RAG commented that they were "of the usual design, having no special features except the method of equalization and spring suspension at the back."
EW King, Jr., in Drury (1993), comments that this class was the Class A Ten-wheeler running gear with a larger boiler and large firebox.
Alco-Richmond started the series with 5 in 1905; these used Stephenson link motion. Baldwin delivered its 15 in 1907 with Walschaert gear. All used 12" piston valves.
These relatively small 4-6-2s were retired in 1934-1939.
The E2a (Baldwin, 1912, 553-563) and E2b (Roanoke shops, 1913-1914, 543-552 and 559-563) followed and were similar; see Locobase 7820. E were updated with superheaters and became E-2a; see Locobase 7820.
E2s retired gradually, some from each subclass being scrapped as early as the late 1930s while some lasted until the late 1950s.
As noted in Locobase 4394, the 6 E-2a Baldwin Pacifics were similar to the Richmond E2s delivered in 1910; their works numbers were 37720-37725 in May 1912. Like the E2s, they had long careers on the N & W, retiring 1940-1958.
The E2b that came from the N & W's own shops in 1913-1914 (343-352) had "Hobart-Allfree"cylinders and valve gear, about which Ed King wrote:
"...no drawings or diagrams of these cylinders have surfaced and from the side view and other action views of E-2bs, there seems to be little or no difference in the external appearance of the cylinders." [November/December 2002 Arrow -- Vol 18, No 6 -- (http://www.nwhs.org/arrowdb/issueList.php?issue_id=16, last accessed 25 April 2008)]
But Volume 52 of the Brotherhood of Locomotive Firemen and Enginemen's magazine from 1912 later surfaced in Google Books. (See also a detailed explanation in "A New Radial Valve Gear," American Engineer and Railroad Journal, Vol 84, #10 (October 1910), pp. 408-409.)
The LFE published a Q & A about valve gears and valves that included this catechism concerning the Allfree cylinders (p. 339):
"Each cylinder together with its steam chest is cast in one piece. The valve seat is close to the cylinder bore and is inclined at an angle of from 15 degrees to 30 degrees, dependent upon the location of the valve stem. The steam chest and cover, as well as the cylinder heads, have heavy double walls with dead air spaces between ...
"15. Q.·What is the purpose of the double walls and dead air spaces?
A.·By so surrounding the live steam passages the steam is thereby insulated and protected to a large extent from sudden changes of temperature, with resulting condensation. Also cylinders and steam chests so constructed are exceptionally strong."
The Q & A went on to describe the assembly's compression valve (a device that increased exhaust area by about 50%) as "...virtually a piston valve, having solid heads and provided with wide snap rings." Increasing the exhaust area "...allows the expanded steam in the cylinders to almost instantly escape, reducing the back pressure in the cylinders, and making it possible to run with an enlarged exhaust nozzle and maintain a proper fire."
The Q & A's elucidation of benefits of avoiding the expenditure of "energy, or negative work ... in compressing a large quantity of steam" proclaimed they stemmed from "...considerably reducing the clearance, or waste, volume that obtains with cylinders employing the usual types of slide or piston valves and carrying the final exhaust closure to a very late point in the stroke." In other words, the Allfree seems to have acted most like a poppet valve, such as would be introduced later by designers like Caprotti.
Even without knowing the exact internal details of the Allfree design, however, King was able to note:
"Some aspect of the [Allfree] application, however, required a different location of the valve stem enabling the combination lever to be ahead of the crosshead and hung from a traveler which moved on a guide below the valve stem. Normal E-2a Baker Valve Gear hung the combination lever from the bell crank. Six of the E-2bs were rebuilt with "normal" cylinders and the valve gear was altered accordingly, and were reclassed E-2a. The 549 was one of the four not rebuilt, and lasted until 1948."
Sylvan Wood's survey of Santa Fe locomotives discussed the Hobart Allfree valve gear, commenting on an unwanted consequence of the poppet action. Although new installations with valves "in good shape" made for "very fast and powerful" engines, its action had unpleasant results: "The valve held the steam through most of the stroke, then let it loose all at once, losing the cushioning effect of conventional cylinders, thus resulting in broken rods, pistons, and keys."
|Specifications by Steve Llanso of Sweat House Media|
|Railroad||Norfolk & Western (N&W)||Norfolk & Western (N&W)||Norfolk & Western (N&W)|
|Number in Class||20||16||21|
|Locomotive Length and Weight|
|Driver Wheelbase (ft)||12||12.50||12.50|
|Engine Wheelbase (ft)||30.54||32.87||32.87|
|Ratio of driving wheelbase to overall engine wheebase||0.39||0.38||0.38|
|Overall Wheelbase (engine & tender) (ft)||54.99||72.19||72.83|
|Axle Loading (Maximum Weight per Axle) (lbs)||47,725||56,000||55,000|
|Weight on Drivers (lbs)||125,000||166,000||168,200|
|Engine Weight (lbs)||195,250||247,000||256,950|
|Tender Loaded Weight (lbs)||109,900||167,500||212,000|
|Total Engine and Tender Weight (lbs)||305,150||414,500||468,950|
|Tender Water Capacity (gals)||6000||9000||12,000|
|Tender Fuel Capacity (oil/coal) (gals/tons)||10||14||16|
|Minimum weight of rail (calculated) (lb/yd)||69||92||93|
|Geometry Relating to Tractive Effort|
|Driver Diameter (in)||68||70||70|
|Boiler Pressure (psi)||200||200||200|
|High Pressure Cylinders (dia x stroke) (in)||20" x 28"||22.5" x 28"||22.5" x 28"|
|Tractive Effort (lbs)||28,000||34,425||34,425|
|Factor of Adhesion (Weight on Drivers/Tractive Effort)||4.46||4.82||4.89|
|Firebox Area (sq ft)||177.50||180||180|
|Grate Area (sq ft)||45.50||45.50||45.50|
|Evaporative Heating Surface (sq ft)||3464||4169||3320|
|Superheating Surface (sq ft)||730|
|Combined Heating Surface (sq ft)||3464||4169||4050|
|Evaporative Heating Surface/Cylinder Volume||340.24||323.54||257.66|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||9100||9100||9100|
|Same as above plus superheater percentage||9100||9100||10,738|
|Same as above but substitute firebox area for grate area||35,500||36,000||42,480|