8/11/2019 Air_springs(1).pdf

1/1

RCF/Qlty/TL/01 (22.01.10)

RCF - Leveraging technology for transforming Indian Railways

AIR SUSPENSION FOR MAINLINE COACHES

INTRODUCTION

Air suspension, also called pneumaticsuspension, uses the properties of air for thecushioning effect (springiness). It is a proventechnology on Indian Railways and is beingused on EMUs for last many years. Now thesehave been introduced in mainline coaches withICF bogies because it is technically superior inmany ways;

Provide better ride quality for passengersRide index with air springs is 2.72 against3.37 in steel coil springs (lower the ride indexbetter the ride quality)

Maintain constant buffer height even with

dense crush load on the coaches Improved reliability and less maintenance Isolation of structure borne noises Maintain one natural frequency at all

speeds which reduces vibrations and inturn reduces passenger fatigue

To start with, these springs are being providedon hybrid coaches of Duronto rakes whichhave stainless steel body and conventional ICFbogies. Trials of air springs on high speedFIAT bogies of stainless steel coaches havealso been completed with satisfactory resultsand in due course, all coaches will be providedwith air springs.

WORKING PRINCIPLE OF AIR SPRINGS

Air springs are basically pressurized airchambers made up of rubber bellows whichmaintain constant height under varying loads.The height of the air springs is controlledcontinuously by adjusting the air pressure inthe bellows with the help of a load levelingdevice connected between the bogie frameand the base plate of air springs. The airsprings replace only the secondary suspension,whereas primary suspension continues to usesteel coil springs.

An auxiliary air reservoir of 150 litre capacityis provided below each coach which is fed

CUT-SECTION OF AIR SPRING

from feed pipe through a non-return valve.Driver maintains 7 bar pressure in lococompressor and air springs operate at alimiting pressure of 6 kg/cm 2.

SAFETY OF OPERATIONS

The C&W staff at nominated points and othertrain passing staff should vigilantly see that allthe bellows are in inflated condition. This canalso be checked by seeing that the levelingvalve lever is in horizontal position.

In case of heavy leakage or deflated air spring,the defective bogie is to be isolated with thehelp of isolation valves and driver shouldobserve a speed restriction of 60 Kmph uptoterminal point for maintenance. The airsprings have inbuilt emergency rubber springs

for safety with which train can work at amaximum speed of 60 Kmph up to a distanceof 1000 kms.For further details on air springs and down loadingRDSO maintenance manual, visit TechnicalInformation page on RCF websitewww.rcf.indianrailways.gov.in click here for RDSOmanualhttp://www.rcf.indianrailways.gov.in/works/images

/rcf_docs/RDSO-2009-CG-CMI-01.pdf

Rubber Bellow

EmergencyRubber Springs

Leveling Valve Lever