Trains have been a fast and cheap mode of transportation in the present world. But, the need for trains arose first in the 16th century when coal mines were growing rapidly and the need to transport coal to various locations in a very short time became challenging.
WAGON WAYS
Around 1568 German users started using “Hund” carts with unflagged wheels running on wooden planks which keep the carts to go in one particular direction and also reduces friction making the transport of coal easier. Wagonways improved coal transport by allowing one horse to transport between 10-12 tons of coal per run.
TRAM WAYS
During the Industrial Revolution, the wooden rails were covered with iron to increase the life of the rails and reduce friction. But, this led to more wear on the wooden wheels of the wagons. Also, this Iron sheath over the wooden rails couldn’t prevent buckling under the passage of heavy loaded wagons. Thus, finally the rails driven by horses were made completely using cast iron in 1767 to facilitate proper passage and diminish maintenance costs.
STEAM TRAINS
Steam Locomotives produces its pulling power using a steam engine. These are the first type of trains that replaced the use of horses to drive the wagons/carts. Major evolution can be seen in steam locomotives caused by the rapid development in steam engines over time.
We can have a look at different changes in steam engines as follows:
PULLMAN’S SLEEPING CAR
The railroad sleeping cars were built and operated on most U.S railroads by the Pullman Company. These sleeping cars made long distance travelling convenient for the people. A standard Pullman design has around ten open sections, one drawing room, and one compartment.
ELECTRIC ENGINE LOCOMOTIVE
The first electric locomotive was built in 1837 by Robert Davidson powered by galvanic cells. Later a 7 ton vehicle with two direct reluctance motors with fixed electromagnets was made which exhibited a speed of 6kmph. Due to the limited power of batteries its use is prevented. Then, the first electric tram line was opened in 1879. Electricity became the power supply of most of the street rails by the early 1900s. Later, three phase AC tramways were constructed between 1896-98.
DIESEL ENGINE LOCOMOTIVE
We have the prime mover as a Diesel engine designed by Rudolf Diesel in 1898. Later on with steady improvements in diesel engine design the engine size was reduced and power-weight ratio improved to a point that these can be used in locomotives.
First, Internal combustion engines were used but these worked efficiently in limited torque ranges. Thus, low power gasoline engines are forced to be used in locomotives because high power engines would need development of new modes of transmission as the clutches would be very large at this high power level.
Diesel-Mechanical Engine Locomotives:
This type of transmission is generally limited to low-powered, low speed shunting (switching) locomotives, lightweight multiple units and self-propelled railcars. This is limited by the difficulty of building a reasonably sized transmission capable of coping with the power and torque required to move a heavy train.This hasn't been a successful model but had several attempts to use in high power applications.
Diesel-Electric Engine Locomotives
These locomotives use diesel engines that drive either an electrical DC generator(<3000HP) or an AC alternate rectifier(~3000HP). This output is connected to traction motors which are connected to the wheels and move the locomotive. There were several developments that took place in propulsion systems, dynamic braking, traction inverters,.... And resulted in present day modern diesel-electric locomotives.
MAGLEV
Basically works on the principle of Magnetic Levitation. It has two sets of magnets, one set to repel and move the train up(levitate the train) and the other set is to move the train forward. These can accelerate and decelerate much faster than conventional trains. The highest speed achieved by a maglev train is 430kmph by the Shanghai Maglev train.
Limitations : Comfort and safety of passengers and costly to establish the rail track ways though maglev vehicles are cheaper to manufacture and maintain.
HYPERLOOP
Hyperloop will have passengers or cargo placed in a floating pod which would runalong inside low pressure tubes. Most of the air is removed from the tubes to minimize friction, which allows the hyperloop pods to achieve top speeds around 750 mph. This hyperloop will be 2-3 times faster than the present high-speed maglev trains. At a speed of 750 m/h or higher, the drag resistance of a Hyperloop system - which can be operated at significantly higher speeds than conventional high-speed trains (ICE) is already expected to be lower than the drag of a commercial aircraft.
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