The present application relates to counterweight blocks and associated assemblies; mobile lift cranes using the counterweight blocks to provide counterweight to its loads; and methods of making and utilizing the counterweight blocks and associated assemblies.
Mobile lift cranes such as the one referred to herein are very heavy and must be broken down into pieces for transportation between job sites, wherein the weight of each piece that is transported must be within highway transportation weight limits. The allowable weight limit of each piece may vary in some countries, and may also vary based on the weight of the transportation vehicles. Accordingly, it is necessary to build the crane in a modular way, keeping each piece within at least the weight limits of the largest transportable load.
In the United States, the maximum weight that may be placed on a trailer for long haul transportation, without a special permit, is 44,000 pounds, or 20 metric tonne. Typical counterweight blocks each weigh 10 metric tonne. While the counterweight blocks could be transported in a stacked configuration on a flat bed, typically two counterweight blocks are placed one over each axel of the flat bed to spread the load out. Some countries also have maximum width limitations. In addition to transportability, customer needs, and supplier or foundry availability affect design of counterweight blocks, which are typically cast or built in weights of 5, 10, or 20 metric tonne.
A crane at a job site lifts very heavy loads, and therefore, requires a substantial number of the counterweight blocks on a counterweight tray of the crane to provide a counterweight for lifting those loads. The heavier the load, the more counterweight blocks that are needed on the counterweight tray, which means that the counterweight blocks are often stacked together. Since some cranes use hundreds of metric tonne of counterweight blocks, it can take a long time to transport and stack the counterweight blocks at the job site. Additionally, it can be difficult to keep higher stacks of counterweight blocks secured to prevent them from tipping while the crane is in operation, especially if the stack is moveable with respect to the rest of a rotating bed of the crane.
The present embodiments will now be further described. In the following passages, different aspects of the embodiments 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, Swing Drive System For Cranes,” Ser. No. 12/710,960, filed Feb. 23, 2010, “Crane Hook Block,” Ser. No. 12/709,678, filed Feb. 22, 2010, “Folding Jib Main Strut And Transportable Reeved Strut Caps,” Ser. No. 61/165,403, filed Mar. 31, 2009, “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.
While the embodiments of the counterweight blocks and associated assemblies will have applicability to counterweight blocks used on other cranes or machinery, it will be described in connection with a mobile lift crane 10, shown 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; a backhitch 30 connected between the mast and a rear portion of the rotating bed; and a moveable counterweight unit 34, which include stacks 84 of individual counterweight blocks 100 on a support member 33, sometimes also referred to herein as a counterweight tray 33. (
Boom hoist rigging 25 between the top of mast 28 and boom 22 is used to control the boom angle and transfers load so that the counterweight can be used to balance a load lifted by the crane. A load hoist line 24 extends from the boom 22, supporting a hook 26. The rotating bed 20 may also include other elements commonly found on a mobile lift crane, such as an operator's cab and hoist drums for the rigging 25 and load hoist line 24. If desired, the boom 22 may include a luffing jib pivotally mounted to the top of the main boom, or other boom configurations. 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 designed to carry both compression and tension loads 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 supports the counterweight unit in a suspended mode. A counterweight movement structure is connected between the rotating bed 20 and the counterweight unit 34 such that the counterweight unit 34 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.
At least one linear actuation device, in this embodiment a rack and pinion assembly 36, and at least one arm pivotally connected at a first end to the rotating bed and at a second end to the a rack and pinion assembly 36, are used in the counterweight movement structure of crane 10 to change the position of the counterweight unit 34. The arm and a rack and pinion assembly 36 are connected between the rotating bed and the counterweight unit 34 such that extension and retraction of the rack and pinion assembly 36 changes the position of the counterweight unit 34 compared to the rotating bed 20. While
The pivot frame 40, a solid welded plate structure, is connected between the rotating bed 20 and the second end of the rack and pinion assembly 36. The rear arm 38 is connected between the pivot frame 40 and the counterweight unit 34. A set of pins 37 are used to connect the rear arm 38 and the pivot frame 40. 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 crane 10 is equipped with a counterweight support system 80, which may be required to comply with crane regulations in some countries. The counterweight support system 80 includes at least two ground engaging members in the form of support feet 82 that can provide support to the counterweight in the event of a sudden release of the load. However, during normal crane operations, including pick, move, and set maneuvers, the support feet 82 are never in contact with the ground.
Because the counterweight unit 34 can move far forward with respect to the front of the rotating bed, the support feet 82 on the support system 80 may interfere with swing operations unless they are sufficiently spaced apart. This, however, makes the support structure itself very wide. The crane 10 thus uses a telescoping counterweight support system 80 that includes a telescoping structure 83 connected to and between the support feet 82 such that the distance between the support feet 82 can be adjusted.
The counterweight unit 34 is constructed so that the counterweight support system 80 can be removed and the crane can function both with and without it. The counterweight movement and support structures are more fully disclosed in U.S. patent application Ser. No. 12/023,902, entitled “Mobile Lift Crane With Variable Position Counterweight,” filed Jan. 31, 2008, published as US 2008-0203045 A1.
The counterweight block 100 includes a male interlocking piece 112 and a female interlocking space 116 which, as seen in
Furthermore, the counterweight block 100 may include multiple protrusions 124 on a top thereof and corresponding recesses (not shown) on a bottom thereof for receipt of the protrusions 124 of another counterweight block 100 when stacked thereon. Displayed are four protrusions 124 on a block, but other embodiments are envisioned including two, three, five, six, eight, etc., protrusions 124 on the top of the block. Advantageously, a matching number and location of recesses on the bottom of the block 100 would be included in these other embodiments. In still further embodiments, the bottom of each block may include more recesses than there are protrusions 124. While protrusions 124 are for side-to-side alignment, use of additional recesses—more than the number of protrusions 124 in the bottom of each block—allows blocks stacked on top of two other blocks to span cross the lower blocks in varying arrangements.
Each counterweight block 100 may also include a plurality of, preferably three, raised bumps 125, which are designed to come into planar contact with the flat surface of the bottom of a block 100 being stacked on top thereof. The raised bumps may be circular or of some other shape. The recesses in the bottom of each block 100 may be deeper than the protrusions 124 are thick, so that the bumps 125 provide the only contact between the top and bottom surfaces of stacked blocks 100. Because three raised bumps 125 are used, as shown in
Furthermore, a portion of a cavity may be formed within a side of each block 100 at a corner. Each cavity portion may correspond to the cavity portion of the other block so as to be combined into a single longitudinal cavity 128 when the blocks 100 are interlocked side by side. An additional (or storage) cavity 129, substantially matching the shape of the longitudinal cavity 128, may be formed in a top of the counterweight blocks 100. A shear bar 130 may be inserted in the longitudinal cavity 128 for reasons discussed with reference to
The shear bar 130 may include an anti-rotational feature, which may include forming the shear bar with one or more flat sides, such as making it rectangular in shape. The anti-rotational feature may also include a side extension member, such as a handle 142, which resists rotational movement of the shear bar 130 within the longitudinal cavity 128. Resisting rotational movement substantially prevents the shear bar 130 from taking on rotational momentum during movement of an interlocked pair of blocks 100, to resist dislodgement of the shear bar 130 from the longitudinal cavity 128. The handle 142 also facilitates insertion and removal of the shear bar 130 from the cavity 128. The cavity 128 may further include an additional cavity 144 extended therefrom for receipt of the handle 142 so that the handle 142 does not protrude from the side of the block 100. The handle 142 may also include a hole 143 therethrough for reception of a stud 170 and retaining pin, discussed below with reference to
While not displayed, a pair of brackets, one on each counterweight block 100, may also be used in lieu of the cavity 128. Accordingly, the shear bar 130 could be spanned between the outside of the intersection of the two blocks 100 and the brackets (or some other structure) could be used to retain the shear bar 130 in place.
A ring 154 may be attached to a portion of the indentation, e.g., to the indentation wall, to be used as a personal protection tie-off point for a worker climbing up a stack 84 of blocks 100 such as that displayed in
Furthermore, the counterweight blocks 100 configured as described above may be stacked in single stacks of blocks 100—not interconnected stacks of blocks—on different crane models having shorter trays 33 that can only fit a single stack of blocks. Likewise, the ability to separate the blocks 100 may be beneficial for different configurations in transport to maximize the carrying capacity of trailers without overloading them.
In
The preferred embodiments of the present invention provide numerous advantages. Because the counterweight blocks 100 may be built in various sizes, they may be advantageously transported to a job site up to an amount of weight required by the crane 10 on that site. Furthermore, together with the lifting lugs 104 located along the center of gravity of the counterweight blocks 100, the interlocking connection 134 allows two blocks 100 to be lifted simultaneously, side by side, for quicker stacking, thus enabling quicker setup of the crane 10 at the job site. The interlocking connection 134 also allows the center of gravity of two interconnected blocks 100 to be located along the interconnected sides, preventing tipping over of stacks 84 of blocks 100 located next to each other on a the narrow counterweight tray 33. The shear bar 130 provides resistance to relative vertical movement of the two interconnected counterweight blocks 100 while lifting, when stacked, and when being moved while on the tray 33 during operation of the crane 10. The indentations 120 formed in the side of each counterweight block 100, together with the lip 150, facilitate climbing up and down the stack 84 of counterweight blocks, which may be required to thread the securing strap 164 to a stack 84 of counterweight blocks 100, among other reasons.
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 example, four or more lifting lugs or other structure to facilitate lifting the heavy counterweight block may be used. The lifting lugs may vary in size and shape. Varying the number, size, or shape of protrusions and recesses may be employed on each counterweight block, so long as they are stackable. Varying structures may be used to allow interlocking blocks side by side. Also, apertures through which the retaining strap may be threaded may be located elsewhere on the counterweight blocks. Furthermore, the interlocked counterweight blocks stackable as in
This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 61/158,599, filed Mar. 9, 2009, and titled “COUNTERWEIGHT BLOCK AND ASSEMBLIES FOR CRANES,” which is incorporated, in its entirety, by this reference.
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Number | Date | Country | |
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61158599 | Mar 2009 | US |