Types of rails are mainly divided into three. Double headed rails, bull headed rails and flat footed rails. You will come to know all the important details of each of them with figures in the blog.
Let’s start from scratch. What are rails?
What are Rails?
Rails are an important component of railway track. They are the high carbon rolled steel sections, which are laid end- to- end, in two parallel lines over sleepers to provide continuous and levelled surface for the trains to move and for carrying axle loads of the rolling stock.
Let’s deep into the types of rails.
Main Types of Rails
There are mainly 3 types of rails.
1. Double headed rails
Double headed rails indicate the early stage of development. It essentially consists of three parts, such as upper table, web and lower table. Both the upper and lower tables were identical and they were introduced with the hope of double doubling the life of rails.
When the upper table is worn out then the rails can be placed upside down reversed on the chair and so the lower table can be brought into use.
But this idea soon turned out to be wrong because due to continuous contract of lower table with the chair made the surface of lower table rough and hence the smooth running of the train was impossible.
Therefore, this type of rail is practically out of use. Nowadays, these rails vary in lengths from 20- 24.
The rail sections, whose foot and head are of same dimensions, are called double headed rails. In the beginning, these rails were widely used in the railway track.
The idea behind using these rails was that when the head had worn out due to rubbing action of wheels, the rails could be inverted and reused. But by experience, it was found that their foot could not be used as running surface because it also got corrugated under the impact of wheel loads.
Its time to meet the second type of rails which are bull headed rails.
2. Bull headed rails
The rail section whose head dimensions are more than that of their foot are called bull headed rails. In this type of rail the head is made little thicker and stronger than the lower part by adding more metal to it. These rails also require chairs for holding them in position.
Bull headed rails are especially used for making points and crossings. This type of rail also consists of three parts, such as the head, the web and the foot. These rails were made of steel.
The head is of larger size than foot and the foot is designed only to hold up properly the wooden keys with which rails are secured. Thus, the foot is designed only to furnish necessary strength and stiffness to rails.
Two cast iron chairs are required per each sleeper when these rails are adopted. Their weight ranges from 85lb to 95lb and their length is up to 60ft.
That’s it about bull headed rails. Let’s move on to the third member in the list of types of rails, which are flat footed rails.
3. Flat footed rails
The rail sections having their foot rolled to flat are called flat footed rails. This type of rail was invented by Charles Vignola in 1836.
It was initially thought that the flat footed rails could be fixed directly to wooden sleepers and would eliminate chairs and keys required for the BH rails. But later on, it was observed that heavy train loads caused the foot of the rail to sink into the sleepers and making the spikes loose.
Flat footed rails consist of three parts, such as head web and foot. The foot is spread out to form a base. This form of rail has become so much popular that about 90% of railway tracks in the world are laid with this form of rails.
Flat footed rails have the following advantages.
Advantages of flat footed rails
- They do not need any chair and can be directly spiked or keyed to the sleepers. Thus they are economical.
- They are much stiffer both vertically and laterally. The lateral stiffness is important for curves.
- They are less liable to develop kinks and maintain a more regular top surface than bull headed rails.
- They are cheaper than bull headed rails
- The loads from wheels of trains are distributed over large number of sleepers and hence larger area which results in greater track stability, longer life of rails and sleepers, reduced maintenance, costs, rail failure and few interruptions to traffic
We have reached the end of the journey diving through various types of rails.
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