The Is-C,Illo 1)&11 Compound-Condensing Eugine.—The full-liage engraving repre sents a pair of engines recently put in the Shrewsbury Mills, at East Newark. N. by the Watts-Campbell co., of Newurk. N. .1. The engines are tandem-compound. coupled to the shaft at right angles. The high-pressure cylinders are. 20 in. diameter and the 30 in.: stroke of pistinis, -N in, The engines run at a speed of ill revolutions per min. troth the bight and low 11r0SSIIIT cylinders are steam-jacketed. t he former with steam direct from the boiler lind the latter with the exhaust steam from the high-pressure cylinders.
The exhaust from the high-pressure cylinder passes &wit through the legs to the receiver, which is cast as part of the km--pressure cylinder and includes the jacket-space of that cyl inder. From the low-pressure cylinder the exhaust goes through a large rectangular passage to the connlenser, which is situated midway between the two low-pressure crIinder•s. A small pump minims the water of condensation from the jackets to the boilers, lint one mr-pump is employed, which is driven by a return rod from one of the Milk-Inns. The main shaft is 16 in. diameter at the center or wheel lit, and 13 in. at the journals. The band fly-wheel is 25 ft. in dhumster, built up in ten segments. it has a face of 6 ft. 2 in., turned for two 28-in. belts and one 10-in. belt. The weight of the fly-wheel is 73,000 lbs. The valve-gear is of the Corliss type, with modifications that have been introduced by the Watts-Campbell Co. The speed is controlled by means of a small fly-ball governor, running at very moderate speed the governor controls admission by eight steam-valves with great precision. without the use of a dash-pot or equivalent attachment to prevent flnetnation. This absence of shock to the governor is mainly due to the ac tion of the releasing gear.
Fig. 72 shows the dash-pot used in the Watts-Canphell Cori iss engines. The vac uum which serves to close the valve is maintained in the chamber above the ecn tt•al post. As the piston deseends.closing the steam-valve, any small quantity of air that may have found its way into this chamber is displaced through the auto matic valve shown in the top of post. The cushioning is accomplished in the nular eh/ntier at the bottom. The piston in falling is first partially obstructed in the tapered upper part of the annular chamber: then, as it passes this tapered portion, it is more complotely resisted. the only escape for the imprisoned air being such as is provided hy the adjusting screw. Icy moans of this screw any desired adjustment of cushion can be made, interposed leathers preventing the parts from striking metal to metal while making such ad.
justment. or at any time while in operation.
The piston and piston packing used in these en gines are shown in Fig. 73. The weight rests upon the center ring, to which the piston and follower are securely attached. When, by wear of the bottom of the center ring and Of the cylinder, the piston gets below the center, it can be accurately centered by means of the adjusting screws. This is considered by the builders essential in a horizontal engine. in which, owing to gravity, the bottom of piston and cylinder will be subjected to somewhat the most wear. The center ring carries the weight of the piston, and protects the head and follower from wear. By the Watts-Campbell method of turning the center ring the lower or bearing part is made to exactly fit the bore of the cylinder, the ring being turned out of round to give the requisite clearance. This gives full hearing surface front the start. The packing con sists of INV() small rings, one at either edge of the cen ter ring. These are turned somewhat larger than the bore of the eylinder, then cad and halved together at the joints. When in place they keep in easy contact with the cylinder. without undue friction, compen sating for wear by their own elasticity. Light springs arc supplied, as shlow•n. which assist in keeping the rings in contact with the cylinder until the are worn loot. The governor is connected with a cross-shaft front w'hic'h small single nods extend to I he releasing meehanison of the foot• cylinders, doing away wit It the use of the double rods usually employed. In compound engines the connecting rods are six cranks in length. The piston-rods have two different diam eters in their length. the difierenee being sidliciont to afford a tal)er scat for the low-pressure pistons. Those pistons are held im Have by it key. Ity disconnecting the nod at the eross-head and moving the low-pressure piston bnr•l: into !he spree between the Cylinders the key can be removed : then, by moving I he rod forward. the piston call be removed. A noticeable feature in these engines is the fastenings which hold the lied-plates to the pillOW-1110a. 111 fldll it 1011 to the usual Lilts, east hi I he frOilt sham' of the pillow block and ill the front side of the frame against the pillow-Hoek, and a wronght-iron link is shrink over the parts inclosed by the recesses, binding I he pillow-Hoek and frame firmly together.