Locobase 7873 describes the superheated version of the other nineteen locomotives built for the W-PT by Brooks and Pittsburgh in two batches. The last one of the 1909 engines, however, introduced a variation of the Schmidt fire-tube superheater, to be known as the side header.
The AERJ report doesn't identify the manufacturer, but gives considerable detail. Several significant differences emerge from the account--indeed, they're explicitly stated. All of them are intended to remedy the defects in the superheaters already in use: "...the large number of steam joints to inspect and maintain, the difficulty of getting at the joints between the superheater pipes and the steam headers; the absence of an opportunity for taking care of the difference in expansion of the superheater pipes, thus leading directly to leaky joints; and to the liability of nuts and screw threads in the headers to corrosion."
One change was the reduction in steam pressure by 40 psi (2.76 bar) to relieve pressure on all those joints. Another was to reject the top header and divide the superheater into two side headers. Half of the elements housed in the relatively few large flues went to the left, the other half to the right header.The elements themselves could be single-loop or as many as four (as in the Type E just coming into use).
One of the biggest differences was in the amount of superheat desired. Like the Baldwin superheater, temperature increases would be limited-- in this case to 100-125 deg F--and the total superheater area comprising 10% of the combined heating surface area.
Even in 1909, the trends headed in other directions, most notably in the acceptance of greater maintenance demands to benefit from considerably higher superheated steam temperatures. Locobase has no direct evidence, but imagines that the 918 surrendered its unique setup in favor of the conventional Schmidt installation applied to the other locomotives.
Alco-Pittsburgh: 58080-58082 in January 1918 (delivered to the West Belt Line, but leased to P&WV as 920-922 and later purchased)
Alco-Brooks: 62882-62884 (626-628) and 63011-63013 (623-625) in April 1921.
These were powerful Consolidations with a long-stroke cylinder layout. They were delivered with saturated boilers (with one exception: see Locobase 162) and cylinders bored to 25" bushed with 1 1/2" (38 mm) thick bushings to take 22" (559 mm) diameter pistons. The AERJ report explained that when the boilers were later superheated, the bushings could be removed--and such was the case.
Later, 917 was fitted with Nicholson thermic syphons. The others had four arch tubes contributing 25.6 sq ft (2.38 sq m) of area to the firebox.
|Principal Dimensions by Steve Llanso of Sweat House Media|
|Class||G-5||H-8, H-7, H-8a/G4, G-6|
|Railroad||Wabash Pittsburgh Terminal (P&WV)||Wabash Pittsburgh Terminal (P&WV)|
|Number in Class||1||18|
|Road Numbers||918||910-916, 919, 918, 900-901, 920-928|
|Locomotive Length and Weight|
|Driver Wheelbase (ft / m)||15.75 / 4.80||15.75 / 4.80|
|Engine Wheelbase (ft / m)||25 / 7.62||24.75 / 7.54|
|Ratio of driving wheelbase to overall engine wheebase||0.63||0.64|
|Overall Wheelbase (engine & tender) (ft / m)||59.92 / 18.26||60 / 18.29|
|Axle Loading (Maximum Weight per Axle) (lbs / kg)|
|Weight on Drivers (lbs / kg)||207,000 / 93,894||206,000 / 93,440|
|Engine Weight (lbs / kg)||236,000 / 107,048||234,790 / 106,499|
|Tender Loaded Weight (lbs / kg)||153,650 / 69,695||153,650 / 69,695|
|Total Engine and Tender Weight (lbs / kg)||389,650 / 176,743||388,440 / 176,194|
|Tender Water Capacity (gals / ML)||8000 / 30.30|
|Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)||14 / 12.70|
|Minimum weight of rail (calculated) (lb/yd / kg/m)||86 / 43||86 / 43|
|Geometry Relating to Tractive Effort|
|Driver Diameter (in / mm)||58 / 1473||58 / 1473|
|Boiler Pressure (psi / kPa)||160 / 11||200 / 13.80|
|High Pressure Cylinders (dia x stroke) (in / mm)||25" x 32" / 635x813||25" x 32" / 635x813|
|Tractive Effort (lbs / kg)||46,897 / 21272.15||58,621 / 26590.07|
|Factor of Adhesion (Weight on Drivers/Tractive Effort)||4.41||3.51|
|Firebox Area (sq ft / m2)||190 / 17.65||223.60 / 20.77|
|Grate Area (sq ft / m2)||50.50 / 4.69||50.50 / 4.69|
|Evaporative Heating Surface (sq ft / m2)||3253 / 302.21||3053 / 283.63|
|Superheating Surface (sq ft / m2)||374 / 34.75||644 / 59.83|
|Combined Heating Surface (sq ft / m2)||3627 / 336.96||3697 / 343.46|
|Evaporative Heating Surface/Cylinder Volume||178.93||167.93|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||8080||10,100|
|Same as above plus superheater percentage||8888||11,817|
|Same as above but substitute firebox area for grate area||33,440||52,322|