Air Spring Suspension On EMU/DEMU

Air Spring Suspension On EMU/DEMU:

The EMU/DEMU/MEMU coaches are fitted with Air springs in the secondary suspension to maintain a constant buffer height irrespective of loaded condition to give comfortable riding to the passengers.

Bottom bolsters, Stirrup links and Equalizing stays are eliminated. It is provided with an emergency spring inside the air spring to support the bolster in case of air spring fails. Schaku couplers are provided and Side buffers are eliminated.

Air Spring:

• Air spring is a rubber bellow containing pressurized compressed air with an emergency rubber spring providing various suspension characteristics to maintain a constant Buffer height irrespective of the loaded condition.
• In suburban trains like DEMU, the number of passengers entraining (Super-Dense Crush Load) into the coach cannot be controlled and hence the payload of the coach increases from 18 tons to 34 tons.
• This abnormal increase of payload reduces the Riding Clearances between the Coaches and Wayside platforms and also reduces buffer height resulting in severe hitting of the coach on the platforms.
• Due to the Super-Dense Crush Load, the bolster springs become solid, which in turn damages / breaks the Coil springs resulting in discomfort to the passengers.
• To overcome the above problems an Air Suspension (Air spring) is introduced in the secondary suspension to maintain a constant buffer height irrespective of loaded conditions by varying the pressure of air inside the air spring.