Class T (Locobase 196)

Data from tables in 1930 Locomotive Cyclopedia.

Firebox heating surface included 42 sq ft of arch tubes.

2 engines built by the B&O using a 2-8-2 boiler. Although 74" drivers promised a good dual-role engine, the B&O did not follow up on this design. Both retired in 1953.

Class T-1 (Locobase 3097)

Data from B&O Staufer Locomotive Diagrams (Medina, Ohio: Alvin Stauffer), p. 94 supplied in May 2005 by Allen Stanley from his extensive collection. Works number was 61569 in November 1930.

One of two Mountains built by Baldwin in 1930 to test the Emerson watertube firebox alongside a conventional stayed firebox. In the Emerson, a 40" diameter drum ran along the centerline over the grate and from front sheet to back head. Headers at the top and bottom of the firebox were connected by two rows (190 tubes total) of 2 1/2" diameter water tubes. The top header was joined to the drum by 13 4"-diameter nipples on each side.

The value of the Emerson firebox was held to be the much greater heating surface it offered to the fire. From 474 sq ft of evaporative surface, including syphons, in the stayed firebox, the surface expanded 82% to 866 sq ft in the Emerson (including the 83 sq ft of arch tubes).

Unfortunately for such designs, the system was prey to vibration, insufficient insulation, maintenance headaches. Moreover, it didn't after all offer much of an advantage. The T-1 and the articulated KK-1 were the only watertube engines supplied to the B&O.

Class T-2 (Locobase 3098)

Data from B&O Staufer Locomotive Diagrams (Medina, Ohio: Alvin Stauffer), p. 95 supplied in May 2005 by Allen Stanley from his extensive collection. Works number was 61554 in November 1930.

This was the conventional, stayed firebox variant of the Mountain tested by the B&O against the T-1 (Locobase 3097), which had a watertube firebox. As part of the firebox heating surface, the T-2 had 18 sq ft of arch tubes and 95 sq ft of thermic syphons.

Like the T-1, the T-2 soldiered on solo until 1951.

Class T-3b / T-3c (Locobase 193)

Data from B&O to 1954 Assorted locomotive diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

Similar T-3b class numbered from 5565-5594. 40 locomotives built by the B&O from 1942 to 1948 using boilers from retired 4-6-2 and 2-8-2 engines. The frame was cast steel with integral cylinders. The shops fitted several different fireboxes to engines in this class. One was a 363 sq ft unit that included 35 sq ft of arch tubes and 14 sq ft in a single thermic syphon. The second added the syphon and 49.9 sq ft of circulators to the basic 314 sq ft of grate surface. The third added one more circulator to bring the total to the 388 sq ft shown in the specs. A fourth, apparently mounted only on certain T-3Bs, added 72 sq ft of circulators to the grate area and achieved the same firebox heating surface area.

Last T-3 retired in 1960.