Convertible Level Luffing Crane

Abstract

A crane having a multiple drum hoist structure to which is pivotally attached an inner boom which in turn pivotally supports an outer or jib boom. A pair of the drums are connected to the booms through multiple sheaved lines in such a manner that when the drums are rotated in unison by means of a single control lever, the two booms are caused to perform an essentially level luffing operation A tower boom may be interposed between the inner boom and the hoist structure while retaining the ability to cause level luffing operation of the inner boom and jib boom.

Description

An important crane maneuver is known as "level luffing." This maneuver involves movement of the load in a horizontal plane. The movement may be radial with respect to the base structure of the crane sometimes accompanied with rotational movement of the crane. In the conventional crane, radial level luffing movement has required the crane operator to manipulate two controls simultaneously. If rotational movement of the crane was also required, three controls were used. Usually this was accomplished by halting the level luffing operation, rotating the crane then resuming the level luffing maneuver.

A crane which permits the level luffing maneuver by use of a single control, rather than two simultaneously operated controls is disclosed in the copending application, Ser. No. 779,403, filed Nov. 27, 1968, entitled "Level Luffing Crane" now abandoned. In that copending application, a pair of hydraulic units are interconnected so that the level luffing maneuver is accomplished automatically; that is, the operator with a single control regulates the rate of travel of the load as well as its radial direction.

Cranes utilizing hydraulic units are not readily dismantled for transportation and then assembled at the job site; however, this is conventional practice with cranes which utilize drums and associated lines and sheaves. Such cranes are provided with demountable booms which may be sectional to vary their length or permit transportation, and utilize drums with associated lines and sheaves to operate the booms.

A primary object of the present invention is to provide a crane of the demountable boom type utilizing drums and associated lines and sheaves which incorporates a novel operating means to effect automatic level luffing and a single control to determine the rate and radial direction of movement of the load.

A further object is to provide a crane incorporating a novel demountable tower boom which when inserted permits retention of the automatic level luffing feature.

A still further object is to provide a crane of the type indicated in the preceding objects and having a multiple drum hoisting structure with associated line and sheave assemblies capable of being connected in a wide variety of arrangements to meet different job requirements.

A more specific object is to provide a crane having an inner boom pivotally connected to a hoist structure, an outer boom pivotally connected to the inner boom, a pair of drums interconnected for simultaneous operation and utilizing a single reversible speed control, the drums being connected to the booms by sheaved lines so that, on operation of the drums, one line is drawn in while the other is played out, such operation causing a level luffing maneuver of the booms.

Other and more detailed objects and advantages will appear hereinafter.

In the drawings:

FIG. 1 is a side view of the convertible level luffing crane, shown as assembled for normal operation, and indicating by solid lines an extended position, and by broken lines a retracted position.

FIG. 2 is an enlarged fragmentary partial sectional, partial plan view of the hoisting structure, taken essentially through 2--2 of Figure 1.

FIG. 3 is a sectional view thereof, taken through 3--3 of Figure 2.

FIG. 4 is a fragmentary plan view of the crane, corresponding to the solid line position shown in Figure 1.

FIG. 5 is a diagrammatical view, illustrating the apparatus primarily concerned with luffing control.

FIG. 6 is a side view, corresponding to Figure 1, but showing the crane as assembled with a tower boom.

The convertible level luffing crane is illustrated as mounted on a truck body 1, having conventional outrigging 2 to stabilize the crane structure. The crane includes a hoist housing structure 3, provided with appropriate gears 4, so that the housing structure may rotate on the truck body.

Within the housing structure are parallel mounting frames 5, having forward extensions 6. The forward extensions support a journal shaft 7, to which is removably attached the lower end of an inner boom 8. The extended end of the boom 8 receives a second journal shaft 9 and tension members 10 extend from the shaft 9 to a traveling sheave block 11. A hydraulic unit 12, which forms a compression strut the length of which may be adjusted, extends from the sheave block 11 to the boom 8, and is joined thereto by pivot fittings 13.

Extending upward from the mounting frames 5 is a pair of A-frames 14, which support therebetween a set of fixed sheaves 15. The traveling sheave block 11 is provided with a set of traveling sheaves 16. Mounted on the frames 5, at their forward ends, is a first drum 17. An operating line 18 is wrapped on the first drum and connects the fixed sheaves 15 and traveling sheaves 16.

The extended end of the inner boom 8 pivotally supports by means of the journal shaft 9, an outer boom or jib boom 19. The journaled end of the outer boom 19 is provided with a pair of rearwardly directed strut frames 20, having a first apex 21 provided with a shaft to which is attached a pair of tension members 22, which are also joined to the extended end of the outer boom. The shaft, at the first apex 21 also pivotally supports a pair of tension links 23, which overlie the strut frames 20 and extend a short distance past a second apex 24 of the strut frames 20, connected by a cross bar which when the inner boom 8 and outer boom 19 are extended, as shown by solid lines in Figure 1, support the tension links 23.

The tension links 23 are pivotally connected to a second pair of tension links 25, which in turn are connected to a third pair of tension links 26. The extremities of the tension links 26 support a set of traveling sheaves 27. The journal shaft 7 is provided with a fixed set of sheaves 28, some of which are utilized in conjunction with the traveling sheaves 27 and are connected thereto by an operating line 29 which may be wrapped on a second drum 30, or on a third drum 31 mounted on the frames 5.

A fourth drum 32 is mounted on the frames 5 and receives a line 33 which utilizes one of the fixed sheaves 28, extends within the boom 8 to its extended end, then passes over a fixed sheave set 34 and a traveling block 35 depending therefrom and provided with an appropriate hook. The hoist thus provided is used with the inner boom 8 independently of the outer boom. A fifth drum 36 is mounted on the frames 5 and is provided with a line 37 which utilizes one of the fixed sheaves 28 as well as one of the fixed sheave set 34 and passes over a fixed sheave 38 located at the extremity of the outer boom 19. The line 37 terminates in a hook 39. If desired, a fixed sheave set may be substituted for the single fixed sheave and a traveling block may be provided in the manner shown in conjunction with the line 33. The hook 39, or whatever load carrying means may be substituted therefor, is employed when the booms 8 and 19 are maneuvered to effect a level luffing operation, which will be described in more detail hereinafter.

The inner boom 8 may be disconnected from the journal shaft 7 and a tower boom 40 substituted; that is, the lower end of the tower boom is mounted on the journal shaft 7 and is provided with a journal shaft 41 at its extremity to which the lower end of the inner boom 8 may be attached, as shown in Figure 6. The lower end of the inner boom 8 is provided with a pair of fittings 42, to which are attached diverging struts 43 and 44. The tension members 10 are attached to the upwardly directed struts 43, and tension links 45 extend between the struts. A pair of tension members 46 extend downwardly from the lower or rearward pair of struts 44 and support a set of traveling sheaves 47, connected by an operating line 48 to selected members of the fixed sheave set 28. The operating line 48 is connected to the second drum 30 or the third drum 31, depending upon which drum is being used by the operating line 29.

The journal shaft 41, at the upper end of the tower boom 40, is joined by tension members 49 to the sheave block 11 in place of the tension members 10.

Mounted within the housing structure 3, alongside the frames 5, is a power unit 50. The power unit is connected by a mechanical drive 51, which is provided with appropriate clutches 52 and 53, and appropriate brakes, not shown, so that the fourth drum 32 and fifth drum 36 may be operated independently of each other.

The power unit 50 also drives a pump 54, which supplies hydraulic fluid to hydraulic motors 55, 56 and 57, connected respectively to the first drum 17, the second drum 30 and the third drum 31. The hydraulic motors are connected individually to their respective drums by gear drives 58, 59 and 60.

Drums 17 and 30 are joined by a sprocket and chain drive 62, and drums 30 and 31 are connected by a second sprocket and chain drive 63. The drums are provided, respectively, with brakes 64, 65 and 66 having corresponding brake release or control means 67, 68 and 69.

Drums 17 and 31 are provided with clutches 70 and 71, having corresponding actuators 72 and 73.

Interposed between the pump and hydraulic motors 55 and 57 are corresponding control valves 74 and 75. Interposed between the pump 54 and the hydraulic motor 56 is a combination control valve and level luffing valve 76.

Interposed between the control valves 74, 75 and 76 and their respective hydraulic motors are cross lines having shutoff valves 77 and 78. A selector valve 79, hydraulically controls the two shutoff valves 77 and 78 and their corresponding clutch actuators 72 and 73.

Operation of the convertible level luffing crane is as follows:

Considering first the crane as arranged in FIG. 1, the first and second drums 17 and 30, respectively, are utilized. The selector valve 79 is set so that the shutoff valve 77, between hydraulic motors 55 and 56, is open; whereas the shutoff valve 78 is closed. Closure of the shutoff valve 78 causes the clutch actuator 73 to release the clutch 71. As a consequence, the control valve 76 operates both hydraulic motors 55 and 56; in addition, the first and second drums 17 and 30 are interconnected by the sprocket and chain drive 62.

With this arrangement, the first drum 17 operates the inner boom 8; whereas, the second drum 30 operates the outer or jib boom 19. The interrelation of the two drums is such that when driven under the control of the valve 76, the line is played out from one drum and reeled in on the other drum. It will be noted in Figures 1, 2 and 3 that the line 29 from the second drum 30 passes around certain of the sheaves 28 and sheaves 27. The sheaves 28 are supported on the pivotal mounting 7 of the inner boom 8, so that the line of action passes through the pivotal mounting 7. The sheaving provided for the two lines as well as the proportions of the two booms are such that as the two booms are moved between their solid line positions and their broken line positions, shown in FIG. 1, the tip end of the outer boom moves in an essentially horizontal path. This movement of the tip end of the outer boom is known as a luffing movement, and, by reason of the fact that the path is essentially horizontal, a level luffing maneuver is accomplished by the tip end of the outer boom. Inasmuch as the line from the hook 39 or its equivalent, and the corresponding drum, pass equidistant from the centers of the journal shafts 7 and 9, the level luffing movement of the booms is accomplished without appreciable vertical change in the level of the hook 39.

Operation of the convertible level luffing crane, when arranged as a tower crane as shown in Figure 6, is as follows:

In assemblying the tower crane, it is convenient to use the first drum 17 and associated line 18, its sheaves 15 and 16, in connection with the tower boom 40. The outer or jib boom 19 may be reconnected to the second drum 30 and the connection to the inner boom may be from the third drum 31. Alternatively, the second drum 30 may be connected with the inner boom 8 and the third drum connected with the outer boom 19. The line for operating the outer boom 19 passes around sheaves 27 and 28, and the latter are supported on the pivotal mounting 41 for the boom 8, so that the line of action passes through the pivotal mounting 41.

In either instance, the selector valve 79 is changed so that the shutoff valve 77 is closed and the shutoff valve 78 is opened; and, correspondingly, the clutch 71 is engaged and the clutch 70 is released so that the second drum 30 and the third drum 31 are interconnected, both hydraulically through the motors 56 and 57 and the sprocket and chain drive 63. When this is accomplished, and the control valve 76 is operated, an automatic level luffing maneuver is accomplished, the speed of which is determined by the control valve.

It should be noted that cranes of this type are often assembled to meet operating conditions at a particular site, so that it is desirable that the crane components can be arranged in various ways. Thus, the crane is not limited to the particular configurations illustrated, nor need the drums and associated lines be arranged as illustrated and described. For example, if the particular use of the crane is such that level luffing is a primary maneuver, and that independent operation of the inner and outer booms is not required, then a single drum may simultaneously reel in from one of the booms and play out to the other.

Also, control of the inner boom may remain with the first drum 17 and control of the outer boom may remain with the second drum 30, in which case, the sprocket and chain drive 63, shutoff valve 78 and clutch actuator 73 may be omitted.

The present embodiments of this invention are to be considered in all respects as illustrative and not restrictive.

Claims

I claim:

1. A crane comprising in combination: a base structure including a hoist means, an inner boom having a pivotal mounting on the base structure for movement in a vertical plane, an outer boom pivotally mounted on said inner boom for movement in the same vertical plane, and having a tip end, first means including line and sheave means between the inner boom and the hoist means to swing the inner boom about its pivotal mounting on the base structure, second means including line and sheave means connected between the outer boom and the hoist means to independently swing the outer boom about its pivotal connection with the inner boom, a part of said sheave means of said second means being rotatably supported on said pivotal mounting of said inner boom so that the line of action of said second means passes through said pivotal mounting of said inner boom on the base structure, said hoist means being operable through said first means and said second means to pivot either boom in a first direction and simultaneously pivot the other boom in the opposite direction, the rate of pivotal movements of said booms being such that the tip end of the outer boom describes an essentially horizontal luffing course.

2. A crane as defined in claim 1, wherein said hoist means includes a pair of drums and releasable means interconnecting the drums for simultaneous operation, and wherein said line and sheave means includes a line and sheave unit for each drum.

3. A crane as defined in claim 2, wherein said hoist means further includes: a clutch means for disconnecting at least one of said drums from said interconnecting means, and an individual control for each drum operable, when said clutch is disconnected, to rotate either drum independently of the other, one of said controls being operable, when said drums are interconnected, to cause movement of the tip end of said outer boom to describe said luffing course.

4. A crane as defined in claim 1, wherein said inner boom is demountable from said base structure, a tower boom is adapted to be interposed between said base structure and the inner boom, and three hoist drums and associated line and sheave means are provided, one hoist drum and its line and sheave means being connected to said tower boom.

5. A crane as defined in claim 1, wherein the hoist means includes at least three hoist units, a first drive means connecting a pair of hoist units for operation in unison, a second drive means connecting a second pair of hoist units for operation in unison, there being one hoist unit common to both pairs, said inner boom being removably mounted on said base structure, a tower boom adapted to be removably and pivotally interposed between said inner boom and said base structure, each hoist unit being connected to operate one of said booms, respectively, a first luffing control for the first drive means, operable when the inner boom is connected to the base structure, to cause the line of either hoist unit joined by the first means to pay out while simultaneously taking in the line of the mated hoist unit, a second luffing control for the second drive means operable when the tower boom is interposed between the inner boom and the base structure, to cause the line of either hoist unit joined by the second drive means to pay out while simultaneously taking in the line of the mated hoist unit.

6. A crane structure, comprising: a hoist structure, a first boom structure mounted in pivotal relation to said hoist structure, a second boom structure pivotally connected to said first boom structure, said boom structures being relatively proportioned so that, when rotated at opposite directions about their respective pivotal axes at predetermined relative speeds, the extremity of said second boom structure is caused to describe a luffing course, drum means carried by the hoist structure, line and sheave means extending from the drum means to the inner boom, and line and sheave means extending from the drum means to the second boom structure and having a part of said sheave means being rotatably supported on said pivotal mounting of said inner boom so that the line of action passes through the pivotal connection between the first boom structure and the hoist structure, the two line and sheave means being simultaneously operable to move said booms in opposite directions at said predetermined relative speeds to cause luffing travel at the extremity of the second boom.

7. A claim as defined in claim 6, wherein said drum means includes a pair of drums, a common drive therefor, and a single control means for the drive.

8. A crane comprising in combination: a base structure including a hoist means, an inner boom having a pivotal mounting on the base structure for movement in a vertical plane, an outer boom pivotally mounted on said inner boom for movement in the same vertical plane, and having a tip end, first means connected between the inner boom and the hoist means to swing the inner boom about its pivotal mounting on the base structure, said first means including a tension link pivotally connected to said inner boom and line and sheave means connecting the tension link to the hoist means, second means connected between the outer boom and the hoist means to independently swing the outer boom about its pivotal connection with the inner boom, said second means including a tension link and line and sheave means having a part of said sheave means rotatably supported on said pivotal mounting of said inner boom so that a line of action passes through said pivotal mounting of said inner boom on the base structure, said hoist means being operable through said first means and said second means to pivot either boom in a first direction and simultaneously pivot the other boom in the opposite direction, the rate of pivotal movements of said booms being such that the tip end of the outer boom describes an essentially horizontal luffing course.

9. A crane as defined in claim 8, wherein the base structure includes an upright tower boom having the pivotal mounting for the inner boom at its upper end.