Patent Publication Number: US-7905066-B2

Title: Automatic take-up device and in-line coupler

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an automatic take-up coupler. The coupler is adapted for maintaining two structural members in tension. The coupler of the present invention is connected to two elongated tension members and is designed to draw the two elongated tension members together where dimensional changes in the structures occur as in shrinkage of the wood materials. 
     The device is adapted for maintaining the tension forces between a pair of elongated tension members. The present invention is inserted between two elongated tension members and is designed to allow the ends of the two elongated tension members it connects to draw together, if conditions push the two proximal ends closer to each other or tension on the two ends is reduced. 
     The present invention is particularly suited for use with tie-down systems used to anchor wood-framed buildings to their foundations. Many such systems use a rod or bolt or an in-line series of rods or bolts that are anchored at their lower end to either a lower member of the building or directly to the foundation of the building. The upper ends of the bolt or rod or the series are connected to a plate or a bracket which, in turn, is connected to or rests upon an upper portion of the building. Intermediate portions or levels of the building may also be connected to the rod or the series of rods. Where the rod or series of rods is connected to the building, the rod or bolt is usually connected to the bracket by means of a nut thread onto the bolt or rod that presses against the plate or bracket. The rod or series of rods is placed in tension by tightening the nut against the plate or bracket that receives the rod or bolt and tensioning any coupling devices between the rods. 
     Tying elements of the building together with straps or cables is particularly intended to prevent damage or destruction to the building in the event of cataclysmic occurrences such as earthquakes, flooding or high winds. U.S. Pat. No. 573,452, granted Dec. 22, 1896, to Delahunt teaches the use of a standard turnbuckle to connect threaded rods that tie a building to its foundation. 
     For the rod or series of rods to serve as an effective anchor for the building it is important that the rod or series of rods remain in tension. However, a number of different factors can cause the tie-down system to lose its tension. 
     One such factor is wood shrinkage. Most lumber used in wood-frame construction has a water content when the building is constructed that is relatively high in comparison to the water content in the lumber after the building has been assembled. Once the envelope of the building is completed, the lumber is no longer exposed to the relatively humid outside air, and it begins to lose moisture which leads to shrinkage. A standard 2×4 can shrink by as much as 1/16″ of an inch across its grain within the first two years that it is incorporated in a building. 
     Delahunt &#39;452 taught that as wood building structural members shrink during the life of the building, the cables will go slack and lose their ability to hold the wood members together. The turnbuckles that coupled the rods together in Delahunt &#39;452 enabled workmen to hand rotate the turnbuckles to tighten the cables connecting the foundation and the roof or to connect wood roof members to other wood roof members. See also Williams, U.S. Pat. No. 5,664,389, granted Sep. 9, 1997, which uses non-adjustable clamps to couple multiple lengths of reinforcing bar to tie a roof structure of a multistory wood frame building to a concrete foundation. 
     In most wood frame structures, the cables and devices to tighten the cables, such as turnbuckles are buried within the structure after construction is completed. Manually turning the turnbuckles or other devices used to re-tension the cables is an expensive proposition particularly where building panels must be removed to reach the turnbuckles or other tightening devices. 
     Most of the wood shrinkage occurs during the first couple of years after construction but can continue at a much slower rate for several years. Since any loose connections in the building, during oscillating forces imposed on a building, such as during earthquakes, floods, and high wind, increase the probability of damage or destruction to the building, efforts have been made to tighten the connections by the use of automatic take-up devices. 
     A wide variety of methods have been proposed to automatically maintain the tension in anchoring rods and bolts used in tie down systems for buildings, so that an operator need not tighten them manually. See, for example: U.S. Pat. No. 5,180,268, granted to Arthur B. Richardson on Jan. 12, 1993; U.S. Pat. No. 5,364,214, granted to Scott Fazekas on Nov. 15, 1994; U.S. Pat. No. 5,522,688, granted to Carter K. Reh on Jun. 4, 1996; or U.S. Pat. No. 5,815,999, granted Oct. 6, 1998 to Williams. These devices are interposed between two work members and expand as the two members separate, maintaining the connection or contact between them. These devices are designed to expand without reversing or contracting once they are installed. 
     Another approach is taught by U.S. Pat. No. 4,812,096. This patent was granted to Peter O. Peterson on Mar. 14, 1989. In this method, the tension rods are pulled into connecting brackets as the building shrinks and settles, such that the over-all length of the tie-down system is reduced. 
     The present invention represents an improvement over the prior art methods. The present invention provides a novel take-up tension device that like Peterson &#39;096 reduces the over-all length of the tie-down system as the tension in the in-line rod system attempts to reduce. The present invention is fully adjustable within a certain range of movement and provides a rigid force transmitting mechanism. Certain embodiments of the present invention also provide shielding for some of the working mechanisms of the device from the elements and dirt and grime. 
     The preferred coupler of the present invention is intended to be used in conjunction with holdowns and continuous tiedowns, as part of a restraint system in a wood or steel frame construction, to remove slack from the system by compensating for shrinkage and/or settlement of the framing. The preferred coupler of the present invention is an in-line coupling device that connects threaded rods together between storey levels, and maintains a tight configuration when shrinkage and/or settlement occurs. The device can be installed at any height in the wall, and is capable of compensating for up to one inch (25 mm) of shrinkage and/or settlement from the storey level above. Reducing couplers allow transitions between different rod diameters. Each end of the coupler is manufactured to create a positive stop for the threaded rod. The coupler has witness holes to allow for inspection of proper thread engagement. 
     SUMMARY OF THE INVENTION 
     The present invention consists of a connection, having a first elongated tension member, and a second elongated tension member and a contraction device or coupler that receives the first and second tension members and is loaded in tension by its connection to the first and second structural tension members. 
     The objective of the present invention is to provide an automatic take-up coupler which is relatively small, relatively inexpensive and easy to install. 
     Another objective is to provide an automatic take-up coupler which will reliably achieve a selected design tension during a reasonable selected time period in the life of the building. 
     A still further objective is to provide an automatic take-up coupler which has reduced frictional turning resistance to the take-up action of the device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a connection formed in accordance with the present invention, utilizing a coupler formed in accordance with the present invention and having a single surrounding sleeve. 
         FIG. 2  is an exploded perspective view of a connection formed in accordance with the present invention, utilizing a coupler formed in accordance with the present invention and having a single surrounding sleeve. 
         FIG. 3  is an exploded cutaway side elevation view of a coupler formed in accordance with the present invention and having a single surrounding sleeve. 
         FIG. 4  is a top plan view of a surrounding sleeve of a coupler formed in accordance with the present invention and having a single surrounding sleeve. 
         FIG. 5  is a side elevation cutaway view of a surrounding sleeve of a coupler formed in accordance with the present invention and having a single surrounding sleeve. 
         FIG. 6  is a bottom plan view of a surrounding sleeve of a coupler formed in accordance with the present invention and having a single surrounding sleeve. 
         FIG. 7  is a side elevation view of a second end connection member of a coupler formed in accordance with the present invention and having a single surrounding sleeve. 
         FIG. 8  is a bottom plan view of a second end connection member of a coupler formed in accordance with the present invention and having a single surrounding sleeve. 
         FIG. 9  is a top plan view of a first rotational member of a coupler formed in accordance with the present invention and having a single surrounding sleeve. 
         FIG. 10  is a side elevation cutaway view of a first rotational member of a coupler formed in accordance with the present invention and having a single surrounding sleeve. 
         FIG. 11  is a bottom plan view of a first rotational member of a coupler formed in accordance with the present invention and having a single surrounding sleeve. 
         FIG. 12  is a perspective cross-section of a connection formed in accordance with the present invention, utilizing a coupler formed in accordance with the present invention and having two surrounding sleeves. 
         FIG. 13  is an exploded perspective cross-section of a connection formed in accordance with the present invention, utilizing a coupler formed in accordance with the present invention and having two surrounding sleeves. 
         FIG. 14  is a perspective view of a connection formed in accordance with the present invention, utilizing a coupler formed in accordance with the present invention and having two surrounding sleeves. 
         FIG. 15  is a perspective view of a connection formed in accordance with the present invention, utilizing a coupler formed in accordance with the present invention and having two surrounding sleeves. 
         FIG. 16  is an exploded perspective view of a connection formed in accordance with the present invention, utilizing a coupler formed in accordance with the present invention and having two surrounding sleeves. 
         FIG. 17  is a perspective view of a connection formed in accordance with the present invention, utilizing a coupler formed in accordance with the present invention and having two rotational members. 
         FIG. 18  is an exploded perspective view of the connection shown in  FIG. 17 , utilizing a coupler formed in accordance with the present invention and having two rotational members. 
         FIG. 19  is a side elevation view of the connection shown in  FIG. 17 , utilizing a coupler formed in accordance with the present invention and having two rotational members. 
         FIG. 20  is a side elevation view of the connection shown in  FIG. 17 , utilizing a coupler formed in accordance with the present invention and having two rotational members. 
         FIG. 21  is a perspective view of a wall showing a pair of connections formed in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown in  FIG. 1 , the coupler  8  of the preferred form of the present invention includes a surrounding sleeve  9 , a first rotational member  15 , and a torsion spring  20 . The preferred coupler  8  compensates for wood shrinkage and settlement due to dead load and construction loading, which occur in continuous tiedown systems, and uplift load path systems in wood and steel framed structures. The preferred coupler  8  is an in-line coupling device that compensates for up to one inch of wood shrinkage and settlement from the level above. The coupler  8  connects threaded rods together between storey levels, and maintains a tight configuration when shrinkage or settlement occurs. The preferred device can be installed at any height in the wall. Reducing couplers  8  allow transition between different rod diameters. The coupler  8  is generally not required to lift dead load. 
     The torsion spring  20  must have sufficient energy to rotate the surrounding sleeve  9  and the first rotational member  15  so as to be capable of overcoming the friction resistance of the threads. 
     Furthermore, the torsion spring  20  must be capable of rotating the surrounding sleeve  9  in relation to the first rotational member  15  a sufficient number of times to maintain the design selected tension in the first and second elongated tension members  2  and  5 . 
     As shown in  FIG. 21 , in the preferred embodiment, the dimension of the coupler  8  is small enough so that the torsion spring  20  may be mounted within the walls of the building  58  or other confined space. The present invention is a connection  1  that includes a first elongated tension member  2 , a second elongated tension member  5 , and a coupler  8 . 
     As shown in  FIGS. 3 and 21 , the first elongated tension member  2  has a proximal end  3  and a distal end  4 . The first elongated tension member  2  is anchored at its distal end  4 . The first elongated tension member  2  could be anchored in the foundation of the building  59  or it could be attached to another elongated tension member below it by means of a coupler  8  of the present invention. The second elongated tension member  5  has a proximal end  6  and a distal end  7 . The second elongated tension member  5  is anchored at its distal end  7 . The second elongated tension member  5  could be anchored to a bracket attached to the building  59  or to another elongated tension member above it by means of a coupler  8 . 
     As shown in  FIG. 1 , the proximal ends  3  and  6  of the first and second elongated tension members  2  and  5  are disposed in close proximity to each other. The coupler  8  is attached to the proximal ends  3  and  6  of the first and second elongated tension members  2  and  5 , connecting the first and second elongated tension members  2  and  5  together. 
     The coupler  8  includes a surrounding sleeve  9 , a first rotational member  15 , and a torsion spring  20 . The surrounding sleeve  9  has a connection end  10  and a take-up end  11 , and a central bore  12 . At least a portion of the central bore  12  is formed as a substantially cylindrical inner surface  13  and at least a portion of the cylindrical inner surface  13  is formed with a thread  14 . The first rotational member  15  has a proximal end  16  and a distal end  17 . The first rotational member  15  is received in the central bore  12  of the surrounding sleeve  9  and is operatively connected to the surrounding sleeve  9 . The first rotational member  15  has a substantially cylindrical outer surface  18  formed with a thread  19  that mates with the thread  14  of the cylindrical inner surface  13  of the surrounding sleeve  9 . The first rotational member  15  is connected to the surrounding sleeve  9  only by the mating attachment of the thread  19  on the cylindrical outer surface  18  with the thread  14  of the surrounding sleeve  9 , so that the first rotational member  15  can rotate in relation to the surrounding sleeve  9 . The torsion spring  20  connects the first rotational member  15  and the surrounding sleeve  9 . The torsion spring  20  biases the first rotational member  15  and the surrounding sleeve  9  in opposite rotational directions so that the first rotational member  15  can be drawn into the surrounding sleeve  9 . 
     As shown in  FIG. 1 , the torsion spring  20  is attached to the first rotational member  15  and the surrounding sleeve  9  by insertion into spring retaining openings  75  on the first rotational member  15  and the surrounding sleeve  9 . 
     As shown in  FIG. 1 , preferably, the coupler  8  also includes a locking clip  21  that is releasably attached to the coupler  8 . The locking clip  21  holds the surrounding sleeve  9  and the first rotational member  15  in a selected relationship so that the first rotational member  15  cannot travel further into the surrounding sleeve  9 . The locking clip  21  thereby prevents the surrounding sleeve  9  and the first rotational member  15  from rotating under the influence of the torsion spring  20  and causing the coupler  8  to contract. 
     The coupler  8  preferably has a first end  22  and a second end  23 , with a first coupling aperture  24  at the first end  22  and a second coupling aperture  25  at the second end  23 . The first elongated tension member  2  is inserted in the first coupling aperture  24  and the second elongated tension member  5  is inserted in the second coupling aperture  25 . 
     Preferably, the proximal end  3  of the first elongated tension member  2  is at least partially formed with a thread  26  where the coupler  8  attaches to the first elongated tension member  2 . Preferably, the proximal end  6  of the second elongated tension member  5  is at least partially formed with a thread  27  where the coupler  8  attaches to the second elongated tension member  5 . Preferably, the coupler  8  attaches to the first and second elongated tension members  2  and  5  by means of a first internally threaded portion  28  accessible through the first coupling aperture  24  and a second internally threaded portion  29  accessible through the second coupling aperture  25 . The first and second internally threaded portions  28  and  29  mate with the threads  26  and  27  of the first and second elongated tension members  2  and  5 , respectively. In the preferred embodiment, the first and second internally threaded portions  28  and  29  are both formed with positive stops  60  for the threads  26  and  27  of the first and second elongated tension members  2  and  5 , so that the first and second elongated tension members  2  and  5  can only enter the coupler  8  a selected distance. This prevents the first and second elongated tension members  2  and  5  from interfering with the ability of the coupler  8  to contract. 
     Preferably, the first and second elongated tension members  2  and  5  are first and second threaded rods  2  and  5 . The first and second threaded rods  2  and  5  are preferably cut square and their design complies with code specifications. 
     As shown in  FIGS. 1 and 10 , the first rotational member  15  preferably has a central cavity  30 . At least a portion of the central cavity  30  of the first rotational member  15  is formed as a substantially cylindrical inner surface  31 . At least a portion of the cylindrical inner surface  31  is formed with an internal thread  32 . Preferably, the internal thread  32  of the cylindrical inner surface  31  of the first rotational member  15  receives the thread  26  of the proximal end  3  of the first elongated tension member  2 . 
     The internal thread  19  of the first rotational member,  15  near the proximal end  16  of the first rotational member  15 , is preferably disturbed so that it is not possible for the proximal end  3  of the first elongated tension member  2 , traveling on the internal thread  19 , to travel past a selected point  33  near the proximal end  16  of the first rotational member  15 . 
     As shown in  FIGS. 1 ,  3 ,  7  and  8 , preferably, a second end connection member  34  is received at least partially inside the central bore  12  of the surrounding sleeve  9  and is operatively connected to the surrounding sleeve  9 . The second end connection member  34  preferably has a proximal end  35  and a distal end  36 , and a central cavity  37 . At least a portion of the central cavity  37  is formed as a substantially cylindrical inner surface  38  and at least a portion of the cylindrical inner surface  38  is formed with an internal thread  39 . Preferably, the internal thread  39  of the cylindrical inner surface  38  of the second end connection member  34  receives the thread  27  of the proximal end  6  of the second elongated tension member  5 . 
     The internal thread  39  of the second end connection member  34 , near the proximal end  35  of the second end connection member  34 , is preferably disturbed so that it is not possible for the proximal end  6  of the second elongated tension member  5 , traveling on the internal thread  39 , to travel past a selected point  40  near the proximal end  35  of the internal thread  39 . As shown in  FIG. 5 , preferably, the second end connection member  34  is prevented from withdrawing from the connection end  10  of the surrounding sleeve  9  by a shoulder  41  on the surrounding sleeve  9 . 
     The second end connection member  34  preferably has a substantially cylindrical outer surface  42  where it is received within the surrounding sleeve  9  and the second end connection member  34  can freely rotate within the surrounding sleeve  9 . Preferably, the second end connection member  34  is completely received within the surrounding sleeve  9 . 
     In an alternate embodiment of the present invention shown in  FIGS. 12-16 , the connection  1  can be formed with a coupler  8  that also includes a supplemental surrounding sleeve  43  and a second torsion spring  49 . The supplemental surrounding sleeve  43  has a connection end  44  and a take-up end  45 , and a central bore  46 . At least a portion of the central bore  46  is formed as a substantially cylindrical inner surface  47  and at least a portion of the cylindrical inner surface  47  is formed with a thread  48 . 
     The distal end  17  of the first rotational member  15  is received in the central bore  46  of the supplemental surrounding sleeve  43  and is operatively connected to the supplemental surrounding sleeve  43 . The first rotational member  15  has a substantially cylindrical outer surface  18  formed with a thread  19  that mates with the thread  48  of the cylindrical inner surface  47  of the supplemental surrounding sleeve  43 . The first rotational member  15  is connected to the supplemental surrounding sleeve  43  only by the mating attachment of the thread  19  on the cylindrical outer surface  18  with the thread  48  of the supplemental surrounding sleeve  43 , so that the first rotational member  15  can rotate in relation to the supplemental surrounding sleeve  43 . The second torsion spring  49  connects the first rotational member  15  and the supplemental surrounding sleeve  43 . The torsion spring  49  biases the first rotational member  15  and the supplemental surrounding sleeve  43  in opposite rotational directions so that the first rotational member  15  can be drawn into the supplemental surrounding sleeve  43 . 
     As best shown in  FIG. 16 , in this embodiment of the present invention the thread  19  on the first rotational member  15  that mates with thread  48  of the supplemental surrounding sleeve  43  is oppositely threaded to the thread  19  on the first rotational member  15  that mates with the thread  14  of the surrounding sleeve  9 . 
     As shown in  FIG. 14 , the torsion springs  20  and  49  are attached to the first rotational member  15  and the surrounding sleeve  9  by insertion into spring retaining openings  75  on the first rotational member  15  and the surrounding sleeve  9  and the supplemental surrounding sleeve  43 . 
     As shown in  FIG. 12 , preferably, in this embodiment, the coupler  8  has a first end  22  and a second end  23 , a first coupling aperture  24  at the first end  22  and a second coupling aperture  25  at the second end  23 . The first elongated tension member  2  is inserted in the first coupling aperture  24  and the second elongated tension member  5  is inserted in the second coupling aperture  25 . 
     The proximal end  3  of the first elongated tension member  2  is preferably at least partially formed with a thread  26  where the coupler  8  attaches to the first elongated tension member  2 . The proximal end  6  of the second elongated tension member  5  is preferably at least partially formed with a thread  27  where the coupler  8  attaches to the second elongated tension member  5 . The coupler  8  preferably attaches to the first and second elongated tension members  2  and  5  by means of a first internally threaded portion  28  on the first coupling aperture  24  and a second internally threaded portion  29  on the second coupling aperture  25 . The first and second internally threaded portions  28  and  29  mate with the threads  26  and  27  of the first and second elongated tension members  2  and  5 , respectively. 
     As shown in  FIG. 12 , preferably, the supplemental surrounding sleeve  43  is provided with a first end connection member  50  and the first end connection member  50  has a central cavity  51 . At least a portion of the central cavity  51  is formed as a substantially cylindrical inner surface  52  and at least a portion of the cylindrical inner surface  52  is formed with an internal thread  53 . 
     The internal thread  53  of the cylindrical inner surface  52  of the first end connection member  50  preferably receives the thread  26  of the proximal end  3  of the first elongated tension member  2 . Preferably, the surrounding sleeve  9  is provided with a second end connection member  34 . 
     The second end connection member  34  preferably has a proximal end  35  and a distal end  36 , and a central cavity  37 . At least a portion of the central cavity  37  is formed as a substantially cylindrical inner surface  38  and at least a portion of the cylindrical inner surface  38  is formed with an internal thread  39 . Preferably, the internal thread  39  of the cylindrical inner surface  38  of the second end connection member  34  receives the thread  27  of the proximal end  6  of the second elongated tension member  5 . 
     In an alternate embodiment of the present invention shown in  FIGS. 17-20 , the connection  1  can be formed with a coupler  8  that also includes a supplemental surrounding sleeve  43  and a second rotational member  54 . As shown in  FIG. 18 , in this alternate embodiment, the supplemental surrounding sleeve  43  is connected to the surrounding sleeve  9 . The supplemental surrounding sleeve  43  has a connection end  44  and a take-up end  45 , and a central bore  46 . At least a portion of the central bore  46  is formed as a substantially cylindrical inner surface  47  and at least a portion of the cylindrical inner surface  47  is formed with a thread  48 . 
     As shown in  FIGS. 17 and 18 , in this embodiment, the second rotational member  54  is received in the central bore  46  of the supplemental surrounding sleeve  43  and is operatively connected to the supplemental surrounding sleeve  43 . The second rotational member  54  has a substantially cylindrical outer surface  55  formed with a thread  56  that mates with the thread  48  of the cylindrical inner surface  47  of the supplemental surrounding sleeve  43 . The second rotational member  54  is connected to the supplemental surrounding sleeve  43  only by the mating attachment of the thread  56  on the cylindrical outer surface  55  with the thread  48  of the supplemental surrounding sleeve  43 , so that the second rotational member  54  can rotate in relation to the supplemental surrounding sleeve  43 . 
     Preferably, in the alternate embodiment shown in  FIGS. 17-20 , the coupler  8  has a first end  22  and a second end  23 , a first coupling aperture  24  at the first end  22  and a second coupling aperture  25  at the second end  23 . The first elongated tension member  2  is inserted in the first coupling aperture  24  and the second elongated tension member  5  is inserted in the second coupling aperture  25 . 
     The proximal end  3  of the first elongated tension member  2  is preferably at least partially formed with a thread  26  where the coupler  8  attaches to the first elongated tension member  2 . The proximal end  6  of the second elongated tension member  5  is preferably at least partially formed with a thread  27  where the coupler  8  attaches to the second elongated tension member  5 . The coupler  8  preferably attaches to the first and second elongated tension members  2  and  5  by means of internally threaded portions  28  and  29  on the first and second coupling apertures  24  and  25  that mate with the threads  26  and  27  of the first and second elongated tension members  2  and  5 , respectively. 
     Preferably, the first rotational member  15  is provided with a first end connection member  50 . The first end connection member  50  has a central cavity  51 . At least a portion of the central cavity  51  is formed as a substantially cylindrical inner surface  52  and at least a portion of the cylindrical inner surface  52  is formed with an internal thread  53 . The internal thread  53  of the cylindrical inner surface  52  of the first end connection member  51  preferably receives the thread  26  of the proximal end  3  of the first elongated tension member  2 . 
     As shown in  FIG. 18 , in this alternate embodiment, preferably, the second rotational member  54  is provided with a second end connection member  34 . The second end connection member  34  preferably has a proximal end  35  and a distal end  36 , and a central cavity  37 . At least a portion of the central cavity  37  is formed as a substantially cylindrical inner surface  38  and at least a portion of the cylindrical inner surface  38  is formed with an internal thread  39 . Preferably, the internal thread  39  of the cylindrical inner surface  38  of the second end connection member  34  receives the thread  27  of the proximal end  6  of the second elongated tension member  5 . 
     As shown in  FIG. 4 , the distal end  4  of the first elongated tension member  2  is preferably connected to a structural member  57  in a building  58 . Preferably, the building  58  has a structural frame  59  at least a portion of which is made from wood. 
     Preferably, in the preferred embodiment shown in  FIGS. 1-11 , the surrounding sleeve  20  rotates in relation to the first rotational member  15 . Alternatively, in the embodiment shown in  FIGS. 12-16 , the first rotational member  15  rotates with respect to the surrounding sleeve  9  and the supplemental surrounding sleeve  43 . 
     There are five preferred models of the coupler  8  of the present invention, the ATS-CTUD55, ATS-CTUD77, ATS-CTUD75, ATS-CTUD99 and ATS-CTUD97. The surrounding sleeves  9  and first rotational members  15  of all five models are preferably formed from ASTM A311 Class B, Grade 1144 steel, with a minimum tensile strength of 126,000 psi (869 MPa), and minimum yield strength of 105,000 psi (724 MPa). The torsion spring  20  is preferably formed from ASTM A313, Type 631 stainless steel torsional wire. The ATS-CTUD55, ATS-CTUD77 and ATS-CTUD75 torsion springs  20  are preferably formed from 0.110 inch (2.8 mm) wire. The ATS-CTUD99 and ATS-CTUD97 torsion springs  20  are preferably formed from 0.115 inch (2.9 mm) wire. All five models are preferably coated for corrosion protection when exposed to moisture; the preferred coating is a manganese phosphate finish. 
     The ATS-CTUD55 coupler  8  preferably couples a first elongated tension member  2  that is ⅝ inch in diameter and a second elongated tension member  5  that is ⅝ inch in diameter; the ATS-CTUD55 is preferably 1 ⅞ inches in diameter and 5 inches long and has an allowable tension capacity of 15,520 pounds. The ATS-CTUD77 coupler  8  preferably couples a first elongated tension member  2  that is ⅞ inch in diameter and a second elongated tension member  5  that is ⅞ inch in diameter; the ATS-CTUD77 is preferably 2 inches in diameter and 5 ½ inches long and has an allowable tension capacity of 31,795 pounds. The ATS-CTUD75 coupler  8  preferably couples a first elongated tension member  2  that is ⅞ inch in diameter and a second elongated tension member  5  that is ⅝ inch in diameter—a reducing coupler; the ATS-CTUD75 is preferably 2 inches in diameter and 5 ½ inches long and has an allowable tension capacity of 31,795 pounds. The ATS-CTUD99 coupler  8  preferably couples a first elongated tension member  2  that is 1 ⅛ inches in diameter and a second elongated tension member  5  that is 1 ⅛ inches in diameter; the ATS-CTUD99 is preferably 2 ½ inches in diameter and 6 ⅛ inches long and has an allowable tension capacity of 55,955 pounds. The ATS-CTUD97 coupler  8  preferably couples a first elongated tension member  2  that is 1 ⅛ inches in diameter and a second elongated tension member  5  that is ⅞ inch in diameter—a reducing coupler; the ATS-CTUD97 is preferably 2 ½ inches in diameter and 6 ⅛ inches long and has an allowable tension capacity of 55,955 pounds. Allowable tension capacities are based on ultimate loads divided by a safety factor of 3 and do not include a 33 percent steel stress increase. The threads  26  and  27  of the first and second elongated tension members  2  and  5 , respectively, are both preferably UNC Class  2 A. 
     Preferably, the distal end  17  of the first rotational member  15  is threaded onto the first elongated tension member  2 , which is preferably the one of the first and second elongated tension members  2  and  5  that is below the coupler  8 . The first rotational member  15  is preferably threaded onto the first elongated tension member  2  until the first elongated tension member  2  reaches the positive stop  60  in the first rotational member  15  and can be fully seen in the witness holes  61  in the first rotational member  15 . The activation pins  62  at each end of the locking clip  21  are preferably facing out. Then the second elongated tension member  5  is preferably threaded into the connection end  10  of the surrounding sleeve  9  until the second elongated tension member  5  reaches the positive stop  60  in the surrounding sleeve  9 . The activation pins  62  are not removed until the entire system is installed and inspection of the thread engagements has been completed. Couplers  8  are installed at each level until the run is complete. After the run has been completed and thread engagement has been inspected, the tie wire  63  and activation pins  62  are removed from each coupler  8 . 
     An alternate preferred embodiment of the coupler  8  of the present invention is shown in  FIGS. 17 through 21 . In this alternate preferred embodiment, the coupler  8  includes a first coupler nut  64  and a second coupler nut  65 . The first end  22  of the coupler  8  is located on the first coupler nut  64 , and the second end  23  of the coupler  8  is located on the second coupler nut  65 . The thread  26  of the proximal end  3  of the first elongated tension member  2  is turned into the first internally threaded portion  28  accessible through the first coupling aperture  24  located in the first end  22  of the coupler  8 . The thread  27  of the proximal end  6  of the second elongated tension member  5  is turned into the second internally threaded portion  29  accessible through the second coupling aperture  25  located in the second end  23  of the coupler  8 . The thread  19  on the substantially cylindrical outer surface  18  at the distal end  17  of the first rotational member  15  is turned into the first internally threaded portion  28  of the first coupling aperture  24  opposite the first elongated tension member  2 . The thread  56  on the substantially cylindrical outer surface  55  of the second rotational member  54  is turned into the second internally threaded portion  29  of the second coupling aperture  26  opposite the second elongated tension member  5 . Preferably, the first rotational member  15  includes a circumferential stop  66  that is diametrically larger than the substantially cylindrical outer surface  18  of the first rotational member  15 . A plate member  67 , with a first aperture  68  that accepts and fits the substantially cylindrical outer surface  18  of the first rotational member  15 , is slipped over the proximal end  16  of the first rotational member  15  and slips down until it reaches the circumferential stop  66 . The plate member  67  preferably includes a second aperture  69  that accepts the threaded end  71  of spring-retaining pin  70 . The threaded end  71  passes through the second aperture  69  and is held in place by a nut  72 . In this alternate embodiment, the surrounding sleeve  9  is a spindle around which one end of a flat torsion spring  20  is wound. The other end of the flat torsion spring  20  is wound around the spring-retaining pin  70  in the opposite orientation from the winding around the surrounding sleeve  9 , so that the flat torsion spring  20  forms a compound S-curve. The torsion spring  20  is centered and aligned on the surrounding sleeve  9  by a pair of circumferential discs  73 , one of which is retained on the surrounding sleeve  9  by an enlarged nut  74  that is screwed onto the first rotational member  15 . The circumferential discs  73  also anchor one end of the torsion spring  20 . The thread  14  at the take-up end  11  of the substantially cylindrical inner surface  13  of the central bore  12  of the surrounding sleeve  9  is screwed down on the proximal end  16  of the first rotational member  15 . The thread  56  of the second rotational member  55  is screwed into the thread  14  at the connection end  10  of the substantially cylindrical inner surface  13  of the central bore  12  of the surrounding sleeve  9 .