US2401238A - Conical type level luffing device for derricks and jib cranes - Google Patents

Description

y 2 1946, w R. GOODMAN ET AL x 2,401,238

CONICAL TYPE LEVEL LUFFING DEVICE FOR DERRICKS AND-JIB CRANES Filed Aug. 11, 1944 2 Sheets-Sheet 1 floss/fr 600M M W fiMMJJAcoeY,

IN V EN TORS- May 28, 1946. R. GOODMAN ET AL 2,401,238

CONICAL'TYPE LEVEL LUFFING DEVICE FOR'DERRICKS AND JIB CRANES Filed Aug. 11, 1944 ,2 Sheets-Sheet 2 Meir 6/01 0 Patented May 28, 1946 ()FFICE CONICAL TYPE LEVEL LUFFIN G DEVICE V FOR DERRICKS AND JIB CRANES Robert Goodman and Henry J. J acoby,

New York, N. Y.

Application August 11, 1944, Serial No. 549,005

2 Claims.

In our co-pending application for Letters Patent of the United States for Variable transmission level lufiing devices for derricks and jib cranes, filed August 11, 1944, Ser. No, 549,006, Wehave explained the advantages of the-so called level luffing and the disadvantages, drawbacks and imperfections of the many schemes, methods and devices heretofore proposed for insuring a level luiiing operation of a derrick or jib crane. We have also pointed out that, even with their many faults and deficiencies, such schemes, methods and constructions do not insure an absolute level lufling, that is, they do not insure that the load will remain and move in a horizontal plane while the boom is raised or lowered.

In the said co-pending application we showed and described one of our inventions to attain practically mathematically exact level lufiing by the use and novel control of a variable transmission.

In the present application we disclose, show, and explain, another invention of ours by which the same object of level lufiing as recited in our co-pending application may be attained by difierent means, particularly by the use of a specifically constructed conical drum.

An added advantage of the present improvement, over those recited in our said co-pending application, lies in the fact that the present improvement may attain the same objects with still more simple constructions and elements than is the case with our said application for variable transmission level lufiing, which, as there has been mentioned, is itself a great simplification over similar propositions known at present.

In the drawings forming a part of this specification and accompanying the same:

Fig. 1 is a diagrammatical elevational view of a crane into which our invention has been built;

Fig. 2 is a diagrammatical plan view of the same, and,

Fig. 3 is a fragmentary elevational view, part1 in section, of a conical drum used in our invention, shown on a larger scale than Figs. 1 and 2.

Referring now to the drawings more in detail, by characters of reference, the numeral I indicates a crane, in general, to which our invention has been added, having the supporting base structure II, a rotating platform E2 on which the operating machinery is arranged, and a boom l3.

The load M i suspended at the outer end of the boom, as usual, by the hoist block and hook l5, and it is raised or lowered through the use of the hoist drum it by the winding thereon, or off of it, the first part I! of the hoisting line or cable,

as will be understood by those versed in this art, and as it is indicated in the drawings. The raising or lowering of the boom l3 will be executed by the lufiing drum l8 through the lufiing cable [9 in the usual standard manner, also indicated inv the, drawings.

Appropriate electric motors Ida and Illa, with reducing gearings, are arranged on the platform l2, as usual, to operate the two drums.

It will be seen that when the hoist drum I6 is rotated, in one or in the other direction, it will raise or lower the load l4 without afiecting the positions of the boom l3. On the other hand, when the driun i8 is operated, the boom, will be raised or lowered, and, normally, the load It would be raised or lowered therewith, with a con- I sequent need for stronger structures, more powerful luffing motor, and a great of energy, y

To prevent a needless up and downmovement of the load when only a luffing of the boom is desired we add a specifically'designed, generally conical compensating drum 2|], on the shaft, and rotating with, the lufling drum [8, and the termination part 2i of the load hoisting cable will be secured on said generally conical compensating drum 20 in an opposite direction to the securing of the luffing cable IS on the luffing drum It, as best shown in the diagram of Fig, 1. It will be seen that when the lufiing drum is raising the boom, for which purpose it is running in a counter clockwise direction, (arrow 22), the compensating conical drum 2!! will pay out a certain predetermined amount of the hoisting cable 2! and thereby will lower the load. It also will be seen that if the payed out amount of the hoisting cable line 2! is of the right length, the load I4 will be lowered with the exact amount, that the upward lufiing of the boom [3 would have raised it, and, in such a case, the load will not be raised but will move inwardly, as indicated by the arrow 23, in the same horizontal level.

Similarly, if the lufiing drum I8 is rotated in the opposite direction, clockwise, (arrow 24), the luifing cable l9 will be payed out and the boom l3 lowered, and then, with such a rotation of it, the compensating drum 20 will take up a predetermined length of the line 2| of the hoisting cable, depending on the diameter and contour of the drum in the position in View, to counteract the lowering of the load. If the compensating drum 2%) is designed in a right manner, depending on the data and the dimensions of the crane and of its boom and hoist block, then the load and needless loss M will be prevented from being lowered, at all, and it will retain its original horizontal level.

In a word, the luifing drum [8 and compensating drum 2i] operate in opposite directions, and the compensating drum continuously will take up, or pay out, as the case may be, the exact predetermined amounts of the hoisting cable, so that the load will always remain in the original horizontal plane, in which it was in the beginning of the lufiing operation, and will move radially inwardly or outwardly to an extent depending on the angle by which the boom is raised or lowered and on the position of the boom at such lufiing operation.

At l3 a higher position of the boom is indicated by dotted lines and at M the corresponding position of the load in a lufiing operation when our compensating drum has been installed in the crane. l5, l1 and I9 indicate the new positions of the hoisting and lufiing lines, respectively.

, the compensating drum 2!] is a greatly variable factor.

It depends on the structural dimensions of the crane and its boom, and it also depends on the prevent too sudden start of the lufiing operation and insure a quick enough stopping, that is destroying its momentum. For these ends the profile of the compensating drum may be designed in such a manner as to cause the luffing drum to slightly raise the load, both, at the start, and at the finish of the lufiing operation.

It may also be desirable to carry the load, during a luffing operation, in a predetermined path, different from the horizontal. Obviously, the profile of the compensating drum 20 may be designed to cause such a travel of the load l4.

Every crane, and every desired travel for the load while lufiing will necessitate a specific compensating. drum which may be calculated and designed from said factors by an one versed in this art, as will be obvious. The drum 20 in the drawings is for illustration only for a certain specific case.

Often the profile of the compensating drum 20 will be so steeply inclined that a usual drum construction may not insure that the cable will wind on it in the desired calculated manner and the cable when wound thereon may slip or slide. To prevent this we have designed a specifically constructed compensating drum 2D, the details of which are shown in Fig. 3.

In said figure the shaft of the drum isindicated by the numeral 30, its body by 3|, having a steep conical profile. Deep channel shaped elements 32 are secured on the conical body 3|, being formed and secured in any appropriate manner, as will be understood, and may be practised by engineering experts. In the embodiment of Fig. 3 the channel elements 32 have fiat bottoms whereby they rest on triangular foundations 33 secured on the drum and so provide the predetermined safe grooves for the cable.

A preferred method of ours for forming the channel groove elements and securing them on the drum, is as follows: A suitable length of the channel element 3.2 is formed of any appropriate mate rial, and by a suitable method, as by rolling, sim ilarly to the manufacturing of a structural steel shape, and said length will then be wound on the profile of the drum in the position illustrated in the figures and secured by any appropriate means, as will be understood by those versed in this art.

From the foregoing description, taken in connection with the drawings accompanying the same, and from the remarks and explanations of fered, the advantages and methods of construction and operation of our invention will be readily understood by those versed in the art to which our invention appertains, and while we have described devices which we now consider to be the best embodiments thereof, we desire to have it understood that they are shown as merely illustrative and not limiting, and that such changes may be made when desired, as are within the spirit of this specification and the scope of the claims hereunto appended.

What we claim as new and want to protect by Letters Patent of the United States, is:

1.. In a crane, or like device, having a pivoted boom with means to raise or lower said boom on its pivot, the load being suspended on said boom, and means being provided to raise or lower the load, said respective means including a lumng drum with a cable by which to raise or lower the boom, and a hoisting drum, with a cable to rame or lower the load, the combination of a conical compensating drum, secured on the shaft of said lufiing drum and rotatable therewith, one end of the hoisting cable being secured on said hoisting drum and the other end on said compensating drum, the luifing cable and said second end of the hoisting cable being wound on the lufiing drum and on said compensating drum, respectively, in opposite directions, said compensating drurn being adapted upon an upward luffing of the boom to continually pay out amounts of hoisting cable to allow the load to remain in its original horizontal plane, and, vice v-ersa, upon a downward luffing, to take in amounts of hoisting cable calculated to .prevent any lowering of the load.

2. In a crane, as set forth in claim 1, said hoisting and said lufiing drums being independent of one another, and each having an independent source of power to operate the same.

ROBERT GOODMAN. HENRY J. JACOBY.

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