| MLW RSC-14 | |
| Powertype: | Diesel-electric |
| Builder: | Montreal Locomotive Works |
| Rebuilder: | Canadian National Railway |
| Rebuilddate: | 1975–1976 |
| Numberrebuilt: | 38 |
| Aarwheels: | A1A-A1A |
| Uicclass: | (A1A)(A1A) |
| Weightondrivers: | 160000lb |
| Locoweight: | 240000lb |
| Primemover: | ALCO 251B |
| Rpmrange: | 1000 (max) |
| Enginetype: | V12 Four-stroke diesel |
| Displacement: | 8016cuin |
| Cylindercount: | 12 |
| Cylindersize: | 9x |
| Transmission: | Electric |
| Generator: | DC generator |
| Tractionmotors: | 4 DC traction motors |
| Maxspeed: | 650NaN0 |
| Poweroutput: | 1400-1NaN-1 |
| Tractiveeffort: | Continuous: 300001NaN1 |
| Operator: | Canadian National Railways |
| Operatorclass: | MR-14b and MR-14c |
| Fleetnumbers: | 1750–1787 |
The MLW RSC-14 was a diesel-electric locomotive rebuilt by Canadian National Railway from locomotives originally supplied by Montreal Locomotive Works.
These locomotives began life as MLW RS-18s for the Canadian National Railway (CN). The base RS-18 model was derived by MLW from the ALCO-produced RS-11 model, and was equipped with a 12-cylinder four-cycle model 251B diesel engine rated at . This engine turned a General Electric (of Peterborough, Ontario) DC generator feeding four traction motors - one per axle on two bogies. Many RS-18s were equipped with so-called "light" trucks (made by Dofasco and others) in deference to light rail on Canadian branchlines. RS-18s were owned by Canadian Pacific as well as Canadian National and many other Canadian railways, and continued in service on major railroads into the 1990s. They continue in branchline and secondary service throughout North America today (April 2009).
Using the RS-18 as a starting point, the RSC-14 was created in the mid-1970s to meet CN's requirement for A1A-A1A trucked locomotives for light rural branchline service, particularly in the Maritimes.
CN retired its older A1A-A1A configured MLW RSC-13 and MLW RSC-24 models in the mid-1970s and rebuilt several dozen RS-18s using the A1A trucks from the scrapped RSC-13 and RSC-24 units. The horsepower rating for the locomotives was lowered from 1800-1NaN-1 on the RS-18 to 1400-1NaN-1, thus the new designation "RSC-14".
The locomotives saw extensive use on Prince Edward Island (see Prince Edward Island Railway), and on branch lines in New Brunswick and Nova Scotia. Most were retired or sold by the mid-1990s.
There are only two of these locomotives left in Canada: