P is the air pump, communicating with the lower end of the condenser by means of the valve R, which by the action of the air pump opens to allow the wa ter and air to escape from the condenser, but closes in order to prevent either of them from returning.
to is the upper valve or discharging spout, opening outwards, which conveys the air and hot water into the hot well, from which the boiler is supplied with water by the means of the hot water pump U U, and pipe u, the continuation of which to the boiler is not shown.
V is the injection or cold water pump, which, rising from a tank without the engine-house, supplies water for cooling the condenser, and supplying the injection.
Z is the plug-tree or beam which drives the work ing gear Y of the nozzle and regulator valves.
a is the main lever or working beam, made of oak, and moveable upon its gudgeon or centre of motion b, which is fixed to the upper side of the beam by iron straps.
d is a king-post, from the top of which iron straps c c•extend diagonally to each end of the beam, so as to form a truss.
Two iron catch pins, not seen in the figure, are fixed on the arched heads e, f, to strike upon the springs g, R, in order to limit the downward excursions of the pistons.
g, f, and e, are three arch heads fixed to the main beam. The arched head g is double, the one on the other side, not being seen in the figure. The one is to receive two chains, by which the plug tree Z is sus pended, the rods from the two chains being joined and connected with the upper extremity of the plug trees, while the piston rod S of the air pump P is fixed to its lower extremity. The plug tree is kept steady by a horizontal bar fixed across it at its lower end, the two extremities of which slide in the vertical grooves of two upright posts. Three projecting pie ces of wood, two of which are shown at n. are fixed to the plug tree to give motion to the intermediate handles of the working gear.
e is the arched head for receiving the chain f, which carries the piston rod h, and piston i of the pump j having a clack valve at p.
Operation of lily. Trail's Single Reciprocating Engine.
The engine is supposed to be. at rest, and its valves shut, and all the parts brought into the position shown in the figure, which is effected by the prepon derance of the pump rod h.
When the steam is generated in the boiler n, the three valves, G, K, and L, are opened by relieving the handles from their catches and the steam rushes through them above and below the piston, and into the condenser. The cold metal at first condenses it, but as the different parts become hot, all the above cavities are occupied with elastic steam, which dis places the air, and drives it all out at the blow valve 0, an operation called blowing through, the comple tion of which is indicated by a smart crackling noise at the blow valve 0, arising from the condensation of the steam by the cold water, when the air is all dis charged. When this has been repeated two or three times, the valves G, K, L, are shut, and the farther admission of steam prevented. The steam remaining in the condenser will be speedily condensed, especially when a jet from the injection pipe has been thrown into it ; but the cylinder both above and below the piston I will be occupied with steam.
If we now open the valves G, L, and N, Plate DVII, Fig. I, by allowing the two handles at Y to rise, the steam will pass through G to the top of the piston, and, at the same time, the steam below the piston will escape through L into the condenser, while a jet of water from N will condense the steam, and pro ducing a vacuum beneath the piston B, will allow the elastic force of the steam above it to press it to the bottom of the cylinder. The pump bucket i will be drawn up, and a column of water raised in its barrel j. When the piston B has descended half way down the cylinder, the upper piece of wood /r strikes the expansion handle Z, and forcing it down, shuts the valve G, and excludes the steam, so that the piston performs the other half of its descent by the expan sion of the steam already admitted above it. When the piston is at the bottom of the cylinder, another piece of wood on the opposite side of the plug tree presses down the middle handle above Y, which closes the exhausting valve L, and also the injecting valve, by means of a strap and rod connected with it. At the same time, the equilibrium valve K is opened by the working gear, so as to occasion an equilibrium in the state of the steam above and below the piston.