Western Maryland 2-8-8-2 "Chesapeake" Locomotives in the USA

Class L1 (Locobase 331)

Data from "Examples of Recent Mallet and Mikado Locomotives", Railway Mechanical Engineer, Volume 91, No 1 (January 1917), p 17; and ""Big Locomotives for Western Maryland Ry", Locomotive World, Volume VIII [8] , No 8 (December 1915), p. 3;, supplemented by data from WM MISC steam locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also George H Drury, Guide to North American Steam Locomotives (Waukesha, WI: Kalmbach Publishing, 2015 revised ed), p 327.(Thanks to Chris Hohl for his 7 May 2023 email noting the original tender coal capacity and loaded weight, adhesion and engine weights, and superheater area.) Works numbers were 5085-5094 in December 1915 and 5095-5099 in January 1916.

Lima produced the L-series Mallet compounds to satisfy specifications produced by Superintendent of Motive Power H R Warnock.

The design arrived in three batches, all of which had the same simple (as listed) and compound TE (105,600 lb/47,899 kg or 469.73 kN). Simple expansion was calculated to be 126,700 lb (55,470 kg or 563.59 kN).

L1s (901-910) - Western Maryland later calculated weights as 451,800 lb (204,933 kg) on the drivers and total engine weight of 506,500 lb (229,745 kg).

L1-a (911-915) drivers supported 455,600 lb (206,657 kg)and total weight was 503,100 lb (228,203 kg). These were equipped with Jacob-Shupert fireboxes, details of which appear in Locobase 463.

The L2 class numbered 916-925 and are shown in Locobase 8888.

Locobase is struck by the timing of this contract. Lima had entered the market for full-size mainline power in 1911; for the builder to be offering such a large engine--its first sale of a Mallet--indicates the determination to compete that underlay the decision. Its October 1916 ad for the L class in Railway Mechanical Engineer staked Lima's claim to ride on the leading edge:

"Today's Locomotives Must Be Different

"To carry peak load of modern railroad operation puts locomotive designers to the test.

"Rules and ratios of ten years ago [i.e., 1906] are now obsolete.

"Capacity increasing factors and economy devices have opened a new era and created new possibilities.

"Lima appreciates its responsibility to apply these factors to peak and normal loads.

"This locomotive is a case in point."

The design was in fact competitive with the other US 2-8-8-2 classes then in service, although its cylinder volume was among the smallest. Its mixed valve outfit had 14" (356 mm) American semi-plug piston valves serving the HP cylinders and double-ported Jack Wilson slide valves feeding the LPs.

Lima's ground-breaking superpower would set a new tone ten years later., but several innovative detail design features debuted in these articulateds. Locomotive World pointed out the Smplex steam distribution system, which it claimed "differed considerably" from any used in a Mallet until then. A typical compound locomotive, LW argued, had a bad name for "'blows' and steam leaking to the atmosphere, making it difficult or impossible in cold weather for the engineer to see track or signals." Frequently, illustrations would show the engine, "apparently emerging from a fogbank, with some such title as 'a compound hard at work."

[The tone of the article deepens Locobase's suspicion that LW was a house product of Lima's sales department.]

A general fix eliminated many sources of this fog by "conveying all the various vents, drains and relief discharges to the exhaust passage, and thence to the stack." Lima reduced the number of steam joints and simplified their form. For an exhaustive list of Lima improvements represented in this class, see LW's pages 6-8.

A key change to he intercepting valve design involved casting it independently of the HP cylinders. Placing the valve transversely between the two HP cylinders meant the cylinders could be cast to be interchangeable from left to right and "reversible". This was a first in Mallets with a separate exhaust, LW claimed. Improved access to the valve's internal regions offered another advantage of the transverse layout.

Ragonnet power reversers used late-stage cutoffs of 90% in the HP and 83% in the LP cylinders. An Economy Expansion Regulator allowed the automatic coupling of the HP and LP cylinders, which was intended "to keep the work of the high and low pressure engines more nearly equal at all running speeds."

Firebox design included its own novelties. Its brick arch, which was not a new concept, used Gaines-American fire bricks with air ducts intended to improve combustion. Ten feet from the backhead, a Gaines wall divided the firebox at 4/5 its total length and a combustion chamber extended ahead of that. Its heating surface area included 44 sq ft (4.09 sq m) in arch tubes. A Standard Stoker automatic overfeed stoker satisfied the firebox's voracious demands.

Drury's (1993) wry comment on the effect on top speed of 52" drivers and 40" LP cylinders suggests the limits of at least this early approach to superpower: "...the freight timetables must have listed days instead of hours and minutes."

Three of the class were sold for scrap before the US entered World War II--907 in June 1939, 912 in June 1940, and 905 in December 1940. 915 led the post-war disposals in August 1947. The other eleven went to the ferro-knacker between May 1950 and June 1951.

Class L1/L2 with larger grate (Locobase 8888)

Data from WM - 1 - 1936 steam locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. Works numbers from the range of 5554-5555 in December 1917, 5556-5558 in January 1918, 5559-5563 in April.

Lima's third batch of big Mallets weighed a bit more than the L1s (for which, see Locobase 331), but were otherwise almost identical. Some of the class had Baker valve gear, some were fitted with Walschaert valve gear; all of this class had converted to Walschaert valve gear by 1 February 1938, according to a letter in Volume 41 of the DeGolyer specification bookRail Data Exchange at SMU.

At some later date, several of the L1s and L2s had their grates stretched from 120" (3.048 m) to 150" (3.81 m), which increased the grate area to 100 sq ft (9.3 sq m) and the firebox to 530 sq ft (49.2 sq m). Locobase suspects this was a result of eliminating a combustion chamber ahead of the firebox, especially as the arch tubes had been deleted.