GB2261489A - Buffer - Google Patents

Abstract

A railway side buffer comprises a telescopic casing having a buffer plate (10) at one end of a cylinder (11) which is slidable within a rectangular casing (14) which is for mounting on the railway vehicle. The cylinder (11) slides on a cylindrical member (17) which is within the rectangular casing (14), the cylinder (11) and the cylindrical member (17) together forming the casing of a hydro-pneumatic buffer capsule. A seal (27) operable to seal against leakage of liquid from within the buffer capsule between the cylinder (11) and the cylindrical member (17) is mounted in the cylinder (11) so as to slide on the outer surface of the cylindrical member (17). The hydro-pneumatic buffer capsule comprises liquid chambers (18, 22) and compressed gas chamber (19). <IMAGE>

Description

HALF CASING This invention relates to railway side buffers of the kind that comprises a telescopic casing having external abutment means mounted at one end of a cylindrical part of the casing which is constrained for rectilinearly sliding movement within another part of the casing, that other casing part being for mounting on the railway vehicle, the telescopic casing enclosing a telescopic buffer capsule which acts between the two parts of the casing. The telescopic buffer capsule may be a hydraulic buffer capsule. Alternatively it may incorporate other means, such as springs or elastomeric material in either solid or fluid form whereby energy used to cause lengthwise compression of the capsule is absorbed during such compression and whereby lengthwise compression is opposed resiliently and a recoil force is provided.

The telescopic buffer capsule enclosed within conventional railway buffers is a separate structural element inside the casing which serves to shield the buffer capsule from dirt and the elements, and which protects it from side loads. Where it is a hydraulic buffer capsule, it comprises a plunger slideable within a cylinder which is for mounting on the railway vehicle, the plunger abutting the inner face of the casing in the region of the external abutment means.

Although the construction of such a railway side buffer would be simplified if the external abutment means were to be mounted directly upon the buffer capsule, so that the number of component parts and thus the cost of the railway side buffer would be reduced, the buffer capsule would be directly exposed to the elements with the consequent risk of dirt being carried into its interior on compression which is undesirable for various reasons. Also the buffer capsule would be subjected directly to any side loads.

According to this invention there is provided a railway side buffer comprising a telescopic casing having external abutment means at one end of a cylindrical part of the casing which is slidable within another part of the casing which is for mounting on the railway vehicle, the cylindrical casing part also being slidable on a hollow cylindrical member within the other casing part, the cylindrical casing part and the cylindrical member together comprising a telescopic buffer capsule which also includes means whereby energy used to cause lengthwise compression of the capsule is absorbed during such compression and whereby lengthwise compression is opposed resiliently and a recoil force provided.

In a preferred embodiment of this invention, the interior of the cylindrical casing part forms a compression chamber which communicates via conduit means in the hollow cylindrical member with a reservoir chamber within the hollow cylindrical member, there being a resilient recoil medium in the hollow cylindrical member reacting to urge liquid in the reservoir chamber into the compression chamber and thereby to resist lengthwise compression of the buffer, and liquid damping means which damp flow of liquid between the compression chamber and the reservoir chamber and thereby provide further resistance to compression of the buffer and damp the recoil force under certain conditions of operation.

Preferably sealing means for sealing against leakage of liquid from the compression chamber between the hollow cylindrical member and the bore of the cylindrical casing part are mounted in the latter.

That has the advantage that the part of the film of liquid that inevitably is formed on the cylindrical outer surface of the hollow cylindrical member during high speed impact, that is wiped from that surface by the sealing means during a slower recoil movement is wiped back towards the compression chamber, rather than being wiped in the opposite direction away from the compression chamber to be lost which is a problem with conventional buffer capsules in which the main fluid tight sealing ring is carried by the plunger so that it wipes the bore of the cylinder in which the plunger slides.

One embodiment of this invention will be described now by way of example with reference to the accompanying drawings, of which: Figure 1 is a diagrammatic view in perspective of a railway side buffer; Figure 2 is a longitudinal section of the buffer shown in Figure 1, the section being in a plane which includes the longitudinal axis of the buffer; and, Figure 3 is a fragmentary section substantially on the line III-III of Figure 2, the structure within the radially outer surface of the moveable cylindrical casing part being omitted for convenience.

Figure 1 shows a railway buffer comprising external abutment means in the form of a buffer plate 10 mounted at one end of a cylinder 11 which projects through a circular aperture 12 formed substantially coaxially in a square end wall 13 of a ractangular hollow casing 14 which is mounted on a base plate 15, the base plate being for mounting on structure of a railway vehicle. The part of the cylinder 11 within the rectangular casing 14 is provided with a diametrically opposed pair of radial arms 16, each being shaped at its outer end to be slideably engaged within a respective internal corner of the rectangular casing 14 as is illustrated in Figure 3.

Figures 1 and 2 show a cylindrical member 17 which is closed at one end, which is a sliding fit within the cylindrical member 11 and which has its closed end in abutment with the base plate 15 within the rectangular casing 14. The buffer plate 10 and the cylinder 11 are thus constrained for rectilinear sliding movement over the cylindrical member 17 and within the rectangular casing 14 by the arms 16, the latter also serving to constrain the buffer plate 10 and the cylinder 11 against angular movement about the cylindrical member 17.

The cylinder 11 and the cylindrical member 17 together comprise a buffer capsule, the detailed construction of which is substantially as is described with respect to and as is illustrated in Figure 1 of British Patent Specification No. 1266596. However, the installation and functional orientation of that buffer capsule are different from that described in Patent Specification No. 1266596, because the cylindrical member 17 is a static part in operation of the railway side buffer shown in the drawings instead of being the moveable plunger of the buffer unit as is described in Specification No. 1266596. Also, the cylinder 11 is the moveable part which carries the external buffer plate 10 in contrast to the corresponding part of the buffer capsule shown in Patent Specification No. 1266596 being the static part.It follows that the metering pin of the railway side buffer shown in Figures 1 to 3 is a moveable part of that buffer as distinct from being a stationary part as was the case with the buffer capsule shown in Patent Specification No. 1266596. A consequence of the different functional arrangement is that the cylinder 11 doubles as the moveable part of the outer casing which carries the external buffer plate 10 as well as being the cylinder within which the compression chamber 18 is formed. It follows also that the variable volume chamber 19 formed between the floating piston 21 and the closed end wall 22 of the hollow cylindrical member 17, which is filled with compressed gas that serves as a resilient recoil medium, is formed in a stationary part of the buffer capsule in the arrangement shown in the drawings in contrast to it being formed in the moveable plunger of the buffer capsule described and illustrated in Patent Specification No. 1266596. Likewise, the reservoir chamber 23 formed within the cylindrical member 17 on the other side of the floating piston 21, which communicates with the compression chamber through the orifice 24 with which the metering needle 20 coacts, is also formed in a static part of the buffer capsule rather than in the moveable plunger of the buffer capsule described and illustrated in British Patent Specification No. 1266596.

Two other significant differences between the buffer capsule shown in the drawings and the buffer capsule described and illustrated in Figure 1 of Patent Specification No. 1266596 are the location of the fluid tight sealing means which provide a fluid sealing joint between the cylinder 11 and the cylindrical member 17 and the location of the bearing sleeve that supports the cylinder member near its open end. In each instance, they are mounted in respective annular grooves 25 and 26 formed in the bore of the cylinder 11. In addition to that sealing ring 27 and bearing sleeve 28, the cylinder 11 also carries an annular dust seal at its open end, that dust seal engaging the outer surface of the cylindrical member 17.

On high speed impact which causes compression of the buffer, liquid in the compression chamber 18 is carried past the sealing ring 27 as a relatively thick film on the outer surface of the cylindrical member 17. On recoil, the sealing ring 27 scrapes liquid from that film and pushes it back towards the compression chamber 18. That is in contrast to what happens with conventional buffers where the equivalent sealing ring is carried by the plunger so that it wipes oil away from the compression chamber on recoil.

Figure 3 shows one of the radial arms 16 has an aperture 29 formed in it to receive a pin 31 which is screwed through an aligned aperture 32 in the top of the rectangular casing 14 and arranged to project into the aperture 29 in that arm 16. The pin 31 cannot be removed when the buffer is extended so that it prevents disassembly of the buffer in that condition.

In order to dis-assemble the buffer, it must be compressed, either by discharging the gas from the chamber 19 or by compressing the buffer in a press by which expansion of the buffer after removal of the pin 29 can be controlled.

Claims (6)

1. A railway side buffer comprising a telescopic casing having external abutment means at one end of a cylindrical part of the casing which is slidable within another part of the casing which is for mounting on the railway vehicle, the cylindrical casing part also being slidable on a hollow cylindrical member within the other casing part, the cylindrical casing part and the cylindrical member together comprising a telescopic buffer capsule which also includes means whereby energy used to cause lengthwise compression of the capsule is absorbed during such compression and whereby lengthwise compression is opposed resiliently and a recoil force provided, wherein the interior of the cylindrical casing part forms a compression chamber which communicates via conduit means in the hollow cylindrical member with a reservoir chamber within the hollow cylindrical member, there being a resilient recoil medium in the hollow cylindrical member reacting to urge liquid in the reservoir chamber into the compression chamber and thereby to resist lengthwise compression of the buffer, and liquid damping means which damp flow of liquid between the compression chamber and the reservoir chamber and thereby provide further resistance to compression of the buffer and damp the recoil force under certain conditions of operation.

2. A railway side buffer according to claim 1, wherein sealing means for sealing against leakage of liquid from the compression chamber between the hollow cylindrical member and the bore of the cylindrical casing part are mounted in the latter.

3. A railway side buffer according to claim 1 or claim 2, wherein said other casing part is rectangular and said cylindrical casing part is constrained for rectilinear sliding movement over the hollow cylindrical member within said other rectangular casing part by a diametrically opposed pair of arms which each project radially from said cylindrical casing part and are slidably engaged within a respective internal corner of said other, rectangular casing part.

4. A railway side buffer according to any one of claims 1 to 3, wherein a bearing sleeve operable to support the cylindrical casing part for sliding movement on the hollow cylindrical member is mounted in the bore of the cylindrical casing part near the open end thereof.

5. A railway side buffer according to claim 3 or claim 4 when appended to claim 3, including inwardlyprojecting means which are removably mounted in said other, rectangular casing part and which inhibit disassembly of the buffer when so mounted, and wherein one of said arms is adapted to interact with said inwardly-projecting means when the buffer is extended so as to prevent removal of said inwardly-projecting means such that the buffer must be compressed to enable removal of said inwardly-projecting means and thus to enable disassembly of the buffer.

6. A railway side buffer substantially as described hereinbefore with reference to the accompanying drawings and as shown in those drawings.