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.

[p131]
In October of 1863, under Hudson’s direction, two 2-6-0’s equipped with Bissell trucks were built at the Rogers Works for the New Jersey Railroad and Transportation Company. Probably some fault was found with the suspension of these machines, numbered 35 and 36, for the next 2-6-0, numbered 39, built for the New Jersey road was equipped with Hudson’s equalizer. This engine, completed in January 1865, is believed to be the first Mogul so equipped.[23]

The Locomotive Engine Safety Truck Company (see [fig. 11]) was formed in the 1870’s, with A. F. Smith as president, to exploit the patents of Bissell, Smith, and Hudson. For several years notices appeared in the columns of the Railroad Gazette reporting suits by the Company against various railroads and locomotive builders for unauthorized use of their patents. The Gazette of May 29, 1875, carries a protest of the Company against the Manchester Locomotive Works for unlicensed use of Smith’s patent of 1862. In the issue of August 28, 1875, is reported the Company’s success in establishing the validity of Smith’s patent:

Some important settlements for the use of the patent have lately been made with the company, one of them being with the Western Railroad Association, whose headquarters are at Chicago, which includes the principal western roads. Through this the company receives its royalty on several hundred locomotives.

IN SUMMARY

It can be stated that Hudson’s modification of the Bissell truck is of unquestioned importance, for without the introduction of the equalizer it is doubtful if the 2-wheel pony truck would have been a complete success on American railroads. Bissell’s 4-wheel truck was extensively employed, but it did not enjoy the universal popularity of the 2-wheel truck, and in the 1880’s was eclipsed by other forms of 4-wheel safety trucks. The Hudson-Bissell pony truck, however, survived in its basic form to recent times, when, in the late 1940’s and early 1950’s, the last steam locomotives were constructed in this country.

[1] Three-point suspension in a 4-2-0 was easily gained—the center plate of the truck and the two bearings of the driving wheel axle. On a 4-4-0 the center plate served as one point, while the fulcrum of each equalizing lever served as the other two points, thus providing the desirable and highly stable 3-point suspension.

[2] American Railroad Journal, 1853, vol. 9, p. 427.