beams 5, 6.

Because there are two power actuator units per axle (located one at each side of the centre line of the wagon), there is only a small bending moment on the beams which are therefore of simple I section. This enables the inboard brake beam associated with each axle (i.e. the beam 6 in the case of axle 3) to be bent inwards at its ends to provide more space beneath the wagon. Pivotally mounted at the ends of the brake beams 5, 6 are brake members for each wheel of the axle 3. The two brake members 7, 8 for the wheel 4 each comprise a brake block 9, 10 replaceably mounted in a respective holder 11, 12. Links 13, 14 pivotally interconnect the chassis 1 and the brake block holders 11, 12 respectively to provide, with corresponding links at the opposite ends of the beams 5, 6, pivotal suspensions for the beams 5, 6.

The H-lever assembly for the wheel 4 comprises two depending levers 15, 16 interconnected intermediate their ends by a crosslink 17 and pivotally connected at their lower ends to the free ends of confronting projections 18 19 from the brake beams 5, 6. The lever 15 of the assembly is pivotally connected intermediate its ends to a supporting link 20 pivotal on the chassis 1. The upper end of the lever 16 is pivotally connected to the chassis 1 and the upper end of the lever 15 is pivoted to a connecting rod 21 operatively connected to an actuator unit 22.

The actuator unit 22 is a fluid pressure operated piston and cylinder device of known type with a cylindrical casing 23 from which extends a piston rod 24 connected to one arm of a bellcrankaever 25 forming part of a known slack adjuster 26. The other arm of the bellcrank lever 25 is connected to the connecting rod 21 pivoted to the upper end of the lever 15.

To apply the brakes fluid under pressure is supplied to the actuator units of each axle with the effect which will now be described in relation to the actuator unit 22 associated with the wheel 4. The piston rod 24 is caused to extend thereby rotating the bellcrank lever 25 and exerting a tractive force on the connecting rod 21. The lever 15 of the Hlever assembly is thus rotated about the cross-link 17 in an anti-clockwise direction as seen in Fig. 1, thereby pulling the beam 5 towards the axle 3 and hence the brake block 9 onto the rim of the wheel 4. Once the block 9 has been substantially immobilised the tractive force of the connecting rod 21 is transmitted to the brake block 10 through the H-lever assembly. Finally, both brake blocks 9, 10 are pulled into tight engagement with the rim of the wheel 4.

The handbrake comprises a spindle 27 extending transversely of the wagon parallel to the axle 3. A handwheel 28 at one side of the wagon is connected to the spindle 27 through gearing 29. A corresponding handwheel (not shown) is directly mounted on the spindle 27 at the opposite side of the wagon thereby ensuring that both handwheels are rotatable in the same sense to apply and release the handbrake. The spindle 27 has a threaded section 30 engaged by a nut 31 which is held against rotation so as to move axially along the threaded section 30 upon rotation of the spindle 27. An Hlinkage 32 converts axial movement of the nut 31 into axial movement together and apart of pull rods 33, 34. It will be apparent that, as seen from the side of the wagon shown in Figs. 1 and 2, clockwise rotation of the spindle 27 brought about by anticlockwise rotation of the handwheel 28 will cause the nut 31 to travel towards the handwheel 28 and thus exert a tractive force on the pull rod 34 which is connected to the bellcrank lever 25. The lever 25 is thus rotated to apply the brakes as already described.

A modified version of the braking system described above may also be applied to a bogie wagon but in this case there are particular problems because the vehicle chassis cannot be used to provide anchorage points for the brake gear on the bogie and because the perimeter frame of the bogie causes problems where central mountings are required.

The bogie shown in Figs. 3 to 6 has an open frame 40, a central pivot 41, two axles 42, 43, and wheels 44, 45 and 46, 47 mounted on the two axles. The axles 42, 43 are equipped with brake gear in basically the same way as the axle 3 of the two axle wagon described above. Thus each axle is associated with brake beams 48, 49 and 50, 51, H-lever assemblies 52, 53, 54, 55 for each wheel, and a fluid pressure actuator unit 56, 57, 58, 59 for each H-lever assembly. More specifically, the brake gear associated with the wheel 45 in Fig. 3 comprises brake blocks 60, 61 in respective block holders 62, 63 pivotally mounted at the ends of the respective beams 48, 49 and suspended from the bogie frame 40 by links 64, 65. The H-lever assembly 53 comprises depending levers 66, 67 interconnected intermediate their ends by a cross-link 68.The lower end of the lever 66 is pivoted to a projection 69 from the brake beam 48 and the upper end of the lever 66 is pivoted to a block 70 supported on a slide (not shown) and connected by a connecting rod 71 to a bellcrank lever 72 (Fig. 4) of a slack adjuster 73 which is in turn connected to the actuator unit 57. The other lever 67 of the H-lever assembly is pivotally mounted by its lower end on the brake beam 49 and its upper end is connected by a tie-rod 74 to the upper end of the corresponding lever 75 of the H-lever assembly 55 of the wheel 47.

The operation of the brakes by the actuator units acting through the H-lever assemblies is fundamentally the same as in the embodiment of Figs. I and 2 and will therefore not be described again.

For the sake of simplicity the handbrake of the bogie is shown separately in Figs. 5 and 6 but it will be appreciated that each bogie includes the handbrake and the power brake gear. The handbrake gear illustrated in Figs.

5 and 6 comprises a spindle 76 mounted at the LH end of the bogie parallel and adjacent to the axle 42. Handwheels 77, 78 serve for rotation of the spindle 76, one handwheel 77 being directly mounted on the spindle 76 while the other handwheel 78 is connected to the spindle 76 through reversing gears 79 for the reason already described by reference to the embodiment of Figs. I and 2. The spindle 76 has a threaded section 80 which is engaged by the threaded bore of a trunnion 81 projecting through a slot 82 in one end of a link 83. The other end of the link 83 is fast with a rotatable pillar 84 which is rigid with a lever 85 indirectly connected to the lower end of a lever 86 of an H-linkage also including a lever 87 and a cross-link 88.The upper end of the lever 86 is connected to the centre of a cross-member 89 which is in turn connected by end links 90, 91 to the bellcrank lever 72 of the slack adjusters 73 (Fig. 4).

The lower end of the other lever 87 of the H-linkage is pivotally mounted on a supporting arm 92 anchored on the central pivot 41 of the bogie. The upper end of the lever 87 is pivoted to one end of a connecting rod 93 which is attached to the centre of a further cross-member 94 with end links 95, 96 connected to the bellcrank levers 72 of the slack adjusters 73 associated with the axle 43.

In the position illustrated in Figs. 5 ad 6 the handbrake is released. If the spindle 76 is now turned in the appropriate direction by one of the handwheels 77, 78 the trunnion 81 is caused to move along the threaded spindle section 80 in the direction towards the handwheel 77. The link 83 thus rotates the pillar 84 in an anti-clockwise direction as seen in Fig. 6. The lever 85 therefore pulls the lower end of the lever 86 of the H-linkage to the left in Fig. 5 which produces a corresponding movement to the right of the crossmember 89 thereby applying the brakes through the associated slack adjusters and Hlever assemblies 52, 53 shown in Figs. 3 and 4.At the same time, the brakes for the wheels 46, 47 are operated through their respective H-lever assemblies 54, 55 by movement to the left in Figs. 5 and 6 of the cross-member 94 produced by traction via the cross-link 88, the lever 87 and the connecting rod 93.

In both embodiments the handbrake mechanism and the bellcrank levers of the slack adjusters are connected with a lost motion facility in the form of slots S in the pull rods 33, 34 on the links 90, 91 and 95, 96.

These slots S ensure that operation of the handbrake causes actuation of the brakes but power actuation of the brakes has no effect on the handbrake mechanism.

The brake system described above for fixed axle and bogie wagons can be used with low friction (e.g. cast iron) or high friction brake blocks. When used with h.f.c. blocks no adjustment should be required for combined block and wheel wear. The system may be changed for different brake block material by repositioning the cross-links in the Hlever assemblies and a lever in the handbrake system. The block forces are reduced for h.f.c. shoes but because the static friction is similar the handbrake force has to be increased to counteract the reduction required for the actuator. A control disc in the slack adjusters determines the amount of block clearance, and, because of the different lever ratios for high friction or low friction blocks, a different control disc has to be used for different block materials. The disc is, however, easy to replace and inexpensive.

Moreover, when using high friction brake blocks in a bogie vehicle, the close proximity of the wheels and the use of a balance bar (i.e. the tie rod 74 in Fig. 3) makes it possible to dispense with two of the actuation and slack adjuster units. The change in the lever ratio enables one unit to operate one complete side of the braking system. Thus, for example, in Fig. 4 the actuator units 58 and 59 with their slack adjusters could be omitted. The handbrake mechanism, because it now only operates on two actuator units on the same end is simplified and can take a similar form to that illustrated in Fig. 2.

WHAT WE CLAIM IS:- 1. A rail freight wagon with a brake system comprising, for each axle, a pair of brake beams pivotally suspended for movement towards and away from the opposite sides thereof, wheel brake gear including a pair of brake blocks at each end of the axle carried by the brake beams and for engagement with the wheel tread and further including a lever assembly at each end of the axle for effecting movement of the brake beams relatively toward and away from each other, and a power actuating means for generating a braking force, said power actuating means being operatively associated with said lever assemblies whereby said generated braking force effects movement of the brake beams relatively toward each other to cause the brake blocks to apply a braking pressure to the wheels.

2. A wagon as claimed in claim 1, wherein each lever assembly is an H-lever assembly comprising two depending levers interconnected intermediate their ends by a cross-link and connected at their lower ends to respective brake beams, the upper end of one of said levers being connected to the actuating means.

3. A wagon as claimed in claim I or 2, wherein the power actuating means comprises a fluid pressure operated piston and cylinder device and a rotary lever slack adjuster.

4. A wagon as claimed in any one of the preceding claims, wherein a handbrake mechanism is associated with at least one axle and comprises a manually rotatable spindle extending transversely of the wagon parallel to the associated axles and having a screw threaded section with a non-rotatable axially movable elernent in screw threaded engagement therewith and linked to said lever assemblies.

5. A wagon as claimed in any one of the preceding claims, having two fixed axles.

6. A wagon as claimed in any one of claims I to 4, having two or more bodies.

7. A wagon as claimed in any one of claims I to 6 wherein, for each axle, two power actuating means are provided, each said power actuating means being associated with a said lever assembly.

X. A wagon as claimed in claim 7 whercin, an inboard brake beam is bent inwards at its ends.

9. A rail freight wagon substantially as hcrcin described with reference to and as illus1r;ttcd in Figs. I and 2 or Figs. 3 to 6 of Illc;lccompanying drawings.

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

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. now only operates on two actuator units on the same end is simplified and can take a similar form to that illustrated in Fig. 2. WHAT WE CLAIM IS:-

1. A rail freight wagon with a brake system comprising, for each axle, a pair of brake beams pivotally suspended for movement towards and away from the opposite sides thereof, wheel brake gear including a pair of brake blocks at each end of the axle carried by the brake beams and for engagement with the wheel tread and further including a lever assembly at each end of the axle for effecting movement of the brake beams relatively toward and away from each other, and a power actuating means for generating a braking force, said power actuating means being operatively associated with said lever assemblies whereby said generated braking force effects movement of the brake beams relatively toward each other to cause the brake blocks to apply a braking pressure to the wheels.

2. A wagon as claimed in claim 1, wherein each lever assembly is an H-lever assembly comprising two depending levers interconnected intermediate their ends by a cross-link and connected at their lower ends to respective brake beams, the upper end of one of said levers being connected to the actuating means.

3. A wagon as claimed in claim I or 2, wherein the power actuating means comprises a fluid pressure operated piston and cylinder device and a rotary lever slack adjuster.

4. A wagon as claimed in any one of the preceding claims, wherein a handbrake mechanism is associated with at least one axle and comprises a manually rotatable spindle extending transversely of the wagon parallel to the associated axles and having a screw threaded section with a non-rotatable axially movable elernent in screw threaded engagement therewith and linked to said lever assemblies.

5. A wagon as claimed in any one of the preceding claims, having two fixed axles.

6. A wagon as claimed in any one of claims I to 4, having two or more bodies.

7. A wagon as claimed in any one of claims I to 6 wherein, for each axle, two power actuating means are provided, each said power actuating means being associated with a said lever assembly.

X. A wagon as claimed in claim 7 whercin, an inboard brake beam is bent inwards at its ends.

9. A rail freight wagon substantially as hcrcin described with reference to and as illus1r;ttcd in Figs. I and 2 or Figs. 3 to 6 of Illc;lccompanying drawings.