Rail connection overview - part1: rail joint fastening

Steel rail is an important component of track structure. Steel rail can not only guide the train to run according to the assigned direction, But bear the pressure from wheel, impact force, vertical inertial force and centrifugal force. These entire loads are transmitted to ballast bed through railway sleeper, which can provide resistance for wheel. In the railway, there are some rail connections to connect steel rails or connect rail and sleeper. These track fastenings are used to ensure reliable connection between two steel rails or rail and railway sleeper. By their function, rail connections can be divided into two parts- rail joint fastening and intermediate fastening.

Rail joint fastening

Rail connection can guarantee the connection between two steel rails in a long term. All rail joint fastenings of rail try to keep integrity and continuity of steel rail. Rail joint fastening also prevent steel rail from vertical move relative to railway sleeper. Commonly, rail joint fastening shave good vibration-absorption. Rail joint fastening include rail joint, fish bolt and spring washer, etc.

Rail joint

Rail joint, it is commonly known as railway fishplate. Rail joint is mostly double-end. Upper and lower end face of rail joint is bevel, and its slope is same with rail top and rail bottom. So rail joint and steel rail can fit together. After tightening bolt, there will be a gap between middle of railway fishplate and steel rail web. The gap will increase resiliency of joint. Besides, there are oval eyelets in the rail web and railway fishplate. These eyelets can overcome the thermal expansion and cold shrinkage of steel rails. Therefore, the joints between rails should have a gap less than 5 mm.

Fish bolt

Fish bolt is a fastener that generally used together with railway fishplate. The fish bolt is usually made of high-carbon steel. And diameter of fish bolt should not be too big excessively, which avoid strength reduction of steel rail and rail joint. The bolt consists of head and screw, and it should be cooperated with nut. Fish bolt is used to fix steel rail and railway fishplate. So fish bolt must have enough strength to avoid clipping and bending. Sometimes, bolt is used with a nylon sleeve to reduce vibration.

Spring washer

Spring washer is screwed under nut to prevent nut from losing. Spring washer is made of stainless steel or carbon steel. The spring washer is widely applied in load-carrying structure of mechanical products. The main features of spring washer include low cost, convenient installation. Especially, spring washer is suitable for frequentsetup. As one of the rail joint fastenings, spring washer is usually matched with fish bolt. In a word, spring washer is used to prevent vehicle from losing during running.

Joint is one of the weak links in the track structure, and it has a close connection with railway safety. So Rail joint fastenings play an important role in protecting the rail way safety. In addition to, there are a lot of rail components to keep the rail in gauge. It is different from rail joint fastening what to do, the intermediate fastening is used to fix steel rail and railway sleepers (click for more detail about intermediate fastening).