Know why trains have sandboxes close to wheels

All of us have the experience of train journey. But most of us may not be aware of several facts about the train and one such is trains having sandbox. For the uninitiated, it may sound strange but it is true. 

We must have heard a hissing sound from a train when it comes to a halt. This sound is related to the sandbox, placed below the bogie and close to wheel with its nozzle opening at wheel-rail contact regions. 

Let’s understand the function of the sandbox.

When the loco pilot applies breaks to stop the train, fine particles of sand from the sandbox sprayed on to the rails. It improves braking system and prevents the wheel from slipping. Thus, a train stops at a short distance.  

There is another situation when the loco pilot goes for applying sand box. This situation arises in winter and rainy seasons or when any lubricant substance falls on railway tracks. 

When wheels made of steel run on metal tracks, a countable friction is created. In winter, dew drops reduce the friction. So is the case when there is rain water or lubricant on tracks. In such situations, the wheels tend to lose grip and slip or spin at one place on the tracks. To avoid this, fine particles of sand are also sprayed on to the tracks. 

The most important fact associated with the sandbox is that it is operated manually. This means, it is the loco pilot who is to take decision when and how long to press the button meant for sandbox.