oggy roadbed and produced an
unstable path. In winter this same roadbed could freeze into a hard and
unyielding pavement on which the rolling stock was pounded to pieces.

In those pioneering times the demand for new roads left little capital
to improve or expand existing lines; therefore equipment was needed that
could accommodate itself to the existing operating conditions.

The first locomotives used in this country had been imported from
England. Designed for well-ballasted track with large-radius curves and
gentle gradients, they all too frequently left the rails, and the
unsuitability of the essentially rigid British design soon became
apparent.

The challenge posed by the American roadbed was met by American
mechanics. By the mid-1830's a distinctive American locomotive had
evolved that might best be described by the word "flexible." The basic
features of its running gear were a bar frame and equalizing levers to
provide vertical relief and a leading truck to provide lateral relief.
Of these devices the truck was probably the most important, and more
readily than any one component distinguished the American running gear
from that used by the British before 1860.

[Illustration: FIGURE 1.--Design drawing showing the 4-wheel leading
truck, developed in 1831 by John B. Jervis, applied to the _Brother
Jonathan_. This locomotive, one of the earliest to use a leading truck,
was built in June 1832 by the West Point Foundry Association for the
Mohawk and Hudson Rail Road. The truck is attached to the locomotive
frame by a center pin, but the forward weight of the locomotive is
carried by a roller which bears on the frame of the truck.
(_Smithsonian photo 36716-a_)]

It was John B. Jervis who is generally credited with first applying the
truck to the locomotive. His design, shown in figure 1, was developed in
1831-32. Its merits quickly became apparent, and by 1835 it had been
universally recognized in this country. The truck successfully led the
locomotive around sharp curves, the resultant 3-point suspension enabled
the machine to traverse even the roughest of tracks, and, altogether,
the design did far less damage to the lightly built U.S. lines than did
the rigid, imported engines.[1]

The truck frame, fabricated from iron straps and castings, was attached
to the locomotive by a pin around which it might rotate. At first the
weight was received by rollers or chafing pads mounted on the side beams
of the truck.