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Pennsylvania Railroad 4-4-4-4 T1 LocomotiveIn the late 1930s, Baldwin Locomotive Works (Baldwin) of Eddystone, Pennsylvania sought a partner to support the design of an experimental, rigid-frame, duplex, 4-4-4-4 locomotive. With this wheel arrangement, the engine would have a four-wheel leading truck, two independent sets of four-wheel drivers, and a four-wheel trailing truck. As a duplex engine, each of the four-wheel drivers would be powered by a pair of separate cylinders. Baldwin’s Chief Engineer Ralph P. Johnson believed the newly designed engine would be capable of improved efficiency that would rival diesel locomotives, which were just beginning to outperform steam. Compared to an articulated locomotive, a rigid-frame duplex arrangement created a comparatively light engine well-suited for high speeds. In addition, having four smaller cylinders with a reduced piston speed decreased wear and maintenance compared to two larger, harder-working cylinders as used in a standard locomotive layout, such as a 4-8-4. If not well-balanced, the reciprocating and revolving forces of the drive wheels on powerful two-cylinder locomotives could actually damage the track, an issue that was alleviated with a four-cylinder duplex.[ATTACH=full]130757[/ATTACH]
In the late 1930s, Baldwin Locomotive Works (Baldwin) of Eddystone, Pennsylvania sought a partner to support the design of an experimental, rigid-frame, duplex, 4-4-4-4 locomotive. With this wheel arrangement, the engine would have a four-wheel leading truck, two independent sets of four-wheel drivers, and a four-wheel trailing truck. As a duplex engine, each of the four-wheel drivers would be powered by a pair of separate cylinders. Baldwin’s Chief Engineer Ralph P. Johnson believed the newly designed engine would be capable of improved efficiency that would rival diesel locomotives, which were just beginning to outperform steam. Compared to an articulated locomotive, a rigid-frame duplex arrangement created a comparatively light engine well-suited for high speeds. In addition, having four smaller cylinders with a reduced piston speed decreased wear and maintenance compared to two larger, harder-working cylinders as used in a standard locomotive layout, such as a 4-8-4. If not well-balanced, the reciprocating and revolving forces of the drive wheels on powerful two-cylinder locomotives could actually damage the track, an issue that was alleviated with a four-cylinder duplex.[ATTACH=full]130757[/ATTACH]