John H. White

“ The “Pioneer” is an unusual locomotive and on first inspection would seem to be imperfect for service on an American railroad of the 1850’s. This locomotive has only one pair of driving wheels and no truck, an arrangement which marks it as very different from the highly successful standard 8-wheel engine of this period. All six wheels of the Pioneer are rigidly attached to the frame. It is only half the size of an 8-wheel engine of 1851 and about the same size of the 4—2—0 so common in this country some 20 years earlier. ”

“ 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. ”

“ In running on either a straight or curved track one of the truck wheels often breaks off, and the truck swivels around on its center pin in consequence, and throws the engine off the track, but with my device one wheel, or even the two wheels on the opposite sides diagonally of the truck might break off and still the truck would not run off, because its position is set and it has no axis of motion around which it could swing.... ”

“ The boiler is the most important and costly part of a steam locomotive, representing one-fourth to one-third of the total cost. A poorly built or designed boiler will produce a poor locomotive no matter how well made the remainder of mechanism. The boiler of the Pioneer is of the wagon-top, crownbar, fire-tube [Pg 253] style and is made of a 5/16-inch thick, wrought-iron plate. The barrel is very small, in keeping with the size of the engine, being only 27 inches in diameter. ”

“ Under such strain the truck wheels are particularly likely to leave the rails when they encounter an obstruction. Once derailed, the truck would then spin around on the deadly center pin, throwing the locomotive over.
In effect, then, the center pin of the conventional truck extended the rigid wheelbase of the engine, and caused the truck to act much as would a single set of leading wheels fitted rigidly to the engine frame far ahead of the front driving wheels. ”

“ Without knowing all the circumstances under which these engines are worked on the Cumberland Valley road, we should not venture to repeat all that we have heard of their performances, it is enough to say that they are said to do more, in proportion to their weight, than any other engines now in use. ”

“ 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. ”

“ There are few, if any, surviving 19th-century locomotives that have not suffered numerous rebuildings and are not greatly altered from the original. The John Bull, also in the U.S. National Museum collection, is a good example of a machine many times rebuilt in its 30 years of service. [21] Unless other information is uncovered to the contrary, it can be stated that the Pioneer is a true representation of a light passenger locomotive of 1851. ”

“ Note that the V’s, and thus the point of bearing, are slightly in front of the center line of the truck axle. It was suggested in the patent specification that the V’s might be placed to the front, rear, or directly over the axle, but in most actual applications they were placed directly over the axle. Note also that the locomotive shown on the figure is obviously a standard high-wheel American type which has suffered the rather awkward substitution of a pony truck for its regular 4-wheel arrangement. It is probable that few if any American types were so rebuilt. ”

“ A comparison of the surviving illustrations of Hinkley and Wilmarth engines of the 1850’s reveals a remarkable similarity in their details (figs. 14 and 15) . Notice particularly the straight boiler, riveted frame, closely set truck wheels, feedwater pump driven by a pin on the crank of the driving wheel, and details of the dome cover. All of the features are duplicated exactly by both builders. This is not surprising considering the proximity of the plants and the fact that Wilmarth had been previously employed by Hinkley. ”

“ He proposed to replace the fixed pivot with a radius bar (see fig. 5) one end of which was attached to the locomotive under the smoke-box and the other to rear of the truck frame, at the same point of attachment as in the Bissell plan. Thus, according to Hudson, the pivot point could move laterally so that the truck might more easily accommodate itself to a curve of any radius. He further claimed that a better distribution of weight was effected and that the use of the radius bar relieved the center bearing casting of much of the strain of propelling the truck. ”

“ The safety valve is located on top of the steam dome. Pressure is exerted on the lever by a spring balance, fixed at the forward end by a knife-blade bearing. The pressure can be adjusted by the thumbscrew on the balance. The graduated scale on the balance gave a general but uncertain indication of the boiler pressure. The valve itself is a poppet held against the face of the valve seat by a second knife blade attached to the [Pg 259] lever. The ornamental column forming the stand of the safety valve is cast iron and does much to decorate the interior of the cab. ”

“ The rear of the boiler is attached to the frame by two large cast-iron brackets, one on each side of the firebox (fig. 18) . These are bolted to the top rail of the frame but the holes in the brackets are undoubtedly slotted, so that they may slide since the boiler will expand about 1/4 inch when heated. In addition to the crown bars, which strengthen the crown sheet, the boiler is further strengthened by stay bolts and braces located in the wagon top over the firebox, where the boiler had been weakened by the large hole necessary for the steam dome. ”

“ 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 dry pipe projects up into the steam dome to gather the hottest, driest steam for the cylinders. The inverted, funnel-like cap on the top of the dry pipe is to prevent priming, as drops of water may travel up the sides of the pipe and then to the cylinders, with the possibility of great damage. After the steam enters the throttle valve it passes through the front end of the valve, through the top of the boiler via the dry pipe (fig. 18) , through the front tube sheet, and then to the cylinders via the petticoat pipes. ”

“ 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 ”

“ At the time the engine was built, it was usual to house these valves in an ornamental spun-brass casing. The smokestack is of the bonnet type commonly used on wood-burning locomotives in this country between about 1845 and 1870. The exhaust steam from the cylinders is directed up the straight stack (shown in phantom in fig. 27) by the blast pipe. This creates a partial vacuum in the smokebox that draws the fire, gases, ash, and smoke through the boiler tubes from the firebox. The force of the exhausting steam blows them out the stack. ”

“ 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. ”

“ They are cast-iron construction and are driven by an eccentric on the driving-wheel axle (fig. 27) . The airchamber or dome (1, fig. 27) imparts a more steady flow of the water to the boiler by equalizing the surges of water from the reciprocating pump plunger. A steam line (3, fig. 18) , which heats the pump and prevents freezing in cold weather, is regulated by a valve in the cab (figs. 18, 27) . Note that the line on the right side of the cab has been disconnected and plugged.
The eccentric drive for the pumps is unusual, and the author knows of no other American locomotive so equipped. ”

“ 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) . ”

“ The cab is solid walnut with a natural finish. It is very possible that the second cab was added to the locomotive after the 1862 fire. A brass gong used by the [Pg 267] conductor to signal the engineer is fastened to the underside of the cab roof. This style of gong was in use in the 1850’s and may well be original equipment.
The water tank is in two sections, one part extending below the deck, between the frame. The tank holds 600 gallons of water. The tender holds one cord of wood.
The small pedestal-mounted sandbox was used on several Cumberland Valley engines including the Pioneer. ”

“ In about 1836 he opened a machine shop and, encouraged by an expanding business, in 1841 he built a new shop in South Boston which became known as the Union Works. [17] Wilmarth was in the general machine business but his reputation was made in the manufacture of machine tools, notably lathes. He is believed to have built his first locomotive in 1842, but locomotive building never became his main line of work. Wilmarth patterned his engines after those of Hinkley and undoubtedly, in common with the other New England builders of this period, favored the steady-riding, inside-connection engines. ”

“ 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. ”

“ Figure 10.—The Hudson-Bissell truck permitted the introduction of Mogul and Consolidation type freight locomotives. This drawing shows a typical installation for a Consolidation of the 1880’s. Item A is the equalizing lever which connects the truck to the springs of the front driving wheels. ”

“ Figure 16.—The “Pioneer” as first exhibited in the Arts and Industries building of the Smithsonian Institution prior to restoration of the sandbox. (Smithsonian photo 48069D.)
[BOILER continued]
The steam dome (fig. 18) is located directly over the firebox, inside the cab. It is lagged and jacketed in an identical manner to the boiler. The shell of the dome is of 5/16-inch wrought iron, the top cap is a cast-iron plate which also serves as a manhole cover offering access to the boiler’s interior for inspection and repair. ”

“ The Board of Managers agreed with Smith’s recommendations and instructed him “... to examine the two locomotives lately built by Mr. Wilmarth and now in the [protection?] of Captain Tyler at Norwich and if in his judgment they are adequate to our wants ... have them forwarded to the road.” [2] Smith inspected the locomotives not long after this resolution was passed, for they were on the road by the time he made the following report [3] to the Board on September 24, 1851 ”