CATALOG OF THE MECHANICAL COLLECTIONS 45 



The machine represented by the model is a very early example of the 

 "wobble disk" type of engine or pump. Many engines and pumps 

 using this principle of operation have been designed from time to time, 

 and experiments are carried on today with internal combustion en- 

 gines of this form. Combinations of one unit used as a pump and one 

 used as a fluid motor are very successfully used for power trans- 

 missions. 



The machine consists of four cylinders placed around the axis of 

 a shaft, parallel with and at equal distance from it, with the rods of 

 the pistons that work in the cylinders connected to arms projecting 

 from a shaft not parallel to the axis about which the cylinders are 

 placed. With this arrangement rotary motion of the shaft is accom- 

 panied by reciprocating motion of the pistons, and the device may be 

 used as a motor or a pump. 



LOPER MARINE STEAM ENGINE, 1849 



U.S.N.M. no, 309198; original patent model; transferred from the United States 

 Patent Office ; not illustrated. 



This was submitted with the application for the patent issued to 

 K. F. Loper, of Philadelphia, August 28, 1849, no. 6673. 



This is a nicely made working model of a 2-cylinder vertical marine 

 engine directly connected to a 2-throw propeller shaft, upon which 

 is mounted a 4-blade propeller. The model is complete with boiler, 

 feed-water pump, condenser, and condenser air pump. The peculiar 

 feature of the invention is the manner of connecting the air pump 

 to the engine and the method of quickly converting the engine from 

 condensing to noncondensing operation. 



The engine represented consists of a heavy bed plate shaped to fit 

 the hull of a vessel, upon which are attached the bearing of the pro- 

 peller shaft and the frame that supports the cylinders. The cylin- 

 ders are double-acting and are "reversed from the ordinary position 

 of engines, the piston rod running down through the lower head and 

 connecting by the usual connecting rod with the cranks on the shaft 

 below." "The valves of the engine take their motion from eccentrics 

 on the main shaft coupled with a valve lever by proper eccentric 

 rods. The lever is affixed to its axis by its center and is made double, 

 so that the eccentric rod can be thrown to either end to reverse the 

 motion or may be wholly detached." The cut-off is worked by an- 

 other eccentric on the shaft. The feed-water pump is worked di- 

 rectly from the cross head. The air pump is driven by a beam and 

 connecting rod, which is driven by a crankpin upon a gear wheel 

 that engages a pinion on the crankshaft. The ratio of the gears is 

 such that the air pump performs only one stroke to two of the 

 engine. The air pump communicates with the condenser into which 



