Abstract:
A multi-block rigging system for a heavy crane, pulling or lifting device. The system uses sheave blocks in series orientation to enable the use of standard, economical or preferred, size winch drums and standard, economical or preferred, diameter and length wire rope, each forming a separate set of reeving lines. Each set of reeving lines moves its corresponding load block a proportional distance of the total travel length for the load hook. Alternatively, different line parts of line for each reeved set enables different travel speeds of the load block for different capacity requirements.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     This invention relates to a system of hoisting blocks for heavy cranes and hoisting devices. Specifically, the invention describes a system of load blocks connected in series to enable heavy lifts to be conducted with standard/conventional winch drums and hoist lines that by conventional rigging, would not be able to provide the capabilities of combined lift capacity and hoisting height. 
     2. Related Art 
     The art of rigging and developing mechanical lifting advantage using pulleys has long been known. The development of heavy capacity cranes, however, has changed the load demands on load lines and reeved systems. Heavy capacity cranes have the mechanical and structural ability to lift heavy loads, but the strength of the load line, the winches&#39; maximum line pull and the capacity of the drums to hold sufficient wire rope are often limiting factors. In addition, load blocks reeved for heavy lifts are restrictive in hoisting speed, and those reeved for speed for lift are limited in lift capacity. One way to overcome these limitations is the use of oversized high strength wire rope. The use of oversized wire rope poses operational problems. Since it is thicker and heavier than conventional wire rope, high strength wire rope requires large capacity hoisting drums and sheaves for adequate wrapping, is difficult to handle during set-up and rigging due to its weight and inflexibility, may require special linear winches, and is more expensive than conventional wire rope. 
     The typical alternative to the use of oversized wire rope by heavy cranes is the use of multiple part reeving, which uses standard strength wire rope. Multiple part reeving distributes the weight of the load over multiple parts of the wire rope. Heavy capacity cranes typically use double load lines operating in parallel, each line having a dedicated set of boom and load block sheaves forming distinct reeving systems. 
     Heavy capacity cranes typically have long booms, to be able to lift tall objects, have a long horizontal reach, and/or have a high vertical reach. Boom lengths over 300 meters are becoming more common. If standard wire rope is used, the long boom length of the high capacity crane, combined with the reeving requirements to support a heavy load, require long lengths of standard load line. The amount of line required is at least the length of the boom plus that length multiplied by the number of parts in the multiple reeving. Thus, a boom with a 100-meter boom and an eight part reeving from each drum requires a total of 900 meters of wire rope for each load line. Spooling this length of line requires special handling equipment for the wire rope, including a large capacity hoist drum. It would be a new and useful improvement over the prior art for a hoisting system be capable of using standard wire rope and standard size hoist drums in a high capacity crane. It is understood that there are many sizes of wire rope and hoist drums. However, the term “standard” is nonetheless used to denote sizes that are economical and are not oversized. Also, the words “winch drum” are used herein to describe a mechanical means of applying a tensile (pulling) force to a wire rope or other flexible tensile load support mechanism, and is intended to cover other means of applying the pulling force, such as a linear winch, hydraulic jacks and so forth. 
     BRIEF SUMMARY OF THE INVENTION 
     Accordingly, the objectives of this invention are to provide, inter alia, a new and improved load block system for heavy cranes and lifting devices that: 
     uses standard size (i.e. economical sized) wire rope for the load line; 
     uses standard size (i.e. economical sized) hoisting drums; 
     uses standard boom sheaves and load block sheaves; 
     enables light capacity with high hoist speed and heavy capacity with low hoist speeds all with the one reeving arrangement; 
     enables large capacity lifts on long boom lengths with hoisting equipment that was previously designed for shorter boom lengths only; and 
     is interchangeable between cranes. 
     These objectives are addressed by the structure and use of the inventive multiple load block system. Multiple load block sheaves are vertically oriented in series, each forming distinct sets of reeving lines between lower load block sheaves and upper sheaves or attachment points. This orientation only requires each set of sheaves to move vertically through a proportional percentage of the total vertical height of the boom tip. The use of multiple load blocks vertically oriented in series allows the use of standard sized winch drums, since each set of reeving lines must only traverse a portion of the total travel distance of the load hook. If the number of parts of line in the reeving lines is different, then the different reeving line sections afford different travel speeds. In addition, both high capacity lifts at slow speeds and lower capacity lifts at higher speeds can be effected by the use of this system. As an example, consider a two part reeved system in series with the top set of reeving being reeved for heavy lifts (many parts of line) and the lower set of reeving being reeved for light lifts (few parts of line). When light lifting duties are required, the bottom set of reeving will be run up and down at a resulting high speed, providing a good cycle time. When a heavy lift is required, first the lower and middle set of blocks will be lowered down to the ground, then interconnecting steel link plates will be connected between the lower and middle blocks, effectively bypassing the lower system (and removing the weak link) and then the upper system of reeving will be used for the heavy lift. 
     Other objects of the invention will become apparent from time to time throughout the specification hereinafter disclosed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 depicts a prior art heavy crane with a single hook block. 
     FIG. 2 depicts prior art double-line single-block reeving. 
     FIG. 3 depicts prior art single-line single-block reeving. 
     FIG. 4 depicts a heavy crane using the inventive multiple-line multiple-block reeving. 
     FIG. 5 depicts the preferred embodiment of the inventive multiple-line multiple-block reeving. 
     FIG. 6 depicts the preferred embodiment of the invention showing a single-line multi-block rigging having at least three traveling blocks. 
     FIG. 7 depicts an alternative embodiment of the inventive single-line multiple-block reeving. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is described as system  10 , which comprises at least one upper rigging unit  100  and one lower rigging unit  300 , each rigging unit comprising boom head sheaving, traveling sheave blocks and load lines. Winch drums, hook, boom and power drives typically are associated with heavy crane  15  and the operation of system  10  as described in this disclosure. 
     Prior art for block rigging for heavy crane  15  is shown in FIG.  1  and FIG.  2 . For purposes of clarity, reeving may be illustrated as two part reeving. It is understood, however, that typically reeving comprises multiple line parts numbering greater than two. To support heavy loads, heavy cranes typically use a double-line reeving system operating in parallel, as shown in FIG.  2 . First main hoist line  20  and second main hoist line  21  reeve over boom head sheaves  25  and reeve down to load block sheaves  30 , forming first reeving lines  26  and second reeving lines  28 . First reeving lines  26  and second reeving lines  28  terminate their dead ends at load block  32  if the number of reeving line parts are odd, or typically at boom tip  27  if the number of reeving line parts are even. 
     The load (not shown) attached to hook  40  is supported by the combination of first reeving lines  26  and second reeving lines  28 . First reeving lines  26  are formed by first main hoist line  20 , which is payed in and out from first winch drum  22  mounted on body  35  of heavy crane  15 , shown in FIG.  1 . Second reeving lines  28  are formed by second main hoist line  21 , which is payed in and out from second winch drum  23  in payed line length synchrony with main hoist line  20 . This synchrony (and equal parts of line in each first reeving lines  26  and second reeving lines  28 ) assures an even vertical travel of load block  32 , which is typically supported equally by both first reeving lines  26  and second reeving lines  28 . The synchronization is achieved by connective, mechanical and/or electrical coordination of the rotation of first winch drum  22  and second winch drum  23 . 
     Alternatively, prior art reeving using a single load line  20  is depicted in FIG.  3 . First main hoist line  20  pays in and out from first winch drum  22 , forms first reeving lines  26  by reeving over boom head sheaves  25 , down and under load block sheaves  30 , and terminating at boom tip  27  or load block  32 , depending on the number of reeving line parts. Single load line reeving is typically used for lighter load duty lifts. 
     The present invention system  10  is shown in FIGS. 4-7. In a first embodiment having a double series reeved system, depicted in FIG.  4  and FIG. 5, there are two traveling load blocks, shown as upper load block set  132  and lower load block  332 . It is understood, however, that the number of traveling load blocks can be more than two, the number limited only by the number of winch drums available and physical constraints of the body  35  and boom  17 . Each load block is supported and moved by at least two rigging means operating in parallel, each having a winch drum, load line, and upper and lower sheaves. 
     In FIG. 5, upper rigging unit  100  is defined by two upper load lines  120  forming upper reeving lines  126  that reeve over the boom head sheaving of boom head sheaves  25 , down to and under upper load block sheaves  130 , and terminate at a termination point, typically boom tip  27  if there are an even number of line parts in upper reeving lines  126 . If upper reeving lines  126  have an odd number of line parts, upper reeving lines  126  terminate at upper load block set  132 . Upper load line  120  is payed in and out from upper winch drums  122 , which are physically, mechanically or electrically synchronized to pay upper load lines  120  in and out at the same rate. 
     Lower rigging unit  300  is defined by lower load lines  320  forming lower reeving lines  326  that reeve over boom head sheaves  25 , down to lower load block sheaves  330  and up to the load block sheaves in upper load block set  132 , and terminate at a lower reeving line  326  termination point, that point typically being upper load block set  132  if there are an even number of line parts in lower reeving lines  326 . If there are an odd number of parts of reeving line, lower reeving lines  326  terminate at lower load block  332 . Lower load line  320  is payed in and out from lower winch drums  322 , which are physically, mechanically or electrically synchronized to pay lower load lines  320  in and out at the same rate. 
     As seen in FIG. 6, system  10  can incorporate intermediate rigging unit  200 , defined by intermediate load lines  220  reeving over boom head sheaves  25 , down to intermediate load block set  232  having intermediate load block sheaves  230  and up to higher adjacent load block sheaves  110 , and terminating at an intermediate reeving line  226  termination point. Higher adjacent load block sheaves  110  are upper load block sheaves  130  when intermediate load block set  232  is the only intermediate load block set  232 , or is the uppermost intermediate load block set  232  in a plurality of intermediate load block sets  232 . When a lower intermediate load block set  232  is of a plurality of intermediate load block sets  232  and is not the uppermost intermediate load block set  232 , higher adjacent load block sheaves  110  are the intermediate load block sheaves  230  higher and adjacent to the lower intermediate load block set  232 . Where there are an even number of reeving parts in intermediate reeving lines  226 , the termination point for intermediate reeving lines  226  is a higher positioned intermediate load block set  232 , unless intermediate load block set  232  is the uppermost intermediate load block set  232 , wherein the attachment point for its intermediate reeving lines  226  is upper load block set  132 . If there are an odd number of reeving parts of line, intermediate reeving lines  226  terminate at the intermediate load block set  232  being supported by those intermediate reeving lines  226 . 
     Further depicted in FIG. 6, lower load block  332  reeves to the lowest intermediate load block set  232 . Lower load lines  320  reeve over boom head sheaves  25 , down to and under lower load block sheaves  330  and up to the lowest intermediate load block sheaves  230 . Lower reeving lines  326 , formed by lower load lines  320 , terminate either at lower load block  332  or the lowest intermediate load block set  232 , depending on the number of parts of line in lower reeving lines  326 . 
     For the sake of clarity, FIG. 6 depicts each rigging unit having a single load line. It is understood, however, that in the preferred embodiment, multiple load lines analogous to those depicted in FIG. 5 are used to provide additional strength to the reeving lines. Further, each sheave set shown may be split into two parallel interconnected sets of sheaves in the vertical plane. That is, the vertical systems of reeving and block sets shown in the FIG. 5 can be duplicated to provide multiple planes of reeved sets to provide additional parallel lifting systems supported from the single boom head. 
     Alternatively, system  10  can use single load lines as depicted in FIG.  7 . The rigging of upper reeving lines  126  and lower reeving lines  326  is analogous to that described in the preferred embodiment above. The alternative system  10  having single lines is typically used in the following examples. When loads being lifted by heavy crane  15  are relatively light, single lines of normal size and capacity reeving in moderate line parts numbers will drum around first winch drum  22  and second winch drum  23 . If the length of boom  17  is short enough, a high number of parts of line in the reeving lines can be accommodated by the winch drums. If heavy capacity line is used, typically with a linear winch, a minimal number of parts of line in the reeving is required allowing long travel lengths of upper load block set  132  and lower load block  332 . 
     OPERATION 
     In the preferred embodiment shown in FIG.  4  and FIG. 5, hook  40  is raised and lowered by paying in and out upper load lines  120  and/or lower load lines  320 . Upper load line  120   a  forms upper reeving lines  126   a , while upper load line  120   b  forms upper reeving lines  126   b . Upper reeving lines  126   a  and upper reeving lines  126   b  raise and lower upper load block set  132  at the same synchronized rate. To accomplish this synchronization in FIG. 5, left upper winch drum  122   a  and right upper winch drum  122   b  rotate such that upper load line  120   a  and upper load line  120   b  pay in and out at the same rate, assuming reeving and sheaves are equivalent. 
     Lower load lines  320  must likewise be coordinated to accomplish even movement of lower load block  332 . To accomplish this synchronization, left lower winch drum  322   a  and right lower winch drum  322   b  must rotate such that lower load line  320   a  and lower load line  320   b  pay in and out at the same rate, assuming reeving and sheaves are equivalent. 
     In FIG. 5, when upper rigging unit  100  and lower rigging unit  300  have equivalent reeving, upper load block set  132  and lower load block  323  are each required to travel only half the total lift distance defined by the height of boom  17 . The travel distance of each load block is determined by the amount of load line payed in and out to its associated reeving lines. Thus, each load line must only be long enough to afford travel distance half the height of the load lift height. Typically, to lower a load attached to hook  40 , lower load block  332  is lowered by paying out lower load lines  320  until no more lower load line  320  is safely available, at which point upper load block set  132  is lowered by paying out upper load lines  120  until the load reaches the ground or other lower destination. To raise a load requires the reverse steps to be taken, although the opposite order may be used so long as the bounds of free travel of each load block set is not exceeded, resulting in unwanted contact between two load blocks. 
     In an alternative embodiment, upper reeving lines  126  and lower reeving lines  326  have a different number of reeving line parts. For example, the number of line parts in lower reeving lines  326  may be less than those found in upper reeving lines  126  or may be of different diameter or strength characteristics. This allows the upper load block set  132  and upper reeving lines  126  to have a higher lifting capacity and lower load block and lower reeving lines  326  to have a faster and greater range of motion, affording flexibility to the operator of heavy crane  15 . When light lifting duties are required, lower reeving lines  326  and lower load block  332  will be run up and down at a resulting high speed, providing a good cycle time. When a heavy lift is required, upper load block set  132  is first lowered to the ground. Interconnecting steel link plates (not shown) mechanically then connect upper load block set  132  and lower load block  332 , effectively bypassing the weak link when there are a smaller number of lines in lower reeving lines  326 . The stronger and more numerous parts of line in upper reeving lines  126  are then used for the heavy lift. Load attachment hook  40  must therefore be of a capacity suitable for the heaviest duty to be performed in that configuration. Likewise, interconnecting steel link plates (not shown) can be used to mechanically connect upper load block set  132  and intermediate load block set  232 , intermediate load block set  232  and lower load block  332 , or any combination of connections affording the requisite circumvention of the weakest link of the rigging system having the smaller number and/or weaker lines. 
     In an alternative embodiment depicted in FIG. 6, system  10  comprises upper rigging unit  100 , intermediate rigging unit  200  and lower rigging unit  300  as defined above. First winch drum  22  controls upper reeving lines  126 , second winch drum  23  controls lower reeving lines  326 , and third winch drum  19  controls intermediate reeving lines  226 . First winch drum  22 , second winch drum  23  and third winch drum  19  may operate in synchrony, independently or in a relative mode, as described below in the alternative embodiment depicted in FIG.  7 . Operation is analogous to the embodiment described in FIG. 5, with the additional operation of intermediate rigging unit  200 . For purposes of clarity, FIG. 6 depicts single line rigging units. It is understood, however, that in the preferred embodiment, upper rigging unit  100 , intermediate rigging unit  200  and lower rigging unit  300  have multiple load lines, as depicted in FIG.  5 . 
     In the alternative embodiment depicted in FIG. 7, first winch drum  22  and second winch drum  23  may operate in synchrony, independently, or in a relative mode. In FIG. 7, when the number of parts of line in upper reeving lines  126  and lower reeving lines  326  are equal, and upper load block sheaves  130  and lower load block sheaves  330  have equal diameters, the following occurs. If first winch drum  22  and second winch drum  23  are turning in synchrony, hook  40  travels twice as fast compared to a single winch drum turning at the same speed. If first winch drum  22  and second winch drum  23  operate independently, then the vertical travel rate of upper load block set  132  is linearly independent of lower load block  332 . If first winch drum  22  and second winch drum  23  operate in a relative mode, upper load block set  132  and lower load block  332  move at vertical speeds relative to the relative speeds of first winch drum  22  and second winch drum  23 . These conditions as described are representative of some of the many permutations available with different reeving, drums and sheaves. Many other permutations are obviously possible with different combinations of components described in system  10 . 
     In the preferred embodiment, the winch drums and/or the load lines described in system  10  are of the same size and capacity. Thus, they are interchangeable between different cranes and rigging units. If additional capacity is required for a lift, then additional standard sized winch drums with standard size load line are added to heavy crane  15 . This affords the option of additional parts of reeving lines, with the difference in lift distance required by the additional reeving being made up by the additional rigging units. 
     It is also understood that each rigging unit described above may have the same number of parts of reeving lines. The advantage afforded in this arrangement is that a higher lift height at high capacity (through a high number of reeving parts of line) can be provided economically with conventional sized winch drums and hoist lines. Each rigging unit is responsible for the vertical travel distance of a portion of the total vertical height of lift required. 
     It is further understood that while all embodiments are depicted as a vertical lifting device, the invention may also be utilized in a pulling device, either on an inclined plane or horizontally with the same benefits as described in the use with a crane or similar lifting device. 
     The foregoing disclosure and description of the invention is illustrative and explanatory thereof. Various changes in the details of the illustrated construction may be made within the scope of the appended claims without departing from the spirit of the invention. The present invention should only be limited by the following claims and their legal equivalents.