LOCOMOTIVE ENGINE SAFETY TRUCK CO. OF NEW YORK.
Proprietors of the following Letters Patent granted to Levi Bissell, Aug. 4, 1857, Nov. 2, 1858 (extended Nov. 2, 1872); A. W. Smith, Feb. 11, 1862; D. R. Pratt. Oct. 16, 1860; W. S. Hudson, April 5, 18[digits missing] and May 10, 1864.
DRAWINGS FURNISHED AND LICENSES GRANTED ON APPLICATION.
A. F. SMITH, President. M. F. MOORE, Sec'y and Agent ALBERT BRIDGES. Treas. No 46 Cortlandt st. N. Y.
FIGURE 12.--Notice of the Locomotive Safety Truck Company listing the patents held by it. From _Railroad Gazette_, March 3, 1876.]
John L. Whetstone on April 10, 1860, obtained U.S. patent 27850, which strikingly anticipated the plan Hudson was to develop four years later.[22] Whetstone did not use a Bissell truck and was in fact more concerned in relieving the excess weight, often a 50% overload, from the front axle of 0-6-0 locomotives and in distributing a portion of that weight to a pony truck. His arrangement may be readily understood from the patent drawing in figure 9. Probably the best features of the design was the transverse H-beam that connected the spring hangers to the truck frame, which in this case also served as the equalizing lever (note that the ball "C" acts as the fulcrum).
Hudson made use of this same device but in a more practical manner. He found that while the Bissell pony truck could satisfactorily adjust itself laterally and could lead the locomotive around curves, it could not handle the varying loads imposed upon it by the rough trackage typical of American railroads. At one moment an undue amount of weight would fall upon the truck because the drivers were over a depression in the roadbed. This condition overloaded the truck's springs and also resulted in a momentary loss of adhesion, causing the drivers to slip. Conversely, when the truck hit a depression too much weight was thrust upon the driving wheels, and broken springs or other damage might result.
Hudson's ingenious remedy to this problem was simple and straightforward (see fig. 10). A heavy equalizing lever that connected the truck to the springs of the front driving wheels was placed on the longitudinal centerline of the locomotive, with the fulcrum under the cylinder saddle. Thus the truck and front driver reacted together to all the inequalities and shocks offered by the roadbed.