| Sri Lanka Railways M4 | |
| Powertype: | Diesel-electric |
| Builder: | Montreal Locomotive Works |
| Ordernumber: | M-6080 |
| Serialnumber: | M-6080-01 to M-6080-14 |
| Buildmodel: | MX-620 |
| Builddate: | 1975 onwards |
| Totalproduction: | 14 |
| Uicclass: | Co′Co′ |
| Wheelbase: | Bogie: 11feet |
| Length: | 58feet |
| Locoweight: | 93LT |
| Fueltype: | Diesel |
| Primemover: | ALCO 251C3 |
| Enginetype: | 4 stroke V12 diesel |
| Cylindercount: | 12 |
| Maxspeed: | Design: 104km/h Service: 65km/h |
| Poweroutput: | 1750hp |
| Locobrakes: | Air, Vacuum, Dynamic (Some vary) |
| Operator: | Sri Lanka Railways |
| Operatorclass: | M4 |
| Numinclass: | 14 |
| Fleetnumbers: | 743–756 |
| Officialname: | See table |
| Firstrundate: | 1975 |
The Sri Lanka Railways M4 is a class of diesel-electric locomotive manufactured in Canada by Montreal Locomotive Works. Fourteen of the manufacturers' model MX-620 were imported in 1975.
This was the longest locomotive in the Sri Lanka Railways previously. All units are still operational. On regular operation they are not used beyond Polgahawela on the main line, and are not used on the hill country section. They used to travel on the full main line regularly until the previous decade.
They are painted in a livery of dark blue, light blue, silver with yellow striping; although No. 752 Point Pedro was painted in a special ICE (Intercity Express) livery.
| Number | Name | Notes | |
|---|---|---|---|
| 743 | Madhu | Air Brakes Added | |
| 744 | Sigiri | Air Brakes Added | |
| 745 | Ruwanweli | Air Brakes Added | |
| 746 | Namunukula | Air Brakes Added | |
| 747 | Kelani | Air Brakes Added | |
| 748 | Walawe | Air Brakes Added | |
| 749 | Dunhinda | Air Brakes Added | |
| 750 | Isurumuni | Air Brakes Added | |
| 751 | Diyaluma | Air Brakes Added | |
| 752 | Point Pedro | Special ICE livery was on this locomotive. Now normal livery. | |
| 753 | Samanala | Imported with Dyn Brakes. Air Brakes Added | |
| 754 | Menik | Imported with Dyn Brakes. Air Brakes Added | |
| 755 | Mahaweli | Imported with Dyn Brakes. Air Brakes Added | |
| 756 | Laxapana | Imported with Dyn Brakes. Air Brakes Added |
File:CLASS M4 LOCO OF SRI LANKAN RAILWAYS AT GALLE STATION SRI LANKA JAN 2013 (8560934025).jpgFile:Class M4 MLW - Alco Bombardier -- 745 arriving at Aluthgama, Sri Lanka.jpg|Class M4 No. 745 "Ruwanveli"File:SL Colombo asv2020-01 img37 Maradana station.jpg|Class M4 No. 747 "Kalani"File:CLASS M4 LOCO OF SRI LANKAN RAILWAYS AT GALLE STATION SRI LANKA JAN 2013 (8562036458).jpg|Class M4 No. 748 "Walawe"File:Ruhunu1.jpg|M4 No. 749 "Dunhida"File:CLASS M4 LOCO OF SRI LANKAN RAILWAYS AT JA - ELA STATION SRI LANKA.jpeg|Class M4 No. 754 "Menik"Ruhunu Kumari Express.jpg|Class M4 No. 755 "Mahaweli"File:CLASS M4 LOCO OF SRI LANKAN RAILWAYS AT NEGOMBO STATION SRI LANKA.jpg|Class M4 No. 756 "Laxapana"