Class K-1 (Locobase 1385)

Data from NKP 5 - 1950 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

Lima delivered 4 K-1A, Alco-Brooks 6 K-1B.Drury (1993) says these were smaller and lighter than the USRA designs. The K-1As had slightly less evaporative heating surface even though they had a 6" longer boiler.The firebox heating surface also amounted to less than the K-1Bs

Class Q (Locobase 917)

Data from table in AERJ July 1903. Firebox heating surface included 22.9 sq ft of arch tubes. Drury (1993) notes that these were among the first Pacifics anywhere and that they set the tone for the next several batches. A note on the Q diagram hosted at the NP Research site (http://research.nprha.org/Steam%20Diagrams/Forms/DispForm.aspx?ID=63, last accessed 25 April 2008) shows that the first 7 were delivered with piston valves, the next 8 with slide valves, and the last with Davis counter-balanced slide valves.

Most retired by World War II.

Class Q-1 (Locobase 918)

Data from table in June 1906 AERJ.

According to Drury (1993), these engines differed from the Qs in having larger boilers with a noticeable taper, outside frames on the trailing trucks, and 20,000 lb more engine weight. 2100-2105 were built in 1904, 2106-2117 in 1905.

Class Q-2 (Locobase 919)

Firebox heating surface included 8.9 sq ft of arch tubes. Built as Cole balanced compounds in 1906 and celebrated as such in Railway Age, these engines had inside admission for the high-pressure piston valves, outside for the low-pressure ones. One advantage claimed for the 4-cylinder compound was the reduction of hammer-blow on the rails. Also, tests suggested an increase in horsepower through compounding without an increase in boiler size.

Obviously, these advantages either were illusory or not worth the trouble as these engines were rebuilt as simple-expansion types in 1909. See Q-3, Q-4 for results.

Class Q-3 (Locobase 920)

Data confirmed by locomotive diagrams from 1900 hosted on http://www.nprr.org/Steam%20Diagrams/Forms/AllItems.aspx (7 Feb 2004). http://www.mtmuseum.org/roster/np2156.html (6 June 2005) says that the Q-3s operated primarily on the St. Paul-Duluth section although some were assigned to the North Coast Limited between Livingston and Butte, Montana.

According to the museum, "They were well-liked by the crews, capable of cruising at 95 mph." But see Locobase's assessment of that claim at entry 6568, the superheated upgrade

Class Q-3 (Locobase 2804)

Three of the Q-3s had larger cylinders. Two of these were part of the 10-lcoomotive batch supplied by Baldwin, the other came from Alco-Schenectady's delivery. See Locobase 920 for more information and 6568 for the superheated upgrade.

Class Q-3 - superheated (Locobase 6568)

Data from Form 7310 specification/improvement card available on http://www.mtmuseum.org/roster/np2156.html (visited 6 June 2005).

This is the superheated version of all converted Q-3 Pacifics (see Locobase 920 & 2804). According to the spec card, 8 sq ft of firebox heating surface was represented by an arch tube. Steam admission came through 12" piston valves.

An early example of superheating an existing design, this class had a relatively low degree of superheat. A somewhat unusual result of the exercise was a boiler still pressed to the original psi (many such conversions would reduce pressure) and containing more combined heating surface than before.

Locobase skeptically repeats a comment from 920 because it seems more likely with the superheated version: "They were well-liked by the crews, capable of cruising at 95 mph."

Locobase thinks that's a pretty high speed for 69" drivers. At that pace, they were whirling around at 463 rpm and the piston speed topped 2,000 fpm. And while the ratio between heating surface and cylinder volume runs toward the higher end of similar locomotives, it wasn't the highest.

Class Q-4 (Locobase 923)

This set of Q-4s were Baldwin's supplement to the Q-3s.

Data confirmed by locomotive diagrams from 1900 hosted on http://www.nprr.org/Steam%20Diagrams/Forms/AllItems.aspx (7 Feb 2004).

Class Q-4 (Locobase 2805)

Alco versions of the larger-cylinder Q-3s. Data confirmed by locomotive diagrams from 1900 hosted on http://www.nprr.org/Steam%20Diagrams/Forms/AllItems.aspx (7 Feb 2004).

Further supplemented by reproduction of 1913 Alco Bulletin 1016 on Richard Leonard's http://www.railarchive.net/alcopacifics/index.html (accessed 16 June 2006). Firebox heating surface included 8 sq ft of arch tubes. Note how low (14.1%) is the superheat ratio, indicative of how early in the era this design was produced.

In Northern Pacific's Tell Tale (June, 1950) (http://www.employees.org/~davison/nprha/niftyfiftytelltale.html), R. V. Nixon gave the following account of the Q-4 2222.

ORDER NO 222

NO 222 ENG 2222 RUN 2 HOURS LATE TOWNSEND TO LOGAN

DSC

Yes, that's a lot of deuces. but this train order actually was issued on the Rocky Mountain Division when Q-4 engine 2222 was assigned to [T]rains 221 and 222.

The four deuces has had a strenuous career with the N.P. Built by the Schenectady Works of ALCO in 1910, the 2222 was assigned immediately to the North Coast Limited out of Missoula, in which service it remained for nearly 15 years. It was a rugged job. Many enginemen will recall the scenic, but back-breaking run on No. 2 from Paradise to Missoula in the pre-stoker days. It took a first class fireman to keep a full head of steam on the steadily ascending grade from Paradise to Evaro, even though a helper was added at Arlee for the tough 2.2 [percent] grade to the top of the mountain. Needless to say, the 2222 worked at full capacity for the entire distance.

Quite a contrast to the effortless manner in which the present day Diesel-powered No. 2 slithers from Paradise to Evaro, almost oblivious of any climb. But we doubt if a Diesel could present anything as breath-taking and dramatic as the old 2222 barreling around a curve along the Pend d'Oreille River, throttle wide open, rods flashing in the sunlight, and the sharp exhaust emitting a plume of smoke into the clear, mountain air.

On the 50th anniversary of the North Coast Limited it is interesting to note that Q-4 power was standard on the train for a longer period than any other class of locomotive. The N.P. purchased a total of 49 Q-4s from Baldwin and Alco. Of these, 25 still remain in service, including the 2222 which is now taking it easy as a protection engine at Spokane

Class Q-5 (Locobase 925)

4 arch tubes of 3 1/2" diameter supported the firebox's brick arch; these contributed 35 sq ft to the firebox's heating surface.

According to Drury (1993) these twenty engines were designed to weigh 296,000 lb with no more than 62,500 lb on an axle. They were also to cost no more than current engines of similar size. A year after their delivery, Railway Age (22 Oct 1921) explained that they were intended for the Dilworth, Minn -Missoula, Mont. section of the road, which included 2.3% grades and 16-deg curves. On that section, the Q-5 would have 12-car trailing load with 17-car trains not unheard of. RA claimed that weight on the drivers came to 181,000 lb and total engine weight to 314,000 lb. RA calculated that these engines developed their maximum horsepower at 46.5 mph.

Drury contends that when Brooks delivered the Q-5s in 1920, however, axle load had grown to 65,433 lb, total weight to 323,700 lb and the price to $70,916. Also, they were seen as more complicated and harder to maintain. Variable-lead valve gear proved so daunting to adjust at first that the NP set the maximum speed at 55 mph, considerably less than hoped. NP soon worked out the bugs and the railroad ordered another 20 as Q-6s.

Class Q-6 (Locobase 926)

2261-2265 differed only in the use of oil as a fuel; they had 3,500-gal oil capacity tenders. Six (2252-2257) had 11,000-lb boosters.

Data confirmed by locomotive diagrams from 1900 hosted on http://www.nprr.org/Steam%20Diagrams/Forms/AllItems.aspx (7 Feb 2004). Diagram shows 14" diameter piston valves.