Multiple Units (EMU/DMU) and other self-propelled vehicles
Q. What does the term "multiple unit" or "MU" mean, and what is an EMU or DMU?
There are two senses of the phrase "multiple unit" to be distinguished. Two or more regular locomotives may be coupled together for greater hauling capacity. In such a cases the locos are said to be operating as multiple units, or to be "MU'ed together" (US terminology: "lash-up").
This is not to be confused with the terms electric multiple unit (EMU) or diesel multiple unit (DMU) which refer to cars used for (mostly suburban) train services which have multiple prime movers (either electric motors or diesel engines) for each car. I.e., the same car that carries passengers also has the motive power, as opposed to the normal situation where the passengers are in coaches that are not self-propelling and a locomotive hauls the train.
Q. What kinds of electric multiple units does IR operate?
Note: For information on the suburban / metro systems in different cities, please see the metro section. This section is concerned specifically with the features of the EMU/DMU cars used on such systems.
IR has electric multiple units in operation in several suburban sections (Mumbai, Chennai, Calcutta, Bandel-Katwa, etc.).
The Mumbai region with 1.5kV DC traction has several models of EMUs, classified from WCU-1 through WCU-15 (and beyond??). Most models have DC traction motors with rheostatic control (resistance banks to vary the input power supply). DC EMUs are also used on the Lonavala-Pune section. Information on the precise differences among various older EMU classes is lacking.
EMUs for the 25kV AC sections have classifications WAU-1 through WAU-4 (and beyond??), as well as some MG units classified in the YAU series. Information on the precise differences among various older EMU classes is lacking.
ICF has been building 9-car AC-DC EMU rakes for Mumbai's system. [10/02]. BHEL has also developed [7/00] some AC-DC EMUs for use in the Bombay area in both the 25kV AC and 1.5kV DC traction regions. The new AC-DC EMUs also have 3-phase induction motors and thyristor control. Recently [1/01] WR has signed a contract with Alstom to convert some of the existing 1.5kV DC EMUs to operate with both AC and DC traction power. The first such rakes were already in regular use in 2001-2002. These Alstom AC-DC EMUs have retrofitted pneumatic secondary suspension, a new feature in Indian locos or EMUs (although some WR DC EMUs also have retrofitted pneumatic suspension). Most of the converted rakes are ICF-built. AC-DC rakes are now  in widespread use, including for the Lonavala-Pune section.
AC-DC EMUs built by TRAXX (later acquired by Alstom) and coach bodies built by ICF have 3xx series numbers, while the Alstom-retrofitted or ICF-converted) have 9xx series numbers. EMUs from the two series cannot be coupled together because of differences in the electrical cable connections. All the AC-DC coaches have provision for regenerative braking. The 9xx series rakes fail over to electropneumatic braking directly if regenerative braking does not work, while the 3xx series rakes first fail over to dynamic (rheostatic) brakes first before failing over to the electropneumatic brakes. MRVC rakes (see below) fail over to electropneumatic brakes when regeneration is not possible.
Newer AC-DC EMUs built by ICF have some additional ergonomic features for passengers. Early prototypes had somewhat different seating configurations (2x2 and 3x2), but all production units have regular 3x3 seating. They are factory-fitted with pneumatic suspension. The rakes for these will have 12 cars, and the rated max. speed is 100km/h. Some of the prototypes were [1/03] being tested in the Chennai Beach - Tambaram section, with fuller trials later [11/03]. A full AC-DC EMU rake (the 9th) was being tested [12/04] in Mumbai and had three coaches with trial designs with varying seating arrangements. The windows are nearly one and a half times the normal size. There are roof-mounted blowers for forced ventilation. Other ergonomic options being tried out are the positions of the grab poles, differences in the materials used for the floor, seats, and handles, and variations in the internal lighting.
Most EMU coaches for WR and CR, including the new AC-DC EMUs, are now manufactured by ICF, Perambur. ICF originally began building trailer coaches in 1962 and motor coaches in 1963. Initially, ICF classified these as 'AC EMU B' for motor coaches, 'AC EMU C' for trailer coaches, and 'AC EMU D' for trailer coachs with vendor compartments. There were also a variant trailer coach class 'AC EMU A' but this was merged with the 'D' class later. The newer Calcutta Metro coaches use traction equipment that is similar to that used in the AC-DC EMUs and are also manufactured by ICF. Jessop & Co. build AC EMUs with traction equipment from Bharat Heavy Electricals (BHEL). A few Jessop-built 9-car EMU rakes are now [9/04] in use on the regauged Chennai Egmore - Tambaram section. The coaches of the chopper rakes (see above) are also by ICF (were some by Jessop?). Bharat Earth Movers (BEML) also used to manufacture some EMUs. The BEML coaches have a lower height as they comply with the old IRS standards (like the old ICF coaches), older bogies (although many of the surviving ones have been retrofitted with Flexicoil bogies), and a tapered body profile at each end.
Some variations of the standard EMUs exist in the Mumbai area, including some stainless steel rakes (one ordered by MRVC / WR for field trials ). The stainless steel shells were developed to avoid the problem of corrosion in the coastal climate of Mumbai. Known as the 'Tanaka' design, these shells designed and developed by ICF have a straight sidewall, a simplified design of the sole bar to eliminate places prone to corrosion and to make it easier to inspect and paint. The steel used is a ferritic stainless steel (AISI 409M) in the sole bar, body pillar components, and in the side wall up to a height of 600mm. The trough floor uses an austenitic stainless steel (AISI 301). Apart from the corrosion-resistance features, these EMU coaches also sport somewhat larger windows than the normal EMU coaches. There are other one-off experiments such as a stainless-steel driving trailer at Mahalaxmi that can be coupled with 3xx series EMU rakes. A Millennium Rake was introduced on Oct. 17, 2005, with enhancements such as forced ventilation with 32 fans instead of the normal 24, and audio-visual indications in the coaches of the current location, next station, platform direction, etc. (using GPS technology).
 Titagarh Wagons and Jessop have started production of newer models of EMU coaches with stainless steel bodies.
The regular BG EMUs in operation in several suburban areas are somewhat wider (12') than usual (WAG-5 is 10'8", by comparison). Hence they cannot be used in many places where the clearances are not sufficient. The coach weights range from 118t to 130t. Bombardier and other companies are involved in a proposal [4/03] to manufacture some lighter weight stainless steel coaches (112t or less).
New rakes are being inducted for Mumbai's suburban network to replace the old rakes as well as to add more capacity. These rakes are being purchased under the Mumbai Urban transport project (MUTP). Mumbai Railway Vikas Corporation Limited (MRVC) is the executing agency, hence these are known as 'MRVC rakes'. The first such rake was turned out in July 2007. These rakes have some new features like forced ventilation, better lighting, smoother ride quality, LED displays and announcements inside coaches to indicate the next station, stainless steel interiors (although the shells are not stainless steel), and better acceleration and braking. There is a plan to purchase the equivalent of 174 9-coach rakes in phase 1 of MUTP, manufactured in 12-coach and 9-coach formations. As more than 100 twelve coach rakes have been manufactured [2/11], the actual number of rakes is likely to be in the range of 130-135. The rakes are manufactured at ICF, Perambur. They have propulsion equipment supplied by Siemens. MRVC rakes use IGBT technology. The brake systems include electropneumatic and regenerative braking; the rakes fail over to EP brakes when regeneration is not possible. A few MRVC coaches have been fitted with conical springs in their primary suspension and are cleared to run at 105km/h. The early MRVC rakes suffered from large scale bearing failures in traction motors, which led to delays as the rakes were left stranded on line. Siemens rectified the defect under warranty.
As of 31st March 2011, 123 MRVC rakes have been manufactured.
See the list of MRVC rakes for details of allocation of these rakes to WR and CR.
The recent development of the Main-line EMU (MEMU), manufactured by ICF, was intended to address precisely this, to allow EMU operations in more areas. They have a width of 10'8&uot;. MEMUs run on 25kV AC power. MEMU driving motorcoaches seat 76 and the trailer coaches seat 108. They have a rated top speed of about 105km/h and are equipped with electro-pneumatic brakes. The trailer coaches weigh about 33.6 tonnes and the motor coaches weigh about 60 tonnes. Earlier versions of MEMUs had a top speed of 60km/h. RDSO improved on these by increasing the horsepower of the traction motors and providing a weak-field arrangement in them for higher speeds.
MEMUs were first produced in 1993 by ICF. MEMUs are now [12/00] in operation in many sections such as Kanpur-Shikohabad, Asansol-Jhajha, Jhajha-Kiul, Purulia-Barddhaman, Durg-Raipur-Bilaspur, Vijayawada-Kakinada, Kakinada-Vishakhapatnam, Arakkonam-Jolarpettai (classified as an 'express' in SR timetables!), Bankura-Midnapore, Sonarpur-Sealdah, Kazipet-Dornakal-Vijayawada, Purulia-Adra, Bilaspur-Nagpur, Kanpur-Shikohabad, Bilaspur-Raigarh, Bally-Bandel etc. There are extensive services in the New Delhi and Hyderabad-Secunderabad metro regions as well. WR has [2/11] extensive MEMU services from Ahmedabad to Virar, and some MEMU services to Panvel as well.
RDSO Trials with Weak Field arrangement During Dec. 13-21, 2003, RDSO carried out a series of trials with MEMU rakes carrying 'Dense Crush Loads' ('DCL') stopping at all stations on the Tundla-Kanpur section of NCR. These 4-car MEMUs were provided with a weak-field arrangement. It was seen that the use of the weak field allowed increased acceleration above 40km/h, saving time at 7% at a max. speed of 90km/h and 105 at 100km/h on the 228km stretch.
Q. What's the history of EMU services on IR?
Bombay area EMUs date back to the 1920's. In 1925, EMUs from Cammell-Laird and Uerdingenwagonfabrik (Germany) were used on the line from Victoria Terminus to Kurla (what would become the core of the CR suburban service). In 1928 EMU rakes from Cammell-Laird / BTH were used on what is now WR. These were in use until 1974. The BTH rakes were even wider than the current 12' wide EMUs. A few Hitachi and Nippon SSK EMUs were used by what is now CR (some were acquired in 1925). These early EMUs were all vacuum-braked. (CR's EMU's had very weak horns operated by the vacuum of the brake system; WR had louder horns run by the air pressure of the pantograph reservoir.)
Birmingham Railway Carriage and Wagon Co. supplied 24 trailer cars for WR, and 32 for CR in the early 1950s. These were air-braked. In December 1947, CR ordered 56 (?) EMUs from Metroplitan Cammell, and others from Hitachi, Breda, etc. WR acquired 12 EMUs from Metropolitan Cammell. These coaches were in use until the early 1980s. Met-Cam also supplied 18 EMU coach shells, underframes, and bogies in 1955. In the 1960s EMUs from Jessop, MAN, ICF, etc. were brought into service. Later EMUs were almost all from ICF (a few from Jessop), with traction equipment from BHEL.
CR rakes (1925 stock), especially the ones run on the Harbour Branch, were generally narrower than the WR rakes, usually at 10'8" because of smaller clearances on the Harbour Branch and the need to use the Bombay EMUs for the Race Specials to Pune on the mainline until the 1930s. They were also somewhat heavier than WR EMUs. These were withdrawn around 1966.
Some EMUs from SIG (SIG-Fiat joint venture?) were run in the 1950s but they had rather different operational procedures for isolating defective motors, etc. and were withdrawn from service in the 1960s. Calcutta EMUs are from ICF, as are the MG Madras EMUs. Early MG EMUs running on the Madras-Tambaram line were 3-car rigid units from Metro Cammell. The ICF-built MG EMUs in the Chennai system that ran until June 2004 were notable for their brisk acceleration and crisp braking (they were equipped with vacuum brakes). They were also different from the EMUs in Mumbai and other places as they had a right-hand side seating position for the motorman. In the layout of controls, the master controller was on the left and the brake controller on the right.
Chopper EMUs – In 1981, IR contracted with the Bhabha Atomic Research Centre (BARC) to develop energy-efficient control systems for the Mumbai EMUs. The BARC design included chopper (thyristor) control of the motor power supply instead of rheostatic control, thereby eliminating the waste of power in the resistance grids. The EMUs were also provided with the capability for regenerative braking to convert the kinetic energy of the rake back to electrical energy fed to the catenary when braking.
CR proposed inducting 6 such rakes with the improved design on a trial basis, at a cost of Rs 4.7 crore. ECIL, in conjunction with BARC, began supplying the chopper control equipment in 1992. The first chopper rakes were introduced in 1993. By 1994, 5 such 'chopper rakes' (as they are known) were brought into service. (Equipment for a sixth rake was never finished.) Serial production was never taken up as the AC-DC EMUs for the Mumbai area were anticipated to come into use shortly.
There was also a controversy regarding the actual savings that the new design yielded. BARC claimed a savings of 25% in energy consumption (18% from elimination of rheostatic control and 7% from regenerative braking). However, CR never installed monitoring equipment to measure the energy consumption in actual use which led to a complaint from the Comptroller and Auditor General.
The 9-car chopper rakes are based at Kurla. Most recently [7/02] only two or three of the motor coaches with chopper control have ever been seen; the status of the others is not known. The chopper motor coaches make a characteristic humming or whining noise when beginning to accelerate, different from the standard Mumbai EMUs. Serial numbers of the chopper rakes' motor coaches seen today [7/02] are: 70537, 70528, 70523, 70536, 70531.
Q. In what formations do EMU's run?
Many different EMU formations have been used in different areas. In the 1930's, Madras suburban service started with 3-car EMUs which were notable in having coupled bogies across cars, thereby making the entire 3-car formation a rigid unit. Later Madras also got some 4-car (non-rigid) EMUs. They were sometimes operated in pairs at rush hours, leading to 6-car (two rigid) and 8-car (two non-rigid) formations, and rarely 7-car formations (one 3-car rigid and one 4-car)
In the 1960's Madras received a couple of 2-car EMUs. Following the conversion of the traction from DC to AC, the 3-car EMUs (which were built for DC) were coupled with a single AC power car to make hybrid 4-car formations. More recently 12-car (4+4+4) formations have been common. In these, the power car is usually one of the middle cars in a 4-car unit. NR uses 12-car formations for some long EMU runs (e.g., Ghaziabad-Mathura).
10-car formations were seen rarely (two 3-car rigid EMUs with a 4-car EMU) in Madras. While the MRTS in Chennai normally runs 9-car EMUs; however, in an effort to increase service frequency 3-car rakes have been introduced [5/01]. These have two power cars (driving power car at one end, and trailing power car at the other end), unusual for such short trains. New Delhi has seen 6-car and 8-car EMUs, but now up to 12-coach EMU and MEMU rakes are seen. The power cars (motorcoaches) are usually in positions 1, 3, 10, and 12.
In Mumbai, 9-car formations were standard for a long time (from 1963). (Much earlier, 4-car rakes were in use, with 8-car rakes having started on the main line from 1927.) Then in 1988 the 12-car formation became common (having been used on a trial basis from 1986), following increased demand for services and lengthening of platforms. There is now [7/99] talk of introducing 16-car formations for some services. Churchgate-Virar was expected [8/00] to have 15-car or 16-car services soon but this seems to have been delayed. A 15-car rake was commissioned by WR from Siemens for trial runs on the Dadar-Virar stretch, but as of [8/09] did not seem to have been brought into active use. 12-car formations have been introduced for the Pune-Lonavla/Talegaon EMU services. 15-car rakes were then introduced [11/09] for Dadar-Virar services, and extended later [1/11] to Churchgate. Siemens rakes came [1/10] into regular use on WR and also on CR. Siemens rakes are now [1/10] used on CR's Harbour Line as well (it was thought that they might require modifications to accommodate different clearances on this line, but it appears that these are the same rakes that run elsewhere).
In all these formations, the basic unit consists of 3 cars coupled together: a driving trailer ("C"), a motorcoach or power car ("B"), and a trailer coach ("A"). The 9-car rake therefore looks like this: YSYL - YSZZ - YSFS - YSYL - YSZZ - YSFS - YSFS - YSZZ - YSYL. (YSYL = trailer coach with vendor's compartment, YSYL = driving trailer coach, YSZZ = motor coach). In the late 1960s, WR introduced a "standees" train with far fewer seats. In this rake (#701-702), one of the unused driving trailer in the middle was replaced by a power car. This 9 coach rake therefore had four power cars. Update [7/06]: The standee train was changed to run with only 3 power cars. Later [2010?] the standees train was taken out of service.
1950s stock EMUs from various suppliers had two units of 4 coaches each: 2 driving motor cars (power cars) and two trailer coaches sandwiched between them, so that an 8-car EMU rake had 4 power cars. While these 8-car rakes were used on the main line, 4-car rakes were used on the Harbour line, from about 1927. These 4-car units were dropped later as they put too high a load on the OHE power supply, and all 8-car rakes were converted to 9-car rakes by 1963. On the Kalyan-Kasara/Karjat sections the 4-car rakes were converted to 6-car rakes in 1964.
[12/10] In DC as well as AC-DC EMU rakes in the Mumbai area, the second car from the front is usually the power car and has a pantograph; the AC EMUs and MEMUs in other places have a power car with a pantograph in the leading position.
SER plans to run 12-car EMU formations (announced in 2001) on the Howrah-Kharagpur line. Currently [8/05] it runs 9-car rakes and sometimes 10-car rakes. MEMU rakes of SER have 8 coaches. Sealdah 9-car rakes usually have a formation like this: YSZZ - YS - YS - YS - YSZZ - YS - YS - YS - YSZZ. The YS coaches next to the leading and trailing motor coaches (YSZZ) are usually ladies' coaches and have vendor compartments. [4/01] Services with 12-car EMU rakes have begun (two or three of these are with the Sealdah section, and on Howrah-Mednipur) replacing some of the 10-car rakes used earlier. The 12-car rakes have power cars in the first, fourth, ninth, and twelfth positions. Sealdah Main section mostly 9-car rakes and Sealdah South mostly uses 10-car rakes. Howrah-Kharagpur/Paskura/Mecheda currently use 8-, 9-, or 10-car EMU rakes. In the Calcutta area, for a long time AC EMU rakes were made up of 4-car units, consisting of a driving trailer ("A"), a power car ("B"), a trailer ("C") and a driving trailer ("D").
Q. What classes of accommodation do EMUs offer?
In the Mumbai area, the most commonly seen coaches have General Second Class accommodation. Some coaches or compartments are for First Class ticket-holders. There are also compartments, coaches, or entire trains reserved for women, known as Ladies' Compartments or Ladies' Specials. In some cases the Ladies' coaches or compartments are reserved for women all the time, whereas in some cases they revert to being General Second Class accommodation while being reserved for women only during certain hours. There are also First Class Ladies coaches on all rakes now  (earlier they were featured on only some services. Additionally, compartments are reserved for handicapped or physically challenged persons, and there are also mixed compartments or sections of coaches reserved for older travellers during certain times. Luggage compartments are also seen in the Mumbai trains.
(Need more information on other systems.) EMU services in other cities also generally offer similar categories of General Second Class and First Class accommodation, and some coaches or services reserved for women.
Q. Does IR operate diesel-electric or diesel-hydraulic multiple units of any kind?
[9/98] There are several diesel-electric multiple units (DEMUs) and diesel-hydraulic multiple units (DHMUs) in operation. Most are made by ICF. The BG DEMUs have a Cummins VTA 1710 V-12 prime mover of 705 HP, whereas the BG DHMUs have two 350hp underfloor engines (Cummins 855R) driving two separate Voith hydraulic transmissions via propeller shafts and differentials. These have a rated maximum speed of about 105km/h. The first units were introduced in 1993-94.
[2/01] A newer variant of the DEMU from ICF has been spotted on the Ahmedabad - Abu Road section with two underslung Cummins NT 855R engines each driving a traction alternator whose output is fed to 4 traction motors.
[7/04] A new aerodynamically shaped DEMU model from ICF has been brought into service on the SCR (Bhimavaram - Narsapur - Vijayawada). The leading driving motor cars of these 8-car rakes have a distinctive appearance with a large sloping oval windshield in one piece and can accommodate 54 passengers; the rear motor car accommodates 72. The other six trailer cars of a rake accommodate 84 seated passengers and 240 standing passengers each. A slightly modified version has been brought into service [5/05] for the Shalimar-Digha section.
The MG versions of the DEMU come from RCF. The first rake was commissioned in March 2003 and another is scheduled to be commissioned in 2003. The formation has 6 coaches including two driver cars and four trailer coaches, with a total carrying capacity of over 1000 passengers (with seating for 424). Max. speed is 75km/h.
The MG DEMU has a Cummins NT 855 inline 4-cylinder engine developing about 400hp, with a BHEL traction alternator. They are slated for use on the Indore-Mhow section of WR, and have been recently [2/03] tested on the Delhi - Sarai Rohilla section. Two units are in use [12/06] on the Indore-Mhow section. MG DEMUs are also in use on WR's Mahesana-Taranga hill section [2/11].
Historical note: The RCF rakes are not the first MG diesel multiple units. Fiat supplied some for the Chennai area in 1955. These were diesel-hydraulic units (confirmation needed).
Driving cars with power are classifed "DPC" (driving power car). Non-engine driving coaches with cabs are classifed "DTC". Trailer coaches are classified "TC".
High-Power DMU (High Horsepower DMU): Newer DMU models (the High Powered DMU or HPDMU units, with a 1400hp V-16 engine (Cummins KV-16)) were introduced in 1999 by ICF and are now in regular use at several places. The HPDMUs are coupled in 4-car units (one power car + three trailer cars) as opposed to the 3-car rakes (power car + two trailer cars) for the lower-powered DMUs, and have pneumatic secondary suspension. Acceleration is improved, at 0.54m/s2. A 4-car unit carries 1092 passengers.
The HPDMUs were used around Bangalore at first, and some suburban services around Chennai (Beach - Kanchipuram). Some sections on NR have also been considered. The first HPDMU units underwent trials at Whitefield near Bangalore in 2000. One HPDMU rake was later [9/00] in trial operation between Madras and Sulurpet, while another could be seen running in trials between Madras and Arakkonam. Note: Sometimes these are referred to by the acronyms HHPDMU or HHPDEMU (" High Horse-power DMU/DEMU"). The max. speed for most of these DMU/DEMU/DHMU vehicles is 105km/h.
The HPDMUs have been seen with road numbers in the 14xxx and 15xxx ranges. SCR's new aerodynamic DEMU coaches have 150xx numbers for power cars and 154xx for trailer cars [4/05].
DMU and DHMU services are seen in places such as Secunderabad, Ahmedabad - Abu Road, Lonavala-Pune-Daund, etc. DHMU services on Konkan Railway began in 1997 with a Karwar-Pernem service which was later extended to Ratnagiri. It now [4/01] runs on the Karwar-Madgaon section.
DEMUs are homed at Madgaon, Abu Road, Daund, Shoranur, and Satna, in addition to a sizeable fleet (23?) homed at Jallundhar. Sections worked by these diesel multiple units include Daund-Pune, Tiruchirapalli-Karur, Patna-Rajgir, Anand-Khambat (BG), Vijayawada-Bhimavaram-Narsapur (BG), Delhi-Shamli (BG), Mehasana-Tarangahill (MG), Ahmedabad - Mehsana / Abu Road, Madras Beach / Egmore - Kanchipuram, etc.
In the Bombay suburban area, DMUs used to work the Virar - Dahanu Road section extensively, but now [2/11] only one Diva-Boisar service remains; the DMUs were/are homed at the Bandra Marshalling Yard. The rake formation for these usually has the power car in the middle of the rake. DMUs are also found around Hyderabad, on the Secunderabad-Bolarum, Secunderabad-Medchal routes.
[12/99] More: DMUs also ply on the Dombivli-Vasai-Diva route, and in the Lucknow suburban area. [3/01] New services: Kharagpur-Jaleshwar-Bhubaneshwar, Jalandhar-Hoshiarpur, Kotkapura-Fazilka, Samastipur-Darbhanga.
Other diesel units: Several self-propelled Medical Relief Trains (MRT's) are also in use; these use two Cummins 375hp underfloor diesel engines and are thus rather like DMUs although of course they are used for accident relief operations and not passenger services. The transmission is hydraulic. An MRT has one coach with medical facilities and one driving car with the engines. These MRTs are made by RCF. ICF also plans to make 3-car accident relief / medical relief rakes.
The DMUs are often seen in 3-car units, with one DPC, one TC, and one DTC each. Where the traffic is higher, DEMU and DHMU formations usually consist of 6 (as at Secunderabad), sometimes 9, cars (with 2 power cars, one at either end). Ahmedabad - Abu Road DMU formations regularly have 9 cars, recently [8/00] upgraded to 12 cars, although 6-car formations are also seen.
In sections such as Lonavala-Pune-Daund, the traffic is high enough that 9-car and 12-car formations have been considered. Madgaon has 2-car and 3-car DMUs (power cars at either end), but most DMU rakes have 3-car units, leading to 6-, 9-, and 12-car formations. Diva - Roha trains and KR passenger trains often have a diesel loco (WDM-2) at the head and a DMU in the middle of the rake. (Diva-Vasai trains have a regular loco, and not a DMU, in the middle.)
HPDMU rakes (currently [8/00] being tested at Whitefield near Bangalore) have four cars, making it likely that 8-car and 12-car formations will be common for HPDMU services, although 16-car formations have been tried experimentally. Arakkonam-Jolarpettai MEMU rakes are formed with two driving motorcoaches (one at either end) and six trailer coaches in the middle.
On CR, a 3-coach unit is classified as 76, 70, or 72, where 76 is the leading motor coach (has driving cab if at either end of rake, and reserved seating for handicapped persons when in the middle of the rake), 70 is the motor coach with a pantograph and traction motors (usually has only second-class general accommodation), and 72 is the trailer coach (usually with half first-class accommodation and half second-class). So a nine-coach train has three units in the following sequence:
(76-70-72) (72-70-76) (72-70-76)
A 12-coach train would have the following sequence:
(76-70-72) (72-70-76) (72-70-76) (72-70-76)
A few odd coaches have been seen recently that break with this system, and have classifications 86, 80, and 82. The formation then is:
(86-80-82) (86-80-82) (86-80-82)
These are thought to be coaches transferred from other zonal railways, particularly WR, as WR now is acquiring the newer AC-DC EMUs. There is an 86001 coach, for instance. The 8xxxx coaches do not appear to have been transferred in 3-coach units, but as singletons.
CR's AC/DC rakes (3XX series) and MRVC rakes use the A-B-C system just as in WR (see below) instead of the 72-70-76 system to distinguish the coaches of a 3-coach unit.
The EMU coaches also have alphabetic classifications in line with other rolling stock of IR.
- YSYL = Driving motor coach with Second Class + Luggage = class 76
- YSZZ = Second Class Motor Coach = class 70
- YFYS = First Class + Second Class (trailer coach) = class 72
The identifying number of a coach consists of the prefix corresponding to the type of coach (76, 70, or 72), followed by a 3-digit serial number. E.g., a motor coach may be numbered 70256 and a trailer coach may be numbered 72385.
All Jessop-built CR EMU coaches are allocated a number range between 101 and 399, although the last ones appear to be 350-351-352 (at Sanpada carshed [4/04]). ICF-built ones range from 401 through 590. The ones in the 500-590 range are newer (1990s) coaches. [1/03] CR numbers in the 5xx range have gone past 599 and into the 6xx range now. Blue-livered EMU trailers have been spotted with numbers 72597-72599 and then 72600-72603. Above 524-526, complete rakes with sequentially numbered units don't seem to exist – newer coaches with higher numbers are simply attached to older rakes as required.
More recently new coaches have been introduced in the 700 series, which are from different manufacturers. 701 to 703 are from BEML. 704 through 715 are also thought to be from BEML, but with some fittings and perhaps some electrical equipment from BHEL. Today [3/02] these serial numbers top out at 715. Update [1/04]: New rakes with serial numbers in the 8xx have been brought into service. A rake with numbers 808, 807, 809 (not arranged sequentially) has been spotted and appears to be a Jessop 200 series perhaps painted over. It is thought that the 800 series coaches are ex-Western Railways, repainted at Matunga workshops.
However, there is an anomalous 900 series rake, which appears to have been an entire 9-car rake transferred from WR in 1998. It is formed with the standard 76-70-72 classification, but the motor coach of the original rake has been replaced by one in the 500 series. 72901, 70901, etc., and similarly 902, 903 series are all believed to be ex-WR. The repainting could be seen with careful observation on some coaches: 901 C became a 72901 and the C was overpainted. The words 'Western' and 'Paschim' were painted over with 'Central' and 'Madhya'.
Other oddities: Rake 72349 is marked with class 'YTFS'. Rakes 72570 and 72574 are marked 'YSFY' instead of 'YFYS'.
Prefixes and Suffixes: Lately, CR EMUs have been seen with a prefix 'O' before the coach number (e.g. O-72146). All coaches of the new 86-80-82 combination have a lower-case 's' as a suffix (e.g. 86234s). 'T' is a rare suffix seen on at least one coach: 72185T. Its significance is unknown [3/02]. [1/03] Another suffix 'c' has been seen on at least one EMU coach. It too, is of unknown significance.
CR now has some MRVC rakes. See the list of these MRVC rakes and their numbering.
Updates: Many WR DC rakes have been transferred to CR lately . They retain the WR style numbering (see below) of 'XXX A/B/C'. A few DC coaches from the 900x and 9xxx series are now  being scrapped.
WR EMUs are numbered differently, identified by 3-digit numbers identifying the rake and a letter (e.g., 'C') added to distinguish the individual coach in the EMU rake. (Contrast this with CR's use of '72', '70', '76' prefixes.) 'A' : Trailer coach, 'B' : Motor coach, 'C' : Driving trailer coach
Hence a 3-coach formation could be something like this:
(849A 849B 849C)
These 3-coach units are formed into 9-coach rakes. Usually the serial numbers of successive 3-coach units are sequential, and the rake is denoted by quoting the numbers of the end 3-coach units. E.g., a '501-502' rake has a 3-coach unit numbered 501 at one end, and another numbered 502 at the other end, and a third, 503, in the middle. A '505-506' rake has 505 and 506 as the 3-coach units at either end, and another, 504, in the middle. The driving trailer coaches of the 3-coach units at either end are on the outside so that the entire rake can be driven in either direction. So, for instance:
(501C 501B 501A) (503A 503B 503C) (502A 502B 502C)
Usually a 12-coach rake of WR is set up like this (ex-Churchgate): CBA - CBA - CBA - ABC (contrast with CR, whose rakes are usually like this: CBA-ABC-ABC-ABC (of course, CR uses 72/70/76 instead of the A/B/C nomenclature.)
Additional spare single coaches (not 3-coach units) were ordered in some series, e.g., in the 800 series. They were numbered 8001, 8002, 8003, etc.
Note: 1928 and 1950 EMU stock had a different letter suffix scheme. The configuration of an 8-coach rake then was 'A-B-C-D-D-C-B-A'. With 1928 stock, the 'D' coaches on the Virar side were first class, and part (quarter) of the adjacent 'C' coach with ladies' first class.
With 1950 stock, 'A' and 'D' were both motor coaches. Half of the Churchgate side 'C' coach was the men's first class and the Virar side 'C' coach was half men's first class and half ladies' first class. Later an extra motorcoach was added to each rake. With the 1928 stock, the extra motorcoach was added between two units: 'A-B-C-D-B-D-C-B-A'. For 1950 stock, a custom trailer coach by Jessop was added between the units: 'A-B-C-D-T-D-C-B-A'.
The oldest rakes in use until recently were in the 5xx series, e.g., 505-506 (formerly numbered 105-106), which were introduced around 1965. These have now been withdrawn. WR rakes are numbered roughly in chronological sequence. Originally simple sequential numbers were used, but when new Jessop rakes were introduced in the 1960s, the existing rakes were renumbered.
- 001 - 040 : 1928 Cammell-Laird / BTH stock. All withdrawn, in use untilthe 1970s. Not renumbered.
- 041 - 052 : 1950 Metro Cammell rakes, renumbered to 101-112.
- 053 - ?? : 1960-1961 converted Jessop stock, originally made for ER. Renumbered later to 2xx.
- 07x+ : SIG rakes
- ?? : MAN rakes from Calcutta awaiting conversion from 3kV to 1.5kV at Kandivali (KILE) shed. (These became the 4xx series, see below.)
- 101 - 118 : Original numbering of old Jessop rakes, later renumbered to 501-518.
- 101 - 112 : Renumbering of 1950 Metro Cammell rakes. Now withdrawn. Formerly numbered 41 through 52.
- 201 - 2xx : 1960-1961 Converted Jessop rakes (made originally for ER) All now withdrawn. Formerly numbered 53 onwards.
- 3xx : 1963 ICF rakes. These numbers are being re-used for new AC-DC EMU rakes from ICF/BHEL. Some BHEL 3xx rakes have been transferred [2005-2006] to CR.
- 400+ : MAN rakes from ER converted to 1.5kV DC from 3kV DC. Original numbers? Probably just after the SIG rakes in sequence.
- 500+ : Jessop rakes. 501 through 518 are the older ones. All now [2/11] scrapped.
- 600 : ICF rakes. All now [2/11] scrapped.
- 701 - 703 : Standee train by ICF. All 7xx trains have now [2/11] been scrapped.
- 8xx : Jessop rakes. Some of these have been  transferred to CR, where they retain their WR style numbering. Some have been scrapped.
- 9xx : ICF rakes. These rakes are also undergoing conversion to AC-DC traction.
- 10xx : Originally ICF, now renumbered to 9xx. Now 10xx are MRVC rakes.
July 2006 bombings on WR EMU's: Perhaps of some interest to number crunchers, the EMU coaches in which bombs exploded in the terror attacks of July 11, 2006 ih Mumbai were: 849-A, 0528-A, 935-A, 634-A, 846-A, 864-A, and 8003-A.
WR now has some MRVC rakes. See the list of these MRVC rakes and their numbering.
See the section on sheds for information on where the WR and CR EMU car sheds are.
Q. Where are railcars or railbuses operated?
Historically, many sections have seen railcar or railbus service in India. There have been several imported models used, and also homegrown versions which are often literally buses or truck bodies placed on rails. In recent years, many sections have seen the introduction of railbus or railcar services. This recent program of adding railbus or railcar services probably began with the Merta City - Merta Road service in the 1980's. This section still runs BG railbuses.
BG railbus service is also found on the Bangarpet-Kolar, Mathura-Vrindavan, Goindwal-Beas, and Bobilli-? (on Vizianagaram-Bilaspur line) routes. The Kanpur-Brahmawart railbus service (early 1990s) appears to have been withdrawn. Tumsar Road - Tirodi service introduced in 1998 has been withdrawn, and the two railbuses are reported [5/05] to be stabled at Tumsar yard.
MG railbuses are found in several places (Silchar-Jiribam, Junagadh-Dhari, Tiruturaipundi-Agastiampalli, Banmankhi-Bihariganj, Shimoga-Talaguppa, Ambliyasan-Vijapur-Adraj Moti of WR, etc., and especially on NER). Sometimes two railbus units are operated together, making them technically a railcar formation. The well-known railcar service for Bangalore/Yeshwanthpur stopped a few years ago. Some MG railcars were built by converting ICF MG coaches.
Yelahanka- Kolar Gold Fields - Bangarpet had an NG railcar service in the past, but the section is being converted to BG. The NG railcars (4 in number, class ZRD) were converted to MG for use on the Shimoga-Talaguppa section. A view of one of these appears in Bill Aitken's 'Exploring Indian Railways'. Bankura-Damodar, Bankura-Rainagar, Bodeli - Chota Udepur are other NG sections with railbus service.
[7/00] Ankleshwar - Raj Pipla is also supposed to get NG railcar service soon. In these NG railcars, the power car has a 22-passenger capacity and the trailer cars have a 31-passenger capacity. There was also an NG railbus service between Kalka and Shimla but now single-unit railcars are said to work the line. Shantipur-Nabadwipdham is another section with railcars. Barddham-Katwa and Ahmadpur-Katwa have railbus service. The Shimoga-Talaguppa section now  has railbuses (class YRD-2) that are based on the road buses used by the Karnataka State Road Transport Corporation.
Some railbuses and railcars were made by the Izzatnagar works by placing road vehicle bodies on wheels modified for the rails. Recently BEML has been making many BG railbuses (class WRB) – see below. These are more purpose-built as rail vehicles and not just crudely retrofitted road vehicles. The older railbuses often have an Ashok Leyland bus engine with a Hindustan Motors hydraulic transmission (under licence from Allison). RDSO developed a BG railbus design with 60 seats, powered by a normal bus engine and suitable for bidirectional running, in 1993.
BEML Railbus Specifications
The Length: 10.7m; width: 3.2m; height: 3.65m; wheel-base: 7m. Tare weight is 16t and gross weight is 24t. The body is all steel, with an integral shell design of formed and rolled sections welded together.
There are driving cabs at each end of the railbus, each with access through sliding doors one on the side and one leading to the passenger compartment. A door in the middle of the railbus leads to the passenger compartment.
Max. speed 60km/h. Engine: inline 6-cylinder, with mechanical variable speed governor, 175hp. Transmission: automatic hydraulic with twin turbine torque converters. (Allison torque converter, made by Hindustan Motors.) Drive: single driven axle (axle-mounted bevel gear drive with single stage reduction). Brakes: Service brakes use compressed air; there are also standby brakes (with separate brake valves) in case of main brake failure, and air-assisted parking brakes.
Axle/wheel capacity is 13 tonnes; wheel diameter 915mm. Suspension: single-stage with vertical guide, helical spring, and shock absorber. Electricals: 24V 180Ah lead-acid battery for starting, controls, lighting; 24V 45A alternator.
Other self-propelled vehicles
There are some OHE inspection/maintenance vehicles that use the same prime mover (Cummins 705hp engine) as the DEMU's; these are called diesel electric tower cars (DETC) as they have a diesel-electric transmission. (The term 'tower wagon' is also used instead of 'tower car'.) These can often be seen used for light shunting duties since the 700/750hp engine is powerful enough for that. Most DETC vehicles are built by ICF. A DETC generally has a top speed of about 100km/h. It is equipped with dual brakes. It has a compact workshop for routine maintenance and repairs of the OHE structure, and a telecommunications unit for communicating with the traction power controllers. Most DETC units also have small rest and toilet areas for the crew. (Also see the item on BEML OHE inspection cars below.)
Some OHE maintenance vehicles have a different, smaller engine from Ashok Leyland with hydraulic transmission. The newer ones (class RU) have 8-wheeled bogie stock in contrast to the older 4-wheeler OHE inspection cars (class ERU). They have an all-weather cockpit at roof level for OHE inspection, and a hydraulically operated tower which can be swung up close to the catenary (also sideways to the catenary of the adjacent track). Pantographs with measuring devices allow recording contact wire pressure and stagger, as well as dynamic characteristics of the catenary on the run.
They also house a workshop inside, with machine tools, welding equipment, portable generator, etc., in addition to sleeping/resting quarters for the crew, including toilets and a kitchenette, a rare level of crew comfort on IR.
The BEML OHE inspection cars can run at 110km/h (the older ones could only manage 40km/h and besides, were often in trouble because they had a flaw where they failed to trip the block circuit in many cases). The new ones can also work as wiring trains in case the catenary needs to be rewired (for short lengths of catenary). These cars have driving cabs at both ends.
The older ones (class ERU) exhibit a wide variety in their designs. Most were 4-wheeled, although a few 8-wheeled ones exist(ed). Many were put together by the various loco sheds and workshops. Some old ones even had mechanical transmissions with a manual gearbox in the cabs at either end, often rigged from road truck powertrain components.
BEML OHE Inspection Car Specifications
There are two versions, one with a powerpack consisting of a single 6-cylinder diesel engine of 530hp capacity (KTA 19-R, Kirloskar Cummins), and a double unit using two 285hp engines (NT 855-R4, Kirloskar Cummins). Both have roof-mounted radiators.
Transmission: Automatic, continuously variable hydraulic Voith transmission (T 311-r for single unit powerpack (365kW input), T 211-r for the double (194kW input)); terminating in an axle-mounted helical gear drive. Brakes: Compressed air system with integrated brake block units. Service brakes, emergency brakes (with separate back-up emergency brake valve), and mechanical parking brakes are provided. Gross weight 60t; trailing load up to 60t. Length: 22.3m.
Wheels/suspension: Two double-axle bogies with two-stage suspension and box section fabricated frame; 16t solid forged axles. With the single unit powerpack there is 1 powered axle and 3 trailer axles; with the double unit there are 2 powered axles and 2 trailer axles. Wheels have 915mm diameter.
Electricals: 24V system. 320Ah lead-acid battery for lighting; 330Ah lead-acid batter for engine starting; 30V 4.5kW axle-driven alternator for internal lights; 50A 24V engine-driven generator for headlights and other external lighting, control circuitry, etc. Headlights 250W. In addition, a 8kVA diesel generator is provided to supply power to the inspection tower platform and for the workshop's tools.
A few less powerful OHE inspection cars are also seen; these have a small air-cooled engine and a minimal walkway on the roof for getting close to the catenary.
DETCs and other OHE inspection vehicles are found all over the IR network now that electrification has spread wide. E.g.: Bilaspur, Asansol, Vijayawada, Satna, Mumbai Central, Kalyan, Bhusawal, Itarsi, Baroda and many others. Having ample power (700hp) they are often also seen performing shunting duties.
Accident Relief Medical Vans (classification ARMV) are diesel-powered. In some cases they are actually converted EMU units (e.g., old DC EMU's from the Bombay area are used as ARMV's on KR), with a diesel-generator set added. Usually two such EMU units are coupled together, one supplying the power and the other converted to house an emergency medical treatment facility, where the diesel-generator supplies power for air-conditiioning, etc. The hospital units have emergency medical equipment and surgical facilities. Usually, they also have accommodation (hospital beds) for up to 12 patients on board. ICF usually refers to these coupled units as ARTV (below). Max. speed 95km/h.
Accident Relief Tool Vans (classification ARTV) are usually coupled in pairs, one as a hospital coach (see above, ARMV), and another coach with re-railing and metal working equipment and other tools. (The combination is therefore usually denoted 'ARMV/ART'.) They usually have two underslung diesel engines of about 350hp (total 700hp) with a hydraulic transmission (Kirloskar Pneumatics, under licence from Voith). Some ARTVs belonging to Chennai Central seem to operate [10/03] with three cars, the third one being similar to an OHE wiring car, but its purpose is not clear. Max. speed 95km/h.
SPART RDSO has developed  a design for a three-coach self-propelled ARMV/ART (SPART) train that can be driven from either end and which has a top speed of 140km/h. Classification code not known -- this is identified in RDSO literature as the 'high speed SPART'. In addition to the air-conditioned medical van ('PC') and the tool van ('DPC-II') as with the current two-coach ARMV/ART trains, this one would have an additional supervisory/kitchen van ('DPC-I'). Additionally, compared to the older ARTV, there are some improvements such as a wider sliding door with a ladder arrangement for easy unloading and loading of tools and materials.
Note that accident relief vehicles of different kinds are sometimes generically referred to as Accident Relief Van or ARVs.
NETRA (which stands for Network of Electrification -- Testing and Recording Apparatus) is a special coach designed for inspection of the catenary in electrified sections. It has an IRY shell mounted on IR-20 bogies, with a rated top speed of 160km/h. (It is an unpowered vehicle and must be hauled by a loco.) It has a pantograph (a dummy -- does not draw current) which is used to test and record various mechanical characteristics of the pantograph-catenary interaction while the coach is in motion.
ARTs and Breakdown Cranes Breakdown cranes have always been essential equipment for emergency operations at accident sites. Steam cranes were part of IR's inventory for a long time, even after steam-hauled trains had essentially disappeared from the network. However, steam cranes have been decommissioned now and diesel cranes are used instead. Breakdown cranes form a part of Accident Relief Trains (ART) which are like the ARTV rakes discussed above but carrying additional heavier tools, hydraulic rerailing equipment, and with a breakdown crane usually forming part of the rake. Often they also include a medical van, thus combining the features of both the ARTV and the ARMV. In the past, there were many different formations of ARTs and their composition was not entirely standardized. Two classes, known simply as 'A' type and 'B' type ARTs, were usually recognized. The 'A' type ARTs were the ones equipped with heavier-duty equipment, although there was no firm line dividing the two. In the late 1970s, there were 141 'A' class ARTs and 60 'B' class ARTs on IR's network. The introduction of heavier rolling stock (such as the BOX and other wagons that were replacing the earlier 4-wheeler stock) made it imperative that breakdown equipment be capable of dealing with heavier loads during operations of clearing accident sites, rerailing vehicles, etc. The older steam cranes were often not up to the task. Accordingly, in 1981 the Railway Board decided that all new breakdown cranes had to be diesel-powered and rated for 140t on BG and 75t on MG. Hydraulic rerailing equipment and medical vans were made standard for ARTs as well. The classification of ARTs was then rationalized so that 'A' class ARTs always included a heavy-duty breakdown crane, and were to distributed so that no accident site would be more than 250km from one. The 'B' class ARTs would no longer have a breakdown crane but would be distribed more closely so that no accident site was more than 150km away from one. With this, the required number of ARTs under the new scheme was intended to be 151.
The 1981 requirements for breakdown cranes included the following: 140t rated lifting capacity, max. speed of 75km/h, provision of safe load moment indicator and safety cut-offs, and all-hydraulic motion actuation and control. Twelve cranes were obtained from NEI Cowans Boyd and twelve from Gottwald. In each case, 6 cranes were imported assembled, 3 in knocked-down condition, and 3 in component form. Jessops in Calcutta were entrusted with the production of Cowans design cranes, and Jamalpur workshops with the production of Gottwald cranes. Jamalpur workshops began indigenous production of Gottwald cranes by 1986.
Smaller breakdown cranes (80t, 120t, etc.) are also used by IR. In IR documents, 'small' cranes are those that have load moments up to 700 tonne-meters; 'medium' cranes those which have load moments from 700 to 1,000 tonne-meters, and 'large' cranes those which have load moments above 1,000 tonne-meters. The 140t cranes (Cowans / Gottwald) can lift the 140t load at a radius of 9m, so that their load moments are 1,260 tonne-meters and are therefore considered 'large' cranes.
There are many other self-propelled vehicles such as inspection trolleys (well, the simplest of these are human-powered!), track-laying equipment, oscillograph cars, with various kinds of low-power diesel engines. Road vehicles such as trucks, buses, vans, and even small scooters (Vespa, Lambretta, etc.) are sometimes seen modified for use on the tracks. Picture