Two hundred years will soon come when mankind uses such an amazing invention as a train. Over its rich history, locomotives have managed to gain many features and secrets that not everyone knows about. For example, when a train starts moving, it gives back. This action may seem counterintuitive, but without it the transport may not budge.
Train history
The first models of this transport began to be designed in the early 20s of the XIX century. They were based on a steam engine using coal as fuel. In 1825, the first railway in the UK opened. A small train consisting of a driver’s cab and two wagons rode along it. As an interesting fact, it can be noted that it was called “Locomotion”, after which the people began to call the railway transport “locomotive”.
In 1830, the railway between Liverpool and Manchester opened, and trains for the first time began to transport people along it. If “Locomotion” was engaged in the transportation of only small cargoes, then these trains dealt with several tons of weight, which required to be transported at a considerable speed by those standards. This forced engineers to increase engine power and improve fastening between cars.
At the same time, two facts became apparent: the railway should be laid exclusively in a straight line, bypassing the mountains and ravines, and that before you go forward, you need to pass a little back. And if the first was clear to everyone: it is unlikely that a multi-ton locomotive would climb a steep mountain, then few people thought about the nature of the second. Engineers simply saw: if you don’t turn back, the train does not move, so without hesitation we performed this operation in order to quickly hit the road.
For decades, trains have been modified in every way, become more powerful and faster, but contrary to all expectations, the need to roll back slightly has not disappeared. At a certain point, scientists found a logical explanation for this. As it turned out, it was in elementary physics.
Why do I need to take back?
As mentioned above, if the train does not roll back previously, it will not be able to move forward. To explain this phenomenon is quite simple.
When the locomotive moves forward, it begins to pull attached wagons. The higher their total mass, the stronger the friction force between the wheels and the rails. Accordingly, the harder the composition to move forward. Nowadays, high-speed trains have a powerful enough engine to immediately start moving, but some locomotives cannot boast of this.
When the train leans back a bit, the tensioned clutches between the cars sag. And now, if the driver goes forward, the clutch will not be pulled at the same time, but in turn. Because of this, the cars will also be set in motion in turn. The locomotive will not immediately pull on itself the entire mass of the train, but gradually, one train each.This allows the engine to gain speed, and when the whole train starts moving, it pulls this weight without any problems.
Before starting the movement, the train must be handed back to ease the tension between the cars. Then, at the start, the locomotive will not immediately drag on itself the entire mass of the train, but will increase it gradually, as the clutch tension of each subsequent carriage. This technique allows you to reduce the mass of starting and gain speed engine.
