70 BULLETIN 173, U. S. NATIONAL MUSEUM 



OTTO AND BELL BALANCED SLIDE VALVE, 1883 



U.S.N.M. no. 308719 ; original patent model ; transferred from the United States 

 Patent Office; not illustrated. 



This model was submitted with the application for the patent 

 issued to Henry Otto and Patrick F. Bell, of Bloomington, 111., 

 December 18, 1883, no. 290650. 



The model rej^resents a flat D -slide valve of ordinary shape, with 

 most of the back cut away and formed in the shape of a short hol- 

 low cjdinder. This cylinder is filled with a closed piston suspended 

 on rollers on a flat bar, which, in turn, is suspended from the top of 

 the valve chest. The bar passes through a tunnel in the piston and 

 is of sufficient length to accommodate the valve travel. The effect 

 of this construction is that the steam pressure ordinarily exerted on 

 the back of a flat valve is in this case exerted on a piston that is 

 not a part of the valve but is suspended independently. 



WHEELOCK VALVE AND VALVE SEAT, 1885 

 U.S.N.M. no. 310251 ; model ; gift of the Franklin Machine Co. ; not illustrated. 



This is a nicely made model of the valve and valve seat patented 

 by Jerome Wlieelock, of Worcester, Mass., September 22, 1885, no 

 326820. 



The model represents a wide gridiron slide valve assembled on a 

 skeletonized taper plug, which serves as the valve seat and supports 

 the rock shaft connected to the slide by links or "toggles." The 

 whole assembly is designed to fit into a taper hole bored into the 

 cylinder block and connected by suitable ports to the cylinder. The 

 advantage of this arrangement over ordinary plug valves is that it 

 does not require that a valve seat be formed within the large cylinder 

 casting, and it permits the delicate fitting of the valve to the valve 

 seat to be performed at a work bench or upon a machine away from 

 the engine. 



The complete Wheelock valve gear (Patent no. 326819) consists 

 of one steam valve and one exhaust valve at each end of a cylinder 

 with the rock arms of the exhaust valves permanently connected to 

 the eccentric, so that the valve is at rest during part of the travel 

 of the eccentric, while the steam valves are connected through a de- 

 tachable latch so that they may be detached and closed quickly at 

 any point during the stroke of the piston. 



GREENE-WHEELOCK VALVE AND VALVE SEAT 



U.S.N.M. no. 310250; model; gift of the Franklin Machine Co.; not illustrated. 

 This model represents a skeletonized taper plug in which are 

 formed two gridiron valve seats and a bonnet that carried a rock- 

 arm collar and cams for actuating one steam and one exhaust valve 



