[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. However, the friction of these bearing surfaces and their location at a considerable distance from the center pin combined to restrict the free movement of the truck. By the early 1850's the point of bearing was transferred to the center plate, producing a truck that turned more freely.[2] [Illustration: FIGURE 2.--The 4-wheel Bissell truck as shown in the drawing for British patent 1273, issued May 5, 1857.] [Illustration: A--Truck frame B--Equalizing lever C--Locomotive frame D--Double incline plane (_Centering device_) E--Truck bolster F--Swivel pin (_Pivot point_) _Drawn by J. H. White. June, 1960_ FIGURE 3.--Typical 4-wheel Bissell Safety truck of 1860. This drawing is based on plate 69 of Alexander L. Holley's, _American and European Railway Practice in the Economical Generation of Steam_, New York, 1861. (_Smithsonian photo 46946_)] For single axle engines this simple form of truck was entirely satisfactory, but it proved less satisfactory for 4- and 6-coupled machines. Also, as train speeds increased, so did the number of derailments. Many of these could be traced to the inability of the engine to negotiate curves at speed. Levi Bissell, a New York inventor who investigated this problem in the 1850's, correctly analyzed the difficulty. He observed that when the engine was proceeding on straight tracks the leading truck tended to oscillate and chatter about the center pin, and he noted that it was this action that imparted a fearful pitching motion to the locomotive at speed. The derailments were traced to the action of the truck as the engine entered a curve.