Lesson 3 Coaches and Wagons In this Chapter there are more details about the coaches used for transport of passengers and wagons used for transport of goods. 1. COACHING STOCK 1.1 There are different types of passenger coaches such as II class, I class, II sleeper, AC3 Tier, AC2 Tier and ACI Class. AC Chair Car, AC Executive Chair Car etc. 1.2 had in 2015-16 a stock of about 8805 EMU plus DMU Coaches and 53132 conventional coaches 6899 other Coaches with a total carrying capacity of about 53.75 lacs passengers. 1.3 Different designs of coaches. (i) Integral coaches built by , Madras (I.C.F.) and Rail Coach Factory (RCF) at Kapurthala. (ii) Coaches built by Bharat Earth Movers Ltd. Bangalore (BEML). (iii) Wooden body coaches of Indian Railway Standard Design (IRS). (Now extinct) (iv) New Type of LHB high speed coaches built by Rail coach factory at Kapurthala plus ICF parambur. 1.4 Some of the salient features of these of coaches are given in table 3.1

Table 3.1: Salient feature of different coaches

Item ICF LHB 1 Type of body Light metal body Light metal 2 Type of structure All metal all welded integral coach having Stainlass steel t tubular construction. 3 Coach dimension Overall width 3245 mm 3250 mm Overall Length 21337 mm 23540 mm Overall height 4025 mm 4250 mm 4. Damage during Less damage because of Very less collisions anti telescopic structure damage and derailments and the end wall absorbs shock.

5. Speed Potential 110 Kmph/140 Kmph 200 Kmph

1.5 Passenger comfort and safety are the key words in the design of coaching stock. Research, Design and Standard Organisation (R.D.S.O.) at Lucknow, Integral Coach Factory (I.C.F) at and Rail Coach Factory (R.C.F.) at Kapurthala are constantly engaged with the task of fulfilling these requirements.In the new second class coaches, seats have been specially designed for comfort providing more space including knee room per passenger, and these coaches have a more pleasant interior more number of fans and more spacious lavatories fitted with mirrors and wash-basins. Two-tier air-conditioned sleeper coaches with a capacity of 46 berths are replacing the first class coaches with a capacity of 24 berths. Double Decker coaches introduced on a limited scale on high density short distance routes have a seating capacity of 144 against 90 passengers in a conventional coach. Latest to be introduced are 3-tier AC coaches with 64 berths. These are replacing A.C. Chair Cars in all long distance trains. High capacity Garib Rath 3 tier AC Coaches & AC Chair Cars have also been introduced.

1.6 Design Features of Modern ICF Coaching Stock 1.6.1 The need for carrying more passengers with greater comfort in every coach, the need for having more coaches in every train and the need to run these trains at progressively increasing speeds has necessitated modernisation of rolling stock. 1.6.2 The coaches manufactured by the Integral coach Factory at Chennai are of Integral design. The coach body is an all metal light weight, tubular structure. The trough under flooring, the sides and the roof are welded to form an integral unit. The floor consists of cross-beams, specially designed headstocks and sole bars etc. which are all welded together. Under the cross-beams runs the steel trough flooring welded to the head stocks and sole bars. The advantage is that a trough section can withstand greater longitudinal loads and still helps to keep the weight down. The curved body of the coach is designed to absorb heavy impact shocks. Further, at the ends, the under flooring is designed to be collapsible so that in case of accidents, the maximum energy of the impact is absorbed there. The tubular structure ensures that the coach does not collapse inwards. Maximum passenger safety is thus, ensured against heavy impacts. The ICF coaches are therefore, called “Anti telescopic”.

1.6.3 Like the coach body, the I.C.F. bogie is also of all welded light weight design with 2396mm rigid wheel base running one roller bearings mounted in pendulum type axle boxes. The axle box guides are fitted with dash pots to damp high frequency vertical vibrations and shock absorbers absorb low frequency vibration. All these fittings and all coiled spring design of the bogies ensures very smooth riding of coach. Lateral shock absorbers absorb lateral shocks. All these fittings and all coiled spring design of the bogies ensures very smooth riding of the coach. (Fig. 3.4)

1.6.4 A new factory RCF-Rail Coach Factory to produce modern coaches has been established at Kapurthala. At present, RCF is manufacturing coaches to ICF Designs and in agreement for TOT (Transfer of Technology) signed with Foreign Manufacturers (LHB- ALSTOM) to undertake manufacturing Modern Light Weight air-conditioned High Speed (with a speed potential of 200kms) stock, new LHB Coaches & hybrid Coaches are also being manufactured at RCF. A third Coach manufacturing unit is also coming up at Rae Barielly.

1.7 Design Features of Modern LHB Coaching Stock Till recently, Indian Railways have been transporting passenger traffic mainly through coaches of ICF design. These type of coaches are having limitations in terms of speed potential and riding comfort.

To overcome these limitations, Indian Railways entered into supply and technology transfer contracts with M/s. ALSTOM LHB/Germany and the bogies for these coaches manufactured by M/s. FIAT/SIG Switzerland. These coaches were commissioned in India in the year 2001. These type of coaches are far superior w.r.t. passenger comfort, safety, speed, corrosion, maintenance and aesthetics. These coaches are also longer as compared to ICF design resulting into more carrying capacity. The expected benefits from these type of coaches are as under:- i Higher carrying capacity - These coaches are about 2 meters longer than ICF coaches. With this extra length one additional bay in sleeper coaches can be accommodated. ii The weight of LHB coach is lesser as compared to ICF design coaches. LHB coach can accommodate 72 passengers as compared to 64 in conventional AC III Tier Coach. Thus giving better pay to tare ratio. iii Low corrosion – There will be low corrosion of LHB coaches due to extensive usage of Stainless Steel and better design and manufacturing techniques. iv Low Maintenance – Replacement and removal of sub-systems will be required only after one million kilometers. v LHB Coaches have aesthetically superior interiors with (screw less) FRP panels for side wall and roof. They can be removed easily for maintenance, resist water seepage and are wear resistant; vi. Better passenger comfort: Better Riding Index has been specified as compared to conventional ICF coaches. Ride index is parameter vii. Fitted with Axle Mounted Disc Brakes with Wheel Slide Protection Device and Brake accelerator for early and effective brake application & release to maintain the speed potential of the train. viii. Coaches are fitted with Controlled Discharge Toilet System (CDTS) – eco-friendly toilets to maintain hygiene in coaches and stations as well. ix. LHB coach offers better passenger safety due to:  Use of fire retardant materials for furnishing.  Provision of emergency open able windows  Large Windows with good visibility  Insulation against noise.  Vertically interlocked Centre Buffer Couplers.  More space for pantry;  Inter-gangway (vestibule fall plate) provided with safety lock to prevent trespassing from outside.

1.8 Important features of LHB coaches which make them superior to existing ICF design coaches are summarized below. 1.8.1 Coach Body LHB coach is light weight construction and is about 10 percent less as compared to the conventional coach resulting into lower haulage cost. Each vehicle is equipped with complete pantry to store hot meals and cold beverages. 1.8.2 Heat and Sound Insulation  Heat insulation of the floor, side walls lower area and end walls with Resonaflex insulating mats.  Noise level inside coach is limited to 60 DB. 1.8.3 Sealed Window Glass Unit i. Emergency openable window: 4 per coach ii. Hopper type windows for lavatory: 4 per coach

1.8.4 Composite Wood Flooring Panels. Flooring panels are lightweight, strong, warp resistant and also resistant to vibration/impact forces. These boards are specially treated for fire resistance. These are also resistant to moisture, cigarette burns, staining, ageing, etc. 1.8.5 Berths / Seats : There are 24 berths in First AC, 52 berths in AC 2 tier and 72 berths in AC 3 tier. 1.8.6 Passenger Emergency Alarm : The Passenger emergency alarm is provided at each bay in the coach.

1.8.7 Fiat – Bogie: The FIAT bogie is an adoption of EUROFIMA design. Bogie is designed for maximum operating speed of 160 kmph and has potential for operation upto 200 kmph. 1.8.8 Dampers : Hydraulic shock absorbers to damp the accelerations caused due to track irregularities and opposing force depending on the speed of the movement. 1.8.9 Center Buffer Coupler Couplers are AAR-H type and have ant climbing features because of vertical interlocking. Couplers have adequate strength for:

 Satisfactory hauling of a train of 26 coaches at 110 kmph  Satisfactory hauling of a train of 18 coaches at 160 kmph The draw gear ensures cushioning effective in both buff and draft. 1.8.10 Lavatories : LHB coaches are fitted with controlled discharge toilet units to avoid soiling of track in station and inhabited areas. The toilet system is designed to operate with a pressurized water bowl wash that covers 100% of the toilet bowl area. The waste is removed from the toilet bowl and transferred to a retention tank with minimal amount of water. Water consumption is only 2.5 liters per flush cycle for the Indian style toilet bowl and 1.5 liters for the European style toilet bowl. LHB coaches have both Oriental and European type of lavatories with controlled discharge toilet system.

Fig 3.2

Parameter Value Unit Axle distance 2560 mm Diameter of new wheels 915 mm Diameter of max. worn wheel 845 mm Distance between the wheels 1600 mm Brake disc diameter 640 mm Bogie width 3030 mm Bogie length 3534 mm Bogie weight 6300 kg

1.8.11 Coupler and Draft Gear.

The connection between two adjacent vehicles within a train set is done by a “Coupler System” consisting of the coupler itself and a draw and buffing gear. The centre buffer couplers used on LHB coaches are tight lock centre buffer couplers of AAR type H. They can be coupled with AAR type “E” centre buffer couplers fitted on locomotives. The centre buffer coupler combines the draw and buffing gear in one. It is able to Transmit both the tensile and the compressive forces. Further the tight lock coupler by its special design, hinders the climbing of the vehicles in case of an accident. The AAR type H coupler is a CBC, enabling automatic coupling in straight lines, in Curves, and also (with some limitations) in the transition between straight lines and a Curve. Main components of the coupler system are:

 Tight lock coupler head (AAR type H) with drawbar.  Drawbar guide (Support) ‐ The Supporting device comprises of four preloaded compression springs. The device is placed on a platform and bolted to the car structure. The coupler head rests on the top wear plate of the Supporting device and this device supports the coupler weight.  Draft Gear‐ The draft gear is a double acting device for energy absorption. The device is designed to fit into the draft gear pocket of the coach and absorbs the dynamic energy in both draw and buff modes. 2. Goods Wagons 2.1 Goods wagons area is primarily meant for carriage of goods traffic. Indian Railways have presently a stock of about 2.73 lac goods wagons with carrying capacity of about 14 million tonnes of goods. These contain mostly covered and open wagons including wagons like BOX type wagons etc for carriage of coal and other bulk traffic. 2.2 It has now been decided to go in for bogie type wagons only as the 4-wheeler wagon is a non- viable unit in the present context of bulk movement of commodities. The special type of wagons have been evolved in order to carry higher loads and with better facilities to unload and load the commodities in the wagons. Axle loads on BG are 20.3t and MG 12t respectively. 2.3 Design features of various types of wagons have been progressively improved. Broad particulars of these wagons designed after eighties are given in Table 3.2 for general guidance. It may be brought out that Vaccum Brake system on the wagons has been replaced with Air-Brake System gradually over the years. Similarly screw coupling is also being gradually replaced with Centre Buffer Type of Coupler. Table 3.2 : BROAD GAUGE WAGONS DESIGNED AFTER EIGHTIES Type of Wogons Code Open covered Flat Tank Hopper Open BOXN BCNA BRN/Rail BTPN BOBN BOXNHS Axle Load (Tonnes): 22.82 22.82 20.3 20.3 22.82 22.82 *TLD (Tonnes/in) 7.59 5.625 5.59 6.54 7.0 7.0 Pay to Tare Ratio: 2.44 2.31 2.47 2.01 2.12 2.44 Brake System: Air Air Air Air Air Air Type of Coupler CBC CBC CBC CBC CBC CBC Bearing Catridge Catridge Catridge Catridge Catridge Catridge Bogie Casnub Casnub Casnub Casnub Casnub Casnub Under Frame Welded Welded Welded Welded Welded Welded Type of Suspension Secondary Secondary Secondary Secondary Secondary Secondary Max. Speed/Kmph 80 80 80 80 80 100 * TLD = Track loading density 2.4 Salient Features of new BLC Wagon 1. Wagon Unit Consist of 5 wagon 6. Coupling CBC & slack less drawbars 2. Platform height R.L. 1009 mm 7. Twist lock Automatic 3. Pay Load 61 t 8. Side bearer Spring loaded 4. Wheal dia 840 mm 9. Brake System Air brake 5. Speed 100 kmph 10. Carrying capacity 45 wagon 3. INDIAN RAILWAY CONFERENCE ASSOCIATION 3.1 After the British introduced railway in this country in 1853, many companies came forward to operate and develop it. There was multiplicity in types of wagons and components with no rationalization in terms of axle load, pay to tare ratio, track loading density etc. In order to bring about some kind of uniformity and discipline in operator among the different company Railways, the British Government set up in 1903, a body called the Indian Railway Conference Association (IRCA) which framed the rules of interchange of traffic among the member railways. When the Railway Board was formed in 1905, IRCA was brought under it. 4. UPGRADATION OF WAGON STOCK 4.1 Standardisation of freight stocks in Indian Railways was started as a necessity to enforce discipline in operation and cut down cost and time of maintenance. It got a flip with the creation of RDSO in 1957. The post-Independence period witnessed successive up gradation in standards of freight stock designs to keep pace with the changing demands of traffic and technological climate. 4.2 The Wagon Directorate of RDSO is primarily responsible for carrying out all developmental as well as standardization works on freight stocks of Indian Railways. Safety being the key consideration in train operation the steps to standardization follows an elaborate procedure of testing, field monitoring and record keeping. For adopting a new design the prototype is made first, which is subjected to testing for strength under static and dynamic loads. Then the wagon is put on instrumented running trial to test its riding and safety in operation on the existing track conditions at different speeds. The oscillation trial fixes the safe speed of the wagon is actual service condition. The field data are recorded and the results of trials are presented to Railway Board with recommendations based on the results, the Board take a decision to accept the design as an Indian Railway standard and permit mass production. 4.3 Requirements for higher speed and load carrying capacity were met through the introduction of roller bearings and centre buffer coupler as new standards and brake system was upgraded by including automatic slack adjuster and empty load adjustment device necessary for effective braking in high speed operation. 4.4 The CBC has a working strength of 85t against 27.5t of screw coupling. CBC has eliminated the need for side buffers used with screw couplings and the need for a man to go in between wagons for attaching them CBC has a knuckle, claw, lock, yoke, draft gear and operating lever. The CBC has improved safety by reducing train partings drastically. 4.5 In the eighties and after, designs like BOXN, BCN, BCNA, BRN, BOBR, BTPN etc. were put on line. They incorporated air brake, cast steel friction damped bogie and cartridge taper roller bearings, high tensile CBC with enhanced working strength of 120T was also introduced. With intent to carry more load in each wagon, modification is form of additional spring were carried out & BOXN MI, BCNMI, BCNAMI & soon wagons were pressed into steed. Now High speed stainless wagons e.g. BOXNHL, BCNHL have also been introduced which are capable of running at higher speeds with higher load. 4.6 Cast Steel casnub bogie with Cartridge tapered roller bearing has been adopted as the standard for all new designs of bogie stocks. Brief details of these bogies are as below 4.6.1 General Description This bogie was first fitted in BOXN wagons and was designated as CASNUB 22W. This was later modified as CASNUB 22W(M) to take care of high wheel wear reported on earlier version. Subsequently CASNUB 22NL (Narrow jaw) and CASNUB 22 NLB (Narrow jaw with fish belly bolster) versions were introduced. The CASNUB 22 HS bogie has been developed for high- speed operation with maximum permitted speed up to 100 km/h.

4.6.2 These bogies are now used in the following wagons:-

Bogie Axle load Type of wagon CASNUB -22 NLB 20.32t& BOXN , BCN, BCNA BOBR, BOBRN, BRN, BRNA, BTPN, BTPGLN, 22.9t BOBYN, BOBSN, BOY etc and M1 variant of above. CASNUB -22HS 20.32t& BOXNHS, BCNHS, BCNAHS BOBRNHS, BRNHS,BOST, BOXNHL 22.82 BOXNLW etc and M1 variant of above CASNUB - 20.32t& BOSTHS, BOSTHS M1 22HS(Mod-1) 22.32t CASNUB - 22.32 t BOSTHS M2 2HS(Mod-II) CASNUB-22 NLC 25.0 t BOBRNEL, BOYEL, BOXNEL IRF-108HS 22.82t BOXNHAM

4.6.3 Construction Details

The bogie comprises of two cast steel frames and a floating bolster. The bolster is supported on the side frame through groups of nested helical springs. This also provides a friction damping proportional to load. A fabricated mild steel spring plank connects the side frames. A photograph of BOXN-RHS wagon is as shown in Figure 3.4. Figure 3.5 the CASNUB bogie general arrangement.

Figure 3.4: Photograph of BOXN Wagon

Figure 3.5: CASNUB Bogie – General Arrangement (CASNUB 22W Bogie)

1.4 The salient features of CASNUB Bogie:-

SN Feature Description 1 Gauge 1676 mm 2 Axle load 20.3 t, However all bogies except CASNUB 22HS can be upgraded up to 22.9 t 3 Wheel diameter  1000 mm (New)  956 mm (New) for Retrofitted CASNUB 22 W  906 mm (Condemn) for all types.

4 Wheel base 2000mm (+/- 5mm) 5 Type of Axle CASNUB 22W & 22W(M): Bearing Standard AAR Tapered Cartridge Bearing Class E suitable for 144.5 x 277.8 mm wide jaws. CASNUB 22NL,22NLB & 22 HS: Standard AAR tapered Cartridge Bearing Class E suitable for 144.5x277.8 mm narrow jaw 6 Distance between 2260 mm journal centres 7 Distance between 1474 mm side bearers 8 Type of side  Retrofitted CASNUB 22W, CASNUB 22W(M),22NL, 22NLB:-Constant bearers contact type (Metal bonded rubber pad, housed inside side bearer housing)/PU Type  CASNUB 22HS: Spring loaded constant contact type/PU Type side bearer.

9 Type of pivot  CASNUB 22W:- IRS Type Top Pivot - RDSO Drg. No. W/BE-601, Bottom Pivot– RDSO Drg. No. W/BE-602 or similar mating profile integrally cast with bolster.  CASNUB 22W(M), 22NL, 22NLB, 22 HS :-Spherical Type to RDSO Drg. No. WD-85079-S/2

10 Pivot pin  CASNUB 22 W, WR :Head less pin  CASNUB 22WM: Castle nut pin  CASNUB22NL,WM : Shackle type with 173mm height  CASNUB 22NLM,NLB&HS : Shackle type with 149mm height

11 Anti rotation Anti rotation lugs have been provided between bogie features bolster and side frame 12 Type of brake  CASNUB 22W, 22NL, 22NLB, 22 HS: Unit type fabricated brake beam beams supported and guided in the brake beam pockets. CASNUB 22W(M) : Unit Type Cast Steel brake Beam suspended by hangers from side frame bracket. Air brake systems and centre buffer couplers are the same for all air brake bogie stocks. 

13 Suspension details Long travel helical spring

6.1 Load Bearing Springs and Snubber Springs The different types of coil springs used in casnub Bogies in the Secondary Suspension. On each Bogie frame rests a nest of seven (outer and inner) coil springs and two simple coil snubber springs on each side; thus making a total of 32 coil springs for each bogie (latest Design). And 64 for each ‘N’ type of wagon. The bogies are fitted with two groups of long travel helical spring nests. The spring details are shown in fig 3.6. These springs are provided to transfer the load from the bolster to side frame. Bogie during movement of the track may have to pass through track irregularities causing more impact load. Moreover rocker action of bogie due to twist in the track can be avoided by providing springs.

Fig 3.6 types of springs and their location The bogies are fitted with two groups of long travel helical spring nests. The spring details are shown in fig 3.6. These springs are provided to transfer the load from the bolster to side frame. Bogie during movement of the track may have to pass through track irregularities causing more impact load. Moreover rocker action of bogie due to twist in the track can be avoided by providing springs.

5. FURTHER UPGRADATION 5.1 The designs are constantly under review for improvement. They are updated to incorporate changing demands of operation, service feedback, and modernization in allied fields like Permanent Way, Signaling, terminal facilities, and developments of new and more economical materials, improvement in manufacturing technology and improvements in welding technology. The new wagons have welded design as opposed to riveted designs of the past. Development of low tare weight wagons is being given priority. It benefits in two ways: firstly it increases the carrying capacity per wagon for the axle load and secondly, it saves on energy in empty movement. Use of polymers in place of metals in selected areas is being pursued. To start with bushes made of Nylon-66 have been adopted as standard in the brake rigging to replace steel. Efforts are on to uses high tensile corrosion resistant steel and cold rolled thin sections instead of hot rolled sections in the construction of wagons underframe to reduce the tare weight. Development of bogie mounted brake to eliminate elaborate brake rigging is again directed towards this goal. Raising the axle load to 25 tons from the present level of 22.9 tons to utilize the present maximum track loading density of 8.25 tons/m in BG has been developed recently. 5.2 SPECIAL TYPE OF WAGON FLEET Type of Wagon Brief description BOX High-sided open bogie wagons with side discharge arrangement for transport of coal and other bulk traffic. BOY Low-sided open bogie wagons to carry Iron Ore. BTPN Tank wagons for liquid consignments like Petroleum products, Molasses, Vegetable Oils. BFKI Flat wagons to carry containers for door-to-door service. BCX Water-tight covered wagons for food grains, cement etc. BOBX/BOBX Open hopper wagons with bottom discharge arrangement to carry ballast, ores etc. BOX ‘N’ High-sided bogies open wagons with improved components like cast steel bogies, high tensile couplers, Cartridge taper roller bearing, air brakes etc. for enabling greater trailing loads for movement of bulk Commodities like coal, iron ore etc. BCN Water-tight covered bogie wagons with cast steel bogies, cartridge tapered roller bearings and air Brakes. BOXNHS Similar BOXN with maximum speed of 100kmph. BLCA/B Special open flat wagons with small dia wheel for carrying ISO containers having speed potential of 100kmph. BCCN Double decker bogie covered wagon for automobile cars low platform, 100 kmph speed. BVZ1 Guards Brake Van. 6. PRINCIPLES OF MAINTENANCE 6.1 The economic life-span of a coach or a wagon has been prescribed as 25 years and 36 years respectively. In order to keep them in running condition all through the life span, the coaches and wagons, go through cycles of periodic maintenance: The basic principle followed under the “preventive Maintenance System” is that necessary attention is paid before deterioration sets in and results in service failure. The preventive Maintenance as applied to the coaches and wagons on the railways is classified under the following heads:- (i) Periodical Overhaul in the Workshops. (ii) Scheduled Maintenance in Carriage & Wagon Depots including Routine over haul (ROH) of wagons in wagon depots. (iii) Running repairs at terminals or yards. 6.2 Periodical Overhaul (POH) (a) Coaching Stock: Coaching stock is periodically overhauled in the workshops at prescribed intervals as applicable to the type of service on which it is used. The periodicity for POH varies from 18 months to 24 months. Such overhaul consists of lifting, thorough examination of all components and execution of such repairs as may be necessary to enable the vehicle to be in service until the next periodical overhaul. On integral steel bodied coaches, it is to be ensured that the body panels, roof, ventilators, steel trough and structural members are free from cracks and corrosion. Similarly, the other parts of the vehicle i.e. wheel, roller bearings, buffing-gear brake gear, electrical equipment, suspension, amenity fittings etc. are thoroughly attended. The Coaches are fully painted. (b) Goods Stock All Goods Stock is periodically overhauled at prescribed intervals as shown below for different types of stock. (Table 3.3) Table 3.3 PERIODICITY OF POH OF GOODS STOCK S.NO. Typ. Of wagon Period of First POH Period of Subsequent POH 1. Brake vans 2 years 2 years 2. Departmental Stock etc. 4 years 4 years 3. BOXN 6 4.5 years 4. BCN/BCHA 6 6 years 5. BTPN 6 6 years 6. BLC Container 6 4.5 years The overhaul consists of lifting, through examination of all parts of the wagon and execution of such repairs as may be necessary to enable the wagon to run for full period till the next overhaul. The tank wagon barrels and valves are specially tested according to prescribed methods. 6.3 Scheduled Maintenance 6.3.1 Coaching Stock: (a) Between consecutive overhauls, the coaches undergo a schedule called “Intermediate Lifting” or I.O.H. in coaching depots. This is normally done after nine months the last P.O.H. During this lifting, trolleys, suspension & brake gear, etc. are thoroughly examined and necessary repairs and replacement of components of the running gear are carried out. The side bearer/centre pivot oil is also replenished. I.O.H. is normally adopted for all coaches fitted with roller bearings. (b) On the coaching stock, the type of service determines the standard of maintenance required. Therefore, the coaches are formed into “Block Rakes”. Block Rakes of different Mail, Express and Passenger service are identified with the service and “Block Rake Links” are formed to facilitate proper maintenance at the terminals. (c) The terminal maintenance of block rakes is further classified into (i) Primary and (ii) Secondary maintenance, Primary maintenance covers thorough washing and cleaning, thorough examination and repairs to under gear fittings, examination of alarm chain apparatus, air brake systems, examination of vacuum brake systems, flushing of water tanks, spray of disinfectants etc. Primary maintenance is given at the terminals where the rakes are based. (d) Secondary maintenance is given at the other and terminals. It covers all items which affect passenger safety and comforts and the safe running of the train. In addition to this, safe-to-run examination is given at nominated intermediate stations. As the term implies, these ‘safe-to-run examinations’ cover check of safety items such as hot boxes, loose fittings in the under gear, leakage in the vacuum/air brake pipes etc. (e) In the washing line, every coach is thoroughly washed and cleaned both externally and internally. Lavatories are washed scrubbed and disinfected. All interior fittings are checked for proper functioning, appearance and cleanliness etc. Complaints from passengers regarding carriage fittings such as safety catches, door latches, bolts, lights and fans, cleanliness etc are attended. Thus a block rake is thoroughly checked and attended to in all respects before it is placed on the platform.

(f) Running Maintenance at Terminals/Yards: Rolling stock is on move mostly all the time. It has, therefore, to be looked after all the time. Since the major schedules such as overhaul etc. are given only when due and for which the stock gets temporarily immobilized, the normal running attention is given at terminals and yards. The main activity under this maintenance is ‘examination’ or ‘inspection’ of the train consisting of coaches or wagons. This examination is carried out in two stages. Stage I. At the approach point of the terminal or yard when the train is still moving (Rolling in examination). Stage II. At the terminal or yard where the train normally stops. The first stage of the inspection helps detect those defects of the undergear that are indicated by unusual sounds of disjointed/broken/hanging components. For example a “flat tyre” will be indicated by heavy thudding on the rails as the train passes. Each coach or wagon is than thoroughly examined at the second stage and all the defects both exterior and interior that are found are recorded for rectification. Coaches or wagons found with defects that can be attended to only in maintenance depots are marked for being placed there The remaining coaches and wagons are attended to at the terminal (washing line or in the yard itself). 6.4 The Maintenance Schedule for Wagons (a) The maintenance scheme adopted by Indian Railways is common throughout all Zonal Railway Systems and is broadly akin to the European system of fixed period attention, supplemented by yard examinations, In general wagons are given Routine Overhauls (ROH) and Periodic Overhauls (POH) at intervals determined for each wagon type, which are carried out in wagon depots & workshops respectively. The ROH and POH overhauls call for mandatory stripping down of equipments irrespective of condition. So far as Air brake vehicles area concerned this mandatory work includes a complete bogie and brake gear dismantling and reassembly. Intensive Wagon Examination is undertaken on empty wagons at yards. Enroute examinations are not undertaken. The examination is generally of 4 types. Premium examination valid for 12 days, CC examination valid for 30 days or 6000 kms, intensive examinations valid from End to End & safe to Run examinations. The wagons are given Routine Overhaul (ROH) at selected maintenance depots at intervals of 18 months. The wagon body is lifted and bogies (trolleys) are run out. All components are examined and repaired. The spring and brake gear are attended and bogie alignments checked. All type of wagons also go through R.O.H. (b) Examination of Wagons in Yards Examination at yards is undertaken by teams of approx. 16/20 persons working on both sides of the wagons and under the supervision of a SE/C&W, the team having specialist personnel for:- (a) General Examination (b) Checking brake power, brake gear, Air/Vacuum brake cylinders. (c) Preparation and signing of the brake power certificate (which is then given to the train crew). The examination is invariably undertaken on empty wagons, before loading at departure points and after unloading at arrival points. Supervisors ensure that loading is secure and doors are closed. The focus of yard examination attention is on the underframe equipment. Particularly the brakegear and suspension. (C) Sick Line Repair Yards examination give rise to a number of detachments for out of course defects requiring repair beyond the capabilities of the yard staff. These detachments are generally repaired at specially designated areas called “Sick Lines”. All ROH depots have sick lines. Sick line repaired vehicles are identified by the examiner with chalk marks on body side panel at the end of the vehicle. This also gives instruction to the yard and operating staff to detach the vehicle for repair. 6.5 There are few schedules common to coaching and goods stock. Vacuum brake cylinders fitted on the stock are overhauled at intervals of 18months for coaching stock and 18 to 24 months for goods stock. There are many other schedules such as “Alarm Chain Apparatus Testing, Checking, Filling of Hydraulic Dashpots” “Tank wagons Valve Testing” etc., which are executed in the maintenance depots at the prescribed frequencies. 6.6 P.R.O. Plates 6.6.1 Since the overhaul and scheduled maintenance are to be executed at prescribed periodicities, some indication of the reference dates of such execution on the stock becomes necessary. Each coach and wagon is, therefore, fitted with a P.R.O. plate, the letters stand for:- P. Date periodically overhauled (POH). R. Date of repacking now ROH date O. Date of Oiling (Plain bearing axle boxes). The “Station Code” of the place where these events occur is also indicated before the date. In modern roller bearing stock only P & R are indicated to show POH & ROH dates and place. 6.6.2 Return Date: - Each wagon is marked with a return; date (month and year) on which it is required to be sent for periodical overhaul. Wagons become due overhaul from the last day of the month indicated in the return date. The return date is painted on the left hand top corner of each wagon. The other markings on the wagons indicate the owning railway, the type of wagon, its tare and its carrying capacity. In the case of the coaching stock, the markings are painted in a block stenciled on the left side of the end panel of each coach. 6.7 Coach or Wagon Failures. The maintenance depots cannot attend to all the break down or failures of rolling stock. Breakdowns are, unusual incidents, resulting either from human or equipment failure. Some of these break downs can result in accidents. They are attended to in workshop under the head NPOH. 6.8 Hot Box or Hot Axle The most Prominent failure of coach or a wagon is that which occurs due to the axle box running hot or “HOT BOX”. Any journal (that part of the axle at its ends. Which bears the weight) when running warm and necessitates a coach or wagon being detached from train from its journey to its destination is considered a Hot Box. In conventional plain bearing boxes, hot box is often caused by break in oil film between the journal and the brass. In roller bearing axle boxes, hot box is a result of seizure of the bearing. Any wagon, if allowed to run with hot box, may cause axle breakage and derailment. Other causes for a coach or wagon to be detatched could be (a) wheel defects, (b) spring breakage, (c) bogie defects etc. After a coach or wagon is declared unfit, it is often repaired in the nearby carriage and wagon depot sick line.

6.9 Wheel Skidding or brack binding Wheel skidding takes place on coach/wagon wheel(s) when the braking force applied on the wheel(s) is greater than the reaction force generated due to adhesion (friction) between rail and the wheel(s). It also occurs when brakes on the wheel does not get released after stopping of the train and train starts moving again. This results in longitudinal sliding of the wheel, which keeps on moving forward at speed less than commensurate with actual longitudinal speed of the coach/wagon. It can result in total stoppage of rotation of the wheel resulting in formation of flat spots. Wheel skidding results in damage to coach/wagon wheel initially that is formation of flats. If a large wheel flat is continued to run on a train, it produces undue high stresses on the rail as well as components of the bogies.