Indian locomotive class YDM-4

3 ft 3+3⁄8 in) metre gaugeBogiesALCO Asymmetric cast frame trimountWheel diameter965 mm (37.99 in)Length15.60 m (51 ft 2+1⁄8 in)Width2,730 mm (8 ft 11+1⁄2 in)Height3,635 mm (11 ft 11+1⁄8 in)Axle load12,000 kg (26,000 lb)Loco weight72,000 kg (159,000 lb) ALCo/DLW, 67,000 kg (148,000 lb) MLWFuel typeDieselFuel capacity3,000 L (660 imp gal; 790 US gal)Lubricant cap.530 L (120 imp gal; 140 US gal), 630 L (140 imp gal; 170 US gal) DLWWater cap.22 L (4.8 imp gal; 5.8 US gal), 28 L (6.2 imp gal; 7.4 US gal) DLWPrime moverALCO 251-DRPM range400-1100Engine typeInline-6 dieselAspirationTurbo-superchargedDisplacement(?)GeneratorDCTraction motors6 DCCylinders6Cylinder size228 mm × 267 mm (8.98 in × 10.51 in) bore x strokeTransmissionDiesel-electric transmissionMU working2Loco brake28LV-1, Air brake for Locomotive using SA-9 brake handleTrain brakesOriginally Vacuum using A-9 brake handle, some modified to Dual

Performance figures
Maximum speed	96 km/h (60 mph)
Power output	Max:1,400 hp (1,000 kW) Site rated:1,300 hp (970 kW)
Tractive effort	18.935 t (19 long tons; 21 short tons) maximum 16.050 t (16 long tons; 18 short tons) continuous

Career
Operators	Indian Railways, IRCON, KTMB Malaysia, Myanmar Railways, Vietnam Railways, Royal Railways, Mozambique Ports and Railways
Numbers	6020-6049 ALCo, 6105-6129 ALCo, 6130- 6198 MLW, 6199-6258 DLW, 6259-6288 MLW, 6289-6769 DLW
Locale	All over Indian Railways, Leased to KTMB Malaysia, Leased to Myanmar Railway, 25 units operate by Vietnam Railways
Preserved	3
Current owner	Indian Railway, IRCON, KTMB Malaysia, Myanmar Railway, Vietnam Railways
Disposition	active

The class YDM-4 is Indian Railways' workhorse diesel locomotive. The first units were imported fully built from the American Locomotive Company (Alco) in 1961. Since 1968, it has been manufactured in India by the Banaras Locomotive Works (BLW), Varanasi. The model name stands for metre gauge (Y), diesel (D), mixed traffic (M) engine. The YDM-4 has been the most successful diesel locomotive in the metre gauge operation of Indian Railways. The YDM-4A is a variant of the YDM-4 supplied by MLW . Originally equipped with vacuum brakes. Some were later equipped with dual brakes, particularly those working in the Northeast Frontier Railway were retrofitted with dual brake system by Lumding shed. The YDM-4 locos have a maximum speed of 100 km/h (62 mph),^[1] restricted to 85 km/h (53 mph).^[2]

History

In the mid 1950s Indian Railways began introducing diesel locomotives to its metre gauge system. Metre gauge, though rare in the 21st century, used to be a dominant gauge at that time. After the introduction of YDM-1 locomotives by the North British Locomotive Company, Indian Railway considered more powerful ones and hence General Motors Electro-Motive Division (EMD) and the American Locomotive Company (ALCO) submitted designs of YDM-3/YDM-5 (12-567C) and YDM-4 respectively for new diesel locomotives. Each company supplied 30 locomotives in 1961. While the YDM-3 was 13 tons lighter than the YDM-4, Indian Railways opted for the ALCO design because of the heavier axle load and technology agreement that would allow these locomotives to be manufactured in India.

After Banaras Locomotive Works (BLW) completed construction of its factory in Varanasi, production of the class began in India. The initial 30 YDM-4 locomotives supplied by ALCO in 1961 were numbered between #6020 and #6049. Another batch of 8 locomotives soon followed and were numbered #6105 to #6112. YDM-4 #6113-6129 were built around 1964. Siliguri Diesel Locoshed was the first DLS to station YDM-4 locomotives in 1962. The very first YDM4, #6020, was allotted to the New Guwahati Diesel Loco Shed, which was an outbase of Siliguri DLS on 30 October 1962.

YDM4 #6130 to #6198 were built by Montreal Locomotive Works (MLW) in 1964 under the license of ALCO and were classified as YDM-4A. All the YDM-4 delivered up to then were presumably based at three premier DLS across India namely Siliguri (SGUJ), Ponmalai Goldenrock (GOC) and Sabarmati (SBI). Another batch of YDM-4A was dispatched from MLW in 1969, numbered #6259 to #6288.

The first YDM-4 built by Banaras Locomotive Works (BLW) Varanasi was #6199 Hubli. This loco entered service in 1968 and was dedicated to the then Deputy Prime Minister of India, Morarji Desai. DLW built locos in the range #6199 to #6258.

From 1969 till 1993 DLW produced YDM-4 locomotives for Indian Railways in the number range #6289 to #6769. The last YDM-4 was based at Rangapara North outbase of Siliguri DLS but later on transferred to Myanmar (Burma) Railways and possibly renumbered as DF1332.^{[3][better source needed]}

Locomotive sheds

Zone	Name	Shed Code	Quantity
North Eastern Railway	Izzatnagar	IZN	10
North Western Railway	Mavli	MVJ	8
Southern Railway	Ponmalai Goldenrock	GOC	5
Western Railway	Sabarmati	SBI	11
	Mhow	MHOW	7
Total Locomotives Active as December 2023[4]			41

Technical specifications

Source:^[5]

Manufacturers	Alco, MLW, DLW
Engine	Alco 251-D, Inline-6, 1,400 hp (1,000 kW) (1,300 hp or 970 kW site rating) with Alco turbocharged engine. 1,100 rpm max, 400 rpm idle; 228 mm × 267 mm (8.98 in × 10.51 in) bore x stroke; compression ratio 12.5:1.
Transmission	Electric, DC-DC (DC Generator and DC Traction motor)
Traction motors	GE for original Alco and MLW models, BHEL for DLW
Axle load	12.0 t (11.8 long tons; 13.2 short tons)
total weight	72.0 t (70.9 long tons; 79.4 short tons) ALCo and DLW, 67.0 t (65.9 long tons; 73.9 short tons) MLW
Bogies	Alco design cast frame trimount (Co-Co) bogies with asymmetrical arrangement of traction motors
Starting TE	18.94 t (18.64 long tons; 20.88 short tons)
Continuous TE	16.05 t (15.80 long tons; 17.69 short tons)

References

External links

• YDM-4 Diesel Locomotive Internals