CATALOG OF THE MECHANICAL COLLECTIONS g3 



ALLEN CUT-OFF VALVE, 1842 



U.S.N.M. no. 308640; original patent model; transferred from the United States 

 Patent OflSce ; not illustrated. 



This model was submitted with the application for the patent 

 issued to Horatio Allen, of New York, N. Y., April 30, 1842, no. 

 2597. 



The model represents a valve gear in which separate steam chests 

 are employed for the head-end and crank-end main steam valves. 

 The supply of steam to each of these steam chests is controlled by 

 additional cut-off valves, the movement of which is adjustable. The 

 inventor refers to this invention as an improvement in the valve gear 

 patented by him August 21, 1841 (see U.S.N.M. no. 308649, p. 62). 



The model shows a portion of the cylinder of a horizontal engine 

 with only the piston rod and cross head represented. A steam chest 

 in which are located the ports leading to the inner or main steam 

 chests is shown in section, revealing the cut-off valves on their seats. 

 These cut-off valves are plain flat plates connected to opposite ends 

 of a beam, which receives a vibratory motion from the cross head of 

 the engine. The beam and its rock shaft are pivoted in a lever by 

 which the pivot can be moved and the time of cut-off varied. This 

 the inventor calls "cut-off with movable rock shaft." He suggests 

 that a similar result can be obtained by constructing the cut-off ports 

 in a movable plate which he calls "cut-off with single adjustable 

 seat." 



ALLEN CUT-OFF VALVE GEAR, 1848 



U.S.N.M. no. 308643 ; original patent model ; transferred from the United States 

 Patent Office: not illustrated. 



This model was submitted with the application for the patent 

 issued to Horatio Allen, of New York, N. Y., August 29, 1848, no. 

 5745. 



This is an adjustable drop cut-off valve gear in which a poppet 

 valve is raised by a lift rod but is permitted to return to its seat 

 ■sooner or more rapidly than the lift rod returns. 



The model represents a poppet steam valve raised from its seat 

 hj an arm fixed at right angles to a lift rod, which works vertically 

 and parallel to the valve stem. Upon the face of the arm is a mov- 

 able block a part of the upper surface of which is parallel to the face 

 of the arm and a part of which is a steep curve. All the movement 

 ■of the valve is transmitted to it through a roller on its stem, which 

 rolls on the surface of this block. The block is so linked with a 

 vibratory rod, which receives its motion from the cross head of tha 

 engine, that the block will move along the face of the lift rod arm 

 and bring different points of its surface under the roller of the valve 

 stem. By proper adjustment the roller will rest upon the flat part 



