US6324A - Piston-valve cut-off - Google Patents

Description

UNITED STATES PATENT OFFICE.

GORDO?.T MCKAY, OF PITTSFIELD, MASSACHUSETTS.

PISTON-VALVE CUT-OFF.

Specification of Letters Patent No. 6,324, dated April 1'?, 1849.

T0 all whom t may concern Be it known that I, GORDON MGKAY, of Pittsfield, county of Berkshire, and State of Massachusetts, have invented a new and useful Cut-Off Valve; and I do hereby declare the following to be a full, clear, and exact description thereof, reference being had to the accompanying drawings, whereof- Figure l, is a longitudinal sectional view of the interior of the steam chest, or cylinder, together with a portion 0f the main cylinder of the steam engine; Fig. 2, is a V cross section through the cut-off at the line y, 7], Fig. l, and Fig. 3, is a section through the steam passage 79 from the steam chest into the main cylinder at the line a: m.

My cut off is constructed on the principle of forming a cylindrical valve-chest, within which works a piston rod, carrying two pistons, one near each end, and having the pistons of such thickness as by their edges to close the steam puts or passages at the two opposite ends of the cylinders and to have between the two pistons, a cut-off constructed in such a manner as to be caused to slide with each piston, alternately, through a part of its traverse, and to make a steam joint with the lface of the piston while being pushed before it. The two parts of the cut o are packed so as to fit the interior of the valve chest and are connected together by a pipe or'tube sur rounding the piston rod of the two piston valves above described.

From the above description it will appear that my invention may be properly called a cylindrical-ring cut-ofi'.

By reference to Fig. l, the piston-valve rod will be seen at R; the two piston valves which Vcorrespond to the two steam passages 79 and 79', and to the two opposite ends of the main working steam cylinder of the engine, are B and B ,-the former, (B,) closing and opening the steam passage 79, and the latter, (B), at the same time, opening and closing the steam passage 7). s

I is the induction pipe from the boiler bringing the steam into the steam-chest between the two cut-off valves A and A. These two valves are connected together by the tube t surrounding the valve-rod B. o is a slot in this tube, through which passes t-he pin e, by means of which, when therod R is made to revolve, on its axis, it will carry the cut-off valves AA and A round, also,

whereby if it be desired to work the steam at full stroke, the openings F and F may be brought. to stand opposite to the steam passages 79 and 79, and the steam will not then be intercepted by the movements of A and A, but only by the steam valves B and B.

As the positions of the valves and cut-offs are represented in the drawings, steam may be supposed to be entering by the induction pipe I, passing through the cut-off A by the passages a, a, a, a., (seen in the section Fig. 2,) to enter the main working cylinder of the engine by the passage P. The valves and cut offs are suposed to be moving toward the left, or bottom of the steam chest, the edge j" of the cut-off A being in c0ntact with the surface of the valve B at g, while the cut-off A has the edge j at some distance from the surface g of the piston B. The length of time occupied by this space between f and g in passing across the steam passage 79, determines the length of time or v part of the stroke in which steam iiows into the engine cylinder.

lVhen the piston B has moved so far toward the bottom of the steam chest as to bring the edge f of the cut-off A below the steam passage 79, that passage will be closed and the steam will be cut off, and will remain cut off from the lower end of the cylinder C while the cut off obstructs its passage, a-nd on the return movement of the valve rod R, the cut-off will remain in its position, until the piston valve B returns, comes 1n contact at its face g with the ends f of the cut-off, and moves it upward beyond the passage 79. These two surfaces forming a steam tight joint, and there being less pressure in the cylinder C than in the steam chest, the line of juncture will remain without powery in the steam to open the joint.

At Fig. 3 the steam passage is seen to be traversed by the oblique pieces s, e, which I call guard strips, and which cross the steam passage in such directions as to prevent the packing of the piston B from being thrust into the opening of the steam passage and cut away.

Vilhat l claim as my invention and desire to secure by Letters Patent, is-

The cut-o, composed of two cylindrical port-ions or rings working steam tight with the sides of the steam chest and also fitting steam tight when brought alternately in pistons and attached to each other substantially in the manner herein described.

GORDON MGKAY.

Vitnesses I. A. SEDWIoK, JAMES W. GOWAN.

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