The Pennsylvania Railroad billed itself as "The Standard Railroad of the World" — ironically, since many of its steam locomotive practices were idiosyncratic. These included the almost universal use of Belpaire fireboxes (squared, rather than rounded top), high-mounted headlights, "banshee" whistles on many engines, and a numbering scheme that was no scheme at all but an assortment that saw locomotives of all classes intermixed at random. Thus, the 424 Pacific type locomotives of class K4s were numbered anywhere from 8 to 8378. What the supposedly "standard" Pennsylvania lacked in conformity with other North American practice, it made up for with internal standardization, in which its more than 4500 steam engines were limited to a small number of standardized designs that shared parts with each other. Until the advent of the T1 duplex-drive locomotives during World War II, almost all the PRR's inter-city passenger trains in non-electrified territory were in the hands of durable K4 4-6-2s. No. 5477, seen above in a photo of indeterminate origin, was a typical example with its cast steel pilot, Walschaerts valve motion and keystone number plate. For the dimensions of this type, see the page for No. 5492 below.