Class B1 (Locobase 9857)

Data from Milwaukee Road 1930 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection. Baldwin works numbers were 14581-14590 (produced in December 1895), 15465-15468 (August 1897).

Vauclain compounding system of HP & LP cylinders driving off the same crosshead. the class was rebuilt as 19"x26" simple-expansion engines in the 'teens and operated until the 1940s.

Class B2 (Locobase 9858)

Data from Milwaukee Road 1930 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection. Baldwin works numbers were15509-15510 (September 1897) 15898 (April 1898), 16157-16161 (August 1898), 16186-16190 (September 1898), 17216-17221, 17239-17244 (November 1898).

This larger class of Vauclain compounds followed the B1s described in Locobase 9857 and had greater cylinder volume, which was served by a much larger boiler and grate; the latter resulted from a firebox that was lengthened considerably and widened by 6" .

4102, 4108, 4114, 4123-4125 originally went to the Marinette, Tomahawk & Western.

The class was rebuilt as 20"x26" simple-expansion G-6 class engines in the twenties and operated until the end of steam.

Class B3 (Locobase 9859)

Data from Milwaukee Road 1930 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection. Baldwin works numbers were 16781-16782 (May 1899).

This was one of an interesting pair of Vauclain compounds that featured slightly larger cylinders with longer strokes. This was the smaller-boilered variant; the larger 4300 appears in Locobase 9860.

4200 was never rebuilt as a simple-expansion engine, going to the boneyard instead in February 1927.

Class B3 (Locobase 9861)

Data from Milwaukee Road 1930 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection. Baldwin works numbers were 18053-18054, 18071, 18079-18082 (August 1900), 18083, 18115-18119, 18156-18159, 18167-18170, and 18212-18215 (September 1900).

At the turn into the 20th Century, the Chicago, Milwaukee, & St Paul's Vauclain-compound Ten-wheelers had evolved into a design similar to those used on most other railroads. Compared to other railroads, however, the Milwaukee was relatively late in converting its engines to simple-expansion. This class received 22" x 26" cylinders in the latter half of the 1920s. So refitted, the class carried on until the end of steam.

Class B4 (Locobase 9860)

Data from Milwaukee Road 1930 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection. Baldwin works numbers were 16781-16782 (May 1899).

The smaller of this long-stroke pair of Vauclain compounds appears in Locobase 9859. This engine had a larger boiler with longer tubes.

Like the 4200, 4300 was never rebuilt as a simple-expansion engine and was scrapped in January 1927.

Class B4 (Locobase 9862)

Data from Milwaukee Road 1930 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection. Baldwin works numbers were 18201-18203, 18219-18222, 18246-18249, 18268-18272 (September 1900).

Continuing its evolution of the Vauclain compound Ten-wheeler design, the Chicago, Milwaukee & St Paul procured this batch with a larger boiler than the immediately preceding B-3s (Locobase 9861) and a 30" stroke for the cylinders. In the early 1920s, the Milwaukee rebuilt the class a simple-expansion engines with 21" x 30" cylinders

Class B4 - 62"" (Locobase 9863)

Data from Milwaukee Road 1930 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection. Baldwin works numbers were 19430-19436, 19469-19474 (August 1901); 19508-19509, 19540-19543, 19554-19555 (September 1901); 19556-19560, 19594-19601 (October 1901); 20850-20851, 20856-20858, 20905, 20926-20930, 20973-20975, 21017 (August 1902); 22620-22621, 22645-22647, 22689, 22704, 22707, 22724-22725, 22746, 22748-22750 (August 1903); and 22771, 22802, 22828 (September 1903).

The smaller wheels of this Chicago, Milwaukee & St Paul Vauclain compound Ten-wheeler freight design seem to have cleared the way for a bigger grate to supply a boiler essentially unchanged from the earlier B-4s (Locobase 9861). Obviously pleased with the proportions, the Milwaukee ordered several batches from Baldwin over the next few years.

As with most of the MLW 4-6-0 compounds, this class was rebuilt in the 1920s as simple-expansion engines with 22" x 28" cylinders.

Class G6-fs/G6-gs (Locobase 9864)

Data from Milwaukee Road 1945 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection.

The B2s delivered in 1897 were among the first of Chicago, Milwaukee, St Paul & Pacific's tandem compounds to be rebuilt as simple-expansion engines with outside radial valve gear and piston valves; 20.5 sq ft of the firebox heating surface came from arch tubes.. One group received 20" cylinders and was dubbed G6-fs;they are shown here. Three G6-gs (2369-2371) had smaller tenders.

In the diagram, the superheater area is shown as 471 sq ft. Locobase believes that the Milwaukee used the "equivalent surface area" concept that conferred a 50% "bonus" on each square foot of superheater. When calculated as shown in the specifications, the ratio of superheater area matches other similar designs.

Class G6-ms (Locobase 9865)

Data from Milwaukee Road 1945 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection.

The second half of the B2 class (Locobase 9858) to be superheated was modified 6 years after the start of the earlier program (Locobase 9864). Boiler pressure increased by 20 psi while the cylinder shrank by an inch. Otherwise the two sub-classes were very similar, although the measurements of tube and flue areas vary.

Class G6-ns (Locobase 9866)

Data from Milwaukee Road 1945 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection.

Four of the 1897 B2s (Locobase 9858) to be simpled and superheated had the same cylinder dimensions as the G6-ms, but a few more boiler tubes. The result was a heavier locomotive with a bit more heating surface area, but otherwise similar to the B2/G6 conversions.

Class G6-os (Locobase 9867)

Data from Milwaukee Road 1945 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection.

NB: The superheater area is an estimate. As noted in Locobase 9864, the Milwaukee's 1945 figure is too high, most likely because it included a "bonus" because of the drier steam it created. Locobase has adjusted the area by deducting about 40% and comparing the result with other locomotives of similar superheater layouts.

Class G6-ps (Locobase 9868)

Data from Milwaukee Road 1945 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection.

As noted in Locobase 9864, the Milwaukee's 1945 figure is too high, most likely because it included a "bonus" because of the drier steam it created. Locobase has adjusted the area by deducting about 40% and comparing the result with other locomotives of similar superheater layouts.

Class G6-s (Locobase 9869)

Data from Milwaukee Road 1945 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection.

As noted in Locobase 9864, the Milwaukee's 1945 figure is too high, most likely because it included a "bonus" because of the drier steam it created. Locobase has adjusted the area by deducting about 40% and comparing the result with other locomotives of similar superheater layouts.

Class G7-as (Locobase 9870)

Data from Milwaukee Road 1945 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection.

As noted in Locobase 9864, the Milwaukee's 1945 figure is too high, most likely because it included a "bonus" because of the drier steam it created. Locobase has adjusted the area by deducting about 40% and comparing the result with other locomotives of similar superheater layouts.

Class G7-bs/G7-cs (Locobase 9871)

Data from Milwaukee Road 1945 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection.

All of these B4 freight rebuilds had the 22"x 28" cylinders and piston valves. Fourteen operated the valves with Walschaert gear; the other four used Baker gear.

As noted in Locobase 9864, the Milwaukee's 1945 figure is too high, most likely because it included a "bonus" because of the drier steam it created. Locobase has adjusted the area by deducting about 40% and comparing the result with other locomotives of similar superheater layouts.

Class G8 (Locobase 9872)

Data from Milwaukee Road 1945 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection.

As noted in Locobase 9864, the Milwaukee's 1945 figure is too high, most likely because it included a "bonus" because of the drier steam it created. Locobase has adjusted the area by deducting about 40% and comparing the result with other locomotives of similar superheater layouts.