MLW "RS18" Locomotives: Specs, Roster, History

Published: August 12, 2024

The RS18, produced by the Montreal Locomotive Works (MLW), was a very successful design that left a significant mark on Canadian railroading.

Based from Alco's RS11 in the U.S., the RS18 was built between 1956-1968 and part of the Road Switcher (RS) series. While the model was generally designed for freight service it was also offered with an optional steam generator for passenger assignments.

Known for its versatility, robust performance, and adaptability, the RS18 was regarded as one of the most reliable designs during its many years in service. MLW ultimately sold some 351 units during a twelve year production run.

CP Rail (Canadian Pacific) RS18 #8783 lays over at Saint-Luc, Quebec in September, 1976. Warren Calloway photo.

Historical Context and Development

The RS18 first entered MLW's catalog the end of the transition from steam to diesel locomotives. Railroads were seeking reliable, powerful, and multipurpose locomotives that could handle varying operational demands.

The Montreal Locomotive Works responded to this demand with the RS18, positioning it as a successor to the earlier RS10 model.

Interestingly, MLW designs were generally better received and enjoyed longer service lives in Canada than their Alco counterparts. For example, one could still find RS18s, C424s, and M630s in regular service throughout Canada through the mid-1990s when similar Alco designs in the States had long since disappeared from Class 1 rosters by the early 1980s.

MLW built some 351 units of the RS18. The design improvements and technological advancements from Alco were incorporated into the RS18, ensuring it met the rigorous standards and expectations of the North American railroad industry.

Design and Specifications

In his book, "The Diesel Builders Volume Two: American Locomotive Company and Montreal Locomotive Works," author John Kirkland notes the RS18 was initially referred to as the RS11M before given it's now common moniker, presumably to denote its horsepower rating.

It was nearly identical to the RS11 except for its lack of notches along the upper corners of the high hood, a design feature meant to provide access to the sandbox fillers.

The RS18 could be produced in either a short low, or high hood configuration and was ultimately built in both styles.

**1. Prime Mover and Engine:**

- **Engine:** ALCO 251B
- **Cylinder Configuration:** V12
- **Power Output:** 1,800 horsepower

The RS18 is powered by the Alco 251B prime mover, a V12, four-stroke diesel engine capable of delivering 1,800 horsepower. This engine was renowned for its reliability and performance, enabling the locomotive to handle both freight and passenger services effectively.

**2. Wheel Arrangement:**

- **Configuration:** B-B (four axles, all powered)

**3. Dimensions and Weight:**

- **Length:** 56 feet, 11 ¾ inches

- **Weight:** 232,000 - 247,000 pounds

**4. Notable Features:**

- **Dual-Service Capability:** Canadian National would later modify some of its RS18s with HEP equipment in the short hood for passenger assignments.

Canadian Pacific RS18 #8742 carries out switching chorse at Saint-Jérôme, Quebec in September, 1963. Rick Burn photo.

Operational Use and Impact

The RS18 quickly became a workhorse for many Canadian railroads, particularly Canadian National and Canadian Pacific, the primary operators of this model. Several factors contributed to its widespread adoption and positive reception:

**1. Reliability and Performance:**

The RS18's robust design and reliable 251B engine made it a dependable locomotive for various types of services. Whether hauling freight trains across long distances or managing passenger services, the RS18 consistently delivered performance.

**2. Versatility:**

The RS18’s dual-service capability allowed it to be utilized in a plethora of roles.

**3. Ease of Maintenance:**

Operators found the RS18 relatively straightforward to maintain. This ease of maintenance was a crucial factor for railroads seeking to minimize operational downtimes.

**4. Adaptability:**

As operational needs changed, many RS18 units were rebuilt or upgraded to extend their service life (denoted as "RS18u"). This adaptability ensured that the RS18 remained relevant and functional in evolving rail environments.

Notable Operators and Services

**1. Canadian National:**

CN was one of the largest operators of the RS18, acquiring 233 examples, utilizing the locomotive in a variety of roles across its extensive network. From hauling heavy freight trains to passenger service, the RS18 was a versatile asset for CN.

**2. Canadian Pacific:**

CP also employed a significant number of RS18 units - 72 in all - often using them for similar dual-service roles. The reliability and performance of the RS18 made it a valuable addition to CP’s locomotive roster.

**3. Other Operators:**

Although primarily used by CN and CP, the RS18 was also operated by smaller Canadian railroads and private firms including Pacific Great Eastern, Quebec Cartier Mining, Roberval & Saguenay, Arnaud Railway (Wabush Iron), International Nickel, and Quebec Iron & Titanium. Its versatility and dependable performance made it a viable option for various rail operations.

Legacy and Preservation

The legacy of the RS18 is cemented by its significant contribution to North American railroading, especially in Canada. While many units have been retired from active service, several have been preserved by railway museums and historical societies, including a handful which have found their way into the U.S.

Specifications

Entered Production	12/1956 (Canadian National #3615-3616)
Years Produced	12/1956-6/1968
Model Specification	DL718
Engine	251B, V-12
Horsepower	1,800
RPM	1,000
Carbody Styling	Alco
Length (Between Coupler Pulling Faces)	56' 11 ¼"
Weight	232,000 - 247,000 lbs
Dynamic Brakes	Optional
Trucks	B-B
Truck Type	Swing Bolster, Drop-Side Equalizer (AAR Type-B)
Truck Wheelbase	9' 4"
Wheel Size	40"
Traction Motors	GE 752 (4)
Traction Generator	GT581
Steam Generator	Optional
Gear Ratio	74:18 (65 MPH), 65:18 (75 MPH)
Tractive Effort Rating	46,500 Lbs. at 12 MPH
Top Speed	65 - 75 MPH

Production Roster

Serial Number	Completion Date	Owner	Road Number
81569-81570	3/1957	Canadian Pacific	8729-8730
81571-81572	12/1956	Canadian National	3615-3616
81604-81605	4/1957	Pacific Great Eastern	587-588
81606-81609	3/1957	Canadian Pacific	8731-8734
81610-81615	4/1957	Canadian Pacific	8735-8740
81616-81618	5/1957	Canadian Pacific	8741-8743
81619-81623	6/1957	Canadian Pacific	8744-8748
81624-81631	7/1957	Canadian National	3617-3624
81632-81636	8/1957	Canadian National	3625-3626
82138-82146	8/1957	Canadian National	3627-3637
82149-82157	9/1957	Canadian National	3648-3652
82189-82194	10/1957	Canadian National	3653-3662
82195-821204	11/1957	Canadian National	3663-3671
82205-82213	12/1957	Canadian National	3672-3684
82214-82226	1/1958	Canadian National	3685-3696
82227-82238	2/1958	Canadian National	3697-3700
82239-82242	3/1958	Canadian National	3701-3704
82243-82250	3/1958	Canadian Pacific	8749-8758
82253-82258	4/1958	Canadian Pacific	8759-8764
82241	1/1958	Canadian Pacific	8795
82222-82226	7/1958	Canadian Pacific	8796-8800
82427-82430	6/1958	Canadian National	3705-3714
82431-82440	8/1958	Canadian National	3715-3730
82446-82453	4/1958	Canadian Pacific	8765-8772
82454-82465	5/1958	Canadian Pacific	8773-8784
82466-82472	6/1958	Canadian Pacific	8785-8791
82473-82475	7/1958	Canadian Pacific	8792-8794
82478-82493	9/1958	Canadian National	3715-3730
82494-82499	10/1958	Canadian National	3731-3736
82500-82508	11/1958	Canadian National	3737-3745
82509-82510	5/1958	Pacific Great Eastern	589-590
82511-82518	5/1959	Canadian National	3100-3107
82519-82524	6/1959	Canadian National	3830-3837
82525-82530	7/1959	Canadian National	3838-3843
82531-82532	6/1959	Canadian National	3844-3849
82533-82538	8/1959	Canadian National	3100-3101
82539-82544	9/1959	Canadian National	3102-3107
82545-82547	10/1959	Canadian National	3114-3116
83182	10/1959	Canadian National	3117
83183-83190	11/1959	Canadian National	3118-3125
83191-83194	12/1959	Canadian National	3126-3129
83195-83201	12/1959	Quebec Cartier Mining	101-107
83229	1/1960	Quebec Cartier Mining	108
83230-83233	1/1960	Canadian National	3850-3853
83234-83245	2/1960	Canadian National	3854-3865
83246-83255	3/1960	Canadian National	3866-3875
83256-83261	4/1960	Canadian National	3876-3881
83262-83265	5/1960	Canadian National	3882-3885
83266-83269	6/1960	Canadian National	3886-3889
83270-83271	7/1960	Canadian National	3890-3891
83272-83273	8/1960	Canadian National	3892-3893
83274-83275	5/1960	Pacific Great Eastern	591-592
83276-83277	9/1960	Pacific Great Eastern	593-594
83278	4/1960	Roberval & Saguenay	24
83279	5/1960	Arnaud Railway (Wabush Iron)	901
83280	6/1961	Arnaud Railway (Wabush Iron)	902
83281-83283	6/1962	Pacific Great Eastern	595-597
83304-83305	6/1962	Pacific Great Eastern	598-599
83306	9/1962	Arnaud Railway (Wabush Iron)	903
84817-84818	8/1964	Pacific Great Eastern	614-615
84819-84821	9/1964	Pacific Great Eastern	616-618
84822-84825	10/1964	Arnaud Railway (Wabush Iron)	904-907
84826-84829	10/1964	Arnaud Railway (Wabush Iron)	908-911
84830-84831	3/1965	Pacific Great Eastern	619-620
84832-84835	5/1965	Pacific Great Eastern	621-624
84836	6/1965	Pacific Great Eastern	625
84871	6/1965	Roberval & Saguenay	25
84872	6/1965	Pacific Great Eastern	626
See Note	6/1965	Pacific Great Eastern	627
3460-01 thru 3460-03	10/1966	Pacific Great Eastern	628-630
3497-01 thru 3497-03	5/1968	International Nickel	208-2 thru 208-4
6007-01	6/1968	Quebec Iron & Titanium	6

* Pacific Great Eastern #627 was wrecked and rebuilt using Pacific Great Eastern #616's construction number (84819).

Canadian National RS-18 #3153 is seen here at Spadina Street in Toronto on October 11, 1976. This unit illustrates how CN extended the short hood out to the end of the frame, eliminating the walkway, in order to house the HEP engine. Doug Kroll photo.

Legacy

The RS18 stands as a testament to the innovation and adaptability of mid-20th-century locomotive engineering.

Its legacy endures through preserved units in railway museums and the continued use of some locomotives in heritage operations. The RS18 remains a cherished part of railway history, symbolizing a period of technological advancement and operational excellence in the rail industry.