Abstract:
A high force traction apparatus which operates along the cable linear axis with no cable bending. The cable is encircled with links from several looping chain drives. The links have a concave friction surface to match the cable radius. Rollers apply pressure to multiple links thereby providing a high normal force on the cable. The staggered and synchronized links keep the high squeeze force evenly distributed. This allows the traction apparatus to impose a pulling force that approaches the cable tensile limit without cable damage.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   Not Applicable 
   FEDERALLY SPONSORED RESEARCH 
   Not Applicable 
   SEQUENCE LISTING OR PROGRAM 
   Not Applicable 
   BACKGROUND OF THE INVENTION 
   This invention relates to the field of high force cable retraction means. Present devices generally utilize spool winding methods. These are limited in the amount of cable that can be retracted (only until the spool is full). Spool winding is also limited in maximum retraction force due to cable damage. The high force retraction causes excessive cable stress from bending and squeezing between the windings on the spool. 
   Rotating sheaves such as used for elevators cannot provide high force retraction. Elevators overcome this deficiency with counterweights and by utilizing multiple cables. 
   This invention further relates to a continuous cable pulling device (no limit on pulling length.) U.S. Pat. No. 4,256,199 granted to Sellards shows a serpentine device. This device is limited due to the high bending strains imposed on the cable. U.S. Pat. No. 5,009,353 granted to Alquist shows a continuous loop friction device. This device cannot provide a high normal force needed to achieve high pulling force. U.S. Pat. No. 4,456,226 granted to Stumpmeier shows a piston operated device to provide step action cable retraction. This intermittent motion limits the speed of the traction device and imparts repetitive accelerations on the cable. U.S. Pat. No. 5,082,248 granted to Harig shows a grooved bull wheel device with a continuous looping pressure chain. This apparatus provides continuous cable pulling. With additional pressure chains, the apparatus would also be capable of high pulling force. The disadvantages remaining would include the 360 degree cable bending arc, complexity, risk of the cable coming out of the bull wheel groove, and difficulty in threading cable through the apparatus. 
   The present invention further relates to gondola movement on a cable. The cable traction apparatus would be the motive force to cause movement of the gondola along the cable. In this configuration, the traction apparatus is affixed to the gondola and the cable is stationary. 
   SUMMARY OF THE INVENTION 
   The object of the invention is to provide a continuous and high force cable pulling mechanism. Two key systems are at work to accomplish this objective. The first system is a power linkage that converts rotary engine power to lineal force along the axis of the cable. This power linkage could consist of a group of gears, chain drives, belts, pneumatics, hydraulics or other power devices. A looping chain is used to apply this lineal force in a continuous manner. The second system provides the transfer of this lineal force to the cable. Frictional force is defined as the coefficient of friction times the normal force. The chain to cable coefficient of friction is nominally bounded by the materials used for the chain and cable. A reasonable clean steel to steel surface has a coefficient of friction of about 0.7 and is generally not able to be dramatically increased. A more direct method to dramatically increase the friction force is to increase the normal force. A group of rollers are used to provide the high normal force. 
   The moving chain links have a concave surface that matches the radius of the cable. This allows the high normal force to be distributed over a larger area. The limiting factor for normal force is to not exceed the stress deformation limit of the cable that is resisting this force. The cable is surrounded with two or more links—thus exerting even pressure completely around the cable. The normal force is applied to the chain links through pressure rollers. The pressure rollers and links are staggered in such a way that the force of the pressure roller is always distributed over a substantial area on the cable. This allows a much higher normal force to be applied without damaging the cable. The rollers are biased with Belleville springs. These springs are adjustable and provide a very high force over a short range of movement. 
   The invention includes several unique features as part of the mechanism. The multiple chain drives surround the cable. The drive line to bring this power to the chains from a single engine is accomplished in a unique manner. A worm drive pinion is positioned in a manner to allow the cable to run through the center of this pinion. Multiple worm output gears (one for each chain drive) are driven by this worm drive pinion. This gearing method keeps the multiple chain drives synchronized and reduces the number of parts required. The synchronization is required to maintain the staggered links. 
   The straight line path of the cable through the mechanism allows a smaller diameter pilot cable to freely pass through the device. The mechanism self engages the traction cable when it first contacts the moving chain links. 
   Further features include methods to maintain the optimum coefficient of friction between the chain links and cable.
         A cleaning surface is brought into contact with the moving chain to remove moisture or oil.   The drive mechanism is enclosed in a cabinet to limit snow or rain encursion.   Lip seals are provided at the cable entrance and exit to squeegee water or snow off the cable.   Heat is added to the cabinet to increase the temperature of the chain links and rollers. This is to aid in melting any ice on the cable and evaporate moisture.       

   The power linkage for this apparatus could be quite varied in configuration. The key requirements of the power linkage include:
         a. providing linear motion to the friction surface that contacts the cable   b. keeping the friction surfaces in synchronization       

   Other arrangements of gears, belts and chain drives that accomplish these requirements are readily apparent to one skilled in the art. 
   Some of the areas that further design engineering work could improve include:
         a. the sizing of components for power transfer or force—these could include V-belt section, shaft diameter, etc.   b. the style of components—these could include using a ball bearing rather than a sleeve, or a roller chain rather than a V-belt, etc.   c. methods for providing adjustment—these could include shims or adjustment screws for chain or V-belt length, bearing to shaft length, etc.   d. lubrication methods—these would include grease zerks, bearing oil reservoirs, chain greasing routines, etc.       

   These are all areas that the improvement would be readily apparent to one skilled in the art and are not integral to the present invention. For that reason, the details are not included in this specification. 

   
     DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       FIG. 1  is a side view of the cable traction apparatus. 
       FIG. 2  is a front view of the cable traction apparatus. 
       FIG. 3  is a section view through the centerline of the cable traction apparatus—taken along section lines  3 — 3  from  FIG. 2 . 
       FIG. 4  is a section view through the front wall of the gear case—taken along section lines  4 — 4  from  FIG. 1 . 
       FIG. 5  is a section view of the transfer chain—taken along section lines  5 — 5  from  FIG. 2 . 
       FIG. 6  is an enlargement of the gear case from  FIG. 3   
       FIG. 7  is a section view of the gear case drive details—taken along section lines  7 — 7  from  FIG. 1 . 
       FIG. 8  is a section view of the drive chain details—taken along section lines  8 — 8  from  FIG. 1 . 
       FIG. 9  is an enlargement of the drive chain and chain drive sprocket from  FIG. 3   
       FIG. 10  is a section view of the pressure roller—taken along section lines  10 — 10  from FIG. 
       FIG. 11  is a section view of the pressure roller collar—taken along section lines  11 — 11  from  FIG. 2 . 
       FIG. 12  is an enlargement of the Row  1  pressure roller from  FIG. 3   
       FIG. 13  is an isometric schematic view of the cable and links 
       FIG. 14  is a section view of the cable chain idler—taken along section lines  14 — 14  from  FIG. 1 . 
       FIG. 15  is an enlargement of the cable, chain drive and pressure rollers from  FIG. 10   
       FIG. 16  is a side view of the cable traction apparatus attached to a container. 
     
       
         
               
             
               
               
             
           
               
                   
               
               
                 REFERENCE NUMERALS OF THE DRAWING- 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                  25 cable 
                  26 base 
               
               
                  27 anchor bolts 
                  28 rear support 
               
               
                  29 engine rear support 
                  30 front support 
               
               
                  31 engine 
                  32 transmission/clutch 
               
               
                  33 output shaft 
                  34 engine pulley 
               
               
                  35 drive belt 
                  36 input pulley 
               
               
                  37 cabinet 
                  38 front cover 
               
               
                  39 rear cover 
                  40 side cover 
               
               
                  41 screw 
                  42 outlet hose 
               
               
                  43 return hose 
                  44 radiator 
               
               
                  45 louvers 
                  46 worm output gear 
               
               
                  47 chain drive sprocket 
                  48 pressure roller 
               
               
                  49 chain idler sprocket 
                  50 water pump 
               
               
                  51 transfer chain drive sprocket 
                  52 spacer cylinder 
               
               
                  53 support channel A 
                  54 gear case 
               
               
                  55 front axle block 
                  56 rear axle block 
               
               
                  57 drive chain 
                  58 cleaning block 
               
               
                  59 screw 
                  60 spring bracket 
               
               
                  61 bolt 
                  62 support channel C 
               
               
                  63 support channel B 
                  65 fan motor with shaft 
               
               
                  66 fan 
                  67 transfer chain driven sprocket 
               
               
                  68 worm gear shaft 
                  69 transfer chain 
               
               
                  70 sprocket shaft 
                  71 worm pinion 
               
               
                  72 inner worm gear bearing 
                  74 worm output seal 
               
               
                  75 outer worm gear bearing 
                  76 cabinet/cable lip seal 
               
               
                  77 gear case lip seal 
                  78 gear case cover lip seal 
               
               
                  79 gear case bearing 
                  80 gear case cover bearing 
               
               
                  81 bolt 
                  82 gear case cover 
               
               
                  83 gear case lubricant 
                  84 inner sprocket shaft bearing 
               
               
                  85 outer sprocket shaft bearing 
                  86 cable link 
               
               
                  87 bushing 
                  88 pin link plate 
               
               
                  89 pin 
                  90 cable link 
               
               
                  91 cable link 
                  92 cable link 
               
               
                  93 cable link 
                  94 pin 
               
               
                  95 adjustment screw 
                  96 collar for roller 
               
               
                  97 inner roller bearing 
                  98 outer roller bearing 
               
               
                  99 roller shaft 
                 100 Belleville spring 
               
               
                 101 pressure roller collar 
                 102 pressure roller collar 
               
               
                 103 cable link 
                 104 cable link 
               
               
                 105 cable link 
                 106 idler sprocket shaft 
               
               
                 107 cable idler wheel 
                 108 idler wheel bracket 
               
               
                 109 bolt 
                 110 cable traction apparatus 
               
               
                 111 gondola bracket 
                 112 gondola 
               
               
                 113 console 
                 114 operator 
               
               
                 115 window 
                 116 door 
               
               
                   
               
             
          
         
       
     
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  shows the side view of the cable traction apparatus. The cable  25  enters and passes through the cable traction apparatus in a straight line. This cable could typically be a steel wire rope such as the AISI (American Iron and Steel Institute) standard 6x27H flattened strand (3 wire center) IWRC (independent wire-rope core) shown in  FIG. 15 . A cable is frequently mentioned, however the apparatus would provide traction to any reasonably rigid and reasonably constant cross section elongate member. Examples of this could include pipe, hose, dowel, or rope. Other non-circular cross sections would include a box-beam or hex-pipe. For a non-circular cross section, the cable link  86 , shown in  FIG. 8 , would be shaped to match. The elongate member materials could include steel, aluminum, wood, copper and various multi-layer constructions. These shape and material examples are only representative and there are many others. 
   The base  26  provides support for the various mechanism parts. The anchor bolts  27  affix the base  26  to an immovable object such as earth footings or a building frame. The rear support  28 , engine rear support  29  and front support  30  are plate steel members to provide structure support. They are rigidly attached to the base  26 . 
   The engine  31  is an internal combustion device that provides the motive power for the cable traction apparatus. Alternate motive power methods such as an electric, pneumatic or hydraulic motor would be possible. The engine  31  output is directed to the transmission/clutch  32 . The transmission/clutch  32  provides speed reduction, reversal, and clutch action to the output shaft  33 . The engine pulley  34  is connected to the output shaft  33 . The V style belt  35  transfers power from the engine pulley  34  to the input pulley  36 . 
   The cabinet  37  is the main sheet metal enclosure of the apparatus. Additional enclosure parts include the front cover  38 , rear cover  39  and side cover  40 . All of the covers are attached via screws  41 . 
   Heated coolant is pumped from the engine  31  to the radiator  44  via the pump  50  and outlet hose  42 . The coolant exits the radiator  44  and returns to the engine  31  via the return hose  43 . The side panel  40  includes a plurality of louvers  45  to facilitate air movement to the radiator  44 . 
   Most of the internal parts in this view have been omitted for clarity. The following are included to provide position and perspective for section views—worm output gear  46 , chain drive sprocket  47 , pressure roller  48  and chain idler sprocket  49 . 
     FIG. 2  is a front view of the cable traction apparatus. The end view in crosshatch of the cable  25  is shown. This view more clearly shows the relationship of the engine pulley  33 , drive belt  35  and input pulley  36 . The cable  25  goes through the center of the input pulley  36 . There is a clearance between the two parts. Only the input pulley  36  rotates, not the cable  25 . 
   Most of the internal parts in this view have been omitted for clarity. The following are included to provide position and perspective for section views—transfer chain drive sprocket  51  and spacer block  52 . 
     FIG. 3  is a section view through the centerline of the cable traction apparatus—taken along section lines  3 — 3  from  FIG. 2 . This section view is down the center of the apparatus. The cable  25  can be seen fully sectioned and continuous from one end to the other. The rear support  28  and front support  30  are shown extending into the cabinet  37 . For clarity, many of the details behind the section line have been omitted. The internal attachments to the rear support  28  and front support  30  fit this criteria and will be shown in later sections. 
   The drive belt  35  extends into the cabinet  37  via a cabinet opening that allows belt motion. Support channel A  53 , support channel B  63  and support channel C  62  are the main structural elements in the apparatus. Only support channel A  53  is shown in this section view. The gear case  54  houses the worm gear  46 . 
   There are three front axle blocks  55  and three rear axle blocks  56 . Only one of each is shown in this section view. 
   The pressure roller  48  and spacer block  52  in row  1  are identified in this section view. The five rows of pressure rollers are shown. 
   The chain drive sprocket  47  and chain idler sprocket  49  are shown. They are connected with multiple links of the drive chain  57 . 
   The cleaning block  58  is composed of a flexible porous material and pressed against the drive chain  57 . The pressure is caused by the spring bracket  60 . The spring bracket  60  is connected to the cleaning block  58  and cabinet  37  via multiple screws  59 . The relative motion between the cleaning block  58  and chain drive  57  would remove moisture and grease substances from the chain drive  57 . This contaminant removal is desired to maintain a high coefficient of friction between the chain drive  57  and the cable  25 . There are three sets of cleaning blocks  58  and spring brackets  60 . One for each of the three chain drives  57 . Only one is shown in this section view. 
   The power transmission path of the cable traction apparatus is as follows. Not all of the below components are shown on  FIG. 3 . Some will be first shown on  FIG. 5 .
         1. The engine  31  output goes through the transmission/clutch  32  to the output shaft  33 .   2. The output shaft  33  is connected to the engine pulley  34  that drives the belt  35 .   3. The belt  35  rotates the input pulley  36 .   4. The input pulley  36  rotates the worm pinion  71 .   5. The worm pinion  71  causes rotation of the worm gear  46  and worm gear shaft  68 .   6. The worm gear shaft  68  is connected to the transfer chain drive sprocket  51 .   7. The transfer chain drive sprocket  51  drives the transfer chain driven sprocket  67  and sprocket shaft  70  via the transfer chain  69 .   8. The sprocket shaft  70  is connected to chain drive sprocket  47 .   9. The chain drive sprocket  47  drives the drive chain  57  in conjunction with the chain idler sprocket  49 .   10. The drive chain  57  contacts the cable  25  and imparts linear motion.       

   There is one worm pinion  71 , but it drives three output axis of approximately identical gear train. Steps 5 thru 10 above are repeated on axis A, axis B and axis C. 
     FIG. 4  is a section view through the front wall of the gear case  54 —taken along section lines  4 — 4  from  FIG. 1 . The gear case  54  is shown fully in cross section because this particular section view is taken through the front wall of the gear case  54 . The gear case  54  is a cast part that attaches to support channel A  53 , support channel B  63  and support channel C  62  via bolts  61 . Support channel B  63  and support channel C  62  also attach to front support  30  via bolts  61 . 
   The cabinet  37  attaches to the three support channels ( 53 ,  62 ,  63 ) via brackets and screws. These brackets and screws are not shown. The radiator  44 , return hose  43 , fan motor with shaft  65  and fan  66  are shown. The radiator  44  and fan motor with shaft  65  are attached via brackets and screws to the cabinet  37 . These brackets and screws are not shown. In operation, outside air is drawn through louvers  45  and heated at it passes through the radiator  44 . The fan motor with shaft  65  is reversible. This allows the air flow to be reversed for warmer outside temperatures. In this situation, no heat would be added to the cabinet  37 . 
     FIG. 5  is a section view of the transfer chain  69 —taken along section lines  5 — 5  from  FIG. 2 . The worm gear shaft  68  is attached to the transfer chain drive sprocket  51 ) The rotation of the transfer chain drive sprocket  51  engages the transfer chain  69  and causes rotation of the transfer chain driven sprocket  67 . The transfer chain  69  is an ANSI (American National Standards Institute) roller chain. The transfer chain driven sprocket  67  is attached to the sprocket shaft  70 .  FIG. 5  shows only the axis A transfer chain and related components. Axis B and axis C have similar components. 
     FIG. 6  is an enlargement of the gear case  54  from  FIG. 3 . The cabinet/cable lip seal  76  is shown. This flexible part is press fit to the front cover  38  and slides on the cable  25 . The purpose is to limit the entrance of contaminants such as water into the cabinet  37 . It also helps remove any adhering contaminant from the cable surface as it passes into the cabinet  37 . 
   The input pulley  36  rotates on the gear case bearing  79  and the gear case cover bearing  80 . The clearance between the input pulley  36  and the cable  25  is shown. This clearance is needed to prevent the input pulley  36  rotation from damaging the cable  25 . The worm pinion  71  is press fit to the input pulley  36 . The gear case cover  82  is attached to the gear case  54  with several bolts  81 . The gear case lip seal  77  and gear case cover lip seal  78  are part of the sealed enclosure that is filled with gear case lubricant  83 . 
   The worm pinion  71  engages the worm gear  46  that rotates with the worm gear shaft  68 . The worm gear  46  is press fit to the worm gear shaft  68 . Worm gearing is standard engineering design. It provides high gear reduction, a 90 degree change in axis of rotation and requires good lubrication due to the sliding contact of the worm teeth. A unique feature of a worm drive is the ability to have one worm pinion engage several worm gears. 
     FIG. 7  is a section view of the gear case  54  drive details—taken along section lines  7 — 7  from  FIG. 1 . The worm gear shaft  68  rotates in the inner worm gear bearing  72  and the outer worm gear bearing  75 . The worm output seal  74  completes the gear case  54  enclosure seal. This view shows the axis A, axis B and axis C worm gears  46  engaging the worm pinion  71 . The clearance as shown in the view is a result of the worm pinion  71  and worm gear  46  tooth geometry in the section plane. As the worm pinion  71  rotates, the three worm gears  46  rotate in a synchronized manner. This synchronization between the three axes will be an important part of the later drive train cable contact. 
   The transfer chain drive sprocket  51  and transfer chain  69  are also shown. Only the axis A components have been labeled. The axis B and axis C components are identical. 
     FIG. 8  is a section view of the drive chain  57  details—taken along section lines  8 — 8  from  FIG. 1 . The sprocket shaft  70  rotates in the inner sprocket shaft bearing  84  and the outer sprocket shaft bearing  85 . The front axle block  55  is attached to support channel A  53  via bolts  61 . The transfer chain drive sprocket  67  and the chain drive sprocket  47  are press fit to the sprocket shaft  70 . The detail parts of the chain drive  57  are itemized. They include the cable link  86 , bushing  87 , pin link plate  88  and pin  89 . All except the cable link  86  would be ANSI (American National Standards Institute) roller chain parts. The sides of the cable link  86  would be similar to an ANSI roller link part, but the top would be shaped to match the radius of the cable  25 . Only the axis A components have been labeled. The axis B and axis C components are identical. Note that there are three separate front axle blocks  55  for the three axes. 
   The friction surface that contacts the cable  25  is shown as a roller chain cable link  86 . The requirements of the friction surface are:
         a. wear resistance   b. bending strength   c. reasonable coefficient of friction against the cable  25     d. properly contoured to match the cable  25  and evenly distribute the pressure load   e. have a linear drive action along the cable  25  axis       

   Other friction surface alternatives could include a contoured part attached to a flexible V belt or a wire mesh belt. There are a variety of friction surface materials that meet the above requirements. 
     FIG. 9  is an enlargement of the drive chain  57  and chain drive sprocket  47  from  FIG. 3 . The centerline distance from the sprocket shaft  70  to the cable  25  is slightly larger that the chain drive sprocket  47  radius plus the cable radius  25  plus the cable link  92  height. Note that as the corner of cable link  93  pivots about pin  94 , it moves toward the cable  25 . This extra pivot clearance must be added to the centerline distance mentioned. Without this extra clearance, the cable links would rapidly damage the cable  25  with dents. The pressure rollers  48  cause the cable links to be pulled out of their straight line motion between the sprockets ( 47  and  49 ) and pushed into the cable  25 . The cable links now have the proper contact with the cable  25  during the linear motion and the extra clearance needed when the angular motion around the chain drive sprocket  47  commences. 
   Several cable links are mentioned with different reference numbers. These links are identical in shape but in different positions in the mechanism. A specific reference number is used to clarify a link in a particular position. 
     FIG. 10  is a section view of the pressure roller  48 —taken along section lines  10 — 10  from  FIG. 1 . Note from  FIG. 3  that there are five rows of identical pressure rollers  48 . Section lines  10 — 10  were taken through row  1 , however the section is applicable to any of the five rows. 
   The pressure roller collar  101  is attached to support channel A with bolt  61 . Support channel A  53  has a tapped hole that matches the thread on adjustment screw  95 . The adjustment screw  95  pushes on the spacer cylinder  52  that pushes on the collar for roller  96 . The inner roller bearing  97  and outer roller bearing  98  are press fit to the collar for roller  96 . The pressure roller  48  is press fit to the roller shaft  99  that is free to rotate in the inner roller bearing  97  and outer roller bearing  98 . 
   The collar for roller  96  slides (up and down as shown for axis A) in a pocket in the pressure roller collar  101 . Rotation of the adjustment screw  95  causes the pressure roller  48  to move closer or further from the cable  25 . The axis A adjustment with the cylinder block  52  is used to center the cable  25  and cable links. 
   The axis B and axis C components would be identical with one exception. Axis B and axis C utilize a group of Belleville springs  100  rather than the cylinder block  52 . Belleville springs are a standard engineering device which exert a high increasing force over a small distance. Only the increasing force action of the Belleville spring would be used, not the snap type action. The Axis B and axis C adjustment screws  95  are used to cause the correct spring force to be applied from the pressure rollers  48  to the cable links. 
   Note that there is one pressure roller collar  101  for each pressure row. The pressure roller collar  101  is a structural member that contains the reaction forces of the pressure rollers  48  in a row (such as Row  1 .) The pressure roller collar  101  could be of one piece construction or several rigidly attached pieces. 
     FIG. 11  is a section view of the pressure roller collar  102 —taken along section lines  11 — 11  from  FIG. 2 . Pressure roller collar  101  is from Row  1 . Pressure roller collar  102  is from Row  2 . The rows are shown in  FIG. 3 . Note that the collar for roller  96  is constrained from all motion except for the one direction as described for  FIG. 10 . This is critical in keeping the pressure roller  48  properly aligned with the cable links. The only motion of the collar for roller  96  is as allowed by the adjustment screw  95  or Belleville springs  100 . 
     FIG. 12  is an enlargement of the Row  1  pressure roller  48  from  FIG. 3 . Note the step on the pressure roller collar  101  that limits the travel of the collar for roller  96  toward the cable  25 . Before a cable  25  is fed into the cable traction apparatus, this travel limit step keeps the pressure roller  48  properly positioned. This position would allow a smaller diameter pilot cable to freely move and also would then adjust out the slight amount needed when the correct cable  25  was fed into the cable traction apparatus. 
   Note the position of cable links  103  and  104  relative to the pressure roller  48 . The pressure roller  48  at this position potentially would be exerting an excessive stress on the cable  25 . Cable links  103  and  104  would pivot slightly due to the high force and the end edge of the cable links would potentially damage the cable  25 . The next figure will outline how an adjacent cable link prevents this potential denting damage to the cable  25 . 
     FIG. 13  is an isometric schematic view of the cable  25  and cable links. Cable links  103  and  104  are shown in a schematic manner with only the arcuate surface represented in the figure. The pressure roller  48  would be tracking along the line between cable links  103 ,  104  and  105 . Note that at the moment the pressure roller  48  passes between pressure links  103  and  104 , the roller is supported by cable link  105 . The pressure roller  48  is always supported with a substantial cable link area. This allows a very high normal force to be imposed between the cable links and the cable  25  without damaging the cable  25 . 
   Each row includes three pressure rollers (as shown in  FIG. 10 ). In the theoretical ideal case, there would always be a cable link centered under each roller at all times. This ideal case would provide 100% of a link area for each roller at all times. Moving to the realistic dynamic case of the present invention, the cable links must move to provide the linear motion. As each cable link joint moves under a pressure roller, the cable link effectively provides no support for the pressure roller. The two cable links at the joint are free to pivot on the roller chain. Therefore the full pressure of the roller must be supported by the cable link on the alternate axis which is not at a joint. If this cable link were centered under the pressure roller at this moment, the pressure roller would be supported by 50% of a link area. 
   There are two realistic requirements that further reduce this 50% target for cable link area. The mechanism operates more effectively with three rather than two axes. This requires that the cable links be staggered by ⅓, therefore the cable link is not centered under the pressure roller when the other axis is at a joint. Also, clearance must be provided between cable links. The apparatus as shown in  FIG. 10  maintains a minimum pressure roller support of 10% of a link at all times. 
     FIG. 14  is a section view of the cable chain idler—taken along section lines  14 — 14  from  FIG. 1 . The idler sprocket shaft  106  rotates in the inner sprocket shaft bearing  84  and the outer sprocket shaft bearing  85 . The rear axle block  56  is attached to support channel A  53  via bolts  61 . The chain idler sprocket  49  is press fit to the idler sprocket shaft  106 . 
     FIG. 15  is an enlargement of the cable, chain drive and pressure rollers from  FIG. 10 . Note the slight gap along axis A between cable link  104  and cable link  105 . These axis A, B and C gaps cause the pressure roller force to be applied to the cable  25 . 
     FIG. 16  is a side view of the cable traction apparatus attached to a container. The specific style of container shown is a gondola. The cable idler wheel  107  is affixed to the cable traction apparatus  110  via the idler wheel bracket  108  and bolts  109 . The purpose of the cable idler wheels  107  is to align the cable  25  with the centerline axis of the cable traction apparatus  110 . The gondola  112  is affixed to the cable traction apparatus  110  via the gondola bracket  111  and bolts  109 . The rear support  28 , engine rear support  29  and front support  30  are rigidly attached to the gondola bracket  111 . The operator  113  controls the machine via the console  113 . Egress to the gondola is achieved through the door  116  and windows  115  provide operator visibility. In this configuration the cable  25  is stationary and the cable traction apparatus  110  moves. 
   An operator  114  would not necessarily be required inside the container. The unit could be operated remotely or automatically. The container merely holds the payload that is desired to be transported up or down the cable  25 . 
   In any event, the invention is only intended to be limited by the scope of the following claims.