USRE2407E - cambrxn - Google Patents

Description

@uiten i gisten getint, @ff-Vins.'

, SPECIFICATIQN.

Beit known that I, .S. vCAME-RON, of the city,' c'ounty', and State of- Nc'wYork, have invented -a new-and useful Improvement in Valve Gear'i'or Steam Engines; and-I do hereby declare that the following is a fr. clear, and exact description thereof, which will enable others'skilled in the art to make and use the same, reference being had to the accompanying drawings, forming' part of this specification. c 'The drawing represents'a longitudinal central section of a st eam'cylinder constructed according to this invention. t

lThis invention relates to a valve motion which is produced by the direct action of the steam piston on valves arranged-in the-cylinde'rfheads, the main valve b eing connected to secondary pistons which work in cylinders .that are formed in the valve-chest. The action of the steam on these secondary pistons is governed by valves situated in the heads of the main cylinder, and acted upon by thefmain piston as the same approaches said dreads, in auch a'mannert-that the main-valve-i's thrown by theactiou o f thesteani itself, and with the least possible friction, andat the same time the mainvalve is reversed before-the pistonrea'ches the end of the cylinder,

ao-asto 'cushionsaid piston.

A represents lan ordinarysteam cylinder provided witha pston,.B Steam is admitted to this cylinder through ports, a d', 'and it exhausts through the port 1 2, -and these pprts are opened and closed by tlie action of the slide-valve, C, which isof thejordinary construction, and which may be arranged so as to admit steam under the valve, as' shown in theidrawing', or which may be constructed inv any other'suitable manner. Theslide-valve is seated on the bottom of thef steam`chest, D, the ends'of which form small cylinders, EE', to receive pistons FF', which are. connected to'each other by a; rod, G, and this rodis.perforatedtransverscly so as to receive a st ud, c, which rises from the back of themain valve, C. Small channels, d d', passing through the secondary pistons, F F', form a communication between the interior of the steam-chest and the outer ends of the supple mentary cylinders, E E', so'th'at said secondary pistons are exposed to a uniform 'pressure 'of steam 'from' all 'sides. The supplementary cylinders, E E', communicate through channels, e e', with A chambers, H H', lwhich are formedin the heads of the main cylinder, and communicate with the interior of said cylinder by openings,

V, ff'. These openings are closed by valves, I I', the stems of which extendout th'iough stuffing-boxes, g g'at one, and through the openingsff' at the opposite end, as clearly shown in thc'drawing. Springs h h', which act on the outer ends of lthe valve stems, havea tendency-to keep seid secondary valves closed. The area of the cross-sections of the channels e e', is much larger than thatof the small channels, d d', passing through the supplementary pistons, F F', andl if the main piston approaches one e'nd of the stroke, it strikes the stem of one of-thc secondary valves, I', (for instauce,) and opens the same. The steam contained in vthe end'of the supplementary cylinder, E', is thereby allowed to escapo through thcchanncl 'port:a', and exhaustl port and the equilibrium of the supplementary pistons, F F', is disturbed, causing said pistons to'move inthe direc. tion of the arrow marked thereon in the drawing. By this. motion the slidevalve is changed before the main l piston has completed itsl stroke, :and the steamadmitted tothe main cylinder cushions 'th'e piston and causes itI to completcits stroke and tobegin the return stroke with the least possible strain to the mechanism. As soon as the main piston begins itsreturn stroke, the valve I' closesby the action of the spring Il', and the equilibrium of the small pistons is restored by the. steam-passingin through the small channel,l d. The' same action takes place at the opposite end of the s trekc of the main piston, andthe' slides-valve is changed automatically by the'actionof the steam itself, govcrnedby the direct action of tho main piston on the supplementary valves,

I I', and a valve gear is obtained which works with the least possible friction, which' isnot liable to get out of order, and permits of running the main piston at a very rapid speed.

It is obvious that the means employed for disturbing the equilibrium of thc secondary pistonsl can' be changed in many different ways; and I do not wish to confino myself to the preciso varrangement shown in. the drawing.

What I claim as new, and desire to secure by Letters Patent, is-

1. The valves I I', in the heads of the main steam cylinder, A, to be operated by the. direct action of the main piston, B, substantially as and for the purpose set forth.

l 2Q The construction of thc stems of the valves I I', at each end of the cylinder, in such a manner that said valves shall be moved, reversing the main valve before the piston reaches the'eud of the cylinder, so as to cushion or arrest the motion of the piston, as set forth.

3. The valve chambers H'H', and valves I I', in the heads of the main cylinder, A, in combination with supplementary cylinders E E', .pistons F F', and main valve C, constructed and operating substantially as and er the purpose described.

' A. s. CAMERON.

Witnesscm WM. F. MCNAMARA,

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