The Buffalo, Rochester & Pittsburgh was not a large passenger railroad, but it did provide its ridership with the best equipment available. In the early years the railroad used the finest 4-4-0 and 4-6-0 it could buy. Later, it began using the 4-4-2 "Atlantics" with four (road numbers 160 through 163) coming in 1903 and by 1909 eleven more (road numbers 164 through 174) were added to it passenger service. These 15 locomotives were designated as Class W.

As passenger cars became heavier and trains longer the Class W locomotives were replaced by a fleet of 4-6-2 "Pacific" locomotives. The first 17 (road numbers 600 through 616) arrived from the American Locomotive Company beween 1912 and 1918 and were designated Class WW. These locomotives had 24 1/2x26 cylinders, 73" drivers, a 200 psi boiler pressure, exerted 36,340 lbs of tractive effort and each weighed 258,000 pounds. In 1923 another five (road numbers 675 through 679) were delivered from ALCO and were designated as Class WW-2. They had 22 1/2x28 cylinders, 73" drivers, a 200 psi boiler pressure, exerted 33,000 lbs of tractive effort and each weighed 241,000 pounds.

In 1932 the Baltimore & Ohio took over the BR&P and renumbered both classes of the WW locomotives. All of the BR&P "Pacific" were retired by 1953 and there are no survivors.