US2589172A

US2589172A - Level luffing crane

Info

Publication number: US2589172A
Application number: US750497A
Authority: US
Inventors: George P Wagner
Original assignee: Individual
Current assignee: Individual
Priority date: 1947-05-26
Filing date: 1947-05-26
Publication date: 1952-03-11
Anticipated expiration: 1969-03-11

Description

March 11, 1952 G. P. WAGNER LEVEL LUFFING CRANE Filed May 26, 1947 3 Sheets-Sheet l 4 L a r 7/ viw e 7. 9 .PW a -HnHHWHufimfi l w w ll L w a ATTORNEY March 11, 1952 G. P. WAGNER 2,589,172

LEVEL LUFFING CRANE Filed May 26, 1947 5 Sheets-Sheet 2 INVEN'IOR.

A TTOR NE Y March 11, 1952 P, WAGNE}; 2,589,172

LEVEL LUFFING CRANE Filed May 26, 1947 3 Sheets-Sheet I5 ATTORNEY Patented Mar. 11, 1952 UNITED STATES PATENT OFFICE LEVEL LUFFING CRANE George P. Wagner, Mount Vernon, N. Y.

- Application May 26, 1947, Serial No. 750,497

7 Claims. 1

This invention relates to cranes and similar hoisting apparatus. The invention more especially relates to cranes having a jib or boom and utilizing both a hoisting cable and a luffing cable to effect hoisting and lowering of the load concomitantly with movement thereof transversely of the vertical hoisting movement thereof. The invention particularly relates to cranes or the like in which luffing movement of the load may be effected in a predetermined path, or-

dinarily in the horizontal direction known as level luffing.

Cranes of the general type above referred to ordinarily utilize a hoisting cable, reeved through a pulley or head sheave adjacent the outer end of the boom and through a sheave carried by the load or hook block and usually comprise a hoisting drum upon which the cable is wound and which is rotatable in forward and reverse directions respectively to produce the hoisting pull when the cable is wound upon the drum and for paying out the cable to lower the load as the cable is unwound from the drum. In order to effect lufiing movement of the boom, which ordinarily i pivoted adjacent its lower or inner end or otherwise is supported for movement thereof through a vertical angle, a luffing cable is connected to the boom at a suitable point outwardly from the pivot or other support thereof so that pull upon the luffing cable raises the boom and paying out this cable lowers the boom through the vertical angle. Such a luffing cable may be wound upon a lufiing drum which is rotatable in the forward and reverse directions so a respectively to raise the boom when winding the cable on the drum when rotated in a given direction and for lowering it when the cable is paid out as the drum is rotated in the opposite direction.

In the operation of such a jib or boom crane a skilled operator, having at hand separate means for controlling the separate power drives for the hoisting and luffing drums, may simultaneously effect hoisting or lowering movement as well as luffing movement of the boom. By suitable manipulation and control of the speeds of the driving means for the respective drums the load may be caused to move throu h a predetermined path having a vertical component as well as a horizontal component. It is possible by careful manipulation to move a load, which may have been hoisted to a given point above the ground, substantially only in the horizontal direction from said point. By combining also with such horizontal movement the swinging the load may be moved in a given path in a horizontal plane. All such operations, however, require considerable skill to efiect manipulation of the several controls and in many cases are not practicable for the ordinary operator, especially where very large loads are to be handled and where, as in loading and unloading ships, the space for maneuvering is limited.

With a view to securing movement of the load in a predetermined path, more particularly in the endeavor to produce level luffing, various devices heretofore have been proposed. In'certain of these devices compensating means are provided which eifect movement of a member carrying a sheave or pulley over which the hoisting rope passes to change the length of the extent of the hoisting cable between the drum and the head sheave, thereby to lower or raise the load to compensate for the lifting or lowering movement of the boom. Such compensating means, however, becomes impractical where a large number of parts of the hoisting cable and of the luffing cable must be utilized, as in cranes designed for-handling large loads.

It has been proposed also to provide difierential gearing connected between a luffing and a hoisting drum arranged so that as the luffing drum is rotated to raise the boom the hoistin drum is rotated to pay out cable and thereby lower the load to compensate for the lift thereof-which otherwise would be effected by the upward movement of the boom. With such a differential mechanism alone, however, it is impossible to produce rectilinear and particularly level lufiing movement. Since the horizontal and the vertical components of the angular movement of the boom 'vary respectively with the cosine and the sine of the angle above the horizontal through which the boom is moved, the constant increment or decrement of movement of the load which is produced by the differential mechanism rotating the hoisting drumrelative to the luffing drum is .not effective alone to secure rectilinear or horizontal movement of the load. Especially in cranes for large loads and of large radius of swing requiring long booms the vertical movement of the load for equal increments of horizontal luffing movement thereof is further variably modified by the conditions of the crane design which determine the points of attachment of the lufi'ing cable and its sheaves both to the boom and to the frame of the crane and therefore determine variations in the length of the lufiing cable between these points of attachment as the boom is moved in luffing movement thereof.

It has been proposed further to utilize a drum of conical form or a fusee which provides at one end a smaller circumference for the wrap of the lufiing cable than at the other. Such a device alone, however, is ineffective to produce rectilinear or level lufiing. Various means have been combined with such conical drums or fusees to vary the position of the hoisting cable sheaves to modify the lengths of stretches of the hoisting cable. The hoisting cable also has been wrapped upon a cylindrical drum mounted on the same shaft as the luffing drum to pay out cable at a constant rate while the luffing cable is wound on a conical drum. These expedients may produce a predetermined line of movement of the load in lufiing but are unsuitable for the conditions of handling heavy loads of large dimensions and with high lifts and with long booms for large swings, as in loading ships, in construction work and similar operations, and utilizing cables of large section.

It is an object of the invention to provide hoisting and lufling apparatus for a crane, especially one of large capacity, which will effect luffing movement of a load in a predetermined path.

It is another object of the invention to provide power driven apparatus adapted to produce level luffing of the load suspended from the jib or boom of a crane or the like.

It is a further object of the invention to provide hoisting and lufiing apparatus for a jib crane for effecting level luifing which is capable also of selectively being operated to efiect hoisting and lowering of the load without luffing.

It is another object of the invention to provide in hoisting and luffing apparatus of the type above referred to a simple operative connection between a luifing drum and a hoisting drum which secures compensating movement of the load relative to the boom movement for level luffing and which provides for selective hoisting operation without luffing.

It is a still further object of the invention to provide a level luifmg and hoisting apparatus for a jib crane utilizing luffing and hoisting drums on which the luffing and hoisting cables are Wound in which the lufling and hoisting drums are so interconnected that the load is always safely under control both when level luffing is effected as well as when hoisting and lowering of the load alone is accomplished.

In order to accomplish the above and other objects, the apparatus of the invention utilizes a hoisting drum, preferably of cylindrical form, to which one end only of the hoisting cable is becketed or otherwise fastened and upon which the cable at this end is wound in successive wraps, the'cylindrical surface of the drum preferably being grooved in the conventional manner to provide a substantially helical groove proceeding along the length of the drum to receive the successive wraps of the cable. Especially in cranes of large capacity, for example, those capable of lifting loads of 250 to 400 tons, the hoisting cable must be passed in a plurality of parts, over the head sheaves and the sheaves carried by the hook or load block. Such a cable may be reeved in six to twelve parts, for example, in order to support loads of the character above referred to. For such loads a hoisting drum of very large diameter or one of extremely long length must be used to secure the requisite circumferential distance for winding on the cable.

Ordinarily, in order to avoid too great an angularity for the hoisting cable as it passes to the drum from the idler sheave adjacent the top of the A frame, a compromise is effected between the diameter and the length of the hoisting drum. For a load of 250 tons, for example, utilizing eight parts in the hoisting cable, the drum may be about twelve-foot pitch diameter and about twelve feet long. The drum may be formed in two rigidly connected sections on a common axis. Two such cables of two and one-half inch diameter each reeved in eight parts through their respective sets of head sheaves and load block sheaves may have one end of each becketed to the respective sections of the hoisting drum.

In a crane of the capacity above referred to the jib or boom may be constructed in the form of a truss with a length of 127 feet, for example, to provide a radius of swing of feet. The boom preferably is pivotally supported at its inner end adjacent the base of the A frame of the crane, this A frame carrying adjacent its upper end a set of sheaves for each of two twelve-part luffing cables of two and one-half inch diameter. These cables are reeved through these sheaves and corresponding sets of sheaves carried in a bail pivotally attached to the peak of the truss of the boom. One end of each lufiing cable may be becketed respectively to the sections of a luffing drum having two rigidly connected sections. The opposite ends of the cables may be fastened to the boom or to other suitable fastening points or a continuous cable may have its two ends becketed respectively to the sections of the lufiing drum and may pass over an equalizer set of sheaves carried by the boom.

In a crane of such capacity, according to the invention, each section of the luffing drum is provided with a contour of varying diameter upon the axis of the drum. One end of each lufiing cable being becketed to the lumng drum section, this cable is wound on this drum so as to be wrapped upon the portion of the smallest diameter thereof when the boom is in its lowermost position, ordinarily extending horizontally from the pivot thereof. The luffing cable becomes successively wrapped upon portions of the lufiing drum of larger diameter as the luffing drum is rotated to raise the boom toward its uppermost position. In a crane of the capacity above referred to the maximum diameter of the lufling drum may be of a degree similar to that of the hoisting drum, for example, about twelve feet. The smallest diameter of the drum for a particular design of the general description above given may be six feet. The length of such lufiing drum may correspond generally to the length of the hoisting drum, namely of the degree of twelve feet. The actual maximum and minimum diameters of the luffmg drum, however, are determined in consideration of the actual construction of the boom and the supporting A frame and of the points at which the sheaves for the lufiing cable are attached to the boom and to the A frame-having regard also to the requisite unwinding and winding rotation of the hoisting drum concomitantly respectively with winding and unwinding rotation of the lufiing drum as more particularly described hereafter. The contour of the luifing drum between the maximum and minimum diameters thereof may be determined to produce a predetermined path of movement of the load. Preferably, this path is determined for rectilinear horizontal movement of the load, that is, for level lufling as the boom is raised or lowered in pivotal movement thereof through a vertical angle. Within the meaning, however, of the term level lufilng, with the apparatus of the invention the load may be moved, concomitantly with swinging movement of the crane, in a path in a horizontal plane predetermined by the composite of the lufiing movement of the load and the swinging movement of the crane.

The use of a lufiing drum of varying diameter alone, however, is ineffective to compensate for the movement of the load upwardly or downwardly resulting from the movement of the boom upwardly or downwardly through a vertical angle. In order that this lifting or lowering. movement caused by movement of the boom may be compensated, it is necessary that a portion of the hoisting line shall be paid out or taken up so as to be delivered to or taken in from the head sheaves and the load block pulleys. In accordance with the invention this paying out or taking up of the hoist line is accomplished by automatically effecting unwinding and winding rotation of the hoisting drum concomitantly respectively with winding and unwinding rotation of the lufling drum of varying diameter. In order thus automatically to effect this paying out or taking up of the hoisting cable a driving mechanism is operatively connected between the drums which will produce rotation of the hoisting drum to effect lowering and hoisting movements of the load respectively upon rotation of the luffing drum to produce raising and lowering movements of the boom. This operative connection of the invention is one which maintains the driving relation of the two drums regardless of the speed of rotation of the lufling drum so that whenever the lufilng drum is rotated the hoisting drum must accordingly rotate in a predetermined relation thereto in the compensating direction. By suitably designing the contour of the lufiing drum in relation to the ratioof the rotation of the hoisting. drum to rotation of the lufling drum effected by the driving mechanism operatively connected therebetween, the load may be moved in any predetermined path, which may be a rectilinear path and preferably is a path of horizontal movement as required for level lufling. In the preferred embodiment of the invention the driving mechanism comprises a train of gears connected between the drums to secure the relative rotation referred to.-

In order, however, to provide for operation of the hoisting drum when desired without operation of the luffing drum so that the load may be raised or lowered to a desired level without effecting lufiing movement thereof, the invention utilizes a driving mechanism between the drums which provides for rotation of the hoisting drum when the luffing drum is stopped while insuring the requisite rotation of the hoisting drum relative to the luffing drum to produce the compensating upward or downward movement of the load whenever the lufling drum is operated. Preferably, in order to avoid the use of clutches or similar devices for obtaining the desired selective as well as the cooperating operation of structed that, when the luifing drum is held sta-.

tionary by the operation of the conventional braking device associated with the luiiing drum driving motor, the hoisting drum may be rotated upon operation of the hoisting drum motor. When, however, the hoisting drum motor is stopped and the motor driving the lufling drum is energized, rotation of the hoisting drum also is effected by the driving connection between the two drums. Thus while retaining the conventional brake devices associated with the driving motors or with the transmissions between the motors and the drums, both the boom and the load remain under control when hoisting alone is accomplished as well as when lufiing, especially level lufling, is effected. As long as the hoisting drum is stopped and its motor braked, level the drums and so as to avoid also the dangers of disconnecting the driving and braking apparatus from the drums as would be required if clutches were used, the invention utilizes a differential mechanism, preferably differential gearing, for the driving connection between the drums. This differential gearing is so conlufiing must take place with the apparatus of the invention upon rotation of the lufiing drum.

Other objects and features of the invention will appear from the following description of the drawings, in which:

Fig. 1 is a diagrammatic representation of a jib or boom crane showing the boom and the load in three positions for level lufiing of the load;

Fig. 2 is a somewhat diagrammatic plan view of the lufiing and hoisting apparatus of the invention;

Fig. 3 is a section taken on line 3-3 of Fig. 2;

Fig. 4 is a section taken on line 44 of Fig. 2 to show the ratchet devices associated with the drums; and

Fig. 5 is a section to enlarged scale through the hoisting drum taken on line 5-5 of Fig. 3.

In Fig. 1 is diagrammatically shown a crane of the type to which the invention relates. The crane boom l is shown in an upper position in full lines and in the horizontally extending position in dot and. dash lines. An intermediate position is shown in dash lines. The boom is in the form of a truss pivotally supported at its inner end on a pivot 3 carried in the A frame 5 of the crane adjacent the base thereof. At the outer end of the boom l the head sheave 1 is carried over which the hoisting cable 9 passes from the hoisting drum II, this cable also passing over a sheave I3 supported on the A frame 5. The hoisting drum is suitably supported on the A frame, this A frame being mounted on the platform of the crane which is adapted to rotate on a vertical axis to produce swinging movement of the crane. One end of the hoisting cable 9 is becketed or otherwise fastened to the hoist-.

ing drum II and, after passing over the head sheave 1 and the sheave 8 supported in the load block in the embodiment of Fig. 1, has its other end fastened to the boom adjacent the head sheave I.

At the peak of the truss of the boom a sheave I1 is carried in a bail I9 pivotally attached to the truss. From the luffing drum 2| a lufiing cable 23 passes over a sheave 25 supported at the peak of the A frame. One end of the lufiing cable is becketed or otherwise fastened to the lufling drum 2| and after passing over the sheaves 25 and I! the other end of the luffing cable in the embodiment of Fig. 1 is fastened to the A frame 5 or other suitable member adjacent the sheave 25.

In Fig. 1 the boom is shown in three positions in which the load suspended therefrom is at points in the horizontal which are equally spaced, the one at the right-hand being that in which the boom extends horizontally from its pivotal support 3. By means more particularly described by rotation of the lufiing drum 2|.

hereafter the extent of the hoisting cable 9 be-' tween the head sheave 1 and the load block sheave 8 is decreased as the boom moves through the successive positions thereof between the upper position thereof, shown in full lines, and the lower horizontally extending position, shown in dash and dot outline. In the'reverse or upward movement of the boom this extent of cable 9 is increased for the successive positions. The difference between the lengths of the hoisting cable for these different positions is the composite result of factors determined by the position of the boom, the length of the hoisting cable between the sheave I3 and the head sheave 'l', which varies with the position of the boom, and the amount of cable paid out or taken up by rotation of the hoisting dru-m I l in the manner referred to above and more particularly described hereafter. increments of movement of the load in the horizontal direction, as shown in Fig. l, are secured These positions are affected by the factors of variation in diameter of the luffing drum along the length thereof which is a feature of the invention and the variation of the relation of the sheave l! with respect to the sheave 25 determining different extents of luffing cable between these sheaves. For a given load and a given radius of swing, the boom and the A frame may be designed so as to provide for the desired overall range of the lift of the load when hoisting operation alone is required in various positions of the boom in the vertical angle as well as to secure the requisite inward and outward movement of the load upon lufiing movement of the boom. In the manner more particularly described hereafter, level luihng of the load during such movements of the boom may be secured by the cooperation of the luffing drum of varying diameter and the hoisting drum with the differential driving connection therebetween above referred to.

In Fig. 2 the hoisting drum II is shown with two symmetrically related rigidly connected

sections

30 and 3| for receiving the two hoisting cables utilized in the embodiment being described. The sections are at either side of the conventional safety ratchet 33 integral with or fastened on the drum II, with which ratchet the pawl 35 supported in bracket 35 cooperates to prevent overhauling of the hoisting drum in the event of failure of the driving motor or of the brake associated therewith. The hoisting drum H is carried by a shaft 31 supported in roller bearings 36, Fig. 5, mounted in

pedestals

38 and 39, these bearing pedestals being suitably supported by the structure of the A frame of thecrane. As shown in Fig. 5, the drum H is provided with heads 4| and 43 in which respectively the hearing housings 45 and 41 are carried. Roller bearings 49 and are mounted in these bearing housings which are fastened to the drum heads 4| and 43 by bolts 46 and 48. Each housing is provided with a retainer ring 53 for the outer race of the bearings 49 and 5| and carries an oil sealing washer bearing on the retaining collar 54 for the inner races of bearings 49 and 5!. The bearing housings 45 and ii! are formed respectively with inwardly projecting flanges 55 and 5'! Keyed on the shaft 37, as shown in Fig. 5, is the.

sun gear 6| with which planetary gears 63 mesh.

The positions of the boom for equal The bearings 19 and El, therefore,

A plurality of these planetary gears 63 preferably is utilized, three such gears being utilized in the embodiment being described, as shown in Fig. 3. Each of the planetary gears 63 is bored to receive i the outer race of a roller bearing 65, the inner race of which is carried on a stud 61 pressed into or otherwise fastened in a bore in the head 4| of the hoisting drum The stud 61 is provided with a flange 69 bearing against the outer face of the drum head 4|. A retainer 7| is brought into engagement with the inner race of the bearing 65 by means of the nut 13 and washer 74 bearing thereagainst. Between the inner race and the flange 69 a ring 12 is carried fitting on stud 61. The outer circumference of the retainer II is provided with a groove for receiving the sealing washer 15 in contact with a ring 16 fastened by bolt 1'! to the hub of the planetary gear 63. The outer circumference of ring 12 also is provided with a groove for a sealing washer bearing on the inner surface of the bore of gear 63. It will be apparent that the inner race of the bearing 65, therefore, is fastened to the drum II and that the planetary gear 63, while revolving about the axis of the shaft 37 with drum I, may rotate on the axis of the stud 31 as the planetary gear meshes with the sun gear 6 Also carried on the shaft 3'! is a pair of roller bearings 8| and 83 located on the portion of the shaft between the pedestal 39 and the sun gear 6|. The inner races of the bearings 8| and 83 are retained by retainers 84 and 85 and nut 86 threaded on the shaft 31 to hold these inner races in spaced relation and against the shoulder 81 of the shaft 31.

The outer races of these bearings 8| and 83 are pressed in the bore of the hub 89 of a spider provided with four arms 9|. Fastened to the end faces of the hub by bolts 92 are retainers 93 for the outer races of the bearings 8| and 83, a spacer retainer 94 being provided between these races. The retainers 93 are formed adjacent the shaft 3'! and the retainer 84 to receive oil sealing washers 95. The spider hub 89 and arms 9| therefore are rotatable 0n and relative to the shaft 37.

The outer extremities of the spider arms 9| are fastened by bolts 96 to a ring gear 91. This ring gear is provided with internal teeth 98 meshing with the planetary gears 63', as shown in Figs. 3 and 5. It will be apparent, since the sun gear 6| is fastened upon the shaft 3! and since both the hoisting drum and the spider "arms 9| are rotatable relative to the shaft 31, that rotation of this shaft 31 will produce rotation of the drum M if the spider is held against rotation, that is, if the ring gear 91 is held stationary. It will be apparent also, if the shaft 31 is held against rotation, the sun gear 6| therefore being stationary, that rotation of the ring gear 91 will produce rotation of the drum II by virtue of the action of the planetary gear 63. Such rotation with the drum I will be in differential relation with respect to the rotation of the ring gear 91, the drum ll rotating On its axis at a rate less than that of the ring gear 91 rotating on the same axis. It will be understood, moreover, that if both the shaft 3! and the ring gear 91 are rotated, the differential rotation of the drum produced by the rotation of the ring gear will be added to or subtracted from the rotation of the drum II which is effected by virtue of the rotation of the sun gear 6| and shaft 31 as above mentioned. It will be understood further-that such differential rotation of the hoistingdrum may be effected in the directions both of unwinding and of winding the hoisting cables from and upon the hoisting drum so that the requisite paying out and taking up of the hoisting cable may be effected in proper relation to the luffing movement of the load as further explained hereafter.

As shown in Fig. 2, a hoisting motor I is provided for driving the hoisting drum. The motor I00 is connected through a reducing gear IOI having an external pinion I02 meshing with driven gear I03. Gear I03, as shown in Fig. 5, is keyed on the shaft 31. Energization of the motor I00, therefore, produces rotation of the shaft 31 and rotation of the drum II either alone when the ring gear is stationary or differentially with respect to the ring gear 91 as above described. The motor I00 is provided with a brake device I04 which may be of conventional design but preferably is constructed and arranged to effect braking action on deenergization of the motor so as to hold the motor shaft against rotation, thereby to prevent rotation of the shaft 31 and of the sun gear 6|. On energization of the motor I00 the brake mechanism is released so that rotation of the shaft 31 may be effected by the motor, suitable conventional control devices being provided in connection with the motor I00 to produce rotation in either the forward or the reverse direction, depending upon the desired direction of rotation of the drum H to secure hoisting and lowering of the load.

As shown in Fig. 2 the lufiing drum 2| also is.

formed symmetrically in two sections H0 and III, each of these sections being of varying diameter along the length thereof. In the embodiment illustrated in Fig. 2, these sections of the drum 2| are of conical form and are in opposed relation with their smaller diameter adjacent the outer ends, that is, adjacent the bearing pedestals I I4 and H6 which house roller bearin s supporting the shaft II! of the drum 2| for rotation thereof. The larger ends of the sections H0 and III are adjacent the middle of the length of the drum, at which place, similarly to the hoisting drum II, the ratchet H3 is provided, with which the pa l I supported in bracket II9 cooperates. Two luffing cables are provided, one cable being wound on each of the sections I I 0 and I I I. These cables are so wound on these tapering sections that when the boom is in the lowermost position, for example, at the horizontally extending position shown in Fig. 1, the cable is Wrapped upon the circumference of the smaller diameter. As the drum ZI is rotated to wind up the luffing cable on these tapering sections H0 and III thereof, the cable becomes wound successively on portions of these tapering sections which are of larger and larger diameter, the maximum diameter corresponding to the uppermost position of the boom. Although in Fig. 2 the sections H0 and III are shown as of conical form, the contours of these sections of this luiiing drum may be modified to a curvature convex or concave or of other outline in relation to the axis of the drum to suit the particular conditions of the crane design which have been referred to above. Such a contour is adopted, however, which, in consideration of the diiferential rotation of the hoisting drum with respect to the ring gear III, will secure the desired path of movement of the load, which may be rectilinear and preferably is the horizontal movement required for level luffing.

In order to secure the requisite cooperation of the luffing drum ZI with the hoisting drum II to 10 produce the differential rotation of the hoisting drum upon the rotation of the lufling drum, a driven gear I2I is fastened on the shaft III to which both sections H0 and III of the lufiing drum are fastened. The drums II and 2| are so positioned with their shafts parallel that the gear I2I meshes with the external gearvteeth I25 provided on the ring gear 91 as shown in Figs. 2 and 3. In the particular embodiment of these figures, the diameter of the driven gear I2I which rotates with the luffing drum is the same as the diameter of the external gear I25, so that for each rotation of the lufling drum 2| the ring gear 01 rotates once on the axis of the hoisting drum II. It will be understood, in view of the planetary action of. the planetary gear 63 revolvingabout the sun gear 6 I, that the hoisting drum II will be rotated on the axis of the shaft'31 at a slower rate than the rotation of the ring gear 91 and of the luffing drum 2I when the sun gear BI is held stationary, that is, when the shaft 31 is not driven by the motor I00. Such a condition is the normal condition of operation of the drums in accordance with the invention to produce level luifing. The combined action of paying out from or taking up cable on the hoisting drum by such differential rotation thereof together respectively with the winding of the lufiing cable on or unwinding from the luffing drum for the respective tapered sections thereof is effective to produce the requisite compensation in lowering or raising the load as the boom moves through the vertical angle in the various positions thereof to secure level lufing.

In order to drive the luffing drum 2 I, a motor I30 is connected to the drum through reducing gear I3I having external pinion I32 which meshes with the driven gear I2I of the luffing drum. Motor I30 also is provided with a conventional brake device I34 which is effective to hold the motor shaft against rotation and therefore prevent rotation of the luffing drum when the motor I30 is tie-energized. This braking device operates to release the motor shaft when the motor is energized so as to drive the lufiing drum. Suitable controls are provided for the motor I30 to produce forward and reverse rotation of the motor to secure forward and reverse rotation of the lumng drum, to eifect lifting and lowering movements of the boom by virtue of the winding and unwinding of the luffing cables on the conical sections of this drum. concomitantly with this rotation the hoisting drum will be rotated at a rate which is in a predetermined ratio to a rotation of the lufling drum by virtue of the differential driven connection between the drums. This rotation of the hoisting drum, driven from the lufling drum, therefore, secures for each rotation of the lufiing drum the paying out or the taking up of a predetermined length of the hoisting cable. This of itself will produce a predetermined raising or lowering of the load, having regard to the movement of parts of the hoisting line which are reeved through the head sheave 'I and the sheave 8 at the load block.

Since, however, the vertical component of th movement of the head sheave I which results from the movement of the boom effected by the lufling cables varies for equal increments of the horizontal component of the movement of the head sheave, that is, of the load, the sections-I I0 and III of varying diameter of the luffing drum each are effective for its cable to compensate for this variation. The result of the combined actions of the differential movement of the hoistload.

ing drum relative to the lufling drum and of the winding of the lufling cable on a luffing drum of varying diameter is that the load is caused to move in a predetermined path which may be a rectilinear path and preferably is in the horizontal direction to provide level lufflng of the It will .be apparent that this combined action is effective for either direction of movement of the boom, that is, in raising the boom or in lowering the boom and that the load will move in the predetermined path, which may be a horizontal line or may be in a horizontal plane if .swinging movement of the crane is effected concomitantly with luffing movement of the boom.

It will be apparent also that, without operation of the lufiing drum, that is, when the motor I30 is deenergized and the brake I34 is effective to hold the gear IZI and the ring gear 91 from rotating, hoisting and lowering operation of the hoisting drum II may be efiected upon energizing motor I to drive the sun gear 6|. These selective operations of luflin and hoisting are accomplished without the necessity of disconnecting, as by means of clutches or the like, one drum from the other and without the need of utilizing auxiliary compensating or take up means acting on hoisting or lufiing cables to secure level luiiing. I

It is a further feature of the invention that the two drums remain continuously interconnected .by their driving gearing so that neither drum without restraint of the other is free at any time to rotateby overhauling action of its cable in the event of failure of the power applied to its motor or of the braking device associated with its motor. Although the conventional ratchets 33 and I I3 are provided for such contingency, the constant interconnection of the drums is additional assurance that neither drum can run away under the action of the load and the weight of the boom before the ratchets may become effective to checksuch rotation.

Moreover, the controls for the lufiing and hoisting operations are simplified because operation alone of the motor I30 drivin the lufiing drum .2I insures level lufling of the load. No operation of motor I00 driving the hoisting drum is necessary. When hoisting or lowering movement of the load alone is required operation of the hoisting motor I00 alone may effect rotation of the hoisting drum in the desired direction to move the load upwardly or downwardly without lufiing movement thereof. By first raising or lowering the load to a predetermined level above the ground, this requiring the operation 'bythe operator only of the controls of the hoisting motor, level lufi'ing of the load thereafter may be effected by operation of the controls of the lufiing drum motor. The operator thus is free to effect level luffing of the load in the horizontal plane by operation with one hand of the controls for the lufiing drum motor concomitantly with operation by the other hand of the controls for the motor and the driving mechanism for effecting swinging movement of the crane. It is a particular feature of the invention, therefore, that level lufiing is accomplished with the apparatus of the invention by the operation only of the controls for the motor driving the 'luffing drum without the necessity of controlling or effecting any operation of the hoisting drum.

Within the scope of the invention the various parts may be designed otherwise than as illustrated in the drawings, while providing the features that the lufling drum is formed with varying diameter along the length thereof, that this drum is positively connected to the hoisting drum by a driving connection which provides for differential rotation of the hoisting drum relative to the luffing drum, that this driving connection is so constructed that the hoisting drum may be operated when the luifing drum is stopped but that Whenever the luffing drum is operated the differential movement of the hoisting drum relative thereto is required to take place to accomplish the level lufling of the load, and that the driving connection between the drum is continuous. All such variations of the form, size, and arrangement of the drums and of the cables wound thereon and the drives for these drums, which may be desirable or necessary to accommodate the invention to the particular design of the crane with which it is to be used, are intended to be within thescope of the claims appended hereto.

I claim:

1. In a crane or similar hoisting apparatus, the combination with a boom pivoted adjacent one end thereof and adapted to suspend a load therefrom'at a point outwardly positioned with respect to the pivot of the boom, a hoisting drum, and a cable operatively connecting said hoisting drum to the load to produce hoisting and lowering movements of said load upon forward and reverse rotation of said hoisting drum, of a luffing drum of varying diameter; along the length thereof, a cable operatively connecting 'said lufiing drum and said boom to efiect luffing movement of said boom upon forward and reverse rotation of said lufiing drum, and a differential mechanism operatively connected between said drums to provide for differential rotation of one with respect to the other upon driving either drum forwardly or reversely.

2. In a crane or similar hoisting apparatus, the combination with a boom pivoted adjacent one end thereof and adapted to suspend a load therefrom at a point outwardly positioned with respect to the pivot of the boom, a hoisting drum, and a cable operatively connecting said hoisting drum to the load to produce hoisting and lowering movements of said load upon forward and reverse rotation of said hoisting drum, means energizable for driving said hoisting drum selectively to produce said forward and reverse rotation thereof, of a lufling drum, a cable operatively connecting said luifing drum and said boom to effect luffing movement of said boom upon forward and reverse rotation of said luifing drum, said luffing drum being of varying diameter along the length thereof to vary the movement of said boom at different points in the lufiing movement thereof in relation to the rotation of said lufiing drum, means energizable for driving said lufilng drum selectively to produce said forward and reverse rotation thereof, and a differential mechanism operatively connected between said drums to produce differential rotation of said hoisting drum relative to said lufiing drum upon energization of said driving means to produce rotation of said luffing drum, said differential mechanism providing for rotation of said hoisting drum upon energization of said means for driving said hoisting drum when said means for driving said luifing drum is deenergized.

3. In a crane or similar hoisting apparatus, the combination with a boom pivoted adjacent one end thereof and adapted to suspend a load from the boom at a point outwardly positioned 13 with respect to the pivot of said boom; a hoisting drum, and a cable operatively connecting said hoisting drum to the load to produce hoisting and lowering movements of said load upon forward and reverse rotation of said hoisting drum, of a luffing drum, a cable operatively connecting said luffing drum to said boom to effect lufiing movement ofsaid boom upon forward and reverse rotation of said lufiing drum, said luffing drum having a diameter varying along the length thereof, said cable being wound on said lufiing drum to wind upon the larger diameter thereof when said boom is adjacent its uppermost position and upon the smaller diameter thereof when the boom is adjacent its lowermost position, and a differential mechanism operatively connecting said luffing drum to said hoisting drum and adapted to produce unwinding and winding rotation of said hoisting drum respectively upon winding and unwinding rotation of said luffing drum, the variation in the diameter of said luffing drum along the length thereof being determined in relation to the ratio of differential rotations of said drums effected by said differential mechanism to produce a predetermined path of movement of a load suspended from said boom by said hoisting cable.

4. In a crane or similar hoisting apparatus, the combination with a boom pivoted adjacent one end thereof and adapted to suspend a load from the boom. at a point outwardly positioned With respect to the pivot of said boom, a hoisting drum, a cable wound on said hoisting drum and connected to the load to produce hoisting and lowering movements of said load upon forward and reverse rotation of said hoisting drum, means for driving said hoisting drum to produce forward and reverse rotation thereof, of a luffing drum having a tapered winding surface, a cable wound on said tapered surface of said luffing drum and connected to said boom to effect lufl-lng movement of said boom upon forward and reverse rotation of said 1uffing drum, said cable being wound on said drum upon a smaller diameter of the tapered surface thereof when the boom is in a lower position and upon the larger diameter thereof when the boom is in an upper position, means for driving said luffing drum to produce forward and reverse rotation thereof, a differential gear mechanism operatively connected to said two driving means and to said hoisting drum to provide respectively for winding and unwinding rotation of said luffing drum on opera- I tion of said lufilng drum driving means concomitantly with differential unwinding and winding rotation of said hoisting drum both when said hoisting drum driving means is operated and is stopped, said two driving means and said differential gear mechanism being adapted to produce winding and unwinding rotation of said hoisting drum when said lufling drum driving means is stopped.

5. In a crane or similar hoisting apparatus, the

combination with a boom pivoted adjacent one wound upon and fastened to said luffing drum and having the other end thereof operatively connected to said boom to effect lufiing movement of said boom upon forward and reverse rotation of said lufiing drum, said luffing drum being of varying diameter along the length thereof, said luffing cable being wound on a smaller diameter of said lufling drum when the boom is in a lower position and upon a larger diameter of .said luifing drum when the boom is in an upper position, and a differential gear mechanism operatively connecting said drums and adapted to produce rotation of said hoisting drum upon rotation of said luffing drum and to provide for rotation of said hoisting drum when said luffing drum is stopped.

6. In a crane or similar hoisting apparatus, the combination with a boom pivoted adjacent one end thereof and adapted to suspend a load therefrom at a point outwardly positioned with respect to said pivot of said boom, a hoisting drum supported for rotation thereof on its axis, and a cable operatively connecting from said hoisting drum to said load for efiecting hoisting and lowering movements of said load upon forward and reverse rotation of said hoisting drum, of a rotatable lufflng member operatively connected to said boom to effect lufiing movement of said boom, and a differential gear mechanism comprising a ring gear supported for rotation thereof on the axis of said hoisting drum and operatively connected to said rotatable lufing member to rotate therewith during luffing operation of said boom, a sun gear supported for ro tation thereof on the axis of said hoisting drum, a planetary gear meshing with said ring gear and with said sun gear and supported for revolution thereof with said rotating hoisting drum about the axis of said hoisting drum and for rotation thereof on an axis parallel to the axis of said hoisting .drum, whereby when said rotatable member for producing luffing movement of said boom is held stationary and said sun gear is rotated rotation only of said hoisting drum on its axis is effected and when said sun gear is held stationary and said rotatable luffing member is rotated to produce luffing movement of said boom rotation of said hoisting drum also is efiected in differential relation to the rotation of said luffing member.

- 7. In a crane or similar hoisting apparatus,

the combination with a boom pivoted adjacentone end thereof and adapted to suspend a load therefrom at a point outwardly positioned with respect to the pivot of said boom, a hoisting drum, and a cable operatively connecting said hoisting drum to the load to produce hoisting and lowering movements of said load upon for ward and reverse rotation of said hoisting drum, of a luffing drum, a cable operatively connecting said lufiing drum and said boom to effect luffing movement of said boom upon forward and reverse rotation of said lufling drum, and a differential gear mechanism operatively connected between said drums to provide for differential rotation of one with respect to the other, said differential gear mechanism comprising a shaft coaxial with said hoisting drum, a sun gear fastened upon said shaft for rotation with said shaft, a stud fastened to said hoisting drum for revolution thereof about the common axis of said shaft and said drum, a planetary gear rotatable on said stud and meshing with said sun gear for rotation of said planetary gear on said stud concomitant with revolution of said stud about said common axis, and

15 a ring gear rotatable on said common axis and operatively connected to said lufiing drum to be rotated upon rotation of said lufling drum, said ring gear meshing with said planetary gear, whereby when said shaft is positively driven and said lufiing drum is held stationary said hoisting drum is rotated and when said shaft is stationary and said lufiing drum is rotated said hoisting drum also is rotated in differential relation to said lufling drum.

GEORGE P. WAGNER.

REFERENCES CITED The following references are of record in the file of this patent:

Number Number UNITED STATES PATENTS Name Date Grafton July 31, 1894 McIntyre Sept. 26, 1911 Hainsworth Jan. 20, 1920 Lange Mar. 6, 1934 Nesbitt Nov. 12, 1940 Goodman et al. May 28, 1946 FOREIGN PATENTS Country Date Great Britain Nov. 27, 1924