Plate 31Larger plate.
Larger plate.
512. Split bar grip,or tool holder.
513. Eye-bolt tool holder.
514. Hand padfor holding small tools.
515. Self-adjusting jawsfor round articles.
516. Adjustable gripping tongsfor lifting heavy stones, boxes, &c. See alsoNo. 761.
517. Revolving tool post, or head,to carry a variety of tools, each being required in use in a certain order, as in special repetition turning work.
518. Double screw gripping tongs.
See alsoNo. 944,912,918, 917,919,923.
The ordinary three or four-jaw chucks, wood chucks with centre screw or fork, and numerous varieties of self-centering chucks, are well known. See tool makers’ lists.
Spindle grips,Nos. 917, 918,919.
There are numerous forms of three and four-jaw chucks, both with universal or centering motions, and with independent jaws. See Horton’s, Cushman’s, the Sweetland, Pratt and Whitney’s, Westcott’s and others, chiefly American.
These are various combinations of the scroll (No. 1384) and screw jaws, as in the ordinary dog chuck. See alsoNos. 1378and1381.
For checking the impact of a blow, or more generally the momentum of a heavy moving part of a machine. The devices in use comprise (a) springs, seeSection 80; (b) air cylinder, seeNo. 1480; (c) pistons driven byelasticfluids, such as steam and air, can be cushioned by imprisoning a portion of the fluid at each end of the cylinder; (d) brakes of various kinds, seeSection 5.
519. Hydraulic cushion.The descending ram, by its tapered end, closes gradually the discharge outlet for the water.
Hydraulic buffer stops are constructed on this principle.
520. Cushioning device,at the upper end of a steam-hammer cylinder. Should the piston pass the exhaust holes, the steam above is imprisoned, and checks the piston without shock.
Besides the ordinary tools in use, as gimlets, bradawls, pin and brace bits, augers, &c., which do not need description, the following arenoteworthy:—
521.Is theordinaryVdrillfor metal work.
522. Flat point,or “bottoming” drill.
523&524. Countersinking drillsfor metal.
525. Centre bitfor wood.
526. Twist bitfor wood; clears its own borings. There is a variety with rounded cutter edges.
527,528, &529. Rock drills,or “jumpers.”
530. Earth borer,or mooring screw.
Plate 32Larger plate.
Larger plate.
531. Twist drillfor metal.
532&533. Countersinking drillsfor wood.
534. Diamond drillfor rock; bores an annular hole, the core of which breaks out at intervals.
535to545. Well boring toolsfor different kinds of strata; tools for raising broken rods, &c.
546. Hollow boring cutterfor cutting a shoulder on a central core; dowelling bit.
Devices to utilise the difference of velocity, or power, between two distinct moving parts.
547. Equational box.Two driversA,A′, equally speeded in opposite directions, will drive the bevil gear at same velocity without revolving the spur wheelC′which is loose on the shaft; but any alteration in the relative speeds ofAandA′, causes the bevil pinion to travel round, carrying the spur wheelC′at a speed equal to half the difference of the two velocities. This gear is used on traction engines to drive the swivelling wheels round curves, where the proportionate velocities of the wheels will vary with the radius of the curve. In this application of the gearBis the driving shaft, andAandA′the swivelling wheels.
548. Is a modification of547.The pinionAmay be controlled in speed by any hand or automatic device, to vary the speed of the driven pinionB. The belt pulleyCcarries round the bevil wheelD, drivingBat a speed varying with the motion given toA.
549. Two wheels(one of which has a different number of teeth to the other) gearing into one pinion; used for counters and slow motions of all kinds.
550. Is an application ofNo. 549by internal or epicycloidal gear to pulley blocks. Moore’s patent (No. 1545) and Pickering’s patent are examples. The arm shown is not required where two internalloosewheels are used with different numbers of teeth, and one pinion as inNo. 1545, but if used is fixed to the pinion so that it is prevented from revolving, but retains its circular swaying motion; in this case, one internal wheel is movable and the other fixed, the speed being equal to the difference in number of teeth of the loose wheel and pinion at each revolution of the eccentric shaft.
551. Weston’s differential pulley block,consisting of a two-grooved pitched chain-sheave having different numbers of teeth, in combination with a return block and endless chain.
552. Differential screws.These may be both of the same hand, or one right and one left-handed, and any fractional speed secured by proportioning the pitches.
Plate 33Larger plate.
Larger plate.
553. Two-speed gear,operated by a double clutch, which throws either pair into gear as required.
554. Stewarts’ differential gear.Two cranks, one fixed to a sleeve and the other to a centre shaft, are driven round at varying velocities by a slotted crosshead revolving with the driving shaft. The two shafts are not in the same line.
555. Differential hydraulic accumulator.The effective area of the ram is the annular shoulder, or the difference between the areas of the top and the bottom rams.
556. Differential governing device.The motive power drivesAwhich winds up the large weight; the small weight tending to run down, drives the fan regulator, and the two weights are so adjusted that when the proper speed is attained, both weights are stationary; any change of speed causes them to run up or down, so actuating the regulation by the bell crank lever and rod.
557. Varying differential regulator.The upper rodAis connected to the regulator valve or other device, and it is capable of receiving motion from either the piston, which acts against a spring, or from the rodBattached to some positive reciprocating part, so that the nett movement ofAis due to the difference of motion ofBand the pistonC.
Differential Worm Gear,No. 1559.
The following sketches are type drawings of the most important forms of Steam Engines in use, and are intended to afford a choice of outline arrangements from which in any scheme under consideration a selection may be made as a basis, without reference to details.
558. Overhead cylinder engine.
559. Overhead crank engine,
560. Overhead crank engine, cylinder oscillating.
561. Overhead cylinder engine,with oscillating cylinder.
564. Overhead one-crank compound oscillating engine,cylinders at right angles and receiver between.
565. Overhead double-crank compound oscillating engine,with receiver.
566. Overhead crank compound tandem oscillating engine.
Plate 34Larger plate.
Larger plate.
567. Vertical engine,with top guides, double connecting rods, and underneath crank shaft.
568. Vertical trunk engine.
Notethat the trunk plan is applicable to any of the preceding arrangements, and is employed where a very short engine is required.
569. Vertical triple compound engine,single acting cylinders. The high pressure steam acts first on the under side of the small piston, is then expanded into the annular under side of large piston, and finally expanded into the upper side of large piston.
570. Vertical compound engine,with annular cylinder. The central cylinder is the high pressure, and the annular cylinder the low pressure.
571. Vertical annular cylinder engine,with crank below.
572. Vertical slotted crosshead engine.
573. Standard vertical engine;a type largely used and possessing many good points.
574. Double cylinder engine,withTconnecting rod. (Bernay’s patent.)
580. Diagonal engine.See alsoNo. 564.
Plate 35Larger plate.
Larger plate.
581. Horizontal tandem compound engine.
582. Galloway’s oblique compound engine.
583. Double cylinder compound engine,with receiver, cranks at right angles.
584. Trunk bed engine.
585. Double piston engine.The pistons are sometimes coupled to two crank pins at right angles.
Condensers(seeSection 25) may be driven (a) from horizontal engines either direct by continuation of the piston rod, or (b) may be worked horizontally below by a vertical rocking beam coupled to the main crosshead, or (c) worked vertically below by a bell crank coupled to the main crosshead, or (d) by a separate small steam cylinder working independently, or (e) by a connecting rod or gearing from the crank shaft.
ForJet CondensersseeSection 25.
586. Ordinary pillar and overhead beam engine.
587.Has extended beam and double cylinders, either as a compound engine or one cylinder may form a pump or blast cylinder. In some designs the high and low pressure cylinders are placed side by side and coupled to the same end of the beam by a modified parallel motion.
588. Side lever engine.
589. Plan of beam engine,with compound cylinders.
590. Walking beam engine.
591. Diagonal engine.
592. Three or four cylinder high-speed engine,with single-acting cylinders.
593. Vertical high-speed single-acting engine,with one or more cylinders.
Plate 36Larger plate.
Larger plate.
594. In this engine the boiler forms the standard for supportof engine parts, but it is better to fix these on a vertical bed-plate bolted to the boiler, or asNo. 595.
595. Any type of vertical engine and any type of vertical boilercan be combined on this plan.
596. Vertical boiler(any type) and horizontal engine (any type).
597. Any type of vertical boiler,with short horizontal engine on crown.
598. Vertical boiler,with cylinder sunk in the centre of crown.
599. Overhead crank engine and boiler,the latter forming the base to which the engine parts are fixed.
600. Loco.-type semi-fixed horizontal engine.
601. Loco.-type semi-fixed horizontal engine,with engine on top. When placed on wheels this type constitutes the well-known “Portable.”
602. Horizontal semi-fixed boiler,with circular shell and engine on top. (SeeNo. 72.)
603. Horizontal semi-fixed boiler,with underneath fire-box. (SeeNo. 71.)
604. Ellipsograph;by gearing; the bevil wheelAis fixed, the other three revolving with the whole machine on the fixed central standard, the distanceA′should equal the difference between the major and minor axes of the ellipse.
605. Performs the same operationin a similar way;Ais fixed;Bis same diameter asA; andC=1⁄2diameter ofAandB.
606. Common trammel or ellipsograph.
There are other forms of apparatus fordrawingellipses merely (see Knight’s Dictionary of Mechanics). SeeTrammel Gear,Sec. 40.
607&608. Two forms of ellipsographsor elliptical cranks.
See alsoNo. 144.
Plate 37Larger plate.
Larger plate.
Wheels with rubber tyres are the common form. Wheels with a loose flat tyre outside a fixed tyre and with various forms of springs inserted between the tyres. (See Springs,Section 80.)
609. Huxley’s wheel,with spring tyre and jointed spokes.
610. Wheel with double tyresand intermediate springs.
611. Two plans of bent spoke, spring formation.
612. Two plans of bent spoke, spring formation.
613. Has an outer elastic tyreand an inner rigid ring, to which the tension or compression springs are fixed.
614&615. Sections of rubber tyres.
Wheels are also made with rubber rings applied between the boss and shaft so as to allow a limited amount of elasticity between the wheel and axle.
Common expedients for these purposes are—jointed folding rods, as a carpenter’s rule; the telescope tube; net work; diagonally crossed and jointed bars; lattice work; springs (seeSection 80); lazy tongs (No. 623).
616. Telescopic ram hydraulic lift.(See alsoNo. 1217.) Consisting of two or more rams sliding within each other.
617. Parallel bar expanding grille,or gate.
618. Parallel bar expanding grille,with lazy tongs motion, each alternate bar has slotted holes as shown.
619. Modification of618.The number of horizontal bars can be multiplied indefinitely.
620. Venetian blind;this method is used also for movable doors or partitions, sliding horizontally.
621. Venetian blind,but without revolving motion to the laths or slats.
622. Perforated bar and hooked rod suspender.
623. Lazy tongs expanding connecting rod.
624. Four-guide expanding link device,for varying motion.
625. Thorburn’s tube expander,operated by a central cone and ring of conical rollers.
626. Gasometer.
627. Timms’ expanding boring tool.Operated by a central cone and three or more diagonal feathers, sliding in dovetail grooves in the central cone.
Expanding Mandrel,No. 507.
Expanding Chucks,Nos. 489,491, &506.
Plate 38Larger plate.
Larger plate.
628. Expanding basket,with chain corner suspenders.
629. Expanding socket,with sliding ring grip.
630. Expanding grating,formed of bent steel laths on edge.
631. Bridge or flapbetween cars, having buffers.
632. Expanding core barrel,in three parts, expanded by a wedge.
633. Expanding mandril or chuck.See alsoSection 28.
Expansion Joint,Nos. 1076,1077.
Expanding Pipes,No. 1079.
Besides the ordinary plan of shrinking them on while hot, the following are the chief devices inuse:—
634. Square shaft and single key.
635. Square shaft and two keysat right angles; two keys should always be used for a square shaft, unless it has been machined to fit to the hole.
636. Round shaft and hollow key.
637. Round shaft and flat key.
638. Round shaft and sunk key.
639. Staked fastening,four keys, usually on flats cut on shaft, but better if slightly sunk into shaft.
640. Set screw.Cannot be depended on for any but light strains.
641. Taper pin.
642. Split pin;always used where a pin, bolt, or centre is liable to work loose.
643. Cotter and slot.
644. Screwed pinthrough shaft and boss of wheel.
645. Octagonal shaft of cast iron,with four keys, or the four keys may be cast on shaft.
646. Cotter or pin through side of shaft.
647. Large wheelsare sometimes wedged with iron and wood wedges all round on a square or octagonal shaft having feathers cast on it.
648. Set screw,tapped half into shaft and half into wheel.
649. Screwed shaft, nut and clamping plates;used for emery wheels, grindstones, circular saws, and milling cutters.