How do electric trains brake?

Your question is not clear. Do you mean that how the electric engine hauled train brake system or the working of electric brake(regenerative/dynamic) in the diesel electric and electric engines? read more

Braking system of a train works on the principle of"Vacuum Brakes". On the metallic wheels which are mounted on the axles of each bogie, brake liners are mounted. With the help of spring tension, these brakes are applied. By supplying compressed air, this spring force is overcome and the brakes are released. read more

The train brakes are released by admitting air to the train pipe through the engineer's brake valve. A fully charged brake pipe is typically 70–90 psi (4.8–6.2 bar; 480–620 kPa) for freight trains and 110 psi (7.6 bar; 760 kPa) for passenger trains. read more