Sri Lanka Railways Class W1
Class W1 No. 663
Type and origin Power type Diesel Builder Rheinstahl Henschel Model DHG-1200[1] Build date 1969 Total produced 45 Rebuilder Sri Lanka Railways
Specifications Configuration: ​  • AAR B-B Gauge 1,676 mm (5 ft 6 in) Length 12.8 metres (41 ft 11+7⁄8 in)[2] Loco weight 60.5 t (59.5 long tons; 66.7 short tons) Prime mover Paxman 12YJXL[1] RPM range 1500 Engine type V12 4 stroke diesel[1] Transmission Voith L 520 R U2[3] Train brakes Vacuum
Performance figures Maximum speed 80 km/h (50 mph) Power output 1,150 hp (860 kW)
Career Operators Sri Lanka Railways Class W1 Number in class 45 Locale Sri Lanka Delivered 1969 Retired 1995
10 locomotives from W1 class were later fitted with new engines and renumbered as W3 class.

The Sri Lanka Railways Class W1 is a class of Sri Lankan diesel hydraulic locomotive that was built by Rheinstahl Henschel in 1969. A total of 45 W1s were built and imported. This is the first diesel-hydraulic locomotive which ran on Sri Lankan rail.

The history of W1 begins in 1969. 45 of W1s were imported to Sri Lanka which made W1 the most numerous class of SLR locomotives that time. At that time only Class M1 and Class M2 locomotives were in operation. Most of other services were carried out by steam locomotives. But with the introduction of W1s most of steam locomotives were taken out of service and those services were taken by W1. These locomotives have been used for Upcountry trains Udarata Menike and Podi Menike for about 25 years until 1995, along with the M6. Also, this locomotive can be operated on any of railway lines in Sri Lanka.^[2]

By 90's most of W1s were out of service all because of problems in the prime-mover and some due to serious accident damages. These condemned locomotives were scrapped.^[2]

With declination of W1s 2 locomotives (650 & 657) were fitted with new Paxman VEGA SE/RP 160^[1] prime movers of power 1250 HP. By 2011 only 2 of them were in running condition. Those were used in light duties. By 2012 none of W1s were in operation. Note - 657 was a yard shunter at Dematagoda in 2016. On 18 Aug 2016 it took the rerailing van from Dematagoda sheds to Colombo's Fort station to rerail a coach of an arriving train. The coach's rear bogie had become derailed on the points serving platforms 1 and 2. It then returned with the rerailing van to Dematagoda. Eric Hayman travelled in from Dematagoda on 657 and saw the whole operation. He returned on the loco to the sheds.

Sri Lanka Railways Class W3
W3 No. 673
Type and origin Power type Diesel Model DH3 1200 Rebuilder Sri Lanka Railways, Adtranz Rebuild date 1997 Number rebuilt 10
Specifications Configuration: ​  • AAR B-B Gauge 1,676 mm (5 ft 6 in) Prime mover Caterpillar 3512 DI-TA[2] Transmission Voith L 520 R U2 MU working Yes Loco brake Air, Hydro-Dynamic Train brakes Air, Vacuum
Performance figures Power output 1,200 hp (890 kW)
Career Disposition Active
No. 631, 636, 638, 647, 659, 665, 666, 667, 669 and 673 W1 locomotives were reclassified as W3.

In 1997, 10 Class W1 locomotives were extensively refurbished. SLR and Adtranz involved in this. During these refurbishment the locomotives were fitted with new power plants, power transmission systems and electronic engine control systems. As well as a full new repaint of Blue and Silver was undertaken.

After the extensive refurbishment, the locomotives were reclassified as the W3-class.

• Diesel locomotives of Sri Lanka
• Sri Lanka Railways W2

• Sri Lanka Railways Info Page - Class W3
• ෴W3 දුම්රිය එන්ජිම - W1 එන්ජිමට නව බලසැපයුම් එන්ජින් සවිකර දේශීයව නිපැයූ එන්ජිම෴