The present disclosure relates to a mobile lifting crane that uses a rigging winch drum and rigging to help assemble a folded jib main strut when a luffing jib is employed on the crane. Furthermore, the disclosure relates to the disassembly and assembly of the luffing jib struts on a job site in a way that allows the sheaves of strut caps to remain reeved during transport to or from the job site, to prevent re-reeving the strut caps at a new job site.
Mobile lift cranes typically include a carbody having moveable ground engaging members; a rotating bed rotatably connected to the carbody such that the rotating bed can swing with respect to the ground engaging members; a boom pivotally mounted on a front portion of the rotating bed, with a load hoist line extending therefrom, and counterweight to help balance the crane when the crane lifts a load. Additionally, when the crane needs to work on particularly high buildings or structures, or in restricted spaces, a luffing jib pivotally mounted at the top of the boom may be extended out to provide required reach. When the luffing jib is employed, one or more luffing jib struts are connected to the top of the boom or bottom of the luffing jib. These struts support the luffing jib rigging and backstay straps, providing a moment arm about which force can be applied to raise the jib and support a load being lifted by the luffing jib.
Since the crane will be used in various locations, it needs to be designed so that it can be transported from one job site to the next. This usually requires that the crane be dismantled into components that are of a size and weight that they can be transported by truck within highway transportation limits. The ease with which the crane can be dismantled and set up has an impact on the total cost of using the crane. Thus, to the extent that fewer man-hours are needed to set up the crane, there is a direct advantage to the crane owner or renter. When the luffing jib rigging includes multiple parts of line between the struts, each strut cap usually includes multiple sheaves through which the jib hoist line must be reeved whenever the crane is set up, which takes a significant amount of time.
Several methods have been used in the past to assemble the luffing jib with its luffing jib struts. At least one of those methods involves attaching the assembled jib struts to the end of the boom and reeving the caps of the jib struts with a jib hoist line. The reeving process is time consuming. A whip hoist line may then be used to pull the top of the two jib struts (the jib main strut) over center while it is raised with an assist crane to the point that a backstay suspension, connected at the base of the boom, can be pinned to the top of the main strut. The assist crane must travel while it lifts to perform this lifting operation, and assemblers need to work high off the ground in pinning the backstay suspension, which may lengthen the process and puts the assemblers at more risk.
Accordingly, the present disclosure includes solutions to the above drawbacks with previous methods by making the method for assembly of the jib struts more efficient and safer. For instance, the need to re-reeve the jib strut caps during set up of the crane on the job site is eliminated, the assist crane need not travel when erecting the main strut, and the assembly steps may be executed closer to the ground.
The present disclosure will now be further described. In the following passages, different aspects of the disclosure are defined in more detail. Each aspect so defined may be combined with any other aspect or aspects unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.
The preferred embodiment of the present embodiments relates to a high capacity mobile lift crane, other aspects of which are disclosed in U.S. Pat. No. 7,546,928 and the following co-pending United States patent applications assigned to the assignee of the present application: “Mobile Lift Crane With Variable Position Counterweight,” Ser. No. 12/023,902, filed Jan. 31, 2008; “Mast Raising Structure And Process For High-Capacity Mobile Lift Crane,” Ser. No. 11/740,726, filed Apr. 26, 2007; “Connection System For Crane Boom Segments,” Ser. No. 12/273,310, filed Nov. 18, 2008; “Drive Tumbler And Track Drive For Mobile Vehicles, Including Lift Cranes,” Ser. No. 12/368,143, filed Feb. 9, 2009; “Track Connection System For Mobile Vehicles, Including Lift Cranes,” Ser. No. 12/368,125, filed Feb. 9, 2009; “Track Tensioning System For Mobile Vehicles, Including Lift Cranes,” Ser. No. 12/368,113, filed Feb. 9, 2009; “Boom Hoist Transportation System And Crane Using Same,” Ser. No. 12/561,007, filed Sep. 16, 2009; “Carbody Connection System And Crane Using Same,” Ser. No. 12/561,103, filed Sep. 16, 2009; “Trunnion Transportation System And Crane Using Same,” Ser. No. 12/561,058, filed Sep. 16, 2009; “Drum Frame System For Cranes,” Ser. No. 12/561,094, filed Sep. 16, 2009; “Crane Hook Block,” Ser. No. 12/709,678, filed Feb. 22, 2010; Swing Drive System For Cranes,” Ser. No. 12/710,960, filed Feb. 23, 2010; Counterweight Block And Assemblies For Cranes”, Ser. No. 12/728,156, filed Mar. 5, 2010; “Crane Boom Stop,” Ser. No. 61/179,935, filed May 20, 2009; and “Crane Backstay Spreader,” Ser. No. 61/179,983, filed May 20, 2009. Each of these applications is hereby incorporated by reference.
Several terms used in the specification and claims have a meaning defined as follows.
The term “strut cap” designates an arrangement of sheaves secured together in supporting structure so as to act in concert in spreading tensional force between multiple parts of the jib hoist line. The strut caps come in pairs. Each of first and second strut caps includes a number of sheaves through which are reeved a wire rope. In the present disclosure, each strut cap of the pair is connected to the top of one of the luffing jib struts during normal crane operation.
The terms “jib main strut,” or simply “main strut,” designates the luffing jib strut that connects to a lower position on the boom. Through at least one backstay strap connected from the end of the main strut to the bottom of the boom, a fixed angle is maintained between the main strut and the boom. It is the main strut to which the present disclosure refers when discussing erection of a folded luffing jib strut.
The term “jib strut” designates the luffing jib strut that connects higher on (e.g., to the top of) the boom and/or to the bottom of the luffing jib. Through at least one jib support strap connected from the end of the jib strut to the top of the luffing jib, a fixed angle is maintained between the jib strut and the luffing jib.
The term “jib hoist drum” designates a winch used to take up and pay out line that is used to control the angle between the two luffing jib struts (the main and jib struts). The jib hoist drum includes a cylindrical body on which the jib hoist line is wound, as well as the mechanical and hydraulic controls for controlling rotation of the cylindrical body.
The term “jib hoist drum frame” designates the structure that is used to hold the jib hoist drum components together, and to mount them to other crane components, if needed. Also, other components may be mounted to the frame. The term “mounted” includes immobilizing the component to the structure to which it is mounted. However, the term “frame” is meant to designate structure that is reasonably close in size to the drum and used for the above enumerated purposes. Thus structure that is used as another major component of a crane, or that is more than twice as long as the cylindrical part of the drum, or more than twice the diameter of the drum, would not be considered part of a frame of the drum.
The term “strut stop” designates a structure used to prevent the luffing jib from tipping over backwards, and is connected between the jib main strut and the boom. The strut stop works in conjunction with the at least one backstay strap to retain a fixed angle between the jib main strut and the boom, thus preventing the jib strut from rotating too far toward the boom.
The termed “pinned” (and variations thereof, such as “pinning”) is meant to designate a connection between components that allows for the transfer of forces between the components, and also allows the connection to be easily disassembled. Most typically, a pinned connection is one that transfers force though shear forces on a pin passing through holes in the two connected structures. In addition to pins, bolts can be used to make a “pinned” connection as that term is used herein.
While the disclosure will have applicability to many types of cranes, it will be described in connection with a mobile lift crane 10, shown in an operational configuration in
A rotating bed 20 is rotatably connected to the carbody 12 such that the rotating bed can swing with respect to the ground engaging members. The rotating bed is mounted to the carbody 12 with a slewing ring, such that the rotating bed 20 can swing about an axis with respect to the ground engaging members 14, 16. The rotating bed supports a boom 22 pivotally mounted on a front portion of the rotating bed; a mast 28 mounted at its first end on the rotating bed, with a lower equalizer 47 connected to the mast adjacent the second end of the mast; a backhitch 30 connected between the mast 28 and a rear portion of the rotating bed 20; and a moveable counterweight unit 34. Counterweights used on the counterweight unit 34 may be in the form of multiple stacks of individual counterweight members (or blocks) 44 on a support member.
Boom hoist rigging (described in more detail below) between the top of mast 28 and boom 22 is used to control the boom angle and transfer load so that the counterweight can be used to balance a load lifted by the crane. A load hoist line 24 is trained over a pulley on the boom 22, supporting a hook 26. At the other end, the load hoist line is wound on a first main load hoist drum 70 connected to the rotating bed, described in more detail below. The rotating bed 20 includes other elements commonly found on a mobile lift crane, such as an operator's cab, a hoist drum 50 for the boom hoist rigging, a second main hoist drum 80 and an auxiliary load hoist drum 90 for a whip line, also described in more detail below.
As shown in
Two backstay straps 33A are connected between the end of the main strut 29, e.g., to the cap thereof, and the bottom of the boom 22. These backstay straps are made of multiple fixed-length sections. Selection of the number of sections and the length of each section allows changing the hypotenuse of the fixed-angle triangle formed between the main strut 29 and the boom 22 to accommodate different boom lengths. By changing the length of the backstay straps 33A, a constant angle may be maintained between the main strut 29 and the boom 22 for each length of the boom for which the crane is designed.
Similarly, sections of jib support straps 33B may be connected between the end of the jib strut 27 and adjacent the top of the luffing jib 23 to maintain a constant angle therebetween. By using the jib support straps 33B as described, paying out or retracting the luffing jib hoist line 19 allows expanding or retracting the angle between only the first and second jib struts 27, 29. Furthermore, a strut stop 35 is connected between the main strut 29 and the boom 22 to provide support to the main strut 29 if no load is on the jib and the forces pulling the main strut up are less than the forces pulling the main strut down.
The backhitch 30 is connected adjacent the top of the mast 28, but down the mast far enough that it does not interfere with other items connected to the mast. The backhitch 30 may comprise a lattice member, as shown in
The counterweight unit 34 is moveable with respect to the rest of the rotating bed 20. A tension member 32 connected adjacent the top of the mast 28 supports the counterweight unit in a suspended mode. A counterweight movement structure is connected between the rotating bed and the counterweight unit such that the counterweight unit may be moved to and held at a first position in front of the top of the mast, and moved to and held at a second position rearward of the top of the mast, described more fully in U.S patent application Ser. No. 12/023,902.
At least one linear actuation device 36, such as a hydraulic cylinder, or alternatively a rack and pinion assembly, and at least one arm pivotally connected at a first end to the rotating bed and at a second end to the a linear actuation device 36, are used in the counterweight movement structure of crane 10 to change the position of the counterweight. The arm and linear actuation device 36 are connected between the rotating bed and the counterweight unit such that extension and retraction of the linear actuation device 36 changes the position of the counterweight unit compared to the rotating bed. While
In a preferred embodiment of the counterweight movement structure, a pivot frame 40, which may be a solid welded plate structure, is connected between the rotating bed 20 and the second end of the linear actuation device 36. A rear arm 38 is connected between the pivot frame 40 and the counterweight unit 34. The rear arm 38 is also a welded plate structure with an angled portion 39 at the end that connects to the pivot frame 40. This allows the arm 38 to connect directly in line with the pivot frame 40. The backhitch 30 has an A-shape configuration, with spread-apart lower legs, which allows the counterweight movement structure to pass between the legs when needed.
The crane 10 may be equipped with a counterweight support system 46, which may be required to comply with crane regulations in some countries. The counterweight movement structure and counterweight support structure are more fully disclosed in U.S. patent application Ser. No. 12/023,902.
The boom hoist rigging includes a boom hoist line in the form of wire rope 25 wound on a boom hoist drum 50, and reeved through sheaves on a lower equalizer 47 and an upper equalizer 48. The boom hoist drum is mounted in a frame 60 (
The boom hoist drum frame 60, the lower equalizer 47 and the upper equalizer 48 each include cooperating attachment structures whereby the lower and upper equalizers can be detachably connected to the boom hoist drum frame so that the boom hoist drum, the lower equalizer, the upper equalizer and the boom hoist line can be transported as a combined assembly. The combined boom hoist drum 50, frame 60, lower equalizer 47 and upper equalizer 48, arranged as they would be for transportation between job sites, are described in U.S. patent application Ser. No. 61/098,632.
As noted above, in a preferred embodiment, the crane includes four drums each mounted in a frame and connected to the rotating bed in a stacked configuration. (The rotating bed includes a main frame and front and rear roller carriers.) The jib hoist drum is mounted in a frame attached to the front surface of the front roller carrier. Frames of two of the four stacked drums are connected directly to the rotating bed, while the frames of the other two drums are indirectly connected to the rotating bed by being directly connected to at least one of the two drum frames connected directly to the rotating bed. In this case, the four stacked drums are preferably the first main load hoist drum 70 with load hoist line 24 wound thereon, the second main load hoist drum 80 with load hoist line 17 wound thereon, the auxiliary load hoist drum 90 with whip line 13 wound thereon, and the boom hoist drum 50 with boom hoist line 25 wound thereon. Preferably, the frame 91 of the auxiliary load hoist drum 90 and frame 81 of the second main load hoist drum 80 are connected directly to the rotating bed (the frame 91 pins at its front onto the front roller carrier), the frame 71 of the first main load hoist drum 70 is connected to both of frames 81 and 91, while the frame 60 for the boom hoist drum 50 is connected to frame 81. In that regard, the boom hoist drum frame 60 is thus stacked on top of and pinned directly to the second main load hoist drum frame 81, and the first main load hoist drum frame 71 is stacked on top of and pinned directly to the auxiliary load hoist drum frame 91. The drum frames are connected to the rotating bed and to each other by removable pins, allowing the frames to be disconnected from and transported separately from the rotating bed.
A sixth drum includes a rigging winch drum 110 on which is wound a rigging winch line 111. The rigging winch drum 110 is attached to a lower section of the rotating bed 20 and is lighter weight than the other drums. The rigging winch line 111, in one embodiment, may be a 19 mm winch line that is generally used to help assemble cranes. Herein, the rigging winch line 111 is employed to help to speed reeving the sheaves of the strut caps 31, and assembly of the main strut 29.
The strut caps 31 may be transported between job sites while reeved together as a pair. Of the several different embodiments of this concept, three embodiments are shown in
More particularly,
Each strut cap 31 includes, as mentioned, a number of sheaves, and also a pair of side brackets 114, each with an aperture 115 therethrough. Furthermore, each strut cap 31 includes first and second protrusions 116, 118 each having an aperture therethrough. The protrusions 116, 118 may be used for attachment of a strut cap to another strut cap, to the main or jib strut 27, 29, or to the frame of the jib hoist drum 100. These attachments may be executed by pinning. For instance, a pin is displayed in
Reeving the strut caps 31 with the auxiliary line 119 may be done by detaching a dead end of the luffing jib hoist line 19 and attaching it to the auxiliary line. Attachment of two lines to each other like this may be done with a thimble (not shown) having a hole which is attached to the end of the luffing jib hoist line 19. The 19 mm line includes wedged, two-pronged ends with holes that may be positioned over the thimble so that the two lines can then be pinned together. This arrangement is one of several methods commonly used to securely attach two lines to each other. The luffing jib hoist line 19, once attached to the auxiliary line 119, is retracted into the jib hoist drum 100 until the auxiliary line 119 is reeved within the sheaves of the strut caps. The luffing jib hoist line 19 may then be detached from the auxiliary line 119 and retracted the rest of the way into its drum 100 for transportation. The auxiliary line 119 may be dead-ended to one of the strut caps or to the strut, although it need not be, and the strut caps 31 may or may not be attached to each other. The main or jib strut 27, 29 having attached thereto the strut caps 31 reeved with the auxiliary line 119 may then be transported as an assembly.
After arrival on a job site, the crane 10 may be erected to the point displayed in
In the case of the embodiments displayed in
The main strut cap 31 is then attached (pinned) to the top of the main strut 29, as shown in
The other side of the strut inserts 127, 129 may then be pinned to each other to complete assembly of the jib main strut 29. The rigging winch line 111 is disconnected, as is the assist crane from the raising pendant 130. The raising pendant is attached to the main strut 29 for storage during operation of the crane 10. The jib hoist line 19 may now be retracted to pull the jib strut 27 off the ground, generating room on the ground at the end of the boom 22 for attachment thereon of the luffing jib 23. While not displayed, sections of jib support straps 33B are pinned between the top of the luffing jib 23 and the end of the jib (or first) strut 27. Accordingly, a first number of sections of jib support straps 33B may be connected to the jib strut cap 31 before the jib strut 27 is pulled off the ground, to facilitate pinning of the first number of sections of jib support straps to the rest of the sections of jib support straps pinned to the end of the luffing jib 23.
It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. For instance, one or more of the strut caps may not be made removable. Furthermore, the line between the jib struts may be made rigid while one of the angles between the boom and the main and jib struts, respectively, could be made changeable with a reeved jib hoist line, thus changing slightly how the luffing jib is raised and lowered. Certain steps in the transportation of the crane and the assembly or disassembly of the struts may be performed in different orders; accordingly, any order of listing such method steps in the appended claims do not imply a required order, unless specifically required by the language of a claim. Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.
The present application claims the benefit of the filing date under 35 U.S.C. §119(e) of Provisional U.S. patent application Ser. No. 61/165,403, which is hereby incorporated by reference in its entirety.
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Number | Date | Country | |
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20100243595 A1 | Sep 2010 | US |
Number | Date | Country | |
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61165403 | Mar 2009 | US |