GB2091360A

GB2091360A - Braking system for a mine rail car bogie

Info

Publication number: GB2091360A
Application number: GB8136104A
Authority: GB
Original assignee: Underground Mining Machinery Ltd
Current assignee: Underground Mining Machinery Ltd
Priority date: 1980-11-28
Filing date: 1981-11-30
Publication date: 1982-07-28
Also published as: GB2091360B

Abstract

The braking system comprises a lever 5 pivotally mounted about an axis 2a parallel to (as shown, coincident with) the axle of a bogie wheel 2; a brake pad 16 is attached to the upper side of the lever 5 at one side of said axis 2a and in use of the system part of the weight of the car is transferred onto the lever 5 at the other side of axis 2a to apply pad 16 to safety rail 17. As shown, pad 16 is a subsidiary pad and two such pads 16 are mounted on respective levers 5, 6 pivoted together about pin 7. A fail- safe hydraulic piston-cylinder arrangement 8 is vented to apply a main brake pad 15 co-operable with a rail 4. A number of embodiments showing various arrangements of the levers, the piston-cylinder arrangement 8, and the pads 15, 16 are disclosed. <IMAGE>

Description

SPECIFICATION Braking system for a mine rail car bogie This invention relates to a braking system for a rail vehicle bogie, and in particular to a braking system for a mine rail car bogie.

A known type of mine rail car bogie has a braking system whose brake pads are forced into braking engagement with the rails along which the car runs by the weight of the car itself. During normal running of the car along the rails, the brake pads are held out of engagement with the rails, usually by hydraulic piston-and-cylinder means.

Such an arrangement is fail-safe, as a hydraulic failure will immediately result in brake application.

Although braking systems of this type provide adequate braking action in most circumstances, they may not do so where the rail track is steeply inclined.

The aim of the invention is to provide a braking system for a mine rail car bogie which does not suffer from this disadvantage.

In its broadest aspect, the present invention provides a braking system for mine rail car bogie, the system comprising a lever pivotally mounted about an axis parallel to the axle of a bogie wheel, a brake pad attached to the upper side of the lever at one side of said axis, and means for transferring part of the weight of the car onto the lever at the other side of said axis.

Advantageously, the distance between the brake pad and said axis is less than the distance between said axis and the position at which part of the weight of the car is transferred onto the lever at said other side of said axis. Preferably, the distance between the brake pad and said axis is substantially half the distance between said axis and said position.

In a preferred embodiment, the braking system further comprises a second lever pivotally mounted about a second axis parallel to the axle of a second bogie wheel, the first-mentioned bogie wheel and the second bogie wheel being aligned for movement along a common rail, wherein the first-mentioned lever and the second lever are pivotally connected together at a pivot point positioned between the first-mentioned bogie wheel and the second bogie wheel.

Advantageously, said pivot point is positioned between the second bogie wheel and the position at which part of the weight of the car is transferred onto the first-mentioned lever. Conveniently. the first-mentioned axis coincides with the axle of the first-mentioned bogie wheel, and the second axis coincides with the axle of the second bogie wheel.

Advantageously, locking means are provided for holding the first-mentioned lever and the second laver in a first operating position in which the brake pad is in a first, inoperative position, the locking means being releasable so that the brake pad can pivot upwardly about the first-mentioned axis into a second, braking position as a result of the force acting down onto the first-mentioned lever at said position. Preferably, a hydraulic piston-and-cylinder arrangement constitutes the locking means, the hydraulic piston-and-cylinder arrangement being pressurised when the brake pad is in its first position, and being vented to allow the brake pad to move into its second position.In this case, the cylinder of the pistonand-cylinder arrangement may be pivotally attached to the first-mentioned lever, the piston rod of the piston-and-cylinder arrangement being pivotally connected to the second lever.

Conveniently, the braking system further comprises a rail-engaging brake pad attached to the first-mentioned lever.

The invention also provides a braking system for mine rail car bogie, the system comprising a first lever pivotally mounted about a first axis parallel to the axle of a first bogie wheel, a second lever pivotally mounted about a second axis parallel to the axle of a second bogie wheel, the first and second bogie wheels being aligned for movement along a common rail, wherein the first and second levers are pivotally connected together at a pivot point positioned between the first and second bogie wheels, and wherein a first brake pad is attached to the upper side of the first lever, and a second brake pad is attached to the upper side of the second lever, the first brake pad so positioned on the first lever that the first axle is between the first brake pad and the pivot point, and the second brake pad is so positioned on the second lever that the second axle is between the second brake pad and the pivot point, means being provided for transferring part of the weight of the car onto the first and second levers at the pivot point.

Preferably, the first axis coincides with the first axle, and the second axis coincides with the second axle.

Advantageously, the distance between each brake pad and the axis associated with the lever supporting that brake pad is less than the distance between that axis and the pivot point. Preferably, the distance between each brake pad and the axis associated with the lever supporting that brake pad is substantially half the distance between that axis and the pivot point. Thus, the downward force applied by the weight of the car is magnified by the lever arrangement, so that the brake pads can engage a safety rail positioned at the side of the running rail with a braking force which is about twice that which the known type of brake pad would engage the running rail.

Locking means may be provided for holding the first and second levers in a first operating position in which the brake pads are in a first, inoperative position, the locking means being releasable so that the brake pads can pivot upwardly about their associated axes into a second, braking position as a result of the force acting down onto the first and second levers at the pivot point. Advantageously, a hydraulic piston-and-cylinder arrangement constitutes the locking means, the hydraulic piston-and-cylinder arrangement being pressurised when the brake pads are in their first positions, and being vented to allow the brake pads to move into their second positions.

Preferably, the cylinder of the piston-and-cylinder arrangement is attached to the first lever, the piston rod of the piston-and-cylinder arrangement being operably connected to the second lever. A spring may be associated with the pistqn rod of the piston-and-cylinder arrangement, the spring acting, in use, as a shock absorber and/or suspension means. In one preferred embodiment, the piston-and-cylinder arrangement may be positioned horizontally. Alternatively, the pistonand-cylinder arrangement is positioned vertically.

Preferably, the system further comprises a railengaging brake pad attached to one of the levers and positioned below the pivot point.

Alternatively, the system further comprises a railengaging brake pad pivotally attached to the first and second levers about a pivot pin passing through the first and second levers and the railengaging brake pad, the rail-engaging brake pad being positioned below the pivot point. In either case, the rail-engaging brake pad is used for braking in normal situations, the first and second brake pads only coming into operation at steep gradients.

The invention also provides a mine rail bogie comprising two pairs of first and second bogie wheels, the first and second bogie wheels of each pair being aligned for movement along a respective rail, and a cross-piece for connecting the two pairs of bogie wheels, wherein each pair of bogie wheels is provided with a braking system as defined above.

In critical braking situations, flanged safety rails are provided at the sides of the running rails, the flanged safety rails being so dimensioned that, upon venting of the hydraulic piston-and-cylinder arrangements, the weight of the car acting down on the pivot points forces the first and second brake pads against the flanged safety rails before engaging the rail-engaging brake pads have moved far enough to engage the running rails.

Four forms of rail vehicle bogie, each incorporating a braking mechanism constructed in accordance with the invention, will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a side elevation of a first rail vehicle bogie; Fig. 2 is a plan view of part of the bogie shown in Fig. 1; Fig. 3 is a part-sectional end elevation of the part of the bogie shown in Fig. 2; Fig. 4 is a side elevation of a second rail vehicle bogie; Fig. 5 is a plan view of part of the bogie of Fig. 4; Fig. 6 is a side elevation of part of a third form of rail vehicle bogie; Fig. 7 is a plan view corresponding to Fig. 6; Fig. 8 is a side elevation of a fourth form of rail vehicle bogie, this view not showing the outboard subsidiary brake; and Fig. 9 is a plan view of the fourth form of bogie.

Referring to the drawings, Fig. 1 shows a rail vehicle bogie 1 having two pairs of flanged wheels 2 and 3 (only one of each of which can be seen).

The wheels 2 and 3 run along a track constituted by a pair of parallel I-beam rails 4 (only one of which is shown). The two wheels 2 and 3 engaging the same rail 4 are interconnected (in a manner described below) by means of levers 5 and 6, and the two levers 6 are interconnected by a cross-piece C (see Figs. 2 and 3). As the side combinations of wheels 2 and 3 and levers 5 and 6 are identical, only one of them will be described in detail.

As seen in Fig. 2, each lever 5 and 6 is a double-armed lever having respectively arms 5a and Sb, and 6a and 6b. The arms 5a and 56 of the lever 5 rotatably support the wheel 2 therebetween, and the arms 6a and 6b of the lever 6 rotatably support the wheel 3 therebetween.

The wheel 2 rotates about an axis 2a, and the wheel 3 rotates about an axis 3a, (the wheel axles not being shown). Each lever 5 and 6 has a generally L-shaped profile (see Fig. 1) when viewed from the side, the arms 5a, Sb and 6a, 6b forming one leg of the respective L, and an upright 5c, 6c the other leg. The two levers are pivoted together by means of a pivot pin 7 which passes through the two levers in the regions where the pairs of legs meet (that is to say at the "corners" of the L's). The upright portions Sc and 6c are generally parallel to one another, and are operatively interconnected by a hydraulic pistonand-cylinder arrangement, indicated generally by the reference number 8.

The piston-and-cylinder arrangement 8 has a hollow cylinder 9, one end of which is screwed into the face of the upright 6c which is remote from the upright 5c. A piston (not shown) is reciprocable within the cylinder 9, a piston rod 10 being attached to the piston and passing through the free end of the cylinder. Both the piston and the piston rod 10 are formed with a bore 11 which passes right through the centre of the piston/piston rod combination. The bore 11 also passes through both the uprights Sc and 6c. A rod 12 is received within the bore 1 one end of the rod 12 being fixed to the free end of the piston rod 10. A nut 13 is screwed onto the other end of the rod -12, a series of disc springs 14 being positioned between the nut 13 and the adjacent face of the upright 5c.

A main brake pad 1 5 is fixed to the underneath side of the lever 6, the main brake pad 1 5 being positioned beneath the pivot pin 7. Subsidiary brake pads 1 6 are fixed to the upper sides of the arms 5a and 6a at the free ends thereof. The main brake pad 1 5 cooperates (in a manner described below) with the rail 4, and the subsidiary brake pads 1 6 cooperate (in a manner described below) with a safety rail 1 7 positioned adjacent to the rail 4 (see Fig. 3). Such safety rails 1 7 are positioned alongside the rails 4 in the vicinity of curves or swilleys, or where the track has a large gradient.

A mine rail car is usually provided with two bogies, and the body of such a car would be supported by the cross-pieces C of the type of bogie described above. In use, with the car running along the track, the hydraulic piston-andcylinder arrangements 8 of the bogies are fully pressurised. This forces the piston rods 10 outwardly of their cylinders 9, and so forces the pairs of uprights Sc and 6c together, the rods 12 and the disc springs 14 transmitting the hydraulic extension forces to the uprights 5e to force these uprights against their counter-part uprights 6c.

Thus, with the hydraulic piston-and-cylinder arrangements 8 pressurised, the brake pads 15 are clear of the rails 4 (as shown in Figs. 1 and 3).

When the car needs to be slowed down (or stopped), the hydraulic piston-and-cylinder arrangements 8 are vented, and the weight of the car acting down onto the pairs of pivoted levers 5 and 6, via the cross-pieces C, forces their uprights Sc and 6c apart, as the pistons (and piston rods 10) are retracted into their cylinders 9. Thus, the brake pads 1 5 are brought into engagement with the rails 4, the degree of braking which results being determined by the weight of the car and its contents. Moreover, the system is fail-safe, as the brake pads 15 will be forced into engagement with the rails 4, should the hydraulics fail, under the weight of the car.

This method of braking is well known. However, as discussed above, this braking method is not entirely satisfactory in the most critical braking situations (that is to say on steep inclines). It is also known to provide safety rails (such as the safety rails 1 7) at the sides of the track in such positions. These safety rails usually fulfill the function of keeping the bogie wheels on the track rails. With the bogies described above, however, these safety rails can be used (in conjunction with the subsidiary brake pads 16) to provide an improved braking action in such critical braking situations.

Referring now to Fig. 3, it will be seen that, in the normal (brakes-off) running condition, the subsidiary brake pads 1 6 are considerably nearer the inner surface of an upper flange 1 7a of the safety rail 1 7 than is the main brake pad 15 to the rail 4. Consequently, when braking is initiated, by venting the hydraulic piston-and-cylinder arrangements 8, the subsidiary brake pads 16 will engage the flanges 1 7a to provide the necessary braking action. Obviously, in such a case, the main brake pads 15 will not engage the rails 4, and so will not contribute to the braking action.However, by making the distance from each subsidiary brake pad 1 6 to its fulcrum (the axis 2a or 3a of the associated wheel 2 or 3) less than the distance between that fulcrum and the pivot pin 7 (that is to say the point through which the weight of the car acts), the levers 5 or 6 have a mechanical advantage. Consequently, an increased braking force (compared with that applied normally by the main brake pad 1 5) is applied by each of the subsidiary brake pads 16. In the illustrated embodiment, the fulcrum of each lever 5 or 6 is situated about one third of the way along that lever (starting from the free end thereof), and so a mechanical advantage of 2 :1 results.

The embodiments of Figs. 4 and 5 is basically the same as that of Figs. 1 to 3, and so like reference numbers have been used for like parts.

The main differences between the two embodiments are that each piston-and-cylinder arrangement 8 acts directly on its pair of associated levers 5 and 6, and that the levers themselves are shaped differently. Thus, the cylinder 9 of each piston-and-cylinder arrangement 8 is supported by its associated lever 5, and the piston rod 10 of that arrangement acts on the associated lever 6. In this embodiment a spring (not shown) is provided within the cylinder 9 of each of the arrangements 8. Another difference is that the main brake pad 1 5 is pivotally mounted on the pivot pin 7, rather than being fixed to the lever 6. The advantage of this pivotal mounting is that the brake pad 15 will always engage the rail 4 over the entire friction face of the pad.

The embodiment of Figs. 6 and 7 is also basically the same as that of Figs. 1 to 3, and so like reference numbers have been used for like parts. The main differences between the two embodiments are that each piston-and-cylinder arrangement 8 acts vertically, and that the levers 5 and 6 are of different construction. Thus, each of the levers 5 and 6 has only one arm, the subsidiary brake pads 1 6 being fixed to the upper sides of the free ends of the arms. The cylinder 9 of each piston-and-cylinder arrangement 8 is supported by means of a horizontal extension arm 6c formed integrally with the lever 6, and the piston rod 10 of that arrangement is attached to a horizontal extension arm Sc formed integrally with the lever 5.

The embodiment of Figs. 8 and 9 is also similar to that of Figs. 1 to 3, and so like reference numbers have been used for like parts. The main differences between the two embodiments are that the pivot pin 7 is offset with respect to the centre line of the bogie, and that only one subsidiary brake pad 1 6 is provided. As shown in Fig. 9, the lever 5 is a double-armed lever having arms 5a and 5b which rotatably support the wheel 2 therebetween. The lever 6 is a single-armed lever, the lever being positioned outboard of, and rotatably supporting, the wheel 3. As shown in Fig. 8, the two levers 5 and 6 are pivoted together by means of a pivot pin 7 which is positioned nearer the wheel 3 than the wheel 2. The lever 5 is also pivoted, by a pivot pin 7', to the cross-piece C of the bogie at the centre-line thereof.The levers 5 and 6 are provided with respective uprights Sc and 6c, and the piston-and-cylinder arrangement 8 acts directly on these uprights. Thus, as shown in Fig. 8, the cylinder 9 of the piston-and-cylinder arrangement 8 is pivotally connected to the upright 5c, and the piston rod 1 0 is pivotally connected to the upright 6c. The subsidiary brake pad 1 6 is fixed to the upper side of the free end of the arm 5a. As with the embodiment of Figs. 1 to 3, the subsidiary brake pad 1 6 is brought into action against a safety rail (not shown) in critical braking situations.As with the embodiment of Figs. 1 to 3, the lever 5 has a mechanical advantage, so that an increased braking force (compared with that applied normally by the main brake pad 15) is applied by the subsidiary brake pad 1 6. The lever 6 is not provided with a subsidiary brake pad. In use, the weight of the car acting down on the pivot pin 7' will cause the pivot pin 7' to move down when the cylinder is vented. Thus, the lever 5 pivots about the axle of the wheel 2 and about the pivot pin 7'. Similarly, the lever 6 pivots about the axle of the wheel 3 and about the pivot pin 7, which also pivots about the pivot pin 7'. In an alternative arrangement, the lever 5 has only one arm, namely an arm inboard of the wheel 2.In this case, the brake pad 1 6 is attached to the upper side of the free end of the lever 5, this free end being extended beyond the edge of the wheel 2, and having an extension at right-angles thereto, the brake pad being carried by the extension.

In all the embodiments described above, the springs associated with the piston-and-cylinder arrangements 8 (the disc springs 14 in the embodiment of Figs. 1 to 3) act as shock absorbers and/or suspension means. However, these springs are not essential, and can be dispensed with.

Obviously, a number of modifications could be made to the braking systems described above. For example, each of the subsidiary brake pads 16 could be pivotally attached to its respective arm. Moreover, each of the levers could be provided with means (such as slides or rollers) for engagement with the safety rails 1 7 for keeping the bogie wheels 2 and 3 on the rails 4, particularly during cornering. Such means would preferably be attached to the lever arms at positions outboard of the axes of the wheels 2 and 3.

Claims

1. A braking system for mine rail car bogie, the system comprising a lever pivotally mounted about an axis parallel to the axle of a bogie wheel, a brake pad attached to the upper side of the lever at one side of said axis, and means for transferring part of the weight of the car onto the lever at the other side of said axis.

2. A braking system as claimed in claim 1, wherein the distance between the brake pad and said axis is less than the distance between said axis and the position at which part of the weight of the car is transferred onto the lever at said other side of said axis.

3. A braking system as claimed in claim 2, wherein the distance between the brake pad and said axis is substantially half the distance between said axis and said position.

4. A braking system as claimed in any one of claims 1 to 3,further comprising a second lever pivotally mounted about a second axis parallel30 the axle of a second bogie wheel, the firstmentioned bogie wheel and the second bogie wheel being aligned for movement along a common rail, wherein the first-mentioned lever and the second lever are pivotally connected together at a pivot point positioned between the first-mentioned bogie wheel and the second bogie wheel.

5. A braking system as claimed in claim 4, wherein said pivot point is positioned between the second bogie wheel and the position at which part of the weight of the car is transferred onto the first-mentioned lever, and wherein the firstmentioned lever is pivotally mounted on the frame-work of the bogie at said position.

6. A braking system as claimed in claim 4 or claim 5, wherein the first-mentioned axis coincides with the axle of the first-mentioned bogie wheel, and the second axis coincides with the axle of the second bogie wheel.

7. A breaking system as claimed in any one of claims 4 to 6, wherein locking means are provided for holding the first-mentioned lever and the second lever in a first operating position in which the brake pad is in a first, inoperative position, the locking means being releasable so that the brake pad can pivot upwardly about the first-mentioned axis into a second, braking position as a result of the force acting down onto the first-mentioned lever at said position.

8. A braking system as claimed in claim 7, wherein a hydraulic piston-and-cyiinder arrangement constitutes the locking means, the hydraulic piston-and-cylinder arrangement being pressurised when the brake pad is in its first position, and being vented to allow the brake pad to move into its second position.

9. A braking system as claimed in claim 8, wherein the cylinder of the piston-and-cylinder arrangement is pivotally attached to the firstmentioned lever, the piston rod of the piston-andcylinder arrangement being pivotally connected to the second lever.

10. A braking system as claimed in any one of claims 1 to 9, further comprising a rail-engaging brake pad attached to the first-mentioned lever.

11. A braking system for mine rail car bogie, the system comprising a first lever pivotally mounted about a first axis parallel to the axle of a first bogie wheel, a second lever pivotally mounted about a second axis parallel to the axle of a second bogie wheel, the first and second bogie wheels being aligned for movement along a common rail, wherein the first and second levers are pivotally connected together at a pivot point positioned between the first and second bogie wheels, and wherein a first brake pad is attached to the upper side of the first lever, and a second brake pad is attached to the upper side of the second lever, the first brake pad being so positioned on the first lever that the first axis is between the first brake pad and the pivot point, and the second brake pad is so positioned on the second lever that the second axis is between the second brake pad and the pivot point, means being provided for transferring part of the weight of the car onto the first and second levers at the pivot point.

12. A braking system as claimed in claim 11, wherein the first axis coincides with the first axle, and the second axis coincides with the second axle.

13. A braking system as claimed in claim 11 or claim 12, wherein the distance between each brake pad and the axis associated with the lever supporting that brake pad is less than the distance between that axis and the pivot point.

14. A braking system as claimed in claim 13, wherein the distance between each brake pad and the axis associated with the lever supporting that brake pad is substantially half the distance between that axis and the pivot point.

1 5. A braking system as claimed in any one of claims 11 to 15, wherein locking means are provided for holding the first and second levers in a first operating position in which the brake pads are in a first, inoperative position, the locking means being releasable so that the brake pads can pivot upwardly about their associated axes into a second, braking position as a result of the force acting down onto the first and second levers at the pivot point.

1 6. A braking system as claimed in claim 15, wherein a hydraulic piston-and-cylinder arrangement constitutes the locking means, the hydraulic piston-and-cylinder arrangement being pressurised when the brake pads are in their first position, and being vented to allow the brake pads to move into their second positions.

17. A braking system as claimed in claim 1 6, wherein the cylinder of the piston-and-cylinder arrangement is attached to the first lever, the piston rod of the piston-and-cylinder arrangement being operably connected to the second lever.

18. A braking system as claimed in claim 17, wherein a spring is associated with the piston rod of the piston-and-cylinder arrangement, the spring acting, in use, as a shock absorber and/or suspension means.

19. A braking system as claimed in any one of claims 1 6 to 18, wherein the piston-and-cylinder arrangement is positioned horizontally.

20. A braking system as claimed in any one of claims 1 6 to 18, wherein the piston-and-cylinder arrangement is positioned vertically.

21. A braking system as claimed in any one of claims 11 to 20, further comprising a railengaging brake pad attached to one of the levers and positioned below the pivot point.

22. A braking system as claimed in any one of claims 11 to 20, further comprising a railengaging brake pad pivotally attached to the first and second levers about a pivot pin passing through the first and second levers and the railengaging brake pad, the rail-engaging brake pad being positioned below the pivot point.

23. A braking system substantially as hereinbefore described with reference to, and as illustrated by, Figs. 1 to 3, Figs. 4 and 5, Figs. 6 and 7, or Figs. 8 and 9 of the accompanying drawings.

24. A mine rail car bogie comprising two pairs of first and second bogie wheels, the first and second bogie wheels of each pair being aligned for movement along a respective rail, and a crosspiece for connecting the two pairs of bogie wheels, wherein each pair of bogie wheels is provided with a braking system, each of the braking systems being as claimed in any one of claims 4 to 23.

25. A mine rail car bogie substantially as hereinbefore described with reference to, and as illustrated by, Figs. 1 to 3, Figs. 4 and 5, Figs. 6 and 7, or Figs. 8 and 9 of the accompanying drawings.

26. A mine rail car comprising a car body supported by a pair of mine rail car bogies, wherein each of the bogies is as claimed in claim 24 or claim 25.