Pennsylvania Y3-a 2-8-8-2

The prototype

The Class Y developed during the course of decades. Ninety class Y3 were built from 1919 in the Schenectady shops for the Norfolk and Western RR. During WWII N&W sold its surplus of hauling capacity among others to the Virginian RR. The last Y3 ceased in 1959.
One Y3a, N&W 2050, survived and is currently on display in the Illinois Railway Museum, Union, IL
More on this largest compound ever built on steamlocomotive.com

(more details and ©)

Engine number 2027 front end at november 7, 1934
Very impressive!! Note the size of the front end cylinders,
barely staying within the loading gauge!! (more details and ©)

No 2028 (more details and ©)

Class Y-3, engine 2064 being lifted in the shop (more details and ©)

Some Y3's were fitted with Bethlehem booster engines, adding up to 25% tractive at start up. Photo from May 19, 1927. (more details and ©)

A booster engine for steam locomotives is a small two-cylinder steam engine back-gear-connected to the trailing truck axle on the locomotive or the lead truck on the tender. A rocking idler gear permits it to be put into operation by the engineer. It would drive one axle only . They were used to start a heavy trains or maintain low speed under demanding conditions. It could be cut in while moving at speeds under 15 mph (24 km/h). Rated at about 300 hp (224 kW) at speeds of from 10 to 30 miles per hour (16 to 48 km/h). It would automatically cut out at 30 mph (48 km/h). Tractive effort of 10-12,000 lbf (44 to 53 kN) was common.

A closer look at the tender boosters (more details and ©)

The model

Simple: its awesome. It runs terrific, it weighs, and it is smooth. This is as much as a serie production model can give. Never have I seen such detail and accuracy. And I will never forget the moment it first set into motion. The view of the complexity of the motion. Its running capacities are characterized by a striking silence. Its flywheel does a terrific job. The European street price is about 450 euro, not actually cheap but its well worth it. It turns Märklin or Fleischmann to pity toys. This is the real thing, coming really close to brass models.
Like almost all mallets in model this model is not prototypical in that respect that both sets of drivers swivel at some point just off center of each set. A real mallet had the rear set fixed in the frame and only the front set swiveled at a point between the rear cylinders. This is a compromise for operational purposes.