The devices used to connect rails and sleepers together to form the track are known as FASTENINGs. Following devices are used as fastenings to keep the rails in their correct position
- Fish plates
- Bearing plates.
1. FISH PLATES
The function of a fish plate is to hold two rails together both in horizontal as well as in vertical planes. At each, joint a pair of fish plates is used.
Various types of bolts are used in railroad fitting. Some common types are enumerated below.
With each pair of fish plates two, four or six fish bolts are used. The standard practice is to use four bolts. They are made up of high carbon steel to with stand considerable stresses.
Dog Spikes are used for holding the rail to the wooden sleepers. The spike has smooth sites and depends for its holding power on the friction of wood fiber.
Screws pikes are used for the same purpose as dog spikes but have a much greater holding power than dog spikes approximately double that of dogs pikes.
Round spikes are used for fixing chairs to the wooden sleepers. Their use is limited.
They have the same purpose as round spikes. The fang bolts have greater strength as compared to round spikes as they have threads and also grip the sleeper from the Bottom.
Chairs are used to hold the double headed and bull headed rails in position. Invariably chairs are made of cast iron and they help in distributing the load from rails to sleepers
They are wedge shaped wooden pieces or metal pieces. They keep the rail in proper position. Wooden keys are cheaper, but liable to be attacked by vermins. Hence a number of metal keys have been devised.
5. BEARING PLATES
Chair used for flat footed rails are known as bearing plates. They increase the bearing area on the sleeper and thus decrease the loading-intensity.