Old Maude, Preface - Virtual Railroader

America's first high-speed electric locomotive
Old Maude:^
Parts: Preface | First | Second | Third | Fourth | Fifth | Sixth | Notes
A BOLD NEW LOCOMOTIVE
For all the apparent conservatism in the selection of d.c. as the
system of choice, the S-motor design was a bold departure from
earlier electric locomotives. It was primarily the work of General
Electric's Asa F. Batchelder, who patented four of the design's
features. Most significant was a Batchelder innovation that
produced the first successful use of bipolar gearless motors.
Sectional elevation of Old Maude. Street Railway Journal, 1904.
The lure of the gearless motor is the absence of gears, which by
their very nature introduce friction (with its loss of operating
efficiency) and require maintenance. In practice a gearless
motor design is achieved by wrapping the motor armature around
the driving wheel axle. This has the drawback of adding dead
weight to the axle, which in turn lowers the locomotive's center
of gravity, a detriment to good tracking. In an age of early motor
design, placing the armature on the axle also limited the capacity
of a motor by restricting its size to the space available between
the wheels. Previous gearless designs usually placed the armature
in a hollow quill that surrounded but did not contact the axle.