CiiAr. XI.
967
£
Fig 1377.
of the extremities of the cord r, and the first efforts made to put the wheel a in motionin the direction indicated by the arrow causes it to descend until the extremity leans againsta stop; the brake q then rises, and the workman experiences no difficulty ; he can suspendit at pleasure by the ratchet-wheel, and if the cord breaks at the moment the wheel rises bythe action of the counterpoise p , the brake q descends, and the force of the fall is broken.
Fig. 1377. Let a bean axle put in motion by the power w, thatwhich communicates with all the other parts of the machine : itis required, that in the case where the resistance experienced bythe machine is greater than the limit assigned to it, it shouldstop without the mover suspending its motion, and withoutthe communication being interrupted between the two axlesm and n: bb is the piece of iron fixed to the axle n; it iscomposed of a circular plate whose surface on the side of n isplane; that turned towards the axle m is furnished with twocircular crowns nn and mn ; cc is another piece of iron formedof a circular plate; its surface on the side of the piece b isfurnished with a circular crown which fits in the cavity of thepiece b, and of a tooth d in the opposite surface ; there are twosalient pieces a,a, destined to meet the salient pieces s,s, of thepiece c, and a strong salient beak b , which is prolonged to-wards the opposite surface, and enters the hollow which theexterior of the ring or circular spring leaves; this embracesthe throat formed by the edges of the piece b, and its crownmm ; this ring or brake may be closed more or less by means of a key E, and consequentlytlie friction is increased or diminished at pleasure, in order that the axle n may stop, and theaxle m continue its motion ; the latter will conduct the piece b , and the brake where thecommunication shall be established, by means of the piece c which turns with it, and canslide in the direction of its axle: the two salient teeth 8,8, meet the obstacles a,a, of thepiece b when we bring c to b ; by drawing them asunder, the action of the mover is sus-pended, whatever be the resistance the axle n experiences : it is evident if we screw tightlythe key E, and establish the communication by bringing c to b, the two axles m and «will turn as if they were one: if we release it entirely, the axle m will draw in itsmotion the piece b, and the brake oo, but the axle n will remain at rest; we then screwthe key until n turns again. Belancourt has applied this to a machine for cleaning ports,at St. Petersburgh.
Fig. 1378. sis a fly,one of whose extremities of theaxis is fur-nished with two ratchet-wheels r, r; in the interval of these twowheels there are two others toothed, which enter the axle of thefly by gentle friction; both have a catch p placed in the samedirection in each of the opposite sides, and in such a mannerthat they must turn in opposite directions, in order that the catchmay act on the ratchet-wheel which immediately touches it:p Q is a great rod which slides between two tenons, andbeing divided into two parts, forms a kind of frame furnishedwith racks, fg,h,i, which are not in the same plane: fp en-gages the wheel n, and At the wheel m; if we suppose thatthe rod PQ moves from Q to P, the rack hi, acting on thewheel m, by its catch p, will communicate to the fly a a motionof rotation from right to left, whilst the wheel n will turnwithout impressing any motion upon it. When the rod re-turns from P to Q, the wheel n communicates to the fly acircular motion in the same direction; we may suppress oneof the two wheels with its rack, the fly aa will not the lesscontinue by its inertia to move in the same direction.
Camus Pile Driver . — The ram a is attached to the ex-tremity of the rope which passes over the pulleys b,c, andenvelopes the roller d, which with the lever i, is the principalpart of the machine, whose play depends on the manner inwhich this roller is joined to the capstan; the capstan androller have the same diameter and the same axis; the rollershould be encircled with iron, with two or more pins of thesame material attached to the circle ef; the capstan g supportsthe lever hi, which has a claw advancing on the roller, andattached to the capstan by a hinge, in such a manner that itmay lower itself by leaning on the extremity i, and raise itself by means of a spring : thismachine is worked by men at the levers o,m,n,p , which turn the capstan and roller, fixedto the capstan by the lever/?, applied to one of its pins; thus the cord is wound on the
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