"74 BULLETIN 173, U. S. NATIONAL MUSEUM 



The invention of the method of forming the connection between a 

 series of radial cylinders and a single crankpin by means of one 

 disk-ended connecting rod is claimed. 



CORLISS VALVE GEAR, 1859 



U.S.N.M. no. 308648; original patent model; transferred from the United States 

 Patent OflSce ; not Illustrated. 



This model was submitted with the application for the patent 

 issued to George H. Corliss, July 5, 1859, no. 24618. 



The model represents the first valve gear to combine all the ele- 

 ments of the typical Corliss engine. It shoAvs the wrist plate, detach- 

 able steam link, variable disengaging wedge, a spring for closing the 

 steam valve, the air dash pot to prevent jar in closing the valves, and 

 rotating valves. 



The valve gear represented includes the features of the two pre- 

 vious ones, with the exception that a spring is used to supply the 

 force to close the steam valves instead of weights, and rotating valves 

 are used instead of sliding valves. The peculiar feature of the spring 

 is the mode of attaching it to a curved support, which receives motion 

 wnth the valve gear so that the bearing point of the spring is shifted 

 and the best tension is obtained for closing the valve at every position 

 of the cut-off. 



CORLISS CUT-OFF VALVE GEAR 



U.S.N.M. no. 309817; model; gift of the Franklin Machine Co.; not illnstrated. 



This model represents a detachable valve gear in which an inclined 

 block on the slide of a ball governor determines the point of cut-off. 

 The valve is closed by the force of a compressed, coiled spring, and 

 its closing movement is gently arrested by a dash pot. 



This model shows one flat slide valve from which two parallel 

 valve rods extend through a guide block and terminate in a cross 

 head running in guides parallel to the rods. The guide block sup- 

 ports a stationary piston or plunger, which extends into a cylinder 

 bored in a saddle carried between the valve rods close to the cross 

 head. These combine to form a dash pot in which the plunger is 

 stationary and the cylinder moves with the valve. A finger projects 

 from the same saddle and engages a coil spring, which is compressed 

 as the valve opens and serves to close the valve when it is disengaged 

 from the gear. From the cross head a connecting rod extends to a 

 block that is reciprocated by the eccentric on the crankshaft of the 

 model. This connecting rod is provided with a hook that engages 

 with a plate edge on the reciprocating block. It is held in engage- 

 ment by a flat spring pressing it upward. When engaged the valve 

 has a regular movement corresponding to the block reciprocated by 

 the eccentric, but when disengaged the valve is quickly closed by 



