Indian locomotive class YDM-4

YDM-4
Sabarmati based YDM-4 at Talala Jn.
Type and origin Power type Diesel Builder Alco, MLW, BLW Model DL535, DL535A, RSD-30, D13E. Build date 1961-1993 Total produced YDM-4: 695
Specifications Configuration: ​  • UIC Co-Co Gauge 1,000 mm (3 ft 3+3⁄8 in) metre gauge Bogies ALCO Asymmetric cast frame trimount Wheel diameter 965 mm (37.99 in) Length 15.60 m (51 ft 2+1⁄8 in) Width 2,730 mm (8 ft 11+1⁄2 in) Height 3,635 mm (11 ft 11+1⁄8 in) Axle load 12,000 kg (26,000 lb) Loco weight 72,000 kg (159,000 lb) ALCo/DLW, 67,000 kg (148,000 lb) MLW Fuel type Diesel Fuel capacity 3,000 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) DLW Water cap. 22 L (4.8 imp gal; 5.8 US gal), 28 L (6.2 imp gal; 7.4 US gal) DLW Prime mover ALCO 251-D RPM range 400-1100 Engine type Inline-6 diesel Aspiration Turbo-supercharged Displacement (?) Generator DC Traction motors 6 DC Cylinders 6 Cylinder size 228 mm × 267 mm (8.98 in × 10.51 in) bore x stroke Transmission Diesel–electric transmission MU working 2 Loco brake 28LV-1, Air brake for Locomotive using SA-9 brake handle Train brakes Originally 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, Togorail 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 YDM-4 is a class of diesel locomotives operating on Indian Railways. The first units were built by the American Locomotive Company (Alco) in 1961. Since 1968, members of the class have 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 metre gauge diesel locomotive in India. The YDM-4 locos have a maximum speed of 100 km/h (62 mph),^[1] restricted to 85 km/h (53 mph).^[2]

The YDM-4A is a variant of the YDM-4 that is supplied by MLW . Originally equipped with vacuum brakes, some were later equipped with dual brakes, particularly those working in the Northeast Frontier Railway.