Question

Why buffers are provided between the bogies of railway train

Answer 1

Thanks for asking the question.
Buffer is a part of buffer-and-chain coupling which is used in railway systems for attaching railway vehicles with one another. Bogies are train carriages used for transporting goods and people. 
Buffer is used t stop the train. Buffer increases the time of impact between the two bogies before they stop, hence, bump is reduced.
Hope it helps.

Answer 2

Answer:

When a train starts or stops , buffer springs increase the time of impact between the bogies decreases .