nter of the truck, as in the
conventional design, the center plate was no longer the point of
rotation. On a straight track the V's would be at their bottom position
and thus prevent the truck from vibrating.[4] When the locomotive
entered a curve the planes allowed its forward weight to bear
continuously on all four wheels, and at the same time controlled any
exaggerated swing caused by centrifugal force.

The centering device is thus explained in the patent specification
(figure numbers are omitted):

I therefore obviate this difficulty [the oscillation of the truck]
by providing two inclined planes ... formed double as shown and of
an angle proportioned to the weight of the forward part of the
locomotive and the velocity of the same.... The position of the
inclines is such that the blocks [V's] rest in the lowest part of
the double inclines when the engine is on a straight track, and on
coming onto a curve the inertia of the engine ... is expended in
going up the inclines, as the truck moves laterally toward the inner
part of the curve; and on coming onto a straight line the blocks,
descend to the bottom of the inclines and the engine is prevented
from acquiring a sidewise or oscillating motion.

[Illustration: FIGURE 5.--Detail drawing of the radius-bar truck,
patented by William S. Hudson in 1864, as applied to the New Jersey
Railroad and Transportation Company No. 44. From Gustavus Weissenborn,
_American Locomotive Engineering and Railway Mechanism_, New York, 1871,
pl. 8.]

Bissell applied for a U.S. patent on April 23, 1857. His petition was
initially denied. A weary debate of several months duration followed
between the patent examiner and Bissell's attorneys.

During this time Bissell was busy promoting the application of his truck
even though he had no patent for protection. In May of 1857 he showed a
working model of his improvement to Gilbert M. Milligan, secretary of
the Central Railroad Company of New Jersey.[5] Samuel L. Moore, master
mechanic of that railroad, also inspected the model. Both were so
impressed that it was decided to fit the device to the locomotive
_Lebanon_, which at the time was undergoing repairs at the road's
Elizabeth Port, New Jersey, shops.[6] Although the engine was less than
18 months old, her tires were badly worn and she oscillated at high
speed.

Early in June of that year a series of tests were held with the
_Lebanon_. Moore