507 Mechanical Movements - Brown Part 11 potx

Howlett's patent adjustable upper wheel, A, shown in section, is com-posed of arubber diskwith V-edge, clamp-ed between twometal plates.. Continuous circular motion into a working in a

where composed

three straight rules. Thechord and versedsine being

laiddown,drawstraight sloping linesfromends of former

totopof latter,and to these lines lay two of the rules

crossing at the apex. Fastenthese rules together,and

an-otherrule acrossthemto serve as a brace,andinsertapin

or point ateachendofchordtoguidetheapparatus, which,

on beingmovedagainstthese points, will describethearc

by meansof pencil in the angle ofthe crossinttedges of

the sloping rules.

404. Another cyclograph. The elastic arched baris

madehalf the depthat theendsthat it is at the middle,

andisformedso that its outer edgecoincideswith atrue

circular arcwhenbentto its greatest extent. Threepoints

in therequiredarcbeinggiven, thebarisbenttothem by

meansof the screw,eachendbeing confinedto the straight

barby meansof a smallroller.

405.Mechanical meansofdescribing hyperbolas, their

fociandvertices beinggiven. Suppose the curves two

opposite hyperbolas, thepoints in verticaldotted center

line their foci. One endof rule turnson one focus as a

centerthrough which one edgeranges. Oneend of Jhread

being looped onpin inserted at theotherfocus, andother

end heldtootherend ofrule,withjustenough slack

be-tweentopermit heighttoreachvortexwhenrule coincides

withcenter line. Apencilheldin bight,andkeptclose to

rulewhilelatter ismovedfromcenterline,describes

one-halfof parabola; the rule isthen reversedfor theother

half.

406. Mechanicalmeansofdescribing parabolas, the base,

altitude, focus, and directrixbeing given. Laystraight

edge with nearside coincidingwith directrix,andsquare

withstock against the same,so that theblade is parallel

withthe axis,andproceed withpencilinbight ofthread,

as in the preceding.

407. Instrument for describing pointedarches.

Hori-zontal baris slotted andfittedwith aslidehavingpin for

loopof cord. Archbar ofelasticwoodis fixed in

horizon-tal atright angles. Horizontal barisplaced withupper

inconveniently point ; chieflyused per-spective. Upper ordrawing edgeofblade andback of movablelegsshouldintersectcenterof joint. Geometrical diagramindicatesmodeofsettinginstrument,legsforming

itmayform unequal angles withblade- Ateitherendof

| dottedline crossing central, apinis inserted vertically for instrumenttoworkagainst. Supposingit tobe inconve-nient toproduce theconvergentlines untiltheyintersect, eventemporarily, forthe purposeof settingtheinstrument

asshown, a corresponding convergencemaybe found be-tweenthem bydrawing aline parallel toandinward from each.

409. Proportional compasses used incopying drawings

on afjiven larger orsmaller scale. The Livotof com-passesissecuredinaslidewhichis adjustable in the longi-tudinal slotsoflegs,and capable of being securedbya set screw, the dimensions aretakenbetween one pairof pointsand transferred with the otherpair, andthus en-larged ordiminishedinproportionto the relative distances

ofthepointsfromthe pivot. Ascale isprovided on one

orbothlegs to indicate the proportion.

410. Bisectinggauge Oftwoparallel cheeks onthe cross-baroneis fixedandtheotheradjustable,andheldby thumb-screw Ineithercheekiscenteredone of twoshort bars of equallength, united bya pivot, having a sharp point formarking Thispoint isalwaysin a central posi-tionbetweenthecheeks, whatevertheir distance apart, so thatanyparallelsidedsolid towhich the cheeksare

adjust-edmaybe bisected fromendtoendby drawingthegauge alongit Solidsnotparallel sidedmaybebisected in like manner,byleaving one cheek loose,but keepingit in con-tactwithsolid.

411 Self-recording level for surveyors. Consistsof a carriage, the shape ofwhich isgovernedbyan isosceles triangle having horizontal base. The circumference of each wheel equals the base ofthe triangle. Apendulum, whenthe instrumentisonlevelground,bisects thebase, andwhenon aninclinationgravitates to right orleftfrom center accordingly. Adrum,rotated by gearing from one

4J2

Thus provided, the capstancan be usedas

a simple or compound machine, single or

lockedto barrel turns it also,forming

sin-gle purchase ; but when unlocked,

in opposite directions, with velocities as

three toone

413 J. W. Howlett's patent adjustable

upper wheel, A, shown in section, is

com-posed of arubber diskwith V-edge,

clamp-ed between twometal plates. By screwing

produced between thetwowheels.

produce an increasing velocity of

415 P Dickson's patent device for

con-verting anoscillating motioninto

Oscillat-ingmotion communicatedto lever,A, which

is provided with two pawls, B andC,

hing-edtoits upperside, nearshaftof wheel, D.

Small crank, E,on upper side 01 lever, A,

isattachedbycordtoeachof pawls, sothat

when pawl, C, is let intocontact with

inte-rior of rim of wheel, D, it moves in one

the crank, B,indirection atright-angles to

dead-centers

417 Continuous circular motion into a

working in a fixed bearing, D, is bent on one-end, and fitted to turn in a socket at

theupper endofarod, B, the lowerendof which works in a socket in the slide, C

Dotted lines showthe position of therod,

B,and slide,when the shafthasmade half

a revolution from the position shown in

bold lines

slide-valve motion Valve, A, is attached to

lower endofrod, B,and free to slide

B,isattachedtoa pinwhichslidesin verti-cal slots, and a roller, C, attached to the

is intendedtoprevent the valvefrom being pressedwith too greatforceagainstitsseat

bythe pressure of steam,and to relieve it

offriction

419 Continuous circular motion con-verted intoa rocking motion Usedin

self-rockingcradles. Wheel,A,revolves,and is

connected toa wheel, B, of greater radius,

which receives an oscillating motion-, and wheel, B, is provided with two flexible

bands, C, D, which connect eachtoa

stan-dardor post attached to the rocker, E, of

4-21 /"

424

427

425

I

Thepiston has attachedtoita trunkatthelower

end ofwhich the pitman is connected directly

with the piston. The trunk works through a

stuffing-boxincylinder-head Theeffectivearea

of theupperside of the pistonisgreatlyreduced

first used on the upper side and afterward

ex-hausted into and used expansively in the part

of cylinder below

Thepiston, B, isattachedtoarock-shaft,C,and

steamisadmittedtothe cylinder to operateon

one and the other side of pistonalternately, by

meansof aslide-valve, 1),substantiallylikethat

rock-shaftisconnectedwith acranktoproducerotary

motion

single-acting pistons, B, K,are used, and both

connectedwithonecrank, D Thesteamis

ad-mittedto actonthe outer sides of the two

pis-tons alternatelybymeansofoneinductionvalve,

a,andisexhausted through the space between

thepistons. The piston and crankconnections

aresuchthatthesteamacts on*eachpiston

dur-ing about two-thirds of the revolution of the

crank,and hencethere areno deadpoints.

piston engine The "

cylinder," A,ofthis en-gineisofoblong square form andcontainstwo

pistons, B and C, the former working

horizon-tally,andthelatterworkingverticallywithinit;

the piston,C, isconnectedwith thewrist,a,of

thecrankon the mainshaft,b. The ports for

the admissionofsteam are shownblack The

byarrows,andthe pressure of thesteamon one

sideof the pistonproducesitsrotationandthat

thewayof the pistontolet itpass

426 Another formofrotary engine,inwhich

there aretwostationary abutments,D,D,within the

cylinder,andthetwopistons, A,A, inorder

to slide radiallyingroovesinthe hub, C, of the

mainshaft, B. The steam actson bothpistons

atonce,toproducethe rotation of the hub and

shaft Theinductionandeduction are indicated

byarrows

427 Another rotary engine, in which the shaft,B,worksinfixedbearings eccentrictothe cylinder The pistons,A, A, are fittedto slide

inandoutfrom groovesin the hub, C,whichis concentricwith theshaft,but they are always ra-dial to the cylinder, being kept so by rings

(shown dotted)fitting to hubs on the

pack-ings,a, a,inthe hub, C

the cylinder has a flexible lining, E, of india-rubber,androllers,A, A,are substitutedfor pis-tons,saidrollers being attachedtoarms radiat-ing from the mainshaft, B The steamacting between the india-rubber and the surrounding rigid portion of the cylinder presses the

india-rubber against the rollers,and causes them to revolvearound the cylinderandturn theshaft

to-thesteam

431 Undershotwater-wheel.

432; Breast-wheel. This holds

wheels; has float-boards like the former,

but the cavities betweenare converted into

buckets by movingin a channel adaptedto

circumference and width, and into which

water enters nearlyatthe level of axle

433 Horizontal overshot water-wheel

434 A planviewofthe Fourneyron

tur-bine water-wheel In the center are a

num-ber"offixed curved"shutes" or guides, A,

which direct the wateragainst the buckets

of the outer wheel, B, which revolves,and

the water dischargesat thecircumference

435 Warren's central dischargeturbine,

arranged on theoutside of adrum, radial to

trunk or casing, b. The wheel,c, ismade

innearlythesame way;the bucketsexceed

thecurve generallyused is that of the cy-cloidor parabola

437 Volutewheel,havingradial vanes,a,

againstwhich the water impinges and car-riesthe wheelaround Thescrollor volute

man-ner thatitacts against the vanesall around the wheel Bythe addition of the inclined

buckets, c, c, at the bottom, the water is

.made to act with additional force as it

;escapes through the openings of said

buckets

438 Barker's or reaction mill Rotary motion of central hollow shaft is obtained

439

motion fromacontinuousfallof water, bymeans

opens bystrikingtheground andthereby

empty-ing the bucket, whichiscausedto riseagainby

the action of a counter-weightontheother side

of the pulley overwhichit issuspended

440 Representsa trough divided transversely

frame beneath The fall of water filling one

sideof thedivision,the troughisvibratedonits

axis,and at the same time that it delivers the

streamandfilled,whichin likemannerproduces

hasbeen usedas awater meter

441 Persian wheel,usedinEasterncountries

forirrigation. It has ahollowshaftand curved

floats,atthe extremitiesofwhicharesuspended

in a stream acting on theconvexsurface ofits

floats, and as it is thus caused to revolve, a

quantity ofwater will beelevatedby each float

ateach revolution,and conductedtothe hollow

shaft at the same time thatoneof thebuckets

carriesits fillof water to a higher level,where

it is emptied by coming in contact with a

sta-tionary pin placed in a convenient position for

tilting' it.

442 Machineof ancientorigin,stillemployed

on the river Eisach, in the Tyrol, for raising

im-mersed,filled,and emptied intoatrough above

the stream

443.Application ofArchimedes's screwto

power Theoblique shaftof thewheelhas

spring, the current flowing through the pipein the direction of the arrow escapes therebytill

itspressure,overcomingthe resistance ofweight

orspring, closesit. Onthe closing ofthisvalve

pressure onthe othervalve,opensit,and throws

aquantityof water into the globular air-cham-ber bythe expansiveforce ofthe air in which

theupwardstream fromthe nozzleismaintained

the alternate actionof thevalves,a quantity of

water is raised into the air-chamber at every stroke, and the

elasticity of the air gives uni-formitytotheefflux.

445 and446 D'Ectol's oscillatingcolumn,for elevating a portionofa givenfallofwaterabove

the levelof the reservoir or head,bymeansof

a machine allthe parts ofwhichare absolutely fixed Itconsists of anupper andsmallertube,'

which is constantly supplied with water,anda

lowerandlarger tube, providedwith a circular platebelowconcentric with the orificewhich

445,it forms itselfgraduallyinto aconeonthe circular plate, as shown in 446, which cone

supplycontinuingfromabove, thecolumninthe

upper tube rises until thecone on the circular plate gives way This action is renewed

peri-odicallyandisregulatedbythesupplyof water.

447 This methodof passing a boatfrom one

448 450