336 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[October, 



ON REVERSING OF ENGINES. 



Sir — When we look to the methods of reversing the motion of re- 

 ciprocating steam engines which have hitherto been generally adopted, 

 it becomes a matter of surprise that, whilst in almost all patents for 

 rotary engines, where it has been considered the motion would want 

 reversing, it has been done on the principle of changing the steam in- 

 duction and eduction passages, (/. e. what is the induction for one way 

 is made the eduction the other, and vice versa), the same principle has 

 not been adopted for them. The most general and simple way of 

 changing the passages in rotary engines nas been by means of the 

 common slide valve, and my object in now addressing you is to pro- 

 pose the adoption of the same slide valve to the reciprocating engine. 



The accompanying figures represent it as applied to a pair of marine 

 engines, for which it seems particularly suited. Let A in the figures 

 represent the cylinder; B B B B, valve boxes fitted with stop valves 

 r I' V V, almost similar to those of Messrs. Seaward's patent, except 

 that both the valves and boxes are faced on both sides ; C 1, C 2, 

 communication pipes to each pair of boxes ; D D, branch pipes from 

 C 2, C 1, to the apertures in the slide valve box E ; being alternately 

 steam and exhaust as their respective apertures may be covered by 

 the slide valve F; G is the exhaust or eduction to the condenser; H 

 the induction or steam-pipe from the boiler. The valves strike simul- 

 taneously (as Seaward's), and are like them worked by one fast eccen- 

 tric. 



Fig. 1. — Plan of Cylinder. 



It will be seen as the valves stand in the figures that the steam 

 passing down H into the valve box E, and down the uncovered aper- 

 tures to communicating pipeC 1, finds the upper aperture stopped up, 

 it consequently makes its way through the lower one and forces up the 

 piston, at the same time the upper valve on the other side of the 

 cylinder is open, and a vacuum being formed in the condenser, it ex- 

 hausts G, under F, the branch to and the communicating pipe C 2, and 

 the portion of the cylinder above the piston. 



If we wish now to reverse the motion, we have only to push the 

 valve F to the other end of the box, as represented bv dotted lines in 

 fig. 3, the branch pipe, and C 1 is open to the condenser, and the 

 steam passes down the branch into C 2, and presses down the piston. 



The mode of operation will I think be now understood. Fig. 4 is a 

 view of the valve F, as proposed for a pair of engines, showing the 

 midfeather to separate the exhausts or eductions to the respective 

 condensers. The branch pipes to the other cylinder are shown broken 

 off. There is another use of the valve F, it is a perfect regulator or 

 throttle valve, to stop or regulate the engine by ; for it is so constructed 

 tliat supposing the steam to be shut off by it when running either way, 

 still the exhaust apertures remain entirely open. The simplicity of 

 its action, and its doing away with a considerable number of small 

 moving parts consequent on reversing and management in general, by 

 the present methods are its recommendations, not to mention that one 

 man could manage a pair of the largest engines which have yet navi- 

 gated the ocean, better than 4 or (i, or even 1(J men, to jome of our 



Fig. 2.— Section of Cylinder. 



Fig. 3.— Elevation of Cylinder and Section of Valves. 



Tig. 4. 



present large marine engines. 1 have a sketch by me, only in pencil 

 as yet, for working locomotives by the same principle, but being so 

 confined as to space, little difficulties present themselves in the arrange- 

 ment, which a more practical man might soon set aside. 



Your's, 



G. CoE, Civil Engineer. 

 Horbury Bridge, near Wakejield, 

 ^nginl 17, 1841, 



