EMD SW1 - Production Changes

Production Changes

Like most long-running locomotive models, a number of changes were made to the SW1 over its production life. Internally, the post-1945 locomotives were somewhat improved, and used an updated 567A engine.

One easily spotted change is the shape of the two center cab windows over the hood, which were curved to follow the roofline originally, but became flat-topped after mid-1950. Another easily seen is the taper of the hood to the cab, which was a two-stage taper in earlier units but became a single taper in later production. Very early locomotives were delivered with a stubby exhaust stack, but this did not lift the diesel exhaust sufficiently clear of crew visibility. All later units were delivered with EMD's standard conical switcher stack, while early units were generally modified with taller stacks too. Early locomotives had a single large headlight, while later had twin sealed-beam headlights.