Air Suspention

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Air Suspension being used in Indian Railways

Text of Air Suspention

Air Suspension In Coaching Stock of Indian RailwaysPresentation By Bhaskar Srivastava

To take advantage of superior technological standard of LHB coaches and keeping the cost low, stainless steel body coach on ICF bogie with Air Spring as secondary suspension (Stainless steel SG coaches) have been introduced.

Cost

effective compared to LHB/FIAT coaches Stainless Steel Shell LHB design shell longer and corrosion resistant ICF Design Furnishing in initial rakes Future rakes will be with LHB type furnishing ICF Bogie Air springs in Secondary Suspension

LHB Features

Stainless steel shell of LHB type CDTS Coupler Sound insulation paint LHB design windows LHB type main door Auto closing vestibule doors Sound insulating floorboard SS plumbing and air brake pipes SS main & aux. water tanks for AC coaches

ICF FeaturesICF Bogie with Air suspension Single flap lavatory door Bogie mounted Brake cylinder Conventional AC unit Conventional electrics Powder coated aluminum ceiling. (instead of FRP ceiling) LP sheet sidewall panels with FRP window cowl. (instead of full FRP panels)

Powder coated conventional ducting. SS square tube partition frames with LP panels. (instead of honeycomb partition frames) FRP doorway ceiling (instead of hard PVC) Fabricated lavatory (instead of FRP module) Glass wool insulation (instead of resonaflex) ICF type furnishing SG version

Roof

sheet and trough floor Austenitic (304) Other members Ferritic (409M) Under-frame Corten steel

LavatoryArrangement

Cabin Arrangement

Coach AC 2 TIER

No. of Seats/Berths in SS coaches 54

No. of Seats/Berths in Conventional 48

AC 3 TIERSCN GS DSLR

7280 99 30 + 4

6472 90 20+4

AC 2T + AC 3T

24 + 48

24+36

Minimum tare load = 50KN Max. Full load = 140 KN

AC and non-AC coaches are in service as Duranto express. Bogie general arrgt. to drg. No. CA00001 and CA00002 are applicable for AC and non-AC coaches respectively. RDSO Spec. No. C-K509 rev-2 for air spring and C-K407 for control equipments. Guidelines for maintenance of air springs have been circulated by RDSO . (CMIRDSO/2009/ CG/CMI-01)

Common secondary suspension for all hybrid coaches for different loads. No compensating rings are required for buffer hight. adjustment. Easy buffer height adjustment by installation lever. Low maintenance. Wheel life increased due to improvement in lateral riding index. 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, thus improving comfort. Improved reliability, reduced maintenance effort. Flexibility to chose characteristics as per requirement at design stage

Coaches with deflated springs not to

be run beyond 60kmph Feed pipe feeds the air for springs and must be active Air spring height/coach clearances to be maintained as per drg no. CA90001. Tighten the lock nut of installation lever after adjustment of spring height/ clearances.

Provide a safety plate for leveling

valve to avoid stone hitting etc. Ensure that all the fasteners are properly tightened. Check the leakage of all air joints and rectify, if required. Ensure that installation lever is in position and tightened properly.

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 levelling valve .

Air spring 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 levelling 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. This mechanism ensures a constant floor height on coaches provided with air springs, irrespective of the load. This greatly reduce problems associated with low buffer / coupler heights.

Bogie Frame & Suspension: Air spring has been installed at secondary stage replacing steel coil springs. A fixed lower spring beam (as cradle) to accommodate the air spring has been provided on bogie bolster. A lateral hydraulic damper and lateral bump stop have been provided at secondary stage. Primary springs have been retained as steel spring. Details are shown in Fig. Leveling valve provided between bogie frame and bogie bolster.

BOGIE GENERAL ARRANGEMENT

Figure: 4

Bogie bolster Provision made for air inlet to air spring. 40 lit addl. Reservoir connected to each air spring. Duplex check valve is provided. Under frame A pipeline is drawn from M.R pipe (feed pipe) for pneumatic suspension One isolating cock, one non return valve, one 150 lit air reservoir (auxiliary reservoir) one air filter and two separate isolating cocks to isolate each bogie have been provided

BASE PLATE Base plate to be used should be as per drawing No. RDSO sketch- K4018 alt 1 is enclosed as fig.5. OPERATING INSTRUCTIONS

Train Driver to maintain 7 bar pressure in compressor. In case of heavy leakage of air from air spring system, Isolate the affected bogie and observe speed restriction at 60 km/h up to the terminal point for maintenance.

Inspect

for any water collection in rubber bellow of air spring Inspect the air spring for any damage or leakage. Inspect air spring seat and top plates for corrosion, if corrosion noticed is paint with primer & black paint.

Inspect all welding joints of the lower spring beam (cradle) and repair if required. Inspect air spring fixing holes of lower spring beam for elongation, if elongated build them to dia.17 mm or dia. 26 mm. Inspect the corrosion on top surface of lower spring beam, Remove the corrosion paint with primer and black paint.

The air spring piping may be checked for any leakage/damage by soap test and repair if required.

"O" rings provided on air spring spigot must be changed. Mount air spring on lower spring beam and match the holes of bottom plate of air spring and holes of lower spring beam. Tight all 4 nut-bolts with the help of M16 Allen key and suitable spanner. Place the bolster on air spring ensuring no damage to spigot of air spring.

Connect levelling valve arm with installation lever. Mount vertical and lateral shock absorber. Connect all flexible/fixed pipe connections of bogie All the threaded joints of air spring be sealed with thread sealing tape to avoid air leakage. The filter of levelling valve must be cleaned.

Connect the hosepipes on the under frame piping with the leveling valves of the bogies. Connect pressure gauges to the drain plug locations of 150-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 kgf/cm2 . Allow air into the air springs to a value of 9.0 kgf/cm2in the pressure gauge by adjusting 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 kgf/cm2 . Release the air completely by dropping the horizontal lever. Remove the packing.

Firstly find out the type of bogie as AC EOG (16 T), AC SG (16T), or NON AC (13 T) coaches and make RCF or ICF. List of relevant drawings are as under:

TYPE OF COACH

ICF DRAWING No.

RCF DRAWING No.

AC EOG(16 T)AC SG(16 T) NON AC (13 T)

WTAC5-0-0-501 (ANNEXURE.-C)LWGSCWAC-0-0-001 (ANNEXURE.-D) LGS-0-0-001 (ANNEXURE.-E) CA00001(ANNEXURE.-F) CA00002(ANNEXURE.-G)

Than the coach should be placed at leveled track. The primary springs should be grouped as per ICF drawing no. ICF/STD-9-0003 placed at Annexure-H, in which the different type of primary springs is grouped for air spring bogie and other type of bogie.

The primary springs used for the air spring bogies as follows:ICF DRAWING No. WTAC-0-1-202 WTAC-0-1-202 WTAC-0-1-202 WLRRM8-0-1-801 RCF DRAWING No. WTAC-0-1-202 AW01101 CC01129

TYPE OF COACH AC EOG(16 T) AC SG(16 T) NON AC (13 T) POWER CAR

Place the proper primary springs and compensating rings in AC EOG,AC SG and NON AC coaches with air spring bogie as per following suspension diagram:TYPE OF COACHAC EOG(16 T) AC SG(16 T) NON AC (13 T)

ICF DRAWING No.WTAC5-9-0-501(ANNEXURE.-I) -

RCF DRAWING NoCA90001(ANNEXURE.-J) CA90001

Than maintain the bogie corner heights as per relevant suspension diagram. After the bogie corner height is maintained, adjust the air spring height as per relevant suspension diagram with the help of installation lever.

After POH and before assembling the bogie, measure the wheel diameter. Depending upon the wheel diameter, place wooden packing of required thickness under the flange of lower spring seat as indicated in the following tab