CATALOG OF THE MECHANICAL COLLECTIONS 67 



CARHART BALANCED VALVE, 1866 



U.S.N.M. no. 308671 ; original patent model ; transferred from the United States 

 Patent OflSce; not illustrated. 



This model was submitted with the application for the patent 

 issued to John W. Carhart, of Troy, N. Y., March 27, 1866, no. 

 53410. 



Tlie model represents a conical plug valve with an annular ex- 

 haust space between the plug and the valve and a steam passage 

 through the hollow core of the plug. The peculiar feature of the 

 valve is the provision of recessed amiular spaces in the valve, which^ 

 with the valve seat, form small pistons and cylinders designed to bal- 

 ance the valve longitudinally when connected to the steam passages. 

 Screw adjustments on the valve stem and the small end of the valve 

 are provided for setting the valve in a position giving proper con- 

 tact with the minimum of friction. 



BABCOCK AND WILCOX VALVE GEAR, 1866 



O.S.N.M. no. 308673; original patent model; transfer from the United States 

 Patent Office ; not illustrated. 



This model was submitted with the application for the patent is- 

 sued to G. H. Babcock and S. Wilcox, Jr., of Providence, R. L, April 

 24, 1866, no. 54090. 



The valve gear represented by the model is an early governable 

 one of the class of riding cut-off valves in which the riding valve is 

 operated by a small independent auxiliary steam cylinder, equipped 

 with its own steam valve. The valve controlling the admission of 

 steam to the auxiliary steam cylinder is in turn controlled by the 

 action of the engine governor. 



The main valve of the engine is a flat lap valve, machined top and 

 bottom with mortises through the valve near each end. The valve 

 functions as a common D-valve admitting steam through the mor- 

 tises instead of at its ends. Solid cut-off valves working on the back 

 of the main valve, over the mortises, are joined by a rod, which passes 

 through a small auxiliary steam cylinder and at the middle of which 

 within the cylinder is the small actuating piston. The valve of the 

 auxiliary cylinder is operated transversely across the cylinder by 

 an eccentric on the end of a lay shaft. This shaft revolves at the 

 same speed as the crankshaft and the main-valve eccentric, but its 

 position at any time relative to the main-valve eccentric is determined 

 by the governor, as follows : 



The lay shaft is divided into two shafts, one driving, the other 

 driven. The connection between the two is maintained by means of 

 a driving bevel gear on the driving shaft, an intermediate idling 

 bevel gear, and a driven bevel gear on the driven shaft. Though 



