Appendix 3 



J. L. Whetstone (see pages 100-102) published a precise mechani- 

 cal description of his radial valve gear in the Journal of the Franklin 

 Institute in February 1882. The following extract from this article 

 discusses his unconventional valve motion as used on the Sellers 

 Panama locomotives and some of the engines built by Niles & 

 Company. 



From the peculiarity of the general arrangement of the machinery it 

 was found impracticable to use more than one eccentric for operating the 

 valves of each engine, and it was necessary to use a valve with considerable 

 lap. There being barely room for one eccentric for each engine on the 

 driving axle, the device of shifting a lead eccentric across the axle for the 

 purpose of obtaining lead for the forward and backward movements could 

 not be applied. The valve gear which was finally adopted was substanti- 

 ally the same as represented in Fig. 7,[*] with slight modifications. The 

 eccentric was set so as to be at half throw when the crank pin was at the 

 ends of the stroke or at the dead point, and connected by a rod to an arm 

 on the rocker shaft having at its other end a double arm, carrying a link 

 bar for the purpose of giving reversing movements to the valve. The 

 position of the rocker arm and link bar was therefore the same when the 

 crank was at either end of the stroke, viz., that shown in the Fig. 7, at 

 ABC. For the purpose of giving the advanced movement requisite for 

 the lap and lead of the valve, the shifting or reversing rod (one end of 

 which is properly swiveled to the link bar) is connected to the fulcrum F 

 of a lever, the longer arm of which is suitably attached to the cross-head 

 of the engine, the shorter arm being geared to the valve rod at G, or to 

 any suitable device necessary to transmit the movement to the valve. 

 The length of the arms of this lead-lever are such that when the fulcrum 

 F is at the half throw of the eccentric the upper wrist of the lever G is 

 removed from the centre line II K to the extent of the lap and lead of the 



*Reproduced as figure 42 on p. loi. 



135 



