RAIL KEY

Abstract: A rail key for use in securing a railway type rail in a rail chair comprises a first wall (25) which in use engages the web of a rail and a second wall (11) which, in use, engages a wall of the chair. A compressible resilient pad (18) is disposed between the first and second walls and is arranged so that when the key is located in its operative position the pad (18) is compressed to an extent sufficient to resist movement of the rail toward the chair.

Description: Rail Key This invention relates to securing devices for securing a railway-type rail, typically but not exclusively a bullhead type rail, in a rail chair. Many sections of railway track still use bullhead type rails which are secured in position by means of what are known as chairs in which the rails sit and held against lateral movement by securing devices commonly known as rail keys. A known type of securing device or rail key is described in GB-A- 2102478 and comprises an elongate piece of sheet metal which has been bent to provide a central portion having first and second locking portions at its opposite extremities and first and second end portions which are joined together by the central portion and the locking portions. The clip is arranged so that when the bullhead rail is standing in a standard bullhead rail chair the clip can be driven in a direction substantially parallel to the length of the railway rail so that it moves into the space between the web of the rail and the facing surface of a wall upstanding from the base of the chair. When in position one of the locking portions engages around one edge of the wall of the chair and the other engages around the other edge of the wall of the chair, and the end portions of the clip engage one side of the web of the rail and urge the rail away from the surface of the chair so that the side of the web is maintained in contact with a joint in order to prevent lateral movement of the rail in use. Such clips have been in use for a considerable period of time, but have been found to be subject to failure particularly under conditions of high lateral loading on the rails. The present invention is concerned with an improved type of securing device which is not prone to such failure. According to the present invention there is provided a securing device for securing a railway type rail in a rail chair, said device being locatable between the web of a rail and an upstanding wall of the chair, said device comprising a first wall member which in use engages the web of a rail and a second wall member which in use engages a wall of a chair, and compressible resilient material disposed between the first and second wall members and arranged such that when the securing device is moved into the space between the web of the rail and the wall of the chair, said material is compressed to an extent sufficient to resist movement of the rail towards the chair. The securing device may include one or more box shaped elements disposed between one of said wall members and the compressible material. The compressible material may comprise a rubber pad. The rubber pad may be formed from TRACKELAST FC 584. The securing device may include a clip for moving the device into its operative position between the web of the rail and the upstanding wall of the chair. The invention will be described now by way of example only, with particular reference to the accompanying drawings. In the drawings: Figure 1 is a plan view of a securing device or rail key in accordance with an embodiment of the invention, the key being in its non-compressed state; Figure 2 is a side sectional view of the key of Figure 1; Figure 3 is an end view of the key of Figure 1; Figure 4 is a view similar to Figure 1 showing the key in its compressed state; Figure 5 is a view similar to Figure 2 showing the key in its compressed state; Figure 6 is a view similar to Figure 3 showing the key in the compressed state, and Figure 7 is a view of a bullhead rail sitting in a chair. A rail key of unitary structure comprises a base element (10) which has a central planar section (11) which constitutes a first wall member, a curved end section (12) and a planar end section (14) extending generally perpendicular to the planar section (11). Mounted on the central planar portion (11) of the spring base element (10) are three box section elements (16) which are disposed side-by-side and welded together. The elements (16) are attached to the spring base element (10) by welding. A pad (18) made of compressible resilient material such as rubber is mounted on the box shaped elements (16) and secured thereto by a suitable adhesive. The rubber pad may be made from TRACKELAST FC 584 material which is produced by a company Tiflex. As shown in Figure 2 the pad (18) is a rectangular parallepiped with longitudinal side walls (21) and end walls (22). The longitudinal extent of the pad (18) corresponds to the longitudinal extent of the side-by-side box section elements (16) and its lateral extent corresponding substantially to the length of each box-shaped element (16). The rubber pad (18) is covered by a cover plate (24) which is formed from suitable sheet material and whose planar top wall (25) constitutes a second wall member. The cover plate (24) has longitudinal walls (26) which are inclined slightly and the inner surfaces of which define a triangular space (28) along with the longitudinal walls (21) of the rubber pad. The end walls (27) of the cover plate locate alongside the end walls (22) of the rubber pad (18) The cover plate (24) can be secured to the rubber pad (18) by a suitable adhesive. Figures 1 to 3 show the securing device in a condition where the rubber pad (18) is not compressed. The inclination of the walls (26) is such as to match the profile of the rail. With reference to Figure 7 the rail key of Figures 1 to 6 is designed to locate in a space (30) between the web (32) of a bullhead type rail (34) and an upstanding wall (36) of a chair (38). The base (40) of the rail sits on the base (42) of the chair, and the chair includes a jaw (44) which locates against the opposite side of the web (32). In its uncompressed state the distance between the cover plate (24) and the base element (11) is slightly greater than the dimension (L) of the space between the wall (36) and the web (32). In order to locate the securing device in position between the web (32) of the bullhead type railway rail (34) and the upstanding wall (36) of the chair, the device is located so that the planar section (11) of the spring base element (10) is substantially upright and is pulled by means of the curved end portion (12) into that space. A suitable tool such as a Pandrol Panlock Puller can be used to achieve this by engaging the curved end portion (12). The cover plate (24) over the pad (18) is located against the web (32) of the rail during this movement and as the device moves into the space between the chair and the web the pad becomes compressed to allow such movement to be effected. When the securing device is ultimately in its operative position, the pad (18) has been compressed to a state shown in Figures 4 to 6 of the drawings. In this state the pad (18) has become sufficiently rigid to resist movement of the rail (34) along the jaw (44) towards the chair thereby firmly securing the rail in position. This is true even on curved portions of the rail where it has been found that the present rail key is sufficiently robust to resist such movement. The triangular space (28) provides a volume into which the rubber pad (18) can move when it is compressed. An advantage of the present rail key is that it is relatively robust and not subject to the type of failure which occurred with the prior art type rail keys. The box section elements (16) are used to minimise the weight of the device. The base element (10) can be made from 4.75mm thick spring steel. The sections (16) can be constructed from 2.5mm thick 30mm box section mild steel and the cover plate (24) can be formed from 2mm thick mild steel.

Claims: Claims: 1. A securing device for securing a railway type rail in a rail chair, said device being locatable between the web of a rail and an upstanding wall of the chair, said device comprising a first wall member which in use engages the web of a rail and a second wall member which in use engages a wall of a chair, and compressible resilient material disposed between the first and second wall members and arranged such that when the securing device is moved into the space between the web of the rail and the wall of the chair, said material is compressed to an extent sufficient to resist movement of the rail towards the chair. 2. A securing device according to claim 1, wherein the securing device includes one or more box shaped elements disposed between one of said wall members and the compressible material. 3. A securing device according to claim 1 or claim 2, wherein the compressible material comprises a rubber pad. 4. A securing device according to claim 3, wherein the rubber pad is formed from TRACKELAST FC 584. 5. A securing device according to any preceding claim including a formation which can be engaged to enable the device to be moved into its operative position between the web of the rail and the upstanding wall of the chair. 6. A securing device according to any one of claims 3 to 5 wherein the second wall member is formed by a cover located over the rubber pad.

Inventors: GOWEN MICHAEL, RILEY PETER JOHN, GOWEN, MICHAEL, RILEY, PETER, JOHN
Applicants: GOWEN MICHAEL, INFRACO BCV LTD, RILEY PETER JOHN, GOWEN, MICHAEL, INFRACO BCV LIMITED, RILEY, PETER, JOHN
Application year: 2001
Main classification: E01B9
IPC codes: E01B9