Maintenance Manual AC DC EMU (Siemens) PDF

CAMTECH/E/13-14/MM AC-DC EMU/1.0 1 CHAPTER 9 SUSPENSION 9.1 SUSPENSION The bogie features two types of suspension, a primary and...

CAMTECH/E/13-14/MM AC-DC EMU/1.0 1 CHAPTER 9 SUSPENSION 9.1 SUSPENSION The bogie features two types of suspension, a primary and a secondary. The primary spring are arranged in parallel as coil springs. Fig.: Primary spring suspension Each coach having two bogies provided with 16 Nos. of metal bonded conical rubber spring (8 Nos. per bogie) between the bogie frame and axle box which acts as a primary suspension system. Each metal bonded conical rubber spring is subjected to variable, heavy duty dynamic loading in vertical, lateral and longitudinal direction during running. To increase ride comfort, a secondary spring was fitted. This type of suspension is an air spring suspension. In the event of a defect (mechanical damage), this can be disabled via a shut-off valve. This is located below the body. The bogie was equipped with an air spring valve. This ensures that the same body height is maintained independent of additional load. Furthermore, additional damping was provided on the secondary spring in the form of an hydraulic shock absorber to avoid rocking movements. Fig.: Secondary air spring suspension Maintenance Manual for AC-DC EMU (Siemens) Chapter 9 2 CAMTECH/E/13-14/MM AC-DC EMU/1.0 9.2 AIR SUSPENSION (Ref: CMI-9802 (Rev.2), February 2008) Carriage Directorate of RDSO has issued CMI-9802 (Rev.2), February 2008 for “Maintenance Instructions on Air Suspension for DC, AC & AC-DC EMU/HHP DMU Coaches”. This CMI may be referred for details. 9.3 WORKING PRINCIPLE OF PNEUMATIC (AIR) SUSPENSION Air suspension is a suspension where properties of air are used for cushioning effect (springiness). Enclosed pressurized air in a pre-defined chamber called air spring, made up of rubber bellow & emergency rubber spring, provides various suspension characteristics including damping. Air springs are height-controlled load leveling suspension devices. With changing loads, air spring reacts initially by changing the distance between air spring support and vehicle body. The height monitoring valve (called leveling valve) is in turn actuated, either taking the compressed air pressure to the air spring or releasing air pressure from it to the atmosphere. This process continues until the original height is restored as shown in figure given below: Working Principle of Pneumatic (Air) Suspension Chapter 9 Maintenance Manual for AC DC EMU (Siemens) CAMTECH/E/13-14/MM AC-DC EMU/1.0 3 This mechanism ensures a constant floor height on coaches provided with air springs, irrespective of the load. This greatly reduces problems associated with low buffer/ coupler heights. 9.4 ADVANTAGES OF AIR SUSPENSION Capable to sustain Super Dense Crush Loads typical of suburban traffic. Maintain constant floor height of coach. Provide superior ride comfort. Virtually constant natural frequency from tare to full loads, reducing passenger fatigue. Isolation of structure borne noise, this improving comfort. Improved reliability, reduced maintenance effort. Flexibility to choose characteristics as per requirement at design stage. 9.5 CHARACTERISTICS FEATURES OF AIR SUSPENSION Soft flexible characteristics in vertical direction - Achieved by compression of air. Excellent lateral spring characteristics, as desired - Achieved by variation in effective area in lateral direction. Avoids excess air consumption due to instantaneous modes of vehicle oscillation or change in air pressure - Achieved by designing delayed reaction leveling valve. Maintenance Manual for AC-DC EMU (Siemens) Chapter 9 4 CAMTECH/E/13-14/MM AC-DC EMU/1.0 9.6 CONSTRUCTION DETAILS Construction details of air spring are shown in figures given below for air spring with outside emergency spring & air spring with inside emergency spring. AIR SPRING WITH OUTSIDE EMERGENCY SPRING AIR SPRING WITH INSIDE EMERGENCY SPRING Chapter 9 Maintenance Manual for AC DC EMU (Siemens) CAMTECH/E/13-14/MM AC-DC EMU/1.0 5 9.7 SCHEMATIC LAYOUT OF PNEUMATIC SUSPENSION CONTROL EQUIPMENT A schematic layout of pneumatic suspension control equipment has been provided in Fig.7 at page no. 17 of CMI 9802 which is reproduced below: 9.8 OPERATING & MAINTENANCE INSTRUCTIONS Operating Instructions o Motorman to maintain 7 bar pressure in compressor. o In case of heavy leakage of air from air spring system, Isolate the affected bogie and observe speed restriction at 50 kmph up to the terminal point for maintenance. Inspection & Maintenance Of Air Spring o Inspect for any water collection in rubber bellow of air spring. o Inspect the air spring for any damage or leakage. o Inspect air spring seat and top plates for corrosion, if corrosion noticed, paint with primer & black paint. Inspection of Pipe Line o The air spring piping may be checked for any leakage/damage by soap test and repair if required. Inspection & Maintenance of Lower Spring Beam o Inspect all welding joints of the lower spring beam (cradle) and repair if required. o Inspect air spring fixing holes of lower spring beam for elongation, if elongated build them to dia.I3 mm or dia. 22 mm. o Inspect the corrosion on top surface of lower spring beam, Remove the corrosion, paint with primer and black paint. Maintenance Manual for AC-DC EMU (Siemens) Chapter 9 6 CAMTECH/E/13-14/MM AC-DC EMU/1.0 Test for Leakage Connect the hosepipes on the under frame piping with the leveling valves of the bogies. Connect pressure gauges to the drain plug locations of I50-litre reservoir. Provide packing in the gap between bolster & bogie frame. Connect the 150-litre reservoir on the under frame to the compressed air source of pressure 9.0 kg/cm2. Allow air into the air springs to a value of 9.0 kg/cm2 in the pressure gauge by adjusting the horizontal lever of the leveling valve and keep it in the same position. Close the isolating cock connecting MR pipe with 150 litre reservoir. Test all pipe joints for leakages. Check the pressure gauge readings after one hour. The pressure drop should be within 1% of the test pressure 9.0 kg/cm2. Release the air completely by dropping the horizontal lever. Remove the packing. Chapter 9 Maintenance Manual for AC DC EMU (Siemens)