US970773A - Jib-crane. - Google Patents

Description

H. N. WYLIB.

JIBCRANE. APPLICATION FILED IAR,29, 1910.

Patented septh 2o, 1910.

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H. N. WYLIE.

JIB CRANE.

APPLICATION FILED JAN. 29, 1910.

Patented Sept. 20, 1910.

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H. N. WYLIB.

Patented Sept. 20, 1910.

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uivrrm) srarns PATENT ermee.

HAMILTON NEIL WYLIE, 0F EDINBURGH, SCOTLAND.

(IIB-CRANE.

To all whom it may concern.'

Be it known that I, HAMILTON NEIL IVY- LIE, a subject of the King of Great Britain, residing at Edinburgh, Scotland, have 1nvented certain new and useful Improvements in Jib-Cranes, of which the follow ing is a specification.

This invention relates to jib cranes* which term is taken to include all machines for movinof loads in which the load is held out from the main structure by means of a )1b or derrick.

In jib cranes it is frequently desired to move the load away from or nearer to the main structure. This operation is known as traversing the load, and, in existing types of cranes, it entails the lowering and raising of the load and also of the center of gravity of the crane. Means to traverse the load without this lowering and raising have been used, but these have succeeded only by increasing the complexity of the crane, and the wear on moving parts.

Now the object of this invention is to so construct the crane that the load is traversed horizontally, and the center of gravity of the crane maintained at one level and that the combination of parts is simpler, and the wear on moving parts less than in ordinary types.

It may be pointed out here that, if the load traverses horizontally, it has no effect on the balance of the jib; and that, if the center of gravity remains at one level as the jib swings out, the jib is completely balanced.

In this improved crane the jib consists of a rigid strut with a lever pivoted on its outer end, the inner end of the jib being pivoted to the main structure, and the jib and jib lever supported by tension members. The load is suspended from the free end of the jib-lever and is traversed by the jib moving outward and downward, and by the reverse motion. As the jib is thus lowered and raised a counterweight, may be connected wit-h it so as to rise as the jib falls, and vice versa and thus assist the gear for raising and lowering the jib. The counterweight would preferably be made in the form of a loaded lever linked by a tension member directly to the jib, and adapted to either completely or partly balance the weight of the iib. This lever may be arranged so as to Specification of Letters Patent.

Application led January 29, 1910.

Patented Sept. 20, 1910.

Serial No. 540,746.

move through an angle bearing any desired ratio to that moved through by the jib.

In order that the invention may be clearly understood I have hereunto appended drawings which show, by way of example, modes of carrying out my invention.

On the drawings :--Figure l shows one form of crane with a jib having a lever at its outer end and provided with a counterweight lever. Fig. 2 shows a modified form of the jib lever arrangement. Figs. 3 and et show other forms of crane. Fig. 5 shows a crane without a eounterweight lever` Figs. 6, 7, 8 and 9 are diagrams.

Referring to the drawings whereon the same reference letters wherever repeated indicate the same or similar parts, the crane shown at Fig. l comprises a main structure a which may be of triangular shape and to whose front end is pivoted, at o, a jib c carrying, at its outer end, a lever d which is pivotally jointed to the extremity of the jib at c. This lever, which is of special con struct-ion, carries at its nose end a pulley or pulleys f over which the hoisting rope g passes, said rope also passing over a wheel l1, carried on the pivot pin of the jib lever, to the winding drum z.

As will be seen the rear end of the jib lever ci is made with a curved extension m which is channeled on its outer surface for the reception of a flexible tension member j (preferably a wire rope) secured to the lever at 701 and also to the main structure a at a point no, preferably in this form of crane, at or near the apex of the structure.

The ib is moved through a vertical are by means of a toothed sector Z rigidly secured to it and with the teeth of which a worm n meshes said worm being on a worm shaft o driven by a chain p from a motor Q on the main structure. l

Pivotally carried on the top of the main structure a is a count-erweight lever 7 carrya` ing, at its one end, the counterweight s and having, at its other end, a curved part or rest t. A flexible tension member u (preferably a wire rope or chain) extends from the point o on the rest t to the point fw of the jib structure. The point of the struc ture a at which the lever r is fulcrumed I have marked f, and, as shown in this figure, this point may coincide or nearly coincide with the point m. The crane may be swung or rotated in the usual way about its vertical axis.

As, by the operation of thc worm fn., the jib is turned upward from the extended position the axis e approaches the axis (see dotted lines) and the member 7' permits the lever Z to turn downward, the rate of rotation thereof being regulated by the rest m which is so proportioned that as the jib c rises the lever d moves downward in exact relation thereto thereby maintaining the load at a uniform level while being travcrsed.

Since the axis e approaches the winding drum z' when the jib is raised, the hoisting rope g tends to pay out over the pulley f; this is of little consequence when the load is hoisted on a single line, but, when it is hoisted on a tackle of several falls it is a disadvantage. It can be practically obviated by making the pulley h of a suitable lsize (as shown), and properly placing the drum z' relatively therewith.

As the jib rises the counterweight lever fr moves downward through the arc of a circle (see dotted lines) turning on its pivot c,

and the curved rest t of the lever, against which the tension member u bears, is so made that the tension put upon the member u by the action of the counter-weighted lever o' as it turns about its axis k is always that necessary to balance the jib system as it turns about the axis b. The whole system turns about the axes b and 7c and may be designed so as to be in equilibrium in every position within the range of movement of the jib. As the jib c is raised the lever d, carrying the load, turns through a greater angle than the jib. y

Fig. 2 shows a slight modification in which the pulley 71. instead of being mountedon the pivot pin of the lever Z is mounted on a pin carried by the cross stays d1 of the jiblever. As will be seen the pulley l1, in this ligure is much smaller than that in Fig l but its position on the j ib lever is such that its outer arc is at about the same radial distance from the pivot e as the outer arc of the pulley /L of Fig. l.

Fig. 3 shows another form of crane in which the counter-balancing lever 7, instead of having a curved rest t as at Fig. l, has a point t1 to which the tension member u, which may be a non-flexible link in this case, is pivotally connected. The pulley h is in this case shown as carried on the jib c and the point is shifted to near the front of the structure by the addition of members al and jl.

Fig. t shows an adaptation of the invention in which the parts of the crane are so arranged that the curved rests are dispensed with and the tension members connected directly to points on the jib lever and the c ounterweight lever. It will be seen also, in

this case, that the axis 7.1 of the counterweight lever r does not coincide with the point :if of attachment of the member y' to the main `structure but that the latter is in advance somewhat, the main structure being altered to suit.

Fig. 5 shows a form of crane in which the lever (l has a curved rest m and is connected by a tension member direct to the uprights 0, the jib being raised and lowered by the ropes u1 as usual. The dot-ted lines show the jib in the nearly vertical position and also the position assumed by the lever cl. The hoisting rope g pays out over the pulleys 71 f, as the jib rises without raising or lowering the load which moves in a horizontal path.

If a crane, made as nearly in compliance with the foregoing directions as ordinary methods would suggest were experimented with, it would in general be found that the counterweight lever very imperfectly balanced the weight of the jib, and that the jiblever allowed considerable rise and fall on the load. It must therefore be evident that some exact method of determining the position of every point of the curved rests is necessary in order that a satisfactory action will result.

In investigating the condition of equilib# rium of the com ination I found that the equilibrium of the jib under its own weight depended on the position of the member u relative to the axes b, and c, and the equilibrium of the jib under the weight of the load depended on the position of the member j relative to axes b and e. I discovered, moreover, a ready means of determining the exact position of these members and found that this discovery could be applied to practice by making the member u or j fiexible and holding it in position by means of a curved rest fixed on the lever. I discovered, further, that in some cases the parts of the crane could be so arranged that the curved rest approximated to a point and in such cases the member u or might be pivotally connected to the lever.

I have investigated a considerable number of cranes of various types and I find that t-he most economical crane in construction and working will generally have the curved rest on the jib lever as at Figs. 1, 2, 3 and 5) but may have merely a pivot` on the counterweight lever for the tension member u (as at Figs. 3 and 4).

The general method of finding the exact position of the member u is the same as that for finding the exact position of the member 7' and depends on the same principle as will be evident from the diagram at Fig. 6 in which the method is illustrated.

In Fig. 6 let the letters have the same meaning as in previous figures and let L, e, and e, 7', represent simultaneous positions of jib strut and lever. Then, to find the. position of member j. Through points c and Z1 draw horizontal lilies and mark oli' c, el to represent. the resultant moment aboute of the various parts of the hoisting line acting on the lever. Mark otl' l), b1 to represent to the same scale the resultant moment about (2 of the parts of the hoisting line acting on the complete )ibi. e. strut and lever-join L1 el and produce to meet b, e, produced in A and then join A w. A, marks the posit-ion of member y' for that position of the lever. To lind the position of member u so that the loaded counter-Weight lever may completely balance the Weight of the jib, let la, s, and Z), e, represent simultaneous posit-ions of loaded counterweight lever and j ib. Through 7c and b draw horizontal lines and mark off 7c, 7011 to represent the moment about of the Weight of the loaded lever.

IMark off b, Z911 to represent to the same scale, the moment about Z) of the Weight of the complete jib, join b and le and pro duce to meet Z), Ic, in V and join V fw. V lw marks the position of member u.

The proportions of the arts of a crane and the relative lengths of Jib, strut and lever have to be varied to suit the varying.

conditions under Which cranes Work. Vhen everything else has been chosen the position of the jib lever` relative to that of the strut is determined by the condition that the load l must t-raverse horizontally. In general the lever will hang vertically when the strut stands vertically, taking this position as a start and drawing it down, other posit-ions are drawn in; these are most conveniently found by using a model composed of thin pieces of wood pinned together and tothe diagram, with a string as a hoisting line. When a number of positions have been drawn in as shown on Fig. 7 find point A for each position, cut a piece ofV paper to represent the lever, hold it in place in each position of the jib and draiv on 1t the lme A a: for that position, a group of lines such as is shown in Fig. 8 Will be obtained. A curve drawn freely to touch these lines and shifted in by half the thickness of the tension member is the curve required.

The movement of the loaded counter- Weight lever relative to that of the jib, in order that it may exactly balance the weight of the complete jib, is determined by the condition that the center of gravity of the system comprising the loaded lever and complete jib remain at one level during the movements of the jib.

Since the efectof the loaded lever depends only on the moment of its Weight about axis la, it is convenient for purposes of construction to take its Weight as equal to that of the complete jib and to place it at such a point S that its moment about c is the same as that of the actual loaded lever.

A method of finding the various positions of s for positions c1, fr, etc. of the jib is illustrated in Fig. 7 in which (zr, G2, ctc. are the positions of the center of gravity of the complete jib and g1, gg, etc. the projection of these points on a vertical line. The moment of s about 7c may be taken as zero when that of G about ZJ is zero.

S1, S2, etc. rare the various positions of s and s1, s2, etc. the projection of these points on a vertical line. The distances intercepted by s1, S2, etc. are equal to the corresponding distances intercepted by g1, g2, etc. and this equation enables s1, s2, etc. and hence S1, S2, etc. to be found.

Point V is found for each position as explained in connection with Fig. (i, and the cluster of lines shown in Fig. 9 and hence the curve on the nose of the lever is found as explained in connection with Fig. 8.

It is advantageous that the movement of the jib beyond its proper range should be opposed. This is attained by making the curve full beyond the part that is eective when the jib is at the inner end of the range and by attaching the tension member to the curve just before the point that is effective when the jib is at the inner end of the range` To find the position of the drum i and the diameter of the pulley l1, so that the hoist ing line will not run over pulley f during traversing :wdraw a line through point I) sloping away from the jib and making an angle of l5 degrees with the horizontal; choose the position of drum z' so that its center lies anywhere on this line; draw a vertical line tangent to the outer arc of pulley f and meeting line .7), e, produced in A; draw a line from A tangent to the upper arc of drum i; pulley It, which is journaled on axis e must have such a diameter that it touches this line. Where there is thus no motion of the hoisting line over pulley f the path of t-he center of f is parallel to the path of the load and is horizontal.

The lever jib succeeds in traversing the load horizontally by the lever lowering the load as much as the jib strut raises it. That. the cra-ne may economically fulfil the usual conditions of practice it is necessary that the lever be much shorter than the strut and that the strut incline out-ward at a considerable angle. lVith a. crane of such form it is evident that, to maintain the load at one level, the lever must rotate more? than the strut.

Cranes having a lever pivoted on the `iib for the purpose of maintaining the load more nearly at one level, have been proposed: in one case the lever remained nearly horizontal while the strut could incline but little from the vertical, and in another case 1t was necessary that the lever should have an overhung length exactly equal to that of the strut. The use of the curved rest on lever of the jib are therefore included in my claims. Moreover the method of constructing the curve of the rest will in particular cases give a curve so small that without seriously affecting the result the rest may be replaced by a pivot as at Figs. 3 and 4.

Having now fully described my invention what I claim and desire to secure by Letters Iatent is l. A crane comprising, in combination, a jib, a structure carrying the same, a lever provided with a curved rest movably mounted on t-he jib, means .for raising and lowering the jib, means for hoisting the load and a tension member connecting the lever to the structure and permitting the lever, when the load is being traversed to move through a greater angle than the `iib, and lower the load just as much as the jib raises it or viceversa so that the load moves through a horizontal path.

2. A crane, comprising, in combination, a jib, a structure carrying the jib, a lever mounted on the outer end of the jib, means for raising and lowering the jib, means for hoisting the load, a hoisting line, pulleys carrying the hoisting line mounted respectively at the outer end of the lever and on or near the lever pivot, a tension member connecting the lever to the structure, and permitting the lever, when the load is being traversed, to turn through a greater angle than the ib, and lower the load ust as much as the jib raises it or vice-versa, so that the load moves in a horizontal path.

3. A crane comprising, in combination, a jib, a structure carrying the same, a lever shorter in length than the jib and pivoted to the outer end thereof, winding means carried by the structure, a hoisting line, pulleys carrying the same and mounted respectively at the outer end of the lever, and on or near the pivot of the lever, a curved rest on the lever, a tension member secured tangentially to said rest and also connected to the structure and means for raising and lowering the jib.

4. A crane comprising, in combination. a jib, a struct-ure carrying the same, a movable lever mounted at the end of the jib, a'

tension member connecting the lever with the structure and constraining the same to move through a greater angle than the jib, counterbalancing means on the structure and connected to the jib, means for raising and lowering the jib and means for raising and lowering the load.

5. A crane comprising, in combination, a jib, a structure carrying the same, a movable lever mounted at the end of the jib, means connecting said lever to the structure, a counterbalancing lever fulcrumed on the structure and connected to the jib by a linlr spanning directly from the lever to the jib, means for raising and lowering the jib, and means for raising and lowering the load.

6. A crane comprising, in combination, a jib, a structure carrying the same, a lever movably carried at the end of the jib and having a curved rest at its end, a flexible connection from said curved rest to the structure and constraining the lever to move through a greater angle than the jib, means for counterbalancing the jib and connected thereto, means for raising and lowering the jibcuid means for raising and lowering the loa 7. A crane comprising, in combination, a jib, a structure carrying the same, a lever movably carried at the end of the jib, a second lever fulcrumed on the structure and having a curved rest at one end thereof, a counterweight on this second lever, means connecting the second lever to the jib, means for raising and lowering the jib, and means for raising and lowering the load.

8. A crane comprising, in combination, a jib, a structure carrying the same, a lever provided with a curved rest carried at the end of the jib, flexible means connecting this lever to the structure and adapted to bear on the said rest, a second lever fulcrumed on the structure and having a curved rest at one end thereof, a counterweight on this second lever, means connecting the second lever to the jib, means for raising and lowering the jib and means for raising and lowering the load.

9. A crane comprising, in combination, a j ib, a triangular structure carrying the same, a lever pivotally secured to the end of the jib, a tension member connecting the lever to the structure, a counterbalancing lever fulcrumed on the apex of the structure and 'connected to the jib, means for raising and lowering the jib and means for raising and lowering the load.

l0. A crane comprising, in combination, a jib, a triangular structure carrying the same, a lever pivotally secured to the end pf the jib, a curved rest on this lever, a tension member tangent-ially secured to the curved rest at one end and to the top of the structure at t-he other end, a counterbalancing lever fulcrumed at the top of the structure and having a curved end, means connecting said curved end to the jib, means for raising and lowering the load and mechanical means for raising and lowering the jib.

l1. A crane comprising, in combination, a jib, a triangular structure carrying the same, a lever pivotally secured to the end of the jih, a curved rest on this lever, a tension nmlnhol' tiangentially secured to the curved rest'. al' one end and to the top of the structure at the other end, a counterbalancing lever fulci'umed at the top of the structure, and having a curved end, means connecting said curved end to the jib, means for raising and lowering the load, a toothed sector on the jib, a worm engaging said sector and means for rotating the Worm.

In testimony whereof I aix my signature in presence of two witnesses.

HAMILTON NEIL VYLIE. Witnesses:

HUGH D. FITZPATRICK, GEORGE WOLFE BRUCE.

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