Plate 73Larger plate.
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1316. The small crescent-shaped pistonrevolves three times to one revolution of the three-armed piston.
1317. The hinged shutteris thrown out of the way each time the revolving arm passes it.
1318. Sliding shutterand cam piston device.
1319&1320. Varieties of the “Root” engine.
1321. The hinged vanesare closed upon the revolving piston as they pass the flat side of the casing.
1322. Has an eccentric piston and two hinged vanes.
1323. Eccentric piston and sliding diaphragm.
1324. Klein’s motion.The eccentric ring revolves in contact with the inner and outer casings, but is prevented from revolving on its axis by the fixed shutter and slot.
1325. Baker’s pressure blower.
1326. A modification ofNo. 1323.
1327. The eccentric ringrevolves on its centre, allowing the vanes to alternately project into the steam space as the wheel revolves.
1328. Ivory’s.An eccentric cam and two sliding shutters, with a central steam inlet.
1329. Mellor’shas a rocking vane oscillated by an eccentric piston carried round by a crank.
1330. Eccentric piston and two sliding vanesor steam stops.
1331. Differential rotary engine,with elliptical gear (seeSection 34), or Stewart’s differential gear (No. 554) may be employed.
The “Tower” spherical engineis a well-known form of rotary engine. SeeEngineer, August 10th, 1883.
1332. An eccentric four-armed piston,with four rolling stoppers or packings.
1333. Mellor’s patent pumphas a rocking vane or partition, with packing device which accommodates itself to the revolving oval piston.
Plate 74Larger plate.
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1334. Bisschop’s disc engine,with three or four cylinders, single acting, whose rams press alternately on the edge of the disc.
1335. Another form of disc engine,in which partitions (rising and falling vertically) form the steam stops.
1336. A modification of1316.
1337. Rotary or centrifugal pumpor fan, numerous varieties of which are in use. Many of the later forms, as Blackman’s and others, have the vanes fixed diagonally so as to propel the air at right angles to the plane of motion.
Employed to convey motion from a motor to various forms of driven machinery by gearing of various kinds. See Sections3,11,38,40, and84.
Materials employed are:—Round, square, or polygonal wrought iron or steel bars, cast iron, wood, iron or steel tubes, planished round iron and steel bars, &c.
Stow’s flexible shafting.SeeNo. 442.
1338. Longitudinal section of a cast-iron shaft.These are sometimes made of aXsection.
1339. Wooden shaftwith end ferrules and iron end centres.
1340,1341, &1342. End view and sections of ditto,solid hexagonal and hollow circular.
1343,1344, &1345. Arrangements of line shaftingin a machine-shop or factory, with or without overhead travelling crane.
1346. Example of a line shaft,showing bearings (seeSection 46), couplings (seeSection 16), pulleys (seeSection 3), and gearing (seeSections 3,84).
Shafts to be used as rollers are usually made hollow of wrought iron or other metal tube, tin plate, zinc plate, or sheet iron riveted; or sometimes, asNo. 1342, of wood laggings fixed to solid polygonal blocks or centres, either continuous or in short pieces fixed at intervals.
See alsonext Section (77).
1347. Spindlewith sunk end bearings.
1348. Spindlewith one sunk bearing and one collar.
1349. Plain spindlewith two loose collars. Where pedestals with loose caps are used (seeSection 46) the collars may be solid with the spindle, but with a long shaft the collars should be at one end only as shown, to allow of expansion. A wheel frequently occupies the place of one or both collars, and serves the same purpose.
Plate 75Larger plate.
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1350. Coned centre,fixed.
1351. Collar centre pin or stud bolt,fixed.
1352. Coned centrefor roller or similar detail, driven in place.
1353. Parallel centrefor roller or similar detail, keyed in place.
1354. Square centrefor crane barrel, &c. SeeNos. 634and635.
1355&1356. Lathe headstock spindles,solid or hollow; sometimes made with conical and sometimes with parallel necks.
1357. Conical crane post.
1358. Conical cart axle.
1359. Universal centres,employed to allow of a machine (or part of ditto), such as a drill, to be adjusted at any possible angle, the machine being fixed to one end of barA.
1360. Railway carriage axle.For cranked axles, seeSection 10.
1361. Square neck centre bolt.The square neck prevents the bolt turning and loosening the nut.
1362. Coned and cottered crank pinor centre, sometimes secured by a nut, asNo. 1350.
1363. Centre pin and bracket,adjustable to various angles.
1364&1365. Two methods of securing end of rod to any solid part of machine;used for steam hammer heads.
1366. Hollow post centre,with water or steam channel to allow for swivelling.
1367. Group of sleeve centres,employed to allow of several pairs of lever or wheel motions being taken independently on a single shaft.
1368. Ordinary centre pin,with nut, washer, and split pin.
1369. Ordinary centre pin,with split pin and washer.
Plate 76Larger plate.
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1370. Square thread screw.Single, double, or multiple thread.
1371.Vthread screw.
1372. Enlarged section ofVthread.
1373. Strongest threadwhen the strain is always in one direction.
1374. Round thread screw.
1375. Geared thread,to be used with ordinary wheel teeth, the section of thread being that of a rack of the same pitch as wheel.
1376. Earth screw,screw pile, screw mooring, earth borer. SeeNo. 530.
1377. Fixed screw,with hand wheel to revolve the nut, the screw having no rotation.
1378. Conical screw;used for chucks, &c. With two, three, or more sliding jaws chased to fit the conical thread.
1379&1380. Differential screws.One fixed, the other revolving, impart a motion equal to the difference of pitch of the two screws (seeSection 31). SeeNo. 1430.
1381. Screw,with half nut; the bearings of the screw being fixed act as a fulcrum for the motion of the half nut, which may be attached to any sliding device; employed for jaw chucks.
1382. Screw and worm gear,used for screw jacks, &c. The worm gears with a worm wheel having a central nut running on the main screw.
1383. Mutilated screw and nut.In one position the nut can slide on the screw, and a partial turn locks it. Used for instantaneous grip vices, &c.
1384. Spiral wormfor three or four jaw chucks, expanding devices, &c.
SeeSections 28and36.
1385,1386, &1387. Screw driver headsfor screws.
1388&1389. Hexagon and square headsfor ordinary spanners.
1390. Form of headrequiring special spanner or pointed bar.
Plate 77Larger plate.
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1391. Cylinder head bolt,with drilled holes and special spanner.
1392. Cylinder head,but with flutes instead of holes for spanner.
1393. Cylinder head,but with two flats cut on the head to suit an ordinary spanner.
1394. Socket head,to receive a second screw.
1395. Eye bolt.
1396. Thumb screw.
1397. Thumb or shutter screw.
1398. Milled head screw.
1399.Thead screw.
1400. Thumb or fly nut and screw.
1401. Hexagon collar studto receive a nut or other female screwed fixing.
1402. Bolt headfor forked spanner, used for sunk or countersunk heads.
1403. Hexagon head,with solid washer or collar.
1404.Thead boltforTgrooves in castings.
1405&1406. Countersunk heads.
1407. Eye bolt,with flat sides and straight eye for a pin or bolt.
1408. Snap head.
1409. Hook bolt.
1410&1411. Lewis bolts, rag bolts.
1412. Cottered bolt.
1413,1414, &1415. Lewis bolts and key pieces.
Plate 78Larger plate.
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1416. Collar stud.
1417. Split spring head bolt.
1418. Hook bolt.
1419. Solid head and collar bolt, bed bolt.
1420&1421. Heads for boltsto slide and turn inTgrooves of planing machines, &c.
1422. Countersunk bed bolt.Boiler stay.
1423,1424, &1425. Methods of finishing screw headsto prevent catching passing articles.
1426. Screw head,with cross dovetails to carry a key or screwing lever.
1427&1428. Right and left-hand screw couplingsfor tie rods, &c.
1429. Ring couplingfor 2, 3, 4 or more rod ends for tie bracing.
1430. Right and left-hand screw couplingswith halved ends to prevent the rods turning; may be made with one fine and one coarse thread for differential motion, or with right and left-hand threads.
1431. Rifling,as used in ordnance, &c., i.e. an internal multiple screw thread of very long pitch.
1432. Screw spanner;the weight prevents it working loose.
1433. Belt screw.
1434. Gib cotter bolts.
See also pipe couplings,Nos. 1071, 1072, 1073,1074, 1075, and1062,1068,1070.
For spiral worms and creepers, seeSection 57.
Spiral pump,No. 1022.
Notethat it is possible to construct a screw with an increasing or decreasing pitch, as is done with the screw propeller. See alsoNo. 1378.
Double screw gear,No. 727.
Snail worm gear,No. 730.
Worm and crown gear,No. 733.
Worm and spiral gear, seeSection 84.
It would be neither easy nor useful, besides being beyond the scope of this work, to attempt to illustrate all the varieties of gear employed to work the valves of steam and other motor engines. I shall therefore only illustrate the more important types in general use, the details of which may be varied to suit individual cases.
1435. Is the ordinary slide valve gearwith single eccentric for engines running always in one direction.
1436. Ordinary link motion reversing gearwith two eccentrics; the link, having a shifting motion, is so arranged that either eccentric can be put into gear with the slide valve, the other eccentric running idle; or when in the mid position, as in sketch, both eccentrics run idle and the slide valve has no motion. By setting the link at intermediate positions the travel of the valve can be varied, and consequently the cut off also within certain limits.
Plate 79Larger plate.
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1437. Nicholson’s patent reversing gear,without eccentrics. The drawing explains itself. This gear cannot be run in the intermediate positions, as a link motion to vary the cut off. This limits its usefulness to simple reversing only.
1438. Automatic governor expansionfor single eccentric engine; the position of the connecting rod end in the swinging link is dependent on the governor, and thus also the travel of the slide valve.
1439. Side shaft motionfor operating Cornish, Corliss, and spindle valves. The valves can be driven from this shaft by cams, eccentrics, or gearing.
1440. Gab leverfor throwing the eccentric out of gear and thus stopping the engine.
1441. Sector and link reversing motionfor oscillating engine; sometimes a shifting eccentric is used instead of link motion, asNo. 1443.
1442. Reversing sector link motionfor an oscillating engine; the valve is operated from the link, the angle of which is altered by the hand lever, there is therefore no lead to the valve.
1443. Shifting eccentric and balancesometimes used for reversing instead of double eccentrics and link; the loose eccentric is carried round in either direction by a stop piece on the shaft, fixed so as to give the correct lead both ways.
1444. Murdoch’s variable expansion gear(seeMechanical World, September 29th, 1888) has one eccentric which operates a double arm lever, the outer end of which moves a sliding fulcrum along the valve rod lever, so that the leverage of the valve rod lever varies at different parts of the stroke. The sliding fulcrum is attached to a radius rod.
1445. Proell’s automatic expansion gear.Shown applied to special double beat valves, but is sometimes applied to a special throttle valve, and is then applicable to any ordinary engine. The action of the governor alters the lap of the catches upon the ends of the valve levers, thus varying the time that the valves are kept open; the catches are centered on an oscillatingTlever, operated from an eccentric on the main shaft.
1446. Marshall’s valve gear,driven by one eccentric on crank shaft. The sector rocking centre is moved along the curved slot to reverse the engine, giving similar motion to the valve rod as in the case of the ordinary link reversing gearNo. 1436.
Plate 80Larger plate.
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1447. The Bremmé valve gearwith single eccentric; the valve rod is operated by a lever and bent connecting rod from the end of the eccentric rod; the latter is constrained to move in an arc by a three-link attachment to a fixed bearing behind the eccentric rod and a movable one at the right-hand end of the horizontal link. To reverse, the arm and sector are turned to the dotted position by the worm and hand wheel shaft.
1448. Joy’s valve gear,operated by a pin on the connecting rod. The slottedTlever is connected to the hand lever for reversing, and when reversed stands at the same angle from a vertical line but on the opposite side. The fulcrum of the valve rod lever has a sliding motion in the slot of theTlever.
1449. Variable expansion gearby hand power. There are many applications of this type used to vary the travel of a cut-off valve.
1450. Corliss valve gear,operated by a single eccentric, has two steam and two exhaust valves similar toNo. 1642, worked from pins on a rocking wrist plate. The steam valves have trips, regulated by the governor, on a similar principle toNo. 1445.
1451. Crank shaft governorwith shifting eccentric: the centrifugal action of the weights, acting against springs, is used to revolve the inner eccentric so as to vary the throw of the main eccentric from which the slide valve is driven.
1452. Another form:in this also the throw of the eccentric is varied by the action of the governor ball.
1453. Another form of automatic governor expansion trip gearin connection with Cornish valves; a single eccentric operates the four valves, and the contacts of the catches and steam valve levers are regulated by the governor, the lower or exhaust valves having a constant motion.