Geared steam locomotive
A geared steam locomotive is a type of steam locomotive which uses gearing, usually reduction gearing, in the drivetrain, as opposed to the common directly driven design.
Pennsylvania Railroad class J1
As with many of the Pennsylvania Railroad's steam locomotives, the J1 had its headlight above the smokebox. Like the M1 the J1 had a keystone numberplate, unlike the round numberplates seen on the rest of the PRR's freight steam locomotives. They were also equipped with Baker valve gear instead of Walschaerts valve gear which was more common on the PRR. Additionally, they had radial-stay fireboxes instead of the Belpaire fireboxes seen on nearly all of the Pennsylvania Railroad's steam locomotives. Mechanically, these locomotives were identical to the C&O's T-1 class 2-10-4s.