sidewalls of the smokebox. Furthermore, the reciprocating action 

 of the four cyHnders, placed at such a distance from the locomotive's 

 center line, would cause it to lurch from side to side. To correct 

 these difficulties, the cylinders were fitted inside the frame under the 

 smokebox. The gripper wheels, toggles, etc., were brought forward 

 to a position directly before the axle of the forward driving wheel. 

 In short, the basic arrangement of the adhesion wheels, toggles, etc., 

 as originally conceived in the 1 847 patent was retained, but the drive 

 was changed from an outside-geared to a direct inside connection. 

 The engines of each gripper wheel were connected by means of a 

 countershaft, fitted with cranks set at right angles, and other neces- 

 sary rods so that neither engine would stop on dead center. The 

 eccentrics for driving the valve gear were also mounted on this 

 secondary shaft. A clearer picture of this mechanism can be gained 

 from figure 32. 



Other advantages can be credited to the new inside-connected 

 design. The extremely long main rod previously required to con- 

 nect the bevel gearing and the auxiliary engine was eliminated. 

 More important, the rigid wheelbase was shortened by placing the 

 adhesion wheels in front of the front driver. In the old plan, when 

 the adhesion wheels were engaged with the center rail, the rigid 

 wheelbase extended from the center pin of the leading truck to the 

 center of the adhesion wheel's shaft. This increased the wheelbase 

 an estimated 30 inches. In the new plan the rigid wheelbase would 

 naturally be shorter, being no more than that of an ordinary 4-4-0 

 (from the truck's center pin to the rear driving wheel), and would 

 thus allow the engine to traverse sharper curves. 



Sellers also introduced certain reforms in the design of the boiler 

 which would keep water on the crown sheet at all times, whether 

 the boiler was level or inclined and thus insure more complete fuel 

 combustion and better circulation of the water. In the model en- 

 gine the boiler had to be kept almost full of water when ascending 

 or descending steep grades so as not to burn out the crown sheet. 

 This caused priming and resulted in loss of power and strain on the 

 machinery. During the first test of the model in Cincinnati with 

 the grade set at 5 degrees, this actually occurred. Sellers was careful 

 not to attempt a grade of more than 3 degrees during the New York 

 trials. Even with these difficulties, however, there was undoubtedly 



72 



