GB2245941A - Braking apparatus - Google Patents

Abstract

Braking apparatus for a wheel 11 mounted on a frame 10 comprises a pair of shoes 12, 13 pivotally mounted on respective support arms 15, 19 by brackets 14, 18, a brake operating unit 22 mounted on the frame by support link 23 and a pair of tie bars 37 extending between unit 22 and bracket 14. The support arms 15, 19 and link 23 are all pivotally connected to the frame. The link 23 has resilient bushes at each end to protect unit 22 from shocks. The plunger of unit 22 is connected to bracket 18 and when the unit is activated forces shoe 13, to the left in figure 1, into contact with the wheel. The reaction force causes unit 22 to pivot on link 23 which moves tie bars 37 to the right and forces shoe 12 into contact with, and so brakes, the wheel. A ratchet is provided in unit 22 to take up wear of the shoes. <IMAGE>

Description

BRAKING APPARATUS The invention relates to braking apparatus.

The invention is concerned with braking apparatus for braking rotatable wheels of vehicles and is particularly, though not exclusively, concerned with railway vehicles, such as single axle bogied light weight diesel multiple railway units.

Existing units utilise cable operated brakes so that the operating mechanism of the brakes can be mounted at a distance from the single axle bogie mounted wheels, so that the operating means is not subjected to the severe shocks which are imposed upon the wheels and the bogies, particularly as the wheels pass over joints in railway track.

However, the known braking systems have proved somewhat unreliable in practice. Problems have been encountered with friction within the operating cables, for example caused by dust and other debris, with the result that braking is unreliable. The cables are prone to seizure and stopping distances are erratic resulting in the overshooting of station halts. The problem is so serious that the vehicles in question have to travel at speeds significantly lower than their maximum capable speed.

We have now developed braking apparatus which avoids or reduces this problem.

The invention provides braking apparatus for a vehicle wheel which is rotatable on a support frame, the braking apparatus comprising opposed brake shoes, between which the wheel lies, and operating means mounted on the support frame for moving the brake shoes towards one another to apply a braking moment to the wheel.

By mounting the operating means directly on the support frame, the problems associated with connection cables are avoided.

The operating means is preferably connected to one brake shoe directly, and to the other brake shoe by at least one tie bar, such that when the operating means acts on the one brake shoe, to urge one brake shoe against the wheel, reaction force applied to the tie bar pulls the other brake shoe into engagement with the wheel.

There are preferably two tie bars, the brake shoes contacting the rim of the wheel and the tie bars extending across respective faces of the wheel, so that the wheel lies between the tie bars.

Preferably the operating means acts on the said one brake shoe by urging a plunger into contact with the brake shoe or a mounting component thereof.

It is an important subsidiary feature of the invention that the operating means is mounted on the support frame by a specially designed mounting which substantially protects the operating means from shocks applied to the wheel and support frame.

Preferably the mounting means comprises a link extending from the support frame to the operating means, each end of the link being provided with a resilient bushing.

Each resilient bushing may comprise an outer component connected to the link, an inner component pivotally connected to the operating means or support frame, and a rubber bush lying between the inner and outer components.

Each rubber bush may have holes provided therein to control its resilience.

The inner and outer components may provide cylindrical tubes or sleeves.

The link may be connected to the operating means via the tie bars.

Each brake shoe is preferably mounted on a pivot arm, which in turn is mounted on the support frame, to guide the movement of the brake shoe.

The invention includes a vehicle provided with braking apparatus according to the invention.

Another important advantage of the invention is that existing vehicles can be modified by replacing prior art braking apparatus with braking apparatus according to the invention, without significant expenditure in terms of cost and labour. No major remanufacture or substantial modification is required and the braking apparatus according to the invention can be provided on an existing vehicle using many of the original vehicle components.

A specific embodiment of the invention will now be described with reference to the accompanying drawings, in which : Figure 1 is a side view of an embodiment of braking apparatus according to the invention, shown fitted to an axle unit; Figure 2 is a plan view of the apparatus shown in Figure 1; Figure 3 is a view on arrow A-A of Figure 1, to a larger scale; Figure 4 is a cross-sectional view, to an even larger scale, showing a bottom support for the braking apparatus; Figure 5 is a view similar to Figure 4 but showing a top support; and Figure 6 is a view to the same scale as Figures 4 and 5, showing in more detail a connection of the apparatus.

This embodiment of braking apparatus is designed for use with a single axle bogied light weight diesel multiple railway unit.

One bogie is shown at 10 in Figure 1. The bogie 10 supports a single axle in a conventional manner, each end of the axle carrying a wheel 11.

Each wheel 11 is provided with a pair of iron brake shoes 12 and 13. The brake shoe 12 has a mounting bracket 14 which is guided for movement towards the wheel 11 by a support arm 15. The support arm 15 is pivotally connected to the bracket 14 at 16, and is pivotally mounted on the bogie 10 at 17.

The brake shoe 13 has a similar mounting bracket 18 which is pivotally connected to a support arm 19 at 20, the support arm 19 being, in turn, pivotally connected to the bogie 10 at 21.

The embodiment of braking apparatus shown in the Figures has a novel and inventive mechanism for urging the brake shoes 12 and 13 towards one another, to apply a braking moment to the associated wheel 11. A brake operating unit indicated generally by the reference numeral 22 is mounted on the bogie 10 by means of a support link 23.

Figure 4 shows in more detail how the link 19 is connected to the bogie 10. The link 19 has a cylindrical tube 24 welded to the lower end of the link. At each end of the tube 24 there is a pair of bushing sleeves 25 and 26 separated by an annular rubber bush 27, the resiliency of each bush 27 is carefully controlled by forming a series of frusto-conical holes 28 in the bush, spaced apart around the bush.

The inner sleeves 26 are fitted over a boss 29 which projects from the bogie 10, and the assembly is held in position by an end cap 30 which is bolted to the boss 29.

Figure 5 shows the upper end of the link 19, where there is a generally similar bushing arrangement, comprising a tube 31, two pairs of bushing sleeves 32 and 33, one at each end of the tube, and two annular rubber bushes 34.

A rod 35 passes through the sleeves 32 and is secured by a bolt 36 to a pair of tie bars 37. The brake actuating unit 22 is bolted between the tie bars 37, as best shown in Figure 1.

As can best be seen from Figures 1 and 2, two tie bars 37 extend past the wheel 11, one on each side of the wheel, the left hand ends of the tie bars, as viewed in the Figures, being interconnected by a spacer connection 38, the connection 38 also being connected to the bracket 14 of the brake shoe 12. Thus if the tie bars 37 move to the left or right, as viewed in Figures 1 or 2, the brake shoe 12 will move with the tie bars.

Connected to the mounting bracket 18 of the brake shoe 13 there is a block 39, as best shown in Figure 6.

The block is connected to the bracket 18 by a hardened steel pivot pin 40. The block 39 has a V-shaped channel 41 therein, and an appropriately shaped tennon style head 42 is slidingly trapped in this channel by a closure plate 43. The head 41 is mounted on the end of a plunger 44 which projects from the operating unit 22. In Figure 2 the plunger is shown projected by a rubber gasket 45.

Within the unit 22 there is a pneumatic cylinder which acts along the longitudinal axis of the unit 22, but within the unit there is a mechanism for converting the movement of the pneumatic piston into sideways movement of the plunger 44. Thus, if the unit 22 is actuated to extend the plunger 44 from the unit, the brake shoe 13 is pushed into braking contact with the wheel 11. The reaction force tends to move the unit 22, and hence the tie bars 37, to the right, as viewed in Figures 1 and 2.

Thus the brake shoe 12 is also pulled into contact with the wheel 11. In effect the wheel 11 is squeezed between the brake shoes 12 and 13, bringing about the desired braking effect.

Because the movement provided by the unit 22 is applied almost directly to the brake shoes 13 and 14, very effective and efficient braking is brought about, without any of the problems associated with the prior art cable operated brakes.

Although the bogie 10, coupled to the single axle, undergoes very severe shocks, particularly during movement of the wheels 11 over rail joints, the link 23, with its double bushing arrangement, at the top and bottom of the link, effectively damps out the shocks, thus protecting the unit 22.

The unit 22 has a ratchet arrangement therein, so that as the brake locks 12 and 13 wear, an adjustment is made in the datum position from which the plunger 44 starts its working stroke. Thus there is no reduction in the effective working stroke of the plunger 44, in spite of wear of the braking blocks 12 and 13.

Once the brake blocks 12 and 13 have been worn to the maximum permissible extent, they are replaced by new brake locks, the plunger 44 being wound back to its inner most position by manual rotation, using an appropriate tool, of a hexagonal member 46 projecting from the unit 22.

Projecting from the unit 22 there is also a manual brake release member 47. This is required because the unit 22 has a fail safe spring arrangement therein, which applies the brake shoes 12 and 13 to the wheel 11 in the event of failure of the air supply. If it is subsequently desired to move the railway unit, the brakes are manually released for the necessary period of time by operating the member 46.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method- or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims (14)

1. Braking apparatus for a vehicle wheel which is rotatable on a support frame, the braking apparatus comprising opposed brake shoes, between which the wheel lies, and operating means mounted on the support frame for moving the brake shoes towards one another to apply a braking moment to the wheel.

2. Braking apparatus as claimed in Claim 1, in which the operating means is connected to one brake shoe directly, and to the other brake shoe by at least one tie bar, such that when the operating means acts on the one brake shoe, to urge one brake shoe against the wheel, reaction force applied to the tie bar pulls the other brake shoe into engagement with the wheel.

3. Braking apparatus as claimed in Claim 2, in which there are two tie bars, the brake shoes contacting the rim of the wheel and the tie bars extending across respective faces of the wheel, so that the wheel lies between the tie bars.

4. Braking apparatus as claimed in Claim 2 or Claim 3, in which the operating means acts on the said one brake shoe by urging a plunger into contact with the brake shoe or a mounting component thereof.

5. Braking apparatus as claimed in any one of the preceding Claims, in which the operating means is mounted on the support frame by mounting means which substantially protects the operating means from shocks applied to the wheel and support frame.

6. Braking apparatus as claimed in Claim 5, in which the mounting means comprises a link extending from the support frame to the operating means, each end of the link being provided with a resilient bushing.

7. Braking apparatus as claimed in Claim 6, in which each resilient bushing comprises an outer component connected to the link, an inner component pivotally connected to the operating means or support frame, and a rubber bush lying between the inner and outer components.

8. Braking apparatus as claimed in Claim 7, in which each rubber bush has holes provided therein to control its resilience.

9. Braking apparatus as claimed in Claim 7 or Claim 8, in which the inner and outer components comprise cylindrical tubes or sleeves.

10. Braking apparatus as claimed in any one of Claims 6 to 9, when dependent directly or indirectly on Claim 2, in which the link is connected to the operating means via the tie bars.

11. Braking apparatus as claimed in any one of the preceding Claims, in which each brake shoe is mounted on a pivot arm, which in turn is mounted on the support frame, to guide the movement of the brake shoe.

12. Braking apparatus constructed and arranged substantially as herein described, with reference to the accompanying drawings.

13. A vehicle having braking apparatus as claimed in any one of the preceding Claims.

14. A vehicle as claimed in Claim 13, comprising a railway vehicle.