Various Connection Forms of Rail Joints

Ordinary lines, between the rail and the rail with cleats and bolts, called rail joints. The connecting parts of the rail joint are composed of splints, bolts, spring washers, etc. Its role is to connect the rail with the rail and the switch at the joint to have the same integrity as the rail, to withstand the impact force, longitudinal force, horizontal force and temperature changes generated by the rail through the wheel at the rail joint temperature additional force, etc., while resisting bending and displacement, but also to meet the requirements of rail expansion.

According to its position relative to the sleeper, the connection form of the rail joint can be divided into two types: suspension type and cushion type. According to the mutual position of the two strands of rail joint, it can be divided into two types: relative type and phase type.

1. Form of joint

Rail joints can be divided into ordinary joints, insulated joints, frozen joints, cemented joints, special-shaped joints, expansion joints and vibration-damping joints according to their performance and uses.

1.1 Ordinary connector

Ordinary joint connecting parts are composed of plywood, bolts, spring washers, etc.

1.2 Insulation joint

It is used at the junction of two automatic blocking sections to ensure that the track signal current cannot be transmitted from one blocked section to another. There are mainly two types: ordinary high-strength insulated joints and glued insulated joints.

1.3 Freezing joints

The frozen joint refers to a type of joint that uses plywood and high-strength bolts to connect the rails, so that the rail ends are closely attached or small rail seams are reserved, and the rails are locked to prevent expansion and contraction. At present, there are two main ways of freezing rail joints used at home and abroad.

Ordinary frozen joint

Ordinary frozen joints refer to a rail connection method that uses special gaskets and stuffs them into the gaps of the rail bolt holes to make the rail joints close and prevent the rails from free expansion and contraction.

New frozen joint

In recent years, new rail frozen joints such as rail joint connections using Spirök anti-loosening mechanisms and Huck fasteners and MG joints have emerged. Different from ordinary frozen joints, the new frozen joints mainly rely on high-strength bolt connections to provide sufficient friction resistance between the rail and the plywood to prevent expansion and contraction between the rail and the plywood. The rail joint bolts are required to be high-strength and have a certain anti-loosening function. The use of new frozen joint technology in rail joint connections can effectively freeze rail joints and reduce joint diseases. The frozen lines can be managed like ordinary seamless lines.

1.4 Glue the joint

The adhesive joint is also the adhesive insulated joint, a kind of rail insulation joint used to meet the requirements of canceling the buffer zone of the ultra-long seamless line, and all the insulating joints are glued as a whole, which is made into a finished product by the manufacturer or on the spot. It can effectively improve the insulation property and stress state of the joint and enhance the resistance of the rail joint.

The end and side of the joint rail should be padded with sufficient strength of the insulation pad and sleeve, as well as insulation track circuit. In the structure, the end of the rail has two kinds of butt and miter. Miter joint rail end contact surface is large, can play the adhesive shear strength advantage, increase the joint bearing capacity. However, the miter joint needs to process the rail end into the form of a sharp rail, once the rail end cracks, the rail is easy to be rolled over, so the butt is generally used.

The plywood glued to the insulating joint is an important component for connecting the rails. It not only retains the connecting bolts, but also uses adhesive to glue the rails and plywood together. Therefore, it is required that the contact area between the rail and the plywood should be increased as much as possible to increase the bonding area and improve the load-bearing capacity of the joint. Therefore, most of the splints for glued insulating joints use special splints with large contact areas, or modified splints that enlarge the contact area with the rails. The rail joint bolts use high-strength bolts to solidify the adhesive under pressure and enhance the peeling resistance of the insulated joint splints.

Factory bonded insulated joint: In the factory by heating and pressurized bonding process, the two rails are bonded and fastened with cleats, insulated groove plates, insulated end plates, insulated bushings and high-strength bolts.

Field bonded insulated joint: At the construction site, the adhesive is used to glue the insulated plywood to the rail, and the rail joint is secured by high strength bolts.

1.5 Special-shaped connector

Special-shaped joints are used to connect two different types of rails, also called transition joints. The two ends of the special-shaped splints are consistent with different types of rails. The connection of the special-shaped joints should make the gauge line of the working surface of the two rails consistent with the horizontal line of the highest point of the rail top. At present, special-shaped rails are commonly used. For example, one end of a P60 rail is rolled into a P50 rail section, and the special-shaped rail is used as a transition to connect 60kg/m and 50kg/m lines.

1.6 Expansion joint

Expansion joints are temperature regulators used to connect rails with considerable rail end expansion and rail joints for seamless lines on bridges with a span greater than 100m. The expansion joint consists of a basic rail and a pointed rail that are in contact with each other. The basic rail and the pointed rail are installed on a common long pad, and special rail supports and buckle plates are used to keep the basic rail and the pointed rail in the correct position. When the rail expands and contracts, the point rail moves along the base rail.

Expansion joints are divided into two types: broken line type and curve type depending on the shape of the tip rail. The point rail of the polyline expansion joint is planed into a polyline or a diagonal line and is in contact with the corresponding bent part of the basic rail. The tip rail of the curved expansion joint is cut into a circular curve with a radius of 200~500 m, and is fixed on a large pad. The basic rail is also bent into a curve with the same radius as the tip rail.

1.7 Damping joint

Damping joints, also known as bearing over the joints, refers to the rail joints in the middle part of the line outside the clipboard raised to the level with the head of the rail, when the wheel through the rail seam, damping the top surface of the clipboard and the top surface of the rail at the same time contact with the wheel, damping the stiffness of the clipboard can reduce the wheel through the rail seam of the folding angle and the step to slow down the wheel’s vibration impact, so that the wheel can be a smooth transition to achieve vibration damping effect.

1.8 Welded joints

Rail welded joints refers to the use of welding methods to the end of the rail without drilling bolt holes, unquenched rail welded into a continuous long rail bar rail joints. In order to make the long rail welded head basically reach the mechanical properties of the parent material of the rail, in order to safely withstand the role of the seamless line temperature force, the welding method of the rail can be used steel machine contact welding, rail pneumatic ping and rail aluminium heat swing and so on.

Rail joint coupling parts mainly include joint clamp (fishplate), joint bolts spring washers and so on.

2.1 Joint cleat

The head splint is to withstand the bending moment to transfer longitudinal force, to prevent the rail expansion and contraction of the important parts, requires a certain degree of strength. Many forms of splints, China’s use of slope-supported double symmetrical splints, referred to as double-head type splints.

The advantage of double-ended cleats is that they have greater resistance to deflection and lateral displacement under vertical loads. Each clamp on the bolt hole 6 round holes and oblong holes in between. Circular bolt hole diameter, larger than the diameter of the bolt, the long diameter of the oblong bolt hole is slightly larger than the long diameter of the bolt head protruding under the part. Relying on the difference between the diameter of the circular bolt holes and the bolt diameter of the rail, as well as the difference between the diameter of the circular bolt holes and the bolt diameter of the clamping plate, you can get the required value of the reserved rail gap.

2.2 Joint bolts, nuts and spring washers

Joint bolts, nuts are used to clamp the clamping plate and rail fittings washers are to prevent the bolt from loosening, in order to maintain the integrity and strength of the rail joint.

Bolt according to its mechanical properties are divided into 8.8, 10.9 and 12.9 three grades, its tensile strength of 880 MPa, 1040 MPa and 1220 MPa accordingly. 8. 8 bolt diameter is divided into 24 mm and 22 mm two kinds of bolts; 10.9 bolts diameter of 24 mm, the nut are 10 grade; 12. 9 bolts diameter of 24 mm, the nut are 10H. Grade. In order to make the joint bolt force balance, and prevent the train accidentally derailed by the wheel all cut off, it should be staggered to the line inside and outside the installation, rail joints with elastic anti-loosening washers.

Glory Rail has specialized in the R&D and production of rail clips for more than 20 years. A full range of rail clips is available. Products include road studs for transport rails and clip-type rail fixing systems. Have any needs, just feel free to contact us!