CATALOG OF THE MECHANICAL COLLECTIONS I37 



direct-acting pumps, and Knowles is recognized as having contributed 

 much to the final development and refinement of the device. He was 

 one of the first to take up and develop the steam-actuated valve and 

 received several patents for his inventions of improvements in valves 



DOW DIRECT-ACTING STEAM PUMP, 1879 



U.S.N.M. no. 308703 ; original patent model ; transferred from the United States 

 Patent OfSce; not illustrated. 



This model was filed with the application for the patent issued to 

 G. E. Dow, of San Francisco, Calif., November 4, 1879, no. 221220. 



The model represents a form of valve gear for a direct-connected 

 steam engine in which the main valve is partially operated by a 

 system of cam-shaped levers actuated from the main piston rod and 

 partially by a supplementary steam piston, the movement of which 

 is controlled by valves connected to the same levers. 



DAVIES STEAM PUMP, 1880 



U.S.N.M. no. 308711 ; original patent model ; transferred from the United States 

 Patent Office; not illustrated. 



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

 sued to Joseph D. Davies, of Covington, Ky., March 9, 1880, no. 

 225351. 



The model represents a direct-acting steam pump, provided with 

 two auxiliary oscillating cylinders, which offer a constantly decreas- 

 ing resistance to the movement of the steam piston during the first 

 half of its stroke and a constantly increasing assistance during the 

 remaining half. The purpose of this is to equalize the effective force 

 of the steam piston throughout its stroke when the steam is used 

 expansively. 



The two auxiliary cylinders are mounted in trunnions, one on each 

 side of the frame of the engine. The rods from the auxiliary pistons 

 are attached to a clamp on the main piston rod, so located that the 

 auxiliary cylinders are perpendicular to the main piston rod when 

 the main piston is at midstroke. The auxiliary pistons, in the model, 

 work against a spiral spring, which is compressed during the first 

 half of the stroke and which expands during the last half. In effect; 

 the springs act as would a flywheel, storing the energy in excess of 

 the resistance, while steam at high pressure acts upon the engine pis- 

 Ion, and delivering the stored energy after the steam has been cut 

 off and is expanding in the cylinder. The inventor described his de- 

 vice using a fluid, as steam or water under pressure within the 

 auxiliary cylinders. 



49970—39 10 



