Starting in 1929, DL&W began to receive thirty new "Poconos" (road numbers 1601 through 1620 Class Q-2 and 1621 through 1630 Class Q-3) from ALCO. These were intended for freight service and had 70" drivers and a tractive force of 71,600 pounds.
In 1934, it purchased 20 more Class Q-4 (road numbers 1631 through 1650) ALCO "super power" 4-8-4s, this time intended for dual service. They were designed to have 74" drivers, a tractive effort of 72,000 pounds and roller bearings on all axles.
There are no survivors
|Class||Road Numbers||Year Built||Builder|
In his study of the USRA Heavy Mountain (see Locobase 232) and the locomotives it inspired, LeMassena notes that the DL&W had procured five 4-8-2s based on the USRA design but equipped with larger fireboxes ( Locobase 5731). Soon the railroad came back for still bigger descendants of the basic design that needed another axle under the firebox. Thus were erected the first DL&W 4-8-4s
Called Poconos, this group of five engines led the way for 50 more. They had 88 sq ft (8.15 sq m) of thermic syphons and 28 sq ft (2.6 sq m) of arch tubes as part of their firebox heating surface. Also, they had the tallest drivers of any of the DL&W 4-8-4s.
Unlike every other US 4-8-4 design, the D&LW Qs (see also 260) used the smaller flues for its Type A superheater tubes. All others using Type As had 5 1/2" flues."
The next step in the DL&W's Pocono parade belonged to this dual-traffic design. Simliar in most respects to the Brooks-built Q1 (Locobase 259), the new class had smaller drivers and were expected to haul fast freights as well as passenger trains. Firebox had 110.5 sq ft (10.25 sq m) of thermic syphons and 27.5 sq ft (2.55 sq m) of arch tubes contributing to the heating surface.
NB: Unlike every other US 4-8-4 design, the D&LW Qs (see also 259) used the smaller flues for its Type A superheater tubes. All others using Type As had 5 1/2" flues."
This class (Alco works #68623-68632) represented a big boiler redesign compared to the Q2s that had preceded it only a few years earlier (see Locobase 260). Superpower dimensions had arrived: the number of firetubes shrank dramatically while scores of new, smaller-diameter flues for the Type E superheated resulted in an 69% increase in supeheater area (or more than 900 sq ft). The firebox saw little change and had 110 sq ft of thermic syphons and 27 sq ft of arch tubes contributing to the heating surface.
Also, LeMassena notes, the Q3s pioneered roller bearings on the Lackawanna with the first 8 (Q3) sporting roller bearings on the lead trucks and the last two (Q3a) fitted with roller bearings on all engine axles.
The last variant of the DL&W's sizable 4-8-4 stud, the Q4 also sported a superpower boiler on a slightly smaller scale than the Q3 (Locobase 9246), but pressed to a higher degree. The firebox, too, was a bit smaller with 95 sq ft of thermic syphons and 27 sq ft of arch tubes contributing to the heating surface. Driver diameter increased by 4" and the Q4s also traveled on roller bearings on all engine axles.
LeMassena says: "Although intended for fast freight trains between Buffalo and Binghamton, New York, these locomotives handled perishables eastward to Hoboken, New Jersey, returning westward on mainline passenger trains."
|Specifications by Steve Llanso|
|Railroad||Delaware, Lackawanna &Western||Delaware, Lackawanna &Western||Delaware, Lackawanna &Western||Delaware, Lackawanna &Western|
|Locomotive Length and Weight|
|Ratio of driving wheelbase to overall engine wheebase||0.43||0.42||0.42||0.42|
|Overall Wheelbase (engine & tender)||82.21'||84.62'||84.62'||86.54'|
|Axle Loading (Maximum Weight per Axle)|
|Weight on Drivers||269000 lbs||262000 lbs||270000 lbs||274000 lbs|
|Engine Weight||421000 lbs||418000 lbs||432000 lbs||447000 lbs|
|Tender Light Weight||221500 lbs||289000 lbs||287200 lbs||313000 lbs|
|Total Engine and Tender Weight||642500 lbs||707000 lbs||719200 lbs||760000 lbs|
|Tender Water Capacity||12000 gals||15000 gals||15000 gals||16000 gals|
|Tender Fuel Capacity (oil/coal)||16 tons||22 tons||22 tons||26 tons|
|Minimum weight of rail (calculated) on which locomotive could run||112 lb/yard||109 lb/yard||113 lb/yard||114 lb/yard|
|Geometry Relating to Tractive Effort|
|Boiler Pressure||250 psi||230 psi||235 psi||250 psi|
|Cylinders (dia x stroke)||27" x 32"||28" x 32"||28" x 32"||28" x 32"|
|Tractive Effort||64379 lbs||70067 lbs||71590 lbs||72043 lbs|
|Factor of Adhesion (Weight on Drivers/Tractive Effort)||4.18||3.74||3.77||3.80|
|Firebox Area||493 sq. ft||515 sq. ft||513 sq. ft||493 sq. ft|
|Grate Area||88.20 sq. ft||88.20 sq. ft||88.20 sq. ft||88.20 sq. ft|
|Evaporative Heating Surface||5193 sq. ft||5136 sq. ft||5445 sq. ft||5488 sq. ft|
|Superheating Surface||1324 sq. ft||1324 sq. ft||2243 sq. ft||2180 sq. ft|
|Combined Heating Surface||6517 sq. ft||6460 sq. ft||7688 sq. ft||7668 sq. ft|
|Evaporative Heating Surface/Cylinder Volume||244.89||225.21||238.76||240.64|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||22050||20286||20727||22050|
|Same as above plus superheater percentage||26460||24343||26738||28224|
|Same as above but substitute firebox area for grate area||147900||142140||155516||157760|