Patent Publication Number: US-11649145-B2

Title: Lightweight flexible tensioning system for construction equipment

Description:
REFERENCE TO EARLIER FILED APPLICATION 
     This application is a divisional application of U.S. patent application Ser. No. 14/784,010 filed Oct. 12, 2015, which is a 371 national phase of PCT/US2014/072697, filed Dec. 30, 2014, and claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 61/922,055, filed Dec. 30, 2013, and titled “LIGHTWEIGHT FLEXIBLE TENSIONING SYSTEM FOR CONSTRUCTION EQUIPMENT,” which is incorporated, in its entirety, by this reference. 
    
    
     BACKGROUND 
     1. Technical Field Text 
     Embodiments of the invention are directed to flexible tensioning members for a crane system and more particularly to a flexible crane tensioning member and connection assemblies. 
     2. Background Information 
     Large cranes are typically transported to a job site over the highway for at least a portion of the journey to a job site. Because many countries, states or other geopolitical entities impose limitations on the weight of vehicles (sometimes on a per-axle basis) that can be driven on highways within their jurisdiction, a large crane is typically broken into smaller pieces for transport. Once delivered to the job site, the crane is assembled from the smaller pieces. Some cranes, often referred to as mobile hydraulic cranes, are mounted on multi-axle transport carriers and are designed to travel over the highway and be ready for use at the job site with minimal set-up activity. However, to reduce the number of axles, there is a considerable benefit in reducing the weight of the crane, or transporting parts of the crane on a separate carrier to the job site. 
     Large cranes typically use a bracing structure to strengthen components of a crane such as a boom, jib, and mast. For example, a crane&#39;s boom may not be strong enough on its own to support the bending forces it is subject to when carrying a large load suspended from the tip of the boom. Rather than increase the cross section of the boom, which adds significantly to its weight, it is common to use a bracing structure to increase the stiffness and load capacity of the boom. The bracing structure typically includes at least one tensioning member under tension that extends from a location lateral of the boom to a location on the boom forming a triangle. The lateral location may be a strut coupled to the boom, or it may be a location offset from the boom on another structure of the crane. 
     In larger cranes the bracing structure itself may be relatively large and heavy. In some instances the bracing structure may require the use of another crane to lift it into place. In other instances, the bracing structure may be formed from smaller individual piecing connected together. These smaller individual pieces may be assembled in place on the crane, or assembled off of the crane and then attached to the crane as a single unit. 
     The individual pieces are typically formed from high tensile strength steel. In order for a worker to assembly the bracing structure, the individual pieces are typically no larger than a size that the workers can easily manipulate. Additionally, different cranes options may require different lengths of bracing structures or different strengths. For example, a boom may be extendable and require different lengths of bracing depending upon the extent that the boom is extended. For this reason a given crane configuration may have a specific set of bracing pieces associated with it. 
       FIG.  1    illustrates an example of a current tensioning member  100  made of high tensile strength steel. The tensioning member  100  is rigid with a high modulus of elasticity, such that any movement at one end of the tensioning member  100  is translated to the other end of the tensioning member  100 . The tensioning member  100  may be joined end to end with another tensioning member to span a distance greater than a length  104  of the individual tensioning member  100 . Tensioning member  100  has an eye  102  formed at one end of the tensioning member  100 . The eye  102  is used to connect the tensioning member  100  to another component. For example, a pin may extend through the eye  102  and another component, fastening them together. 
     Because the tensioning member  100  is rigid, any movement between the tensioning member  100  and a crane must be accounted for. If the tensioning member  100  were rigidly attached to the crane, the tensioning member  100  would develop torsional loads in addition to a tension load and would likely experience a structural failure. 
     In some cranes the bracing structure may include steel cables as tensioning members. Steel cables are advantageous in some applications because they may be wound for storage and a single cable may be used to span a large distance. Additionally, steel cables are more forgiving in their attachment than sold cross section tensioning members  100  because they have some degree of flexibility. However, steel cables are typically not as strong as a solid cross section tensioning members  100  and therefore are not able to be used in all situations. 
     Tensioning members  100  and cables have been used successfully and continue to be used successfully in cranes. They are strong, readily available, and familiar to the operator. However, it would be beneficial to have a simpler system to replace the various combinations of tensioning members  100  and steel cables that offered similar strength while allowing for simple connection mechanisms. 
     BRIEF SUMMARY 
     Embodiments of the invention are directed to a flexible tensioning member. The flexible tension member includes a middle portion, a first end and a second end. The middle portion comprises a bundle of fibers having a specific tensile strength greater than 1,000 kilonewton meter per kilogram. The first end is connected to the middle portion and has a first connector. The second end is connected to the middle portion and comprises a first member extending axially and laterally from the middle portion and a second member extending axially and laterally from the middle portion and laterally from the first member. The first member has a second connector and the second member has a third connector. 
     In another embodiment of the invention, the flexible tensioning member has a cross pin disposed between first member and the second member. The cross pin has a first pin end and a second pin end. The second connector is sized and shaped to receive the first pin end and the third connector is sized and shaped to receive the second pin end. 
     In another embodiment of the invention a crane static tensioning assembly includes a flexible tensioning member, a shank, and a pivot joint. The flexible tensioning member comprises fibers having a specific tensile strength greater than 1,000 kilonewton meter per kilogram. The shank has a bore shaped and sized to receive a pivot spindle. The pivot joint has a first connector coupled to the flexible tensioning member and a second connector coupled to the shank. 
     In another embodiment of the invention a flexible tension member attachment assembly includes a base, a connector, a plurality of bores, and a rope. The base has a base end and a top end and the connector is disposed at the top end. A plurality of bores extends from the base end towards the top end. The rope having a first portion disposed in a first bore and a second portion disposed in a second bore. 
     In another embodiment of the invention a crane tensioning assembly includes a connection block, a flexible tensioning member, and a pin. The connection block has a plurality of cavities each sized and shaped to receive an end of a flexible tensioning member. The connection block has a first bore extending through a first cavity from among the plurality of cavities. The flexible tensioning member has an eye at a first end of the flexible tensioning member and is positioned in a cavity from among the plurality of cavities with the eye having a centerline coaxial with a centerline of the first bore. The pin is disposed in the first bore and extends through the eye. 
     In another embodiment of the invention, a boom assembly comprises a boom, a mast, and a flexible tensioning member. In another embodiment the boom assembly comprises a boom, a mast, and a crane static tensioning assembly. In another embodiment, the boom assembly comprises a boom, a mast, and the flexible tension member attachment assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    depicts an example of a prior art steel tie rod end used as a static support member. 
         FIG.  2    depicts an embodiment of a flexible tensioning member of the present invention. 
         FIG.  3    depicts a cross section taken across section  3 - 3  at an end of the flexible tensioning member of  FIG.  2     
         FIG.  4    depicts a cross section taken across section  4 - 4  of a middle portion of the flexible tensioning member of  FIG.  2   . 
         FIG.  5    depicts an embodiment of a flexible tensioning member having two split ends. 
         FIG.  6    depicts an embodiment of a flexible tensioning member coupled to a pivot spindle through a cross-pin. 
         FIG.  7    depicts an embodiment of a flexible tensioning member coupled to a pivot spindle through a pivot joint. 
         FIG.  8    depicts an embodiment of a flexible tensioning member coupled to a pivot spindle through an alternative pivot joint. 
         FIG.  8 A  depicts a rope retainer used in  FIG.  8   . 
         FIG.  9    depicts another embodiment of a flexible tensioning member coupled to pivot spindle through a ball and socket joint. 
         FIG.  10    is an exploded view of the ball and socket joint of  FIG.  9   . 
         FIG.  11    is an embodiment of a static tensioning assembly having a single flexible tensioning member. 
         FIG.  12    is an embodiment of a flexible tensioning member for use in the assembly of  FIG.  11   . 
         FIG.  13    is an embodiment of the flexible tensioning member of  FIG.  11    with two flexible tensioning members. 
         FIG.  14    is an embodiment of the static tensioning assembly of  FIG.  11    with three flexible tensioning members. 
         FIG.  15    is an embodiment of the static tensioning assembly of  FIG.  11    with two flexible tensioning members and two pins. 
         FIG.  16    is an embodiment of a flexible tensioning member having more than one row of cavities. 
         FIG.  17    illustrates a schematic of a mobile crane. 
         FIG.  18    illustrates a schematic of a mobile platform crane. 
         FIG.  19    illustrates a schematic of a tower crane  190 . 
         FIG.  20    illustrates a schematic of a crawler type crane. 
         FIG.  21    illustrates an exploded view of an embodiment of a connection block. 
         FIG.  22    illustrates the connection block of  FIG.  21    in an assembled view. 
         FIG.  23    illustrates an exploded view of another embodiment of a connection block. 
         FIG.  24    illustrates the connection block of  FIG.  23    in an assembled view. 
         FIG.  25    illustrates an exploded view of another embodiment of a connection block. 
         FIG.  26    illustrates the connection block of  FIG.  25    in an assembled view. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS AND THE PRESENTLY PREFERRED EMBODIMENTS 
     Throughout this description reference will be made to the specific tensile strength of a material. The specific tensile strength of a material is the tensile strength of the material divided by its density. It may also be known as the strength to weight ratio. In this application, the specific tensile strength of a material will be denoted in the units of kilonewton meters per kilogram. As an example, aluminum has a tensile strength of about 600 megapascals (MPa) and a density of about 2.8 grams per cubic centimeter. It would therefore have a specific strength of about 214 kilonewton meters per kilogram. 
     Throughout this description reference will be made to fibers. The term fibers will be used in its conventional sense to mean a thin filament. Fibers may be naturally occurring such as spider silk, or they may be synthetic. Fibers may be bundled together to form a larger component. The strength of the component will typically depend on the orientation of the fibers. Fibers have their greatest strength in a longitudinal direction and have very little strength in other directions. Therefore, if all the fibers are aligned in a single direction, the component will have its greatest strength in the direction of the fibers and may be flexible in other directions. When fibers are twisted or braided together they may form a rope. The rope has little resistance to bending and it is useful primarily as a tensioning component. 
     Some embodiments of the invention are directed toward the use of high strength rope in place of steel cables and steel tensioning members. The high strength rope is formed of high specific tensile strength fibers formed into yarns. The yarns are then twisted into strands which are woven, twisted, or braided together to form the rope. The strands may be formed of a blend of fibers such as aramid fibers and high modulus polyethylene. The strands may each be coated by an abrasion resistant coating such as polyurethane prior to forming the rope. An outer jacket may be used to protect the fibers from ultraviolet light and foreign matter. The braiding and twisting of the outer stands may be balance such that half of the strands are twisted in one direction while the remaining half is twisted in the opposite direction to obtain torque neutrality. The fibers may be chosen to minimize creep within the rope. However, some creep may be inevitable and the use of a length adjustment system may be necessary. For example, a turn buckle may be used to compensate for any stretching or creep of the rope. 
       FIG.  2    illustrates an embodiment of a flexible tensioning member  200  in accordance with an embodiment of the present invention. The flexible tensioning member  200  may be used as a replacement to the tensioning member  100  shown in  FIG.  1    and may be used as a tensioning member in the embodiments of  FIGS.  17  through  20   . As shown in  FIG.  3    and  FIG.  4   , the flexible tensioning member  200  is comprised of a bundle of fibers  300  covered by jacket  302 . 
     The bundle of fibers  300  is comprised of a fiber having a high specific tensile strength. In one embodiment, poly(p-phenylene-2,6-benzobisoxazole) (hereinafter PBO), commercially available as Zylon®, is used as a fiber. PBO is a synthetic fiber having a specific tensile strength of about 3766 kilonewton meters per kilogram. It is additionally advantageous as it has a high modulus of elasticity and therefore stretches very little under load. Furthermore, it experiences little creep after repeated usage. The bundle of fibers  300  are orientated longitudinally and may be formed using a single fiber continuous winding process. In the process, bushings  206  are set at positions corresponding to a desired configuration. A fiber is then wrapped around the bushings  206  to form the bundle of fibers  300 . Because the width of a single fiber may be 20 micrometers or less, the fiber may be wrapped around the bushings  206  thousands of times or more. 
     In embodiments of the present invention, the fiber is wrapped around at least three bushings  203 ,  205  and  206 ,  203  being at a first end  202  of the flexible tensioning member  200 , and  205  and  206  being at a second end  204  of the flexible tensioning member  200 . The fiber may alternate winding between bushing  203  and  205  and then between bushings  203  and  206 . In other embodiments, the single fiber may be wrapped around four bushings with two bushings at each end of the flexible tensioning member. See  FIG.  5   , discussed below. After winding, the bushings  203 ,  205  and  206  may be left in place in the flexible tensioning member  200  to provide a connector  210 . The bushings  203 ,  205  and  206  may have an eye  207  for connection to another component. In some embodiments the bushing  203 ,  205 , and  206  may be a high strength pin that extends laterally from the flexible tensioning member  200  for connection to another component. 
     The jacket  302  protects the bundle of fibers  300  from abrasion, moisture, and ultraviolet (UV) light. Preferably the jacket  302  is cut resistant, moisture resistant, and UV resistant. To perform all of these functions, the jacket  302  may be comprised of multiple layers. In the embodiment of  FIGS.  3  and  4   , the jacket  302  is comprised of a braided layer  304  and an outer layer  306 . The braided layer  304  may be formed of a cut resistant fiber, such as Kevlar®. The outer layer  306  may comprise an elastomeric coating such as polyurethane. Additionally, the ends  202 ,  204  of the flexible tensioning member  200  may be covered with an additional material shaped to an end termination. For example, a polyurethane foam may cover an end of the flexible tensioning member  200  and be shaped to retain the bushings  203 ,  205  and  206 . Other configurations of materials are possible and the jacket  302  may be comprised of a single layer of material or multiple layers. Additionally, the composition of the jacket  302  may vary between the cross section of  FIG.  3    and the cross section of  FIG.  4   . 
     The cross section of  FIG.  3    illustrates a cross-section in which the flexible tensioning member  200  has separated into a first member  308  and a second member  310 , both extending away axially and laterally from a middle portion  208  of the flexible tensioning member  200 . The first member  308  and the second member  310  are comprised of the same bundle of fibers  300  as the middle portion  208  separated into two portions for the first and second members  308 ,  310 .  FIG.  4    illustrates a cross-section of the middle portion  208  of the flexible tensioning member  200 . The bundle of fibers  300  within the middle portion  208  extend into the first and second members  308 ,  310  such that the number of fibers in the middle portion  208  equals the number of fibers in the first and second members  308 ,  310  combined. 
     Returning to  FIG.  2   , the first end  202  of the flexible tensioning member  200  has a connector  210  for connection to another component. The connector  210  may be coupled to the bushing  203 ,  205 , and  206  or it may be the bushing  203 ,  205  and  206  itself. For example, the bushing  206  may have an eye  207  through which a bolt or pin may be placed. In this example, the eye  207  would be considered to be the connector  210 . 
     A second end  204  of the flexible tensioning member  200  has the first member  308  extending axially and laterally away from the middle portion  208  and a second member  310  extending axially and laterally away from the middle portion  208 . The first member  308  and the second member  310  each have a connector  210  for connection to another component. The connectors  210  may be the same style as the connector  210  at the first end  202  of the flexible tensioning member  202 . For example, the connector  210  at the first end  202  may be a bushing  208  with an eye  207  and the connectors  210  on the first and second members  308 ,  310  may also be bushings  208  having an eye  207 . In other embodiments the connectors  210  of the first and second members  308 ,  310  may be a different style than the connectors  210  on the first end  202  of the flexible tensioning member  200 . For example, the connector  210  at the first end  202  may comprise a pin bushing and the connectors  210  at the second end may comprise bushings having an eye  207 . In some embodiments the bushings  206  on the first and second member  308 ,  310  may be sized and shaped to receive a pin connector at the first end  202 . 
     Spacing the connectors  210  of the first member  308  and second member  310  allows the flexible tensioning members  200  to be connected end to end with a single pin extending through an eye  207  of the first member  208  and second member  210  and an eye of the first end  202 . The spacing further allows stresses to be distributed over a wider area than a single connector. 
     The jacket  302  may bias the first member  308  and the second member  310  towards one another. A spacer  212  may be disposed between the connectors  210  at the first and second members  308 ,  310 . The spacer  212  keeps the first member  308  and second member  310  at a fixed distance apart. 
       FIG.  5    illustrates another embodiment of a flexible tensioning member  500 . The embodiment of  FIG.  5    is similar to the embodiment of  FIG.  2    with the exception that a first end  502  of the flexible tensioning member  500  has two connectors  504  and a second end  506  of the flexible tensioning member  500  also has two connectors  504 . The first end  502  and the second end  506  may be identical in some embodiment but they need not be. The embodiment of  FIG.  5    is similar in construction to the embodiment of  FIG.  2    with the exception that the fiber is wound around four bushings instead of three. For example, the fiber is alternately wound between a first bushing  553  on the first end and a first bushing  555  on the second end, the first bushing  553  on the first end and the second bushing  556  on the second end, the second bushing  554  on the first end and the first bushing  555  on the second end, and the second bushing  554  on the first end and the second bushing  556  on the second end. Because the flexible tensioning member  500  is lighter than a comparable steel tensioning member  100 , it may span a greater distance and not require the use of members joined end to end. In such embodiments, it may be advantageous for both ends to have connectors spaced apart to distribute the stress. 
       FIG.  6    illustrates an embodiment of a flexible tensioning member  600  combined with a cross pin  602  disposed between a first member  604  and a second member  606 . In this embodiment, a bushing  608  having an eye  610  is disposed in the first and second member  604 ,  606 . The eyes  610  are each sized and shaped to receive a pin end  612  of the cross pin  602 . The pin ends  612  are fitted in the eyes  610  of the bushings  608  such that the cross pin  602  is positioned between the first member  604  and the second member  606 . In some embodiments the cross pin  602  may have a retainer constraining the pin ends  612  in the bushings  608 . For example, a pin end  612  may extend through a bushing  608  and have a retaining clip disposed on it preventing the cross pin  602  from retracting into the bushing  608 . 
     The cross pin  602  may have a bore  614  disposed between the pin ends  612 . The bore  614  may be disposed orthogonal to an axis of the pin ends  612 . The bore  614  is sized and shaped to receive a pivot spindle  616 . The cross pin  602  may be secured to the pivot spindle  616  use conventional techniques such as retaining clips, locking collars, bolts, and other techniques as known in the art. This embodiment enables the flexible tensioning member  600  to rotate about the pivot spindle  616  in three axes using only two joints. The cross pin  602  may pivot around the pivot spindle  616 , the flexible tensioning member  600  may pivot around the pin ends  612  of the cross pin  602 , and the flexible tensioning member  600  itself may twist along its own axis. 
       FIG.  7    illustrates one end of an embodiment of a flexible tensioning assembly  700 . The flexible tensioning assembly  700  has a flexible tensioning member  702  formed of fibers having a specific strength greater than 1,000 kilonewton meter per kilogram. A pivot joint  704  has a first connector  706  connected to an end  708  of the flexible tensioning member  702  and a second connector  707  connected to a shank  710 . The shank  710  has a bore  712  sized and shaped to receive a pivot spindle  714 . The first connector  706  may enable rotation of the flexible tensioning member  702  relative to the pivot joint  704  about a first axis  716  and the second connector  707  may enables rotation of the flexible tensioning member  702  about a second axis  718  orthogonal to the first axis  716 . In the embodiment of  FIG.  7   , the flexible tensioning member  702  may be the flexible tensioning member  200  described in relation to  FIG.  2   . In such embodiments the connecters  210  of the first member  308  and second member  310  may connect the flexible tensioning member  702  to the pivot joint  704 . 
       FIG.  8    illustrates another embodiment of a static tensioning assembly  800 . This embodiment is similar to the embodiment of  FIG.  7   , however the flexible tensioning member is formed of a rope assembly  802 . The rope assembly  802  has at least one fiber rope  804  comprised of strands of fibers having a specific strength greater than 1,000 kilonewton meter per kilogram and a connection block  806 . In this embodiment, a pivot joint  808  has a first connector  810  connected to a top end  814  of the connection block  806  and a second connector  812  connected to a shank  814 . The shank  814  has a bore  816  sized and shaped to receive a pivot spindle  818 . The first connector  810  enables rotation of rope assembly  802  relative to the pivot joint  808  about a first axis  820  and the second connector  812  enables rotation of the flexile tensioning member  802  relative to the shank  814  about a second axis  822 . 
       FIG.  8 A  provides a detailed view of the connection block  806  of  FIG.  8   . The connection block  806  has a plurality of bores  824  that extend longitudinally from a base end  826  towards the top end  813 . The plurality of bores  824  are arranged with a horizontal connection between pairs of bores, such that when a rope  804  is threaded into the base end  826  of the connection block through a first bore  830 , the rope  804  crosses over into a second bore  832  and exits the base end  826  of the connection block  806  through the second bore  832 . In the embodiment of  FIG.  8 A , the horizontal connection is a lateral bore  828  formed proximate an exit  838  of the first bore  830 . A rope  804  is threaded through the first bore  830  until it exits the connection block  806 . The rope  804  is then fed into the lateral bore  828  and exits the connection block  806  proximate the second bore  832 . The rope  804  then feeds into the second bore  832  until it exits the base end  826  of the connection block  806 . Each end of the rope  804  may extend the entire length of the static tensioning assembly  800 , or one end of the rope  804  may be tied off near the connection block  806 . The connection block  806  of  FIG.  8 A  has two pairs of longitudinal bores, but other numbers of bores are possible. 
     The connection block  806  may have a tapered cap  834  as shown in  FIG.  8 A , but other configurations are possible. For example, the connection block  806  could have a flat top with the longitudinal bores exiting the top end  813  of the connection block  806 . However, the tapered cap  834  is preferable due to the ease at which it may be threaded by the rope  804 . Because the connection block  806  has a connector disposed at it top end  813 , such as the eye  836  shown in  FIG.  8 A , it may be difficult to thread the connection block  806  when it is attached to a pivot joint  808 . The tapered cap  834  allows the rope  804  to be threaded in and out of the connection block  806  from a lateral position, rather than an end position that is required if the connection block  806  has a flat top end  813 . 
       FIG.  9    illustrates another embodiment of a static tensioning assembly  900 . This embodiment is similar to the embodiment of  FIG.  8   , however the connection between the connection block  902  and the pivot joint  904  differs. In the place of the eye  836 , the connection block  902  connects to the pivot joint  904  through a ball joint  906 . The connection block  902  has a ball  908  and a shaft  910  disposed opposite a base end  908  of the connection block  902 . The ball joint  906  allows rotation of the rope assembly  912  relative to the pivot joint  904  in three different orthogonal axes.  FIG.  10    illustrates an exploded view of the embodiment of  FIG.  9   . The ball joint  906  is comprised of the ball  908  connected to the connection block  902 , a calotte  1000 , two half calottes  1002 , two retainer plates  1004 , and a socket  1006 . The socket  1006  may be integral to the pivot joint  904 , or it may be a separate component that is attached to the pivot joint  904 . 
     The socket  1006  is sized and shaped to receive the calottes  1000 ,  1002 . In the embodiment shown in  FIG.  9   , the calottes  1000 ,  1002  are cylindrical but they need not be. For example, the calottes  1000 ,  1002  could have a square outer shape and the socket  1006  could be a complementary square recess. The ball joint  906  is assembled by placing the calotte  1000  in the socket  1006 . The ball  908  is then placed in a recess  1008  of the calotte  1000 . The two half calottes  1002  are then placed in the socket  1006  above the ball  908  with the shaft  910  extending between them such that the ball  908  is between the calotte  1000  and the two half calottes  1002 . Preferably the calottes  1000 ,  1002  form a spherical recess that is slightly larger than an outer diameter of the ball  908  and have a combined height matching a depth of the socket  1006 . With the calottes  1000 ,  1002  and ball  908  in place, the retainer plates  1004  are placed over the recess and secured in place. The embodiment of  FIG.  9    uses screws  1008  extending through the retainer plates  1004  and into a face of the pivot joint  904  for securement. 
       FIG.  23    illustrates another embodiment of a static tensioning assembly  2300 . The static tensioning assembly  2300  includes a rope assembly  2314  has at least one fiber rope  2316  comprised of strands of fibers having a specific strength greater than 1,000 kilonewton meter per kilogram and a connection block  2318  connection block having an inner ring  2302 , an outer ring  2304 , a cover  2306 , and a bracket  2308 . The inner ring  2302  is fixed to mounting location on a crane, such as a pivot joint at the foot of a boom. The inner ring  2302  may slide over the mounting location and then be secured using a pin passing through apertures  2312  in the inner ring  2302 . An outer ring  2304  is secured over the inner ring  2302  and is configured to rotate about the inner ring  2302 . The inner ring may have a spherical outer surface and the outer ring may have a complementary inner surface, so that together the inner ring and the outer ring form a spherical joint. 
     A cover  2306  having circumferential grooves is disposed around the outer ring  2304 . The circumferential grooves are sized and shaped to receive the rope assembly  2314  which encompasses the cover  2306 . The cover is secured to the outer ring by the bracket  2308  which attached to the cover through bolts  2310  and to the inner cover through bolts  2320 . 
       FIG.  24    illustrates the static tensioning assembly of  FIG.  23    in an assembled configuration. In one application, the inner surface of the inner ring is positioned over a pivot joint at the foot of the boom, and the rope assembly  2314  is connected to a crane component at an opposite end (not shown). In operation, the rope assembly is able to provide tension between the pivot joint and the crane component, but does not twist as the component moves due to the spherical joint, which allows for three degrees of freedom. 
       FIG.  11    illustrates an embodiment of one end of a crane tensioning assembly  1100 . The crane tensioning assembly  1100  comprises a connection block  1102 , a tensioning member  1104 , and a pin  1106 . 
     The connection block  1102  has a plurality of cavities  1108  with each cavity sized and shaped to receive an end of a tensioning member  1104 . The connection block  1102  has a bore  1110  that extends through a first cavity  1112  from among the plurality of cavities  1108 . The bore  1110  may extend from one lateral side  1114  of the connection block  1102  through the other lateral side  1116  of the connection block  1102 , or the bore  1110  may extend partially through the connection block  1102 . 
       FIG.  12    illustrates an exemplary tensioning member  1104 . The tensioning member  1104  has an eye  1200  disposed at a first end  1202  and may additionally have an eye  1204  disposed at an opposite end  1206  of the tensioning member. Between the eyes  1200 ,  1204  is a body  1208  formed of fibers having a specific tensile strength greater than 1000 kilonewton meters per kilogram. In some embodiments the tensioning member  1104  may be the flexible support member  200  shown in  FIG.  2   . In other embodiments the tensioning member  1104  may be a rope having an eye. In use, the tensioning member  1104  is disposed within a cavity from among the plurality of cavities  1108  such that the eye  1200  has a centerline coaxial with a centerline of the bore  1110  extending through the cavity. 
     The pin  1106  is disposed in the bore  1110  and extends into a cavity and through the eye  1200  of the tensioning member  1104 , fixing the tensioning member  1104  in place. The pin  1106  may be a clevis pin, having an enlarged head preventing the pin  1106  from passing completely through the bore  1110  and a cotter pin preventing the pin  1106  from being removed from the bore  1110 . In some embodiments the bore  1110  may have a threaded portion and the pin  1106  may be a bolt passing through the cavities and threaded into the threaded portion of the bore  1110 . In other embodiments the pin  1106  may have a retaining clip preventing the pin  1106  from being removed from the bore  1110 . 
     In embodiments in which the bore  1110  extends through more than one cavity, the pin  1106  may extend through more than one cavity such that the pin is able to fix more than one tensioning member  1104  in place.  FIG.  13    illustrates the crane tensioning assembly of  FIG.  11   , but with a first tensioning member  1300  and a second tensioning member  1302  in place of the single tensioning member  1104  of  FIG.  11   . The pin  1106  extends through the eye  1200  of the first and second tensioning member  1300 ,  1302  such that the single pin  1106  secures both tensioning members.  FIG.  14    illustrates the connection block of  FIG.  11   , but with three tensioning members  1400 ,  1402 ,  1404 . The pin  1106  extends through the eyes  1200  of all three tensioning members.  FIG.  15    illustrates the connection block  1102  of  FIG.  13   , but with a separate pin  1500 ,  1502  securing each of the first tensioning member  1300  and the second tensioning member  1302 . 
     The connection block  1102  may have a second bore  1122  that does not extend through any of the plurality of cavities  1108 . The second bore  1122  may be sized and shaped to receive a pivot spindle. In some embodiments, the connection block  1102  may have a ball disposed opposite the plurality of cavities. The ball may be used in the ball and socket joint described in relation to  FIG.  9   . 
       FIG.  16    illustrates another embodiment of a connection block  1600 . The connection block  1600  has a first plurality of cavities  1602  sized and shaped to receive an end of a tensioning member  1104  and a second plurality of cavities  1604  sized and shaped to receive an end of a tensioning member  1104 . A first bore  1606  extends through the first plurality of cavities  1602  and a second bore  1608  parallel to the first bore  1606  extends through the second plurality of cavities  1604 . The second plurality of cavities  1604  may be the same size and shape as the first plurality of cavities  1604 , or in some embodiments they may be sized and shaped to receive a different size of tensioning members. In the embodiment of  FIG.  16    a first pin (not shown) secures the tensioning members  1104  in the first plurality of cavities  1602  and a second pin (not shown) secures tensioning members  1104  in the second plurality of cavities  1604 . 
       FIG.  21    illustrates an exploded view of another embodiment of a connection block  2100 . The connection block  2100  has a plate  2102  with two arms  2104  extending from the plate  2102 . The plate  2102  acts as a rotating connection between an existing pivot point on a crane and the connection block  2100 . Each arm  2104  may be formed as an individual component as shown in  FIG.  21   , or may be a single piece integral with the plate  2102 . A clevis  2106  is disposed between the two arms  2104  and a pin  2108  secures the clevis  2106  in place. Each arm  2104  has an aperture  2110  sized and shaped to receive the pin  2108 . The clevis  2106  has an aperture  2112  that is aligned with the arm aperture  2110  and the pin  2108  is inserted through the aperture  2110  of the arm  2104  and through the aperture  2112  of the clevis  2106 . A first end of the pin  2108  has an enlarged portion  2114  that prevents the pin  2108  from passing completely through the aperture  2110 , and the other side of the pin  2108  has an aperture  2116  for receiving a locking pin. With the locking pin inserted in the pin  2108 , the pin  2108  is unable to be removed from the apertures  2110 ,  2112  due to interference between the locking pin and the arm  2104 . 
       FIG.  22    illustrates the connection block  2100  of  FIG.  21    in an assembled state. An aperture  2118  in the plate  2102  provides a rotating connection to a point on a crane enabling rotation about a first axis  2120 . The clevis  2106  is connected to the arms  2104  and is free to rotate about a second axis  2122  that perpendicular to the first axis  2120  allowing two degrees of freedom. A flexible tensioning member such as those described in relation to  FIG.  7   , may have an eye  1200  placed in the clevis  2106  and a second pin is inserted through a second aperture  2124  in the clevis  2106 , securing the flexible tensioning member in place. 
       FIG.  25    illustrates another embodiment of a connection block  2500 . This connection block  2500  has a base  2602 , a clevis  2604 , a small pin  2606 , and a large pin  2608 . The base  2602  is configured to be inserted through an aperture of a plate on a crane with an enlarged portion  2610  preventing the base  2602  from passing through the plate. The enlarged portion  2610  may have a bearing between it and the plate, allowing the base  2602  to rotate relative to the plate. In other embodiments, a bearing may be internal to the base  2602  such that a portion of the base  2602  may rotate relative to the remainder of the base  2602 . Opposite the enlarged portion  2610 , the base  2602  has an aperture  2612  passing through the base  2602 . The aperture  2612  is sized and shaped to receive a pin. The base  2602  may also have a recessed portion sized and shaped to receive a portion of the clevis  2604 . In other embodiments, the clevis  2604  may have a recess sized and shaped to receive a portion of the base  2602 . 
     The clevis  2604  has a plurality of arms  2614  on one side and an extended portion  2616  for connection to the base  2602 . The extended portion  2616  may be inserted into the recess of the base  2602  aligning the aperture  2612  of the base with an aperture  2618  of the clevis  2604 , or in other embodiments the extended portion  2616  may receive a portion of the base  2602  aligning the aperture  2618  of the clevis with the aperture  2612  of the base. The small pin  2606  is then inserted through the apertures  2612 ,  2618 , securing the base  2602  to the clevis  2604 . The plurality of arms  2614  of the clevis  2604  form a series of recesses  2620  sized and shaped to receive a tensioning member, such as those described previously. A second aperture  2622  passes through the arms  2614  such that when an eye of a tensioning member is positioned in the recess  2620 , the large pin  2608  may be inserted through the recesses and the eye, securing the tensioning member in the recess  2620 . 
       FIG.  26    illustrates the connection block  2500  in an assembled configuration. In use, the connection block  200  may be used with an existing pivot joint, such as the pivot joint shown in  FIGS.  8  and  9   . The connection block  2500  may replace connection block  806  or connection block  902 . In one embodiment, the connection block  2500  may be used at a pivot joint at a foot of a boom. The connection block  2500  provides an additional degree of freedom preventing torsional stress of the tensioning member. 
       FIG.  20    illustrates a schematic of a crawler type crane  16 . The crane  16  has a lattice boom  161  formed of multiple sections. A mast  162  extends laterally from the boom  161  and is connected directly to a first end of the boom  161 . The mast  162  is connected to a second end of the boom  161  through a system of flexible tensioning members  163 . The flexible tensioning members  163  provide additional support to the second end of the boom  161  and may effect movement of the boom  161 . Because of the extended length of the boom  161 , many flexible tensioning members  163  may be joined end to end to span the distance between the mast  162  and the second end of the boom  161 . Multiple flexible tensioning members  163  may also be used in parallel to increase the load capacity of the system of flexible tensioning members  163 . 
       FIG.  17    illustrates a schematic of a mobile crane  170 . The mobile crane  170  has a telescoping boom  171  that is supported by system of flexible tensioning members  172 . A mast  173  extends laterally from the boom  171  to offset the flexible tensioning members  172  from the boom  171 . During setup, the mast  173  may pivot about the boom  171 , requiring the flexible tensioning member  172  to pivot as well. As described previously, the tensioning members  172  are designed with an attachment to the mast  173  that allows for rotation and movement of the flexible tensioning member  172  relative to the mast  173 . 
       FIG.  18    illustrates a schematic of a mobile platform crane  180 . The crane  180  has a telescoping column  181  with a boom assembly  182  disposed on the end of the telescoping column  181 . The telescoping column  181  is supported through the use of flexible tensioning members  183  that extend from the boom assembly  182  to outriggers  184  at the base of the crane  180 . The flexible tensioning members  183  may be joined end to end to span the distance between the outriggers  182  and the boom assembly  182 . 
       FIG.  19    illustrates a schematic of a tower crane  190 . The tower crane  190  has a lattice tower  191  with a boom  192  disposed on the top of the lattice tower  190 . To support the boom  192 , flexible tensioning members  193  are to connect a mast  194  to the boom  192 . 
     The previously described embodiments of tensioning members, tensioning systems, and connection blocks may be used in the cranes described in  FIGS.  17  through  20   . For example, flexible tensioning member  200  may be used as tensioning members  163 ,  172 ,  183 , and  193 . Because flexible tensioning member  200  is of lighter weight than a similar steel tensioning member, fewer tensioning members are necessary than if steel tensioning members were used. Furthermore, the described connection block and static tensioning assembly may be used to connect the flexible tensioning member  200  to the mast and boom of the described cranes. 
     The present invention, in various embodiments, includes providing devices and processes in the absence of items not depicted and/or described herein or in various embodiments hereof, including in the absence of such items as may have been used in previous devices or processes, e.g., for improving performance, achieving ease and/or reducing cost of implementation. 
     The foregoing discussion of the invention has been presented for purposes of illustration and description. The foregoing is not intended to limit the invention to the form or forms disclosed herein. In the foregoing Detailed Description for example, various features of the invention are grouped together in one or more embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the following claims are hereby incorporated into this Detailed Description, with each claim standing on its own as a separate preferred embodiment of the invention. 
     Moreover, though the description of the invention has included description of one or more embodiments and certain variations and modifications, other variations and modifications are within the scope of the invention, e.g., as may be within the skill and knowledge of those in the art, after understanding the present disclosure. It is intended to obtain rights which include alternative embodiments to the extent permitted, including alternate, interchangeable and/or equivalent structures, functions, ranges or steps to those claimed, whether or not such alternate, interchangeable and/or equivalent structures, functions, ranges or steps are disclosed herein, and without intending to publicly dedicate any patentable subject matter.