GB2083107A

GB2083107A - Fastening railway rails

Info

Publication number: GB2083107A
Application number: GB8027641A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-08-27
Filing date: 1980-08-27
Publication date: 1982-03-17

Abstract

A rail 1 is resiliently held on a concrete sleeper 3 by a rigid clip 6 secured on an upstanding bolt 5 by disc springs 7, cover plate 8 and nut 9, the bolt head being retained in a T-slot of an anchorage member 4. The clip 6 comprises a circular plate having (a) a depending toe engaging the rail flange through an insulator 10, (b) a depending heel engaging a projection on the member 4 and (c) a central upstanding boss (not shown) which passes through the disc springs 7 and engages a recess in the cover plate 8, thereby automatically tensioning the disc springs to the required loading. <IMAGE>

Description

SPECIFICATION Improved means for fastening railway rails This invention relates to rail fastenings, that is to means for securing rails to sleepers orto other rail foundations (particularly foundations of concrete or other cast or moulded material) and has for its object to provide an improvement therein.

Due to passing wheel loads there is a small rapid relative movement between the rail and the structure upon which it rests, and in service a rail fastening needs to accomodate this movement and to exert an effective downward force on the rail foot.

In modern applications a resilient rail pad is placed between the rail and the supporting structure, and a plastic insulator is placed between the rail fastening and the rail foot. Notwithstanding the resilience of the plastic components, and manufacturing tolerances for the various components, and the wear due to attrition of mating parts during service, the toeloading on the rail foot needs to be held as constant as possible.

The life of a concrete sleeper or concrete track foundation in service is generally expected to be from forty to fifty years, and the anchorage members embedded in the concrete should be good for the same period. One type of rail fastening in use has the shank of a malleable iron anchorage member embedded in the concrete sleeper, and at its head a hole and a ledge on the portion farthest from the rail.

A spring clip formed from round section bar has its shaft end held in the hole with its toe pressing on the rail foot. When being inserted the tail end rides up an incline to the ledge and with the shaft end of the spring acting as a fulcrum exerts a downward force at the toe of the spring clip. The heights above sleeper level for the ledge and for the top of the hole in the anchorage member are important, and the manufacturing tolerances generally specified for these dimensions are plus or minus 0.8 mm (+ X,").

Consequently, for a meam toe load value of 7.4 kN the actual values can range between plus and minus 16 per cent of the mean value. Measurements of spring clip toe load values show that although the mean value when installed is 7.4 kN the value falls to less than 6 kN after only a year in service.

All rail fastenings depending for toe-loading on the deflexion of a plate or bar spring have a straight line load-deflexion characteristic, and the assembly generally has about 10 mm to 12 mm deflexion between the tensioned and untensioned conditions.

Springs of the Belleville disc type can be designed to give a required toe loading with the upper part of the load-deflexion characteristic curve being almost horizontal, and the present invention is based on the use of disc springs to provide a fairly constant toe load irrespective of wear of mating surfaces.

In order that the invention may be fully understood and readily carried into effect, the same will be described by way of example only, with reference to the accompanying drawings of which Figure lisa side elevation of a rail fastening assembly embodying the invention.

Figure 2 is a plan view thereof.

Figures 3 to 17 are views which illustrate the com ponent parts of the fastening.

Referring now to Figures 1 and 2, the rail fasten ing illustrated includes at each side of rail 1 which rests on rail pads 2 on a concrete sleeper 3 an anchorage member 4 having a T-slot at its head to hold a plate bolt 5. Placed over the plate bolt is a beam plate 6, which carries disc springs 7 over which is placed cover plate 8. The insulator 10 is inserted between the rail foot and the toe of the beam plate and the assembly then is fastened down by self-locking nut 9 which automatically tensions the disc springs to the required loading.

Figures 3 to 5 illustrate in details the design of a fixed anchorage member, in which the T-slot is denoted by 11 and the shank which is embedded in the concrete sleeper is denoted by 12 and the step denoted by 13 supports the heel of the beam plate.

Figures 6 and 7 illustrate in detail the design of the beam plate, in which the heel is denoted by 14 and the toe by 15 and the boss denoted by 16 locates the disc springs in position and forms a stop on which the cover plate rests.

Figures 8 and 9 illustrate in detail the design of the disc springs which are located in position by the boss on the beam plate. An important feature in the design of the disc springs is that the ratio of free cone height to thickness of spring plate is equal to the square root of two (1.414), when the upper part of the load deflexion curve is almost horizontal. For a variation in deflexion from 95 per cent to 65 per cent of free cone height the loss in spring loading is less than 5 per cent.

Figures 10 and 11 illustrate in detail the design of the cover plate in which the recess denoted by 11 rests on the boss of the beam plate when assembled, thereby tensioning the disc springs to the required loading.

Figures 12 and 13 illustrate in detail the design of the the plate bolt.

Figures 14 and 15 illustrate in detail the design of the self-locking nut.

Figures 16 and 17 illustrate in detail the design of the insulator in which part of the insulator is dis posed between the rail and the anchorage with side lugs to locate the insulator relative to the anchorage.

An important feature is that during assembly the plastic insulator is subjected to compressive forces only and not to abrasive sliding forces.

The assembly shows two disc springs arranged in series, but smaller diameter disc springs stacked in a series-parallel arrangement may be used to suit par ticular requirements.

1. A rail fastening comprising, in combination with a concrete sleeper or other cast or moulded foundation, an anchorage member with a shank embedded in the cast or moulded foundation and with the head of the anchorage member having a T-slotto hold the head of a plate bolt. Placed overthe upright plate bolt is a beam plate with its heel resting on the step of the fixed anchorage and its toe resting on the plastic insulator on the rail foot, and with a boss on its upper surface to locate disc springs bet ween the beam plate and a cover plate, the assembly

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improved means for fastening railway rails This invention relates to rail fastenings, that is to means for securing rails to sleepers orto other rail foundations (particularly foundations of concrete or other cast or moulded material) and has for its object to provide an improvement therein. Due to passing wheel loads there is a small rapid relative movement between the rail and the structure upon which it rests, and in service a rail fastening needs to accomodate this movement and to exert an effective downward force on the rail foot. In modern applications a resilient rail pad is placed between the rail and the supporting structure, and a plastic insulator is placed between the rail fastening and the rail foot. Notwithstanding the resilience of the plastic components, and manufacturing tolerances for the various components, and the wear due to attrition of mating parts during service, the toeloading on the rail foot needs to be held as constant as possible. The life of a concrete sleeper or concrete track foundation in service is generally expected to be from forty to fifty years, and the anchorage members embedded in the concrete should be good for the same period. One type of rail fastening in use has the shank of a malleable iron anchorage member embedded in the concrete sleeper, and at its head a hole and a ledge on the portion farthest from the rail. A spring clip formed from round section bar has its shaft end held in the hole with its toe pressing on the rail foot. When being inserted the tail end rides up an incline to the ledge and with the shaft end of the spring acting as a fulcrum exerts a downward force at the toe of the spring clip. The heights above sleeper level for the ledge and for the top of the hole in the anchorage member are important, and the manufacturing tolerances generally specified for these dimensions are plus or minus 0.8 mm (+ X,"). Consequently, for a meam toe load value of 7.4 kN the actual values can range between plus and minus 16 per cent of the mean value. Measurements of spring clip toe load values show that although the mean value when installed is 7.4 kN the value falls to less than 6 kN after only a year in service. All rail fastenings depending for toe-loading on the deflexion of a plate or bar spring have a straight line load-deflexion characteristic, and the assembly generally has about 10 mm to 12 mm deflexion between the tensioned and untensioned conditions. Springs of the Belleville disc type can be designed to give a required toe loading with the upper part of the load-deflexion characteristic curve being almost horizontal, and the present invention is based on the use of disc springs to provide a fairly constant toe load irrespective of wear of mating surfaces. In order that the invention may be fully understood and readily carried into effect, the same will be described by way of example only, with reference to the accompanying drawings of which Figure lisa side elevation of a rail fastening assembly embodying the invention. Figure 2 is a plan view thereof. Figures 3 to 17 are views which illustrate the com ponent parts of the fastening. Referring now to Figures 1 and 2, the rail fasten ing illustrated includes at each side of rail 1 which rests on rail pads 2 on a concrete sleeper 3 an anchorage member 4 having a T-slot at its head to hold a plate bolt 5. Placed over the plate bolt is a beam plate 6, which carries disc springs 7 over which is placed cover plate 8. The insulator 10 is inserted between the rail foot and the toe of the beam plate and the assembly then is fastened down by self-locking nut 9 which automatically tensions the disc springs to the required loading. Figures 3 to 5 illustrate in details the design of a fixed anchorage member, in which the T-slot is denoted by 11 and the shank which is embedded in the concrete sleeper is denoted by 12 and the step denoted by 13 supports the heel of the beam plate. Figures 6 and 7 illustrate in detail the design of the beam plate, in which the heel is denoted by 14 and the toe by 15 and the boss denoted by 16 locates the disc springs in position and forms a stop on which the cover plate rests. Figures 8 and 9 illustrate in detail the design of the disc springs which are located in position by the boss on the beam plate. An important feature in the design of the disc springs is that the ratio of free cone height to thickness of spring plate is equal to the square root of two (1.414), when the upper part of the load deflexion curve is almost horizontal. For a variation in deflexion from 95 per cent to 65 per cent of free cone height the loss in spring loading is less than 5 per cent. Figures 10 and 11 illustrate in detail the design of the cover plate in which the recess denoted by 11 rests on the boss of the beam plate when assembled, thereby tensioning the disc springs to the required loading. Figures 12 and 13 illustrate in detail the design of the the plate bolt. Figures 14 and 15 illustrate in detail the design of the self-locking nut. Figures 16 and 17 illustrate in detail the design of the insulator in which part of the insulator is dis posed between the rail and the anchorage with side lugs to locate the insulator relative to the anchorage. An important feature is that during assembly the plastic insulator is subjected to compressive forces only and not to abrasive sliding forces. The assembly shows two disc springs arranged in series, but smaller diameter disc springs stacked in a series-parallel arrangement may be used to suit par ticular requirements. CLAIMS

1. A rail fastening comprising, in combination with a concrete sleeper or other cast or moulded foundation, an anchorage member with a shank embedded in the cast or moulded foundation and with the head of the anchorage member having a T-slotto hold the head of a plate bolt. Placed overthe upright plate bolt is a beam plate with its heel resting on the step of the fixed anchorage and its toe resting on the plastic insulator on the rail foot, and with a boss on its upper surface to locate disc springs bet ween the beam plate and a cover plate, the assembly being fastened down until the cover plate bears on the bosks of the beam plate, thereby tensioning the disc springs to the required pre-determined loading.

2. A rail fastening according to Claim 1, in which the accumulated wear in a vertical direction of the mating surfaces of the assembly would not exceed the flat rate portion of the load - reflexion characteristic curve of the disc springs, during the service life of a concrete sleeper.

3. A rail fastening in accordance with Claims 1 and 2, in which any of the removable components may be replaced by new components if and when required.

4. A rail fastening substantially as hereinbefore described with reference to and as illustrated by Figures 1 and 2, and by Figures 3 to 17 of the accompanying drawings.