US2419209A - Variable transmission level luffing device for derricks and jib cranes - Google Patents

Description

APH] 2 2, 1947- R. GOODMAN ET Al. 2,419,209

VARIABLE' TRANSMISSION LEVEL LUFFING DEVICE FOR DERRICKS AND JIB CRANES Filed Aug. ll, 1944 2 S'heecSSheet l lwvEwnms;

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April 22, 1947- R. GOODMAN ET AL 2,419,209

VARIABLE TRANSMISSION LEVEL LUFFING DEVICE FOR DERRICKS AND JIB CRANES Filed Aug. 11, 1944 2 Sheets-Sheet 2v Patented pr. 22, 1947 VARIABLE TRANSMISSI DEVICE FOR DER/RIC N LEVEL LUFEING KS AND JIB CRANES Robert Goodman and Henry J. Jacoby,

' New York, N. Y.

Application August 11, 1944, Serial No'. 549,006

(Cl.l 212*-8) 1.3 claims.

This inventionrelate's to cranes and derricks having a swinging boom and has for its main object to provide means whereby when the boom is lufed, that is raised or lowered, on its pivot, the hook, with the load thereon, will remain in the same horizontal level.

It is obvious that if no such corrections or adjustments are provided the load will be moved up or down while only a luling of the boom is needed, and while the operation is for this movement only.

Such a needless raising or lowering of the load during luliing operations will cause complications in the mechanism, will rcall for heavier structure, will necessitate the use of heavier machinery, and the expenditure of substantial amountsof power and energy without any need or useful purpose for it.

Many methods, schemes, and constructions have been proposed for a so called level luiiing of derricks or jib cranes, but none of them were practical and none of them provided an exact level lullng. All of them necessitate complicated mechanisms, or entail other drawbacks, while,

even so, none of them could provide a real mathematically correct level lufling without any raising or lowering o'f the load. At best, they could provide, with all their disadvantages, an approximate level luiling` only. K The object of this invention is to provide means whereby a substantially mathematically exact level lufhng of a derrick or ji-b crane may be practiced with comparatively simple mechanisms.

Another object of our invention is to provide constructions and means, as characterized hereinbefore, which may be installed into aI derrick or crane without otherwise changing their construction or operation, and which, therefore, may be easily installed even into existing old devices of this type. y Y

Still other objects of our invention will be apparent as the specification` of the same proceeds.

As has been mentioned, ever since the concept of level luliing for derricks or jib cranes first introduced, its inherent advantages, both in the savingof powerV and in details of operation, were at once apparent. But because of the pecularities of its requirements, most proposed schemes, since developed, at best were only able to develop approximate level lufling, or .became so' complicated in construction that they could` be used only for relatively light loads, since the stresses encountered with the heavy loads made the particular mechanisms requiredV for level luing extreinely bulky or impractical.

Many' such schemes have been advanced -involving compensating hanging pulleys, rotating Jibs at the tip of the boom, folding booms, etc. One of the earliest schemes advanced is the twin drum system, one lufling .drum and one hook drum so arranged that while the lufng hoist winds in cable to raise the boom, the hook drums will play out cable to keep the load level. This scheme, still basically the simplest scheme ever advanced, did not come into much use precisely because while the theory was sound, the actual resutls were extremely inaccurate, The inac-A curacy of this method lies in the fact that the relative amounts of cable to be wound upon one drum and played out on the other drum to keep the hook level as the boom goes up or down are constantly changing with thechanging angle of the boom.- Thus, since the diameters of the two drums were xed, and the gearing between the two drums was constant, the amount of cable run on or on the hook drum for each revolution of the luiling. drum was always the same. Thus the original twin drumk method attempted to solve, with a constant speed ratio between the twodrums, a; problem,- whose every nature required` a variable speed ratio between the two drums, a ratio, in other words,- which constantly was undergoing change in the very process of lulng theboom.

The result of this situation was to develop approximate level lufng within a given range when the angular change of the boom was kept within the compass of a few degrees, but as soon as the boom was required to perform over wide changes of radius for the main hook, that is, greatly changing distances from the center of rotation of the crane or derrick, causing the angle of the boom with the horizontal to vary as much as 60 to 70, it became impossible to even approximate level luliing with this twin drum method.

For this reason, though essentially still'v the simplest scheme, in theory, this basic method has been discarded for more complicated methods of compensating the hook against the change in vertical height of the boom point to approximate a level hook during the luing operation.-

The eiTect of our invention to vbe described herein, is t'o use standard hoisting and mechanical devices, in combination with our novel elements, so arranged in an unique and new combination that it is possible to achieve, in the basic twin drum method out-lined above, substantially perfect and exact level luling over any range of hook radius and for all or any changes in the angle of the boom with the horizontal;

From the given construction of a crane or derrick, each degree change of boom angle will require a definite amount cf compensating cable from the hook drum changing for every degree in the change of the boom angle, and changing with the geometry of the construction of every crane or derrick. Such calculations are readily transformed into requiste ratios between the drums for each absolute angle of the boom Vwith the horizontal.

To achieve this variable ratio between the two drums in a given crane so that exact amounts of compensating cable will be run off or on the hook drum to keep the hook level as the boom is raised. or lowered, we have installed between the two drums a variable transmission of any appropriate, but otherwise possibly of standard, manufacture. The ratio between the speeds of the input and output shafts of this transmission will be regulated according to this invention directly by 'the motion of the boom itself, or of the lufng mechanism. Our invention of using the motion of the boom itself to regulate the speed ratios of a variable transmission placed between the lufiing and hook drums, will cause exact precalculated amounts of compensating cable to be run off or on the hook drum for each revolution of the luiiing drum at any and every angle of the boom.

According to this invention the change in ratio between the drums is a continual process constantly taking place under load, thus insuring exact level motion of the load on the hook while the boom is being luifed upwards or down at any angle with the horizontal.

i This above described use of a variable transmission operating as a function of the angle of the boom with the horizontal can be readily applied to any existing crane to transform it to a level luffing crane by using a variable transmission of proper horsepower and by installing our novel connection to the boom or to the lu'lng mechanism to fit the requirements of the geometry of the crane.

' This above described method of level luing is applicable to cranes that handle heavy as well as light loads, since the only extra mechanism needed, the variable transmission, is a mechanical element installed in the crane cab, and does not involve the operation of large structural members, as many other methods do.

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

Fig. 1 is a diagrammatic side elevation of a crane, showing our invention installed therein;

Fig. 2 isa diagrammatic plan of the operating mechanism of said crane on a larger scale;

Fig. 3 is a fragmentary detail of a modification, and

Fig. 4 is a detail showing our novel cam secured on the boom of the crane.

Referring now to the drawings more in detail, by characters of reference, the numeral l indicates a whirler crane, in general, having a base structure Il, a rotating platform with the upper structure and machinery thereon, indicated by the numeral l2, on which is built the usual boom I3. carrying the load block and hook lli.

Asv will be' seen from the diagrammatic plan of Fig. 2- a main drum l5 is provided for hoisting the load. A load hoisting cable i6 is secured on the drum and is led over a ileeting sheave Ita and other usual constructions, the details of which are not shown, as they are well known to those versed in this art, the cable then is led to a d hoisting block Il. It will be seen that when the drum l5 is operated in the direction of the arrow le, the load will be hoisted, while if it is operated in the opposite direction, the load will be lowered.

An electric motor i3 provides the power for hoisting the load and also for luiing the boom,

when desired, as will be more fully described hereinafter. i l f The motor shaft is connected, through a reducing gearing generally indicated by the numeral 23, to the hoist drum l5, and the structure so far described may be used independently of the rest of our device, when desired, to raise or lower the load, without affecting the position of the boom i3, as will be understood.

The motor shaft, however, is extended, as at 2 i, and is connected through a magnetic clutch 22, with a first or input shaft 23 of e, variable transmission device used in our invention, and generally indicated by the numeral 24.

This variable transmission may be of any standard type well known in this art, whether hydraulic, mechanical, or electrical, as they are well known in this art, and the one indicated in the drawings will have a second or output shaft 25, a pair of cones 2B on the rst shaft '23, and a second pair of cones 21, on said second or output shaft 25, and a wide chain 28 connecting the two double cones in the manner best indicated in Fig. 2.

The construction and operation of the variable transmission shown in the drawings is well known in this art. When it is'desired to increase the speedratiobetween shafts 23 and 25, cones 25 will be caused to near each other, while cones 2l will be moved farther apart, and in this Inan-I ner belt or chain 28 will be operated by a large driving radius and will operate on a smaller radius so that the speed of shaft 25 will be larger than that of shaft 23. Of course, when it is desired to reduce the speed ratio, the reverse setting of the respective cones 26 and 21 will be executed.

The adjustment of the pairs of cones, and, ultimately of the speed relation between th'e input and output shafts may be executed through a control lever 29, pivoted as at 3B, the connection to the rest of the mechanism and operation of which will be understood and is well known in this art.

Many such double cone and chain type of variable transmission are on the market, and the one which is illustrated in our drawings for an example only, and no-t in a limiting sense, is manufactured by the Reeves Pulley Co. of N. Y., Inc., and is shown and described in their catalogue, No. (I1-435 its data given on page 55 and designated by Nos. OOO-5. We repeat, however, that many other types of variable speed control devices may be used, whether mechanical, electrical, or hydraulic, controlled by levers,'switches, valves, handwheels, etc., their control elements being influenced by the bo-om similarly as described for lever 23 in the present illustration.

The output shaft 25 is connected with a shaft 3 l, operating the luiling drum, as will be described presently, through a flexible coupling 32.

The lufing drum is indicated at 33, and a reducing gear mechanism, generally indicated by the numeral 34, is interposed between the lumng drum 33 and its driving shaft 3 l The numeral 35 indicates anemergency hydraulic brake for the main hoist drum drive shaft 2i, and the numeral 35. indicates a flexible coupling between said hoist drum drive shaft and the shaft 3l of the motor I9. l

Y The arrangement of Fig. 2 is for a case where a single motor is used, both for hoistingtheload and lufilng the boom, while said motor may be used for operating the hoist drum alone, when desired, as will be seen. The lufng cable 38 is secured on the drum 33 and operates the lufng line 39, and it will be seen that upon the operation of drum 33, boom I3 of the crane will be raised or lowered on its pivot 40.

AS has `been explained hereinbefore, the purpose of our invention is to provide means whereby the load block I4 with the load thereon will always move in a horizontal plane, on any movement, upward or downward, of the boom. For this purpose we provide a novel interconnection between the boom and the variable transmission 24. We secure a specifically designed grooved periphery cam 4I on the boom, to rotate or rock with the same.

In the embodiment shown in our drawings, the pivot pins 42 of the boom are stationary. A small pin 43 vmay be secured into oneof said pivot pins and the cam 4I rotatably arranged thereon. An angular member 44 is secured at one end 45'thereof to the cam, at the other end 46 to the boom; In this manner a rigid permanent connection is established between the boom I3 and the cam 4 i, and, it will be seen that upon an upward or downward swinging of the boom, the cam Will rotate in a right handed or left handed direction on its pin 43. v

A control cable 4l is secured at one end 48 to the cam 4I, riding in the groove thereof, and at the other end 49 the control cable is secured to the control lever 29, of the variable transmission 24.

It will be obvious that when the boom is moved upwardly, as indicated by arrow 5s, cable 41 will be drawn by the cam 4I in the direction indicated by the arrow 5I, will move the lever 49 horizontally, as indicated by the arrow 52, and influence the variable transmission 2e in such a manner that the hoist drum I5 will play out a cable exactly sufficient to prevent a raising of the hook I4 with the load thereon, while the boom is moved upwardly, and to keep said hook and load exactly on the same horizontal level, as it has been in the first position of theboom before luing the same.

In a reverse manner, when the boom is lowered, as indicated by the arrow 53, cable 4l will move in the other direction, arrow 54, the cam 4I playing .out a predetermined amount of said cable, and

a spring device, diagranimatically indicated at 55, taking up the slackness so produced in cable 4l,

by swinging the `control lever 29 in the opposite direction, (arrow 55a) In this manner the variable transmission 2-4 will be inuenced in an-opposite direction, to a predetermined and precalculated amount, defined by the design of the cam 4I, and as the luing -drum 33`lowers the boom, the hoist drum I5 will be idly rotated to take up the cable made loose by the downward swinging of the boom, and, again, keep the load on the same horizontal level, preventing its lowering with the lowering of the boom.

As has been mentioned thereinbefore, from the constructional details and dimensions of a crane, the amount of the cable to be played out by the hoist drum I5, or to be taken up by it, for every angle of luffng of the boom upwardly or downwardly, which may be greatly different at the various positions of the boom, may be figured out, and the contour of the cam 4I designed accordingly, by methods and calculations `well known to engineering experts.

Of course, the data and operation of the variable transmission 24, have to be considered when designing the cam so that the moving of the control lever :is for said transmissi-on, in one direction or the other, by the cam, should produce such a speed ratio between the input and output shafts 23 and 25 of the variable transmission, that, at a certain position of the boom, a certain amount of lung thereof should produce 'such a rotation in one direction or another in the hoist drum I5, as to play out or take up an exact amount of cable needed to keep the load at the previous horizontal level, as will be understood by those versed in this art.

Every crane and every desired path for the load will require a dierent cam 44, and that shown `in the figures is for illustration only. rIhe cam maybe designed for a straight horizontal movement of the load, or in case 0f fast luiIing cranes in such a manner that at the start and at the end of the luing operation the load will be caused to rise to a small extent, to check the lumng operation, or the cam may be designed for any predetermined path fcr the load, as will be understood and obvious to experts in crane engineering. It is also to be understood that the principle and use of our invention may be employed for other movements of the b-oom, different from the one herein described, as when the boom is not raised or lowered but swings on a vertical'axis.

When it is desired to raise or lower the load, only, the clutch 22 will be disconnected, so that the mot-or Iii only acts on the hoist drum I 5, and is disconnected from the lufling drum 33.

As has been mentioned, we prefer to employ a magnetic clutch, many of which are well known in this art, but,'of course, any other standard type of clutch may be used, operating mechanically, hydraulically, or electrically.

At dii we show a magnetic brake of any standard manufacture for the main hoist, and at 51 a similar appropriate'standard brake for the lufng hoist shaft 3l It will be seen that in the embodiment illustrated in Fig. 2, one single motor IS may drive -either the hoist drum I5, alone, operating on the load, or both, the hoist drum i5 and the lufng drum 33, for the lufling operation.

In Fig. 3 we show a portion of a modication 0f this arrangement whereby two motors may be used, one for luiiing and one for hoisting the load.

In Fig. 3 the second motor only is shown with the portion of the arrangement wherein it could be attached to the arrangement shown in Fig. 2.

In the modication of Fig. 3, operating with two motors, every part would remain identical to the ones shown in Fig. 2, with the only difference that the magnetic `brake 5l is removed from the end 5@ of the lufling drum drive shaftY 3|, and a second weaker mo-tor 6G is attached to said shaft SI, as by a nexible coupling e I.

The magnetic brake 5'? will now conveniently be placed at the outer end of the second motor 6B.

In this modification there will be no need to use the heavy motor I9 when only a lufiingoperation is needed. In suoli a case the second motor 6@ would be energized and it would drive the luiiing drum 33 and the variable transmission 24, in' which the role of the two shafts would bethe reoutput shaft. Since the motor I9 now receives 7 no power, its rotor would simply run idly with the rotation of the output shaft 23. The output shaft 23 would then operate the idle hoisting drum l through the shaft 2| and gearing 2U, as before, the amount of rotation of said drum being defined by the angular movement of the boom I3, through the operation of the cam 4|, as before.

l The heavy motor i9 ywould be used only for the plays out the cable 38, and, vice versa, the drum I5 will play out the cable l when drum 33 windsv in its cable 38.

With given drum diameters, and given gear reductions for their shafts 2l and 3i, the relative amounts oi the cables wound on, respectively played ofi, of the two drums, will be a direct function of the variable transmission 2G.

On the other hand, the ratio of speeds of the two 'shafts in the Variable transmission, byour invention, will depend entirely on the boom angle, or the radius of the hook, therefore, the relative amounts of cables simultaneously wound on one drum and olf the other, will be a direct function of the radius of the main hook.

When our device is used only to raise or lower the load, without luing the boom, a main hoist control, indicated diagrammatically at 65, will release the brake 5% and apply the power to the motor l5. Such controllers and their connections to such magnetic brakes and electric motors, are now used and well known in this art, therefore the detailsI of them have not been shown in the drawings.

Clutch 22 also may be of a standard make, and is normally disengaged, as it is well known in this art, and, normally, there is no connection between the main hoist and the luiiing hoist, so that upon operation of the controller 65, the crane will only raise or lower the load without influencing the boom.

When luilng operations are desired, a second, luing, controller de will be used, the operation of which will release both brakes 5% and 5i, said brakes being, again, any standard constructions, said controller also will engage the clutch 22, as it is well known, whereby power will be delivered for the hoisting or lufng of the boom, and the lufng operation, as described hereinbefore, will take place.

in case the two motor system, or modification of Fig. 3, is used, so as to have the power adapted to the special needs of the luiiing hoist only, then in a similar manner as described, the brakes 56 and El would be reieased, the clutch 22 caused to engage, and driving. power would be delivered to the motor 6, by well known means, while no power would be allowed to enter the motor is. Motor Si! would then perform the lufng opera- Ition, rotating both drums in the manner described, and the motor shaft of the motor IS would run idly with a speed transferred to it by the, now output, shaft its of the transmission .24, as has been indicated hereinbefore.

At i3' a raised position of the boom is indicated, the changed positions oi` the .hoisting ele- 8 ments being indicated by I6', Ii", and I4 and the changes in the lufng elements being diagrammatically indicated 33', all by dotted lines, and it will be seenY that hook H and load L will remain in the same horizontal plane P, as indicated by their dotted positions H' and L.

Since the position of either shafts in the variable transmission is a function of the position and amount of the cable on the drum, and this, again, is a function of the position of the boom, the principle of our invention, in possibly the simplest manner, may be used in such a .way that the position of one of the shafts, itself, will influence the variable transmission in the manner and for the objects described hereinbefore.

From the foregoing description, taken in connection with the drawings accompanying the same, and from the remarks and explanations offered, the advantages and methods of construction and operation of our invention will be readily understood by those versed in Ithe art to which our invention appertains, and while we have described the 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 no-t 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:

l. In a crane, or the like, having an upwpardly and downwardly swingable boom on which the load is suspended, a hoisting drum with a hoist cable whereby to raise or lower the load, and a lufng drum to raise or lower the boom, in combination therewith, a changeable driving interconnection between the hoisting drum and the lulng drum, and means controlled by the boom, adapted to continuously influence said interconnection to alter the ratios of rotations between the ltwo drums to desired amounts whereby upon an upward lufiing operation said hoisting drum always will play out an amount of hoisting cable calculated to prevent any raising of the load, and vice versa, upon a downward luiiing, said hoisting drum always will take up suilicient hoisting cable substantially to prevent a lowering of the load. -2. In a crane, or the like, having an upwardly and downwardly swingable boom on which the load is suspended, a hoisting drum with a hoist cable whereby to raise or lower the load, and a luiiing drum to raise or lower the boom, ini combination therewith, a variable transmission device between said hoisting drum and luing drum, and means automatically reacting on the upward or downward movements of #the 'boom and adapted to continuously change the transmission device, said transmission device then changing the relation between the speeds of thefluiing and hoisting drums in such a manner that predetermined amounts of hoisting cable will be played out, ortaken in, as necessary' continuously, and at any position of the Iboom, to prevent the raising, respectively lowering, of the load during any luing operation.

3. In a crane, or the like, having an upwardly and downwardly swingable boom on which the load is suspended, a hoisting drum `with a hoist cable whereby to raise orlower the load, and `a lui-ling drum to raise 01 lower the boom, in combination therewith, a variable transmission device .between said hoisting drum and lufng drum, and means automatically reacting on the Yupward Vor downward movements of the boom and adapted to continuously change the transmission device, said transmission device then changing the relation between the speeds o1" the lumng and` hoisting drums in such a manner that predetermined amounts 'of hoisting cable will be `played out, or taken in, as necessary, continuously, and at any position of the boom, said means being adapted to cause the load to be raised to a small extent at the beginning and ending of any inning operation but to keep the load in the same horizontal plane during the rest of the luiiing operation.

4. In a crane, or the like, having an upwardly and downwardly swingable boom on which the load is suspended, a hoisting drum with a hoist cable whereby to raise o-r lower the load, and a luing drum to raise or lower the boom, in combination therewith, a variable transmission device between said hoisting drum andluing drum, and means automatically reacting on the upward or downward movements of the boom and adapted to continuously change the transmission device, said transmission device then changing the relation between the speeds of the lufling and hoisting drums in such a manner that predetermined amounts of hoisting cable will be played out, or taken in, as necessary, continuously, and at any position of the boom, said means being adapted to cause the load to describe substantially a pren determined path during the luning operations.

5. In a crane, or the like, having an upwardly and downwardly swingable boom on which the load is suspended, a hoisting drum with a hoist cable whereby to fraise or lower the load, and a luffing drum to raise or lower the boom, in cornbination therewith, a variable transmission de` vice between said hoisting drum and lufng drum, and means adapted to continuously change the transmission device, the said transmission device then changing reiation between the speeds of the luiiing and hoisting drums in such a manner that predetermined amounts of hoisting cab-le will be played out, or taken in, as necessarycontinuous- 1y, and at any position of the boom, to cause the load to describe respective predetermined paths at respective luing operations, said means to change said transmission device including a member adapted to inuence the transmission device,

in one or in the other direction, upon its movevment in one or the other direction, and means interposed between said member and the boom of the crane adapted to move said member with the movements of the boom in a predetermined manner.

6. in a crane, or the like, having an upwardly and downwardly swingable boom on which the load is suspended, a hoisting drum with a hoist cable whereby to raise or lower the load, and a luiiing drum to raise or lower the boom, in combination therewith, a variable transmission device between said hoisting drum and lufling drum, and means adapted to continuously change the transmission device, said transmission device then changing the relation between the speeds 01"' the luing and hoisting drums in such a manner that predetermined amounts of hoisting cable will be played o-ut, or taken in, as necessary, continuously, and at any position of the boom, to cause the load to describe a predetermined path during respective luiT operations, and said means to change said transmission device including a pivoted lever inuencing the transmission device, a spring having the tendency to keep said lever in a normal position, an element influenced by the angularfmovement's of the boom, and .a connection between said element and said lever, whereby the movement of said element upon the lumng of the boom in one direction will rock .said lever out of its normal position, while an opposite movement of said element will cause a rocking of said lever towards its normal position.

' '7. In a crane, or the like, having an upwardly and downwardly swingable boom on which the load is suspended, a hoisting drum with a hoist cable whereby to raise or lower the load, and a lufring drum to raise or lower the boom, in combination therewith, a variable transmission device between said hoisting drum and luing drum, and means adapted to continuously change the transmission device, said transmission device then changing the relation between the speeds of the luing and hoisting drums in such a manner that predetermined amounts of hoisting cable will be played out, or taken in as necessary, continuously, and at any position of the boom, to cause the load to describe a predetermined path during a lun-lng operation, said means to change said transmission including a member on said transmission adapted to move in one or other directions, and thereby iniiuence said transmission to effect high-v er or lower speed ratios, respectively between the hoisting and luing drums, a cam rotatable on the pivotof the boom, a connection between the boom and the cam, whereby the cam will rotate in proportion to the angular movements of .the boom, and a connection between said cam-and said member on the transmission device whereby said member will react on the movements of the cam in a predetermined manner. n In a crane, or the like, having an upwardly and downwardly swingable boom on which the load is suspended, a hoisting drum with a hoist cable whereby to raise or lower the load, andV Aa lufng drum to raise or lower the boom, in c0111-,A bination therewith, a variable transmission device, between said hoisting drum and luling drum', and means automatically reacting on the upward or downward movements of the boom and adapted to continuously change the transmission device, said device then changing the relation between the speeds of the luiing and hoisting drums in such a manner that predetermined amounts of hoisting cable will be played out, or taken in, as necessary, continuously, and at any position of the boom, to cause the load to describe respective predetermined paths at respective luft"- ing operations, an electric motor to drive the hoisting drum shaft, means to disconnect said shaft from the hoisting drum and means then to connect it to the respective end of said transmission device, for a luing operation, said last two disconnecting and connecting means being adapted to act in the reverse manner for a hoisting operation.

v9. In a crane, or the like, having an upwardly and downwardly swingable boom on which the load is suspended, a hoisting drum with a hoist cable whereby to raise or lower the load, and a lumng drum to raise or lower the boom, in combination therewith, a variable transmission device between said hoisting drum and luiing drum, and means automatically reacting on the upward or downward movements of the boom and adapted to change the transmission device, said transmission device then changing the relation between the speeds of the luiing and hoisting drums in such a manner that predetermined amounts of hoisting cable will be played out, or taken in, as necessary, continuously, and

atany position of the boom, to cause the load to describe apredetermined path during a, luing operation, a rst electric motor normally connected to said-hoisting drum, and adapted to drive the same, means to disconnect said hoisting drum from said transmission device when hoisting, a second electric motor normally connected to and adaptedto drive said luiring drum, and means to connect said transmission to said hoisting drum, means to de-energize said rst motor, and means to energize said second motor, when lufng.

10. In a crane or the like, having a boom, a hoisting and a lu'ing drum, a combination, of a shaft operatively connected to the hoisting drum, a shaft similarly connected to the lufng drum, a variable transmission device between said two shafts to determine the ratio between their speeds, means adapted to change said variable transmission device and thereby change the ratio of rotation between said two shafts, and means to continuously influence said transmission changing means in accordance with the movement of the boom.

11. In a crane or the like, as set forth in claim 10, said means to continuously influence the transmission changing means including a cam secured on and rockable with the boom.

12. In a crane or the like, as set forth in claim 10, said means to continuously influence the transmission vchanging means including la cam rockable with the boom, a lever connected to said ratiot changing means, and a connection between said cam and said lever.

13. In a crane, or the like, having an upwardly and downwardly swingable boom on which the load is suspended, a hoisting drum with a hoist cable whereby to raise or lower the load, and a luing drum to raise or lower the boom, in combination therewith, a variable transmission device between said hoisting drum and lufling drum, and means automatically reacting on the up- 12 ward or downward movements of the boom and adapted to continuously change the transmission device, said device then changing the relation between the speeds of the luing and hoisting drums in such a manner that predetermined amounts of hoisting cable will be played out, or taken in, as necessary, continuously, and at any position of the boom, to cause the load to describe respective predetermined paths at respective luing operations, a source of power to drive the hoisting drum shaft, means to disconnect said shaft from the hoisting drum, and means then to connect it to the respective end of said transmission device, for a luffing operation, said last two disconnecting and connecting means being adapted to act in the reverse manner for a hoisting operation.

ROBERT GOODMAN.

HENRY J. JACO-BY.

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

UNITED STATES PATENTS Number Name Date 1,731,879 Thompson Oct. 15, 1929 1,434,076 Watkins Oct. 31, 1922 1,769,750 Niemann July 1, 1930 1,908,028 Lange May 9, 1933 523,705 Grafton July 31, 1894 1,589,727 Travell June 22, 1926 2,323,088 Foner June 29, 1943 FOREIGN PATENTS Number Country rDate 15,650 British June 30, 1914 225,033 British Nov. 27, 1924 245,477 British Jan. 4, 1926 516,196 German Jan. 19, 1931 289,083 British July 26, 1928

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