US22361A - Cut-off gear fob - Google Patents

Description

.reference being had to the accompanying narran entras T CFFIC.,

P. W. GATES, D'. R. FRASER, AND THOS. CHALMERS, OF CHICAGO, ILLINOIS.

CUT-OFF GEAR FOR Specification of Letters Patent No.

To all whom it may concern.

Be it known that we, P. W. GATES, D. R. FRASER, and THOMAS CHALMERS, of Chicago, in the .county of Cook and State of Illinois, have invented a new and Improved Variable Cut-@ff Gear for Steam-Engines; and we do hereby declare that the following is a full, clear, and exact description of the Same,

drawings, making part of this specication, in which Figure l is a front elevation. Fig. 2 is a vertical Section in a plane at right angles to Fig. l. Fig. 3 is a horizontal section in the plane indicated by the line in Fig. 1. Fig. l is a back view of the rocking frame and its appendages by which the cutoff valve is lifted.

Similar letters of reference indicate corresponding parts in the several figures.

This invention consists in a novel construction of two sliding toe-pieces and a mode of applying the same to a rocking frame operated by the steam-engine, in coinbination with a double lifter attached to the stem of the cut-ofta valve and with a governor or other regulating apparatus .to produce and vary the action of the cut-off for the purpose of controlling the speed of an engine.

To enable others skilled in the art to apply our invention to use, we will proceed to describe its construction and operation.

A, is a valve box containing the cut-off valve which may be of the balanced puppet or any other known kind, and therefore does not need to be shown. This valve box is intended to be placed on the valve chest of a steam engine or otherwise applied so that all the steam supplied to the engine must pass through its valve.

. B is the valve stem working vertically through the top of the box A, and entering a box C, which is attached to the valve-box by standards F, F, and within which the stem has attached to its upper end a crosshead D, to the ends of which are attached two guide rods E, E, which are parallel with the valve Stem and which pass through guide holes in the bottom of the said box C. The lower parts of these rods E, E, have screw threads cut upon them and are fitted with nuts b, o, between which and the bottom of the box C, there are spiral springs a, a, coiled upon said rods for the purpose of exerting a downward pressure upon the valve stem to STEAM-ENGINES.

22,361, dated neeember 21, 1815s.

close the valve. The box C is merely to inclose the crosshead and the upper ends of the valve stein and guide rods, and its bottom contains the guides for said stem and rods to prevent the stem turning.

G, is a crosshead secured to the valve stem and having its ends bent laterally at right angles as shown at e, e', in Fig. 3, to make it constitute a double lifter.

H, is a rock shaftarranged horizontally with its axis in the same plane as the axis of the valve stem, and I is a bearing which supports the said rock shaft. This rock shaft carries the rocking frame J, to which are litted the two sliding toe-pieces L, L,

which by the rocking motion of the frame J, are made to act alternately upon the projections c, e, of the lifter; L, upon e, and L upon e, and thus lift the valve open. These toe-pieces are fitted to slide past each other in a longitudinal recess formed in the back of the rocking frame and are furnished with tail-like pieces z, t, which project down ward through an opening in the bottom of the recess in the frame in such a manner that they stand on opposite sides of a roller e', fitted to a stud j, which is attached to a slide, M, that is fitted to slide up and down on the valve stem. The faces of the said tail-like pieces which are next to the roller are inclined so as to approach each other toward their lower extremities, as shown in Figs. l and 4. The toes la, 7c', on the toe-pieces have angular extremities which are arranged to act upon the bent extremities e, e', of the lifter.

rlhe toe-pieces are secured in the frame Gr, by screws f, f, which pass through slots g, g, in the said frame and screw into the said pieces; and the screws f, f, serve to attach to the toe pieces a spring N, which exerts a tendency to force them toward the ends of the frame as far as permitted by their tails 7L, L, which come in contact with the roller z', on the op-posite side to their respective toes lc, 7c.

The rockshaft H is furnished with an arm P, which is intended to be connected with an eccentric on the crankshaft of the engine or to have some connection with the engine which will cause it to oscillate once back and forth during every revolution thereof so that the toes acting upon the lifters will lift the cut-off vavle to admit steam to the cylinder for ever Y stroke of the piston.

The slide M, is connected with a rod Z,

which may be supposed to be connected with a governor or provided with a screw adjustment to raise or lower said slide and its stud j, and roller z'. here is a stationary slotted guide R, attached to the top of the valve box A, for the roller z', to work in, to keep the slide M, from turning on the valve stem.

The operation is as follows: As the toe pieces L, L, are caused to lift the valve by their action below the laterally projecting ends e, e', of the lifters, produced by the rocking movement of the frame J, their toes 7e, c, are caused, both by the arc-formed movement of the rocking frame and by reason of the toe-pieces being drawn into the frame by the action of their respective taillike pieces L, fr', against the roller z', as the toes are raised, to slide under the ends e, e, until the toes, if the roller i, is not too high up, slip from under the laterally projecting ends e, c', and let the valve drop suddenly and close. Fig. l shows the toe 7c, as just about to escape from the end e, and let the valve drop. As the toes descend with the rocking movement of the frame J, they work down the inner faces of the projection e, and are thereby forced into the frame J, until, after working clear of the said faces, the spring N, forces them out again to positions to act under the said projections e, e, as they rise again. The time of the escape of the toes to let the valve drop depends upon the position of the stud j, and roller i; the lowering of the said st-ud and roller between the inclined surfaces of the tail pieces 7L, 72,', forcing them farther apart, and thereby drawing in the toe-pieces so that they will escape earlier in the stroke of the piston, and the raising of said stud and roller producing an opposite effect. The stud and roller may be raised so high as to permit the spring N, to keep the'toe-pieces always so far outas to prevent the escape of the toes and compel the valve to be lowered gradually, as well as raised, by the toes, and thus permit the piston to work under a full head of steam throughout the Whole stroke. In applying a governor, the rod is so connected with it as to lower the slide M,

and the attached stud y', and roller z', as any

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