Abstract:
A method and apparatus for transporting heavy machinery, equipment or other heavy load from one location to another, whereby the apparatus is constructed to steer the load in order to move the load in a desired path to a set position, one embodiment directed to a walking machine including a plurality of lifting assemblies operative to lift the load above the supporting surface and then move or rotate the load relative to the supporting surface by transporting the load via rollers or tracks in the walking machines, the lifting assembly including a steering mechanism using an actuator operative for rotating, via a multi-linkage assembly, whereby the lifting assembly lower structure is rotated relative to the lifting assembly structure to set the walking machine at a desired angle so that lifting assemblies may be driven in a desired walking direction,

Description:
RELATED APPLICATION DATA 
       [0001]    This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application No. 62/138,318 filed on Mar. 25, 2015, hereby incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    The field of the present disclosure relates to a class of transportation machines commonly referred to as “walking machines” which are large, typically non-wheeled, power-driven structures operable for transporting massive and heavy loads, upwards of several thousand tons, over a surface such as ground, snow, a prepared gravel area, etc. These machines and the heavy substructures in themselves are fabricated from steel and other high strength materials and find particular use in carrying and sequentially transporting large and huge structures such as oil drilling rigs to position, and re-position, them over a drilling well bore in a new field undergoing exploration for oil, or existing well bores in oil fields previously worked, as needed. 
         [0003]    Instead of using wheels to move the heavy loads, these walking machines comprise a plurality of lifting assemblies that typically use hydraulic lift cylinders to lift the load above the supporting surface and then move or rotate the bad relative to the supporting surface by transporting the bad via rollers or tracks in the walking machines. 
         [0004]    In order to position the oil rig or other heavy load in a precise position, these walking machines may be provided with a steering mechanism whereby the walking machine unit may be rotated or steered to a desired position. U.S. Pat. No. 6,581,525, hereby incorporated by reference, shows walking machine systems  and methods for moving heavy loads, such as oil rig structures. The U.S. Pat. No. 6,581,525 also discloses a steering system for a walking machine in which a substructure of the walking unit may be disengaged and rotated relative to its upper structure thus repositioning the substructure for travel at a desired steered angle. Other steering systems for walking machines are disclosed in U.S. Pat. No. 8,573,334 and U.S. Pat. No. 7,806,207. These steering systems have various limitations and potentially undesirable characteristics, which may include depending upon the design: only manual repositioning; complicated rotational position detection and control; complicated or unreliable rotational drive mechanisms. 
       SUMMARY 
       [0005]    The present invention is directed to a method and apparatus for transporting heavy machinery, equipment or other heavy load from one location to another, whereby the apparatus is constructed to steer the load in order to move the load in a desired path to a set position. A preferred embodiment is directed to a walking machine comprising a plurality of lifting assemblies operative to lift the load above the supporting surface and then move or rotate the load relative to the supporting surface by transporting the load via rollers or tracks in the walking machines, the lifting assembly including a steering mechanism operative for rotating the lifting assembly lower structure relative to the lifting assembly structure to set the walking machine at a desired angle so that lifting assemblies may be driven in a desired walking direction. 
         [0006]    Additional aspects and advantages will be apparent from the following detailed description of preferred embodiments, which proceeds with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a diagrammatic view of an example walking machine system for moving a large support structure shown as an oil rig. 
           [0008]      FIG. 2  is a partial view of the walking machine system of  FIG. 1  with the walking machine units in position connected to the oil rig.  
           [0009]      FIGS. 3-7  are partial views of the walking machine system of  FIG. 1  illustrating the operation of the walking machine units. 
           [0010]      FIG. 8  is a top plan view of a walking machine system according to a preferred embodiment, with four walking machine units, one disposed at each of the four corners of the oil rig. 
           [0011]      FIG. 9  is a front left top isometric view of a walking machine unit of  FIG. 8 . 
           [0012]      FIG. 10  is right side elevation view of the walking machine unit of  FIG. 9  with the lift cylinder in the retracted position. 
           [0013]      FIG. 11  is front side elevation view of the walking machine unit of  FIG. 9 . 
           [0014]      FIG. 12  is a cross-sectional view of the walking machine unit of  FIG. 11  taken along lines  12 - 12 . 
           [0015]      FIG. 13  is a top plan view of the walking machine unit of  FIG. 9   
           [0016]      FIG. 14  is a cross sectional view of a portion of  FIG. 13  taken along lines  14 - 14 . 
           [0017]      FIG. 15  is an exploded isometric view of the walking machine unit of  FIG. 9 . 
           [0018]      FIG. 16  is an isometric view of the steering linkage and actuator portion of  FIG. 9  on an enlarged scale. 
           [0019]      FIG. 17  is a partially exploded isometric view of the steering linkage and actuator portion of  FIG. 16 . 
           [0020]      FIG. 18  is an isometric exploded view of the turret assembly portion of the steering linkage of  FIG. 17 . 
           [0021]      FIG. 19  is a right side elevation view (slightly rotated relative to the view in  FIG. 10 ) of the walking machine unit of  FIG. 9  with the lift cylinder in the extended position. 
           [0022]      FIG. 20  is a side elevation view of the walking machine unit as in  FIG. 19  with the lift cylinder in the retracted position. 
           [0023]      FIG. 21  is an isometric view of the walking machine unit of  FIG. 20  with the lift cylinder in the retracted position and the steering actuation cylinder in the retracted position. 
           [0024]      FIG. 22  is a top plan view of the walking machine unit of  FIG. 21  with the steering actuation cylinder in a first position, fully retracted.  
           [0025]      FIG. 23  is a top plan view of the walking machine unit of  FIG. 21  with the steering actuation cylinder in a second position, partially extended. 
           [0026]      FIG. 24  is a top plan view of the walking machine unit of  FIG. 21  with the steering actuation cylinder in a third position, partially extended more than in  FIG. 23 . 
           [0027]      FIG. 25  is a top plan view of the walking machine unit of  FIG. 21  with the steering actuation cylinder in a fourth position, fully extended. 
           [0028]      FIG. 26  is a top plan view of the torsion ring illustrating the gauge and indicator. 
           [0029]      FIG. 27  is a graph of the rotational position of the steering assembly relative to the actuation position of the steering actuator. 
           [0030]      FIG. 28  is a partial cross-sectional view of the lifting device with the lift mechanism in the extended position. 
           [0031]      FIG. 29  is a partial cross-sectional view of the lifting device with the lift mechanism in a first retracted position, with the rolling mechanism still in contact with the pad. 
           [0032]      FIG. 30  is a partial cross-sectional view of the lifting device with the lift mechanism in a second retracted position, with the rolling mechanism lifted off the foot pad. 
           [0033]      FIG. 31  is a partial cross-sectional view of the lifting device with the lift mechanism in a third retracted position, with the foot pad lifted off the ground. 
           [0034]      FIG. 32  is a schematic diagram of a control system according to an embodiment. 
           [0035]      FIG. 33  is a diagram of the remote control of the control system of  FIG. 32 . 
           [0036]      FIG. 34  is a diagram of settings for steering linkages for straight ahead travel mode. 
           [0037]      FIG. 35  is a diagram of settings for steering linkages for basic, simple steering travel mode. 
           [0038]      FIG. 36  is a diagram of settings for steering linkages for complementary steering travel mode. 
           [0039]      FIG. 37  is a diagram of settings for steering linkages for diagonal steering travel mode.  
           [0040]      FIG. 38  is a diagram of settings for steering linkages for lateral steering travel mode. 
           [0041]      FIG. 39  is a diagram of settings for steering linkages for spin steering travel mode. 
           [0042]      FIG. 40  is a flow chart of a control scheme according to an embodiment. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0043]    The preferred embodiments will now be described with reference to the drawings. With reference to the above-listed drawings, this section describes particular example embodiments and their detailed construction and operation. To facilitate description, any element numeral representing an element in one figure will be used to represent the same element when used in any other figure. The embodiments described herein are set forth by way of illustration only and not limitation. It should be recognized in light of the teachings herein that there is a range of equivalents to the example embodiments described herein. Notably, other embodiments are possible, variations can be made to the embodiments described herein, and there may be equivalents to the components, parts, or steps that make up or augment the described embodiments. 
         [0044]      FIGS. 1-7  are a series of schematic drawings for an example walking machine system for moving a large support structure shown as an oil rig  10  along a ground surface  5 . The oil rig structure  10  is supported onto the ground or support surface by a plurality of support legs  55  attached to the bottom of the oil rig structure  50 . The walking machine system includes a set of four lifting assemblies  100 ,  102  (other assemblies  104 ,  106  shown in  FIG. 8  described below) with a lifting assembly arranged in position proximate each of the corners of the oil rig  10 . 
         [0045]    To avoid repetition, operation of the lifting assemblies  100 ,  102 ,  104 ,  106  will be described with respect to assembly  100 . The lifting assembly  100  is set in position as illustrated in  FIG. 1  with its lifting cylinder retracted. The lifting cylinder is raised partway as in  FIG. 2  and contacts the oil rig support beam/structure  50  and connected thereto by bolting or other suitable attachments. The lifting cylinder is then retracted, thereby lifting the lower structure or jack pad of the lifting assembly off the ground (due to its attachment to the support beam  50  of the rig) and then the  lifting assembly lower structure and jack pad are driven forward by the push-pull mechanism to the forward position as in  FIG. 3 . The lifting cylinder is then partially extended lowering the lifting assembly lower structure and jack pad to the ground as shown in  FIG. 4 . The lifting cylinder is then raised to the extended position thereby lifting the support structure  50  and support legs  55  off the ground as in  FIG. 5 . Once the rig is lifted, the lifting assembly lower structure (the foot) is driven rearward by the push-pull mechanism to the rearward position thereby moving the rig  10  forward as in  FIG. 6 . The lifting cylinder is then retracted, raising the lifting assembly lower structure as in  FIG. 7  after which the lower structure may then be driven forward to the position as in  FIG. 3 . The process steps are then repeated. 
         [0046]    Further details of the lifting assembly and steering mechanism will now be described.  FIG. 8  illustrates a top plan view of the walking machine comprised of the four lifting assemblies  100 ,  102 ,  104 ,  106  connected to the rig  10  (the substructure  50  of the rig  10  being removed), and the controller assembly  75 . The lifting assemblies  100 ,  102 ,  104 ,  106  in  FIG. 8  have each been steered to a selected spin or steering angle α (alpha), with the illustrated example of about 12° to the horizontal. Thus when engaged in the walking operation, the structure will be moved at a 12° diagonal walking direction (clockwise from straight forward as shown in the figure). The walking direction may be either diagonally forward and to the right or diagonally backward and to the left as desired depending the order and direction of the drive mechanisms. 
         [0047]    As will be described, the steering mechanism comprises a control system and steering linkage operable to rotate/steer about an angle of at least on the order of about 179°, or slightly more, to accommodate steering of the walking unit (in combination with the push-pull drives driving the walking mechanisms forward or backward) in any desired direction. 
         [0048]      FIGS. 9-23  illustrate details of the walking machine unit  100  according to an embodiment. The walking unit  100  includes generally a lift assembly  120  and a walking foot assembly  300  including a lower foot or pad for contacting the ground  5 , the travel mechanism  305  (that includes the rolling assembly  400 ), the lifting assembly or lift mechanism  120 , the steering assembly and drive  150 ,  200 , and the steering support assembly  130 .  
         [0049]    It is noted that in  FIGS. 9-13  all the actuators are shown in the retracted conditions including the actuator of the lift mechanism  120 , the actuators  330 ,  340  of the travel mechanism  305 , and the steering actuator  250  of the steering assembly  150 - 200 . 
         [0050]    Specifics of the elements will now be described with particular reference to exploded view of  FIG. 15  as well as the prior figures. 
         [0051]    The lift assembly  120  includes an outer housing or main housing  125 , in which is disposed an actuating piston cylinder  126 . The main housing includes a top flange  122  which attaches to the load/rig and a bottom flange  121 . The piston cylinder  126  has a bottom collar  128  with a shoulder  127  for engaging a lifting plate  380  as will be described in more detail below with respect to subsequent figures. The bottom surface of the piston cylinder  126  comprises a spherical concave surface  129  (see also  FIG. 28 ) for engaging the corresponding convex dome surface  372  of the engaging plate  370  in the foot assembly  300 . The top plate  122  is connected via bolts  124  to the support structure  50  of the load. The foot assembly  300  includes the bottom foot or pad  110  upon which the various components are mounted including side plates  310  and  312  which are interconnected by guide rods  314 ,  316  which nests within saddles or indentations  351 ,  357  and  352 ,  358  within plates  350 ,  356 . The actuators  330 ,  340  are operative for translating the travel mechanism  305  between the forward and rearward positions for the push pull operation. The left actuator  330  is attached on one end by a pin connection  334  to the support plate  310  and on the other end to support plate  350  by a pin connector  336  and cross support  349 . The right actuator  340  is constructed in similar fashion. 
         [0052]    The steering mechanism  150 ,  200  is now described with particular reference to  FIGS. 15-18 . The steering mechanism comprises an actuating assembly  250 , a double linkage assembly  200 , and a steering torsion ring assembly  150 . 
         [0053]    The actuation assembly  250  (as best shown in  FIGS. 16-17 ) comprises the main housing  252  comprising a piston and cylinder combination wherein the piston rod  256  actuates and travels outwardly from the cylinder housing  252  which includes disposed thereon a magneto-strictive linear sensor or linear encoder  254 , such as a Temposonics® sensor available from MTS Sensors of Cary, N.C., that directly registers the displacement of the cylinder rod  256  with respect to the cylinder  housing  252 . An end connector  257  is disposed or attached on the end of the piston rod  256 . The end connector  257  includes a central hole  258  for attachment to the two bar linkage  200 . 
         [0054]    Though an embodiment of a two-bar linkage is shown and described, a three bar linkage or other multi-linkage system may be employed. 
         [0055]    Though shown as a hydraulic actuator, other actuation mechanisms may be employed such as a servo motor, a screw drive, a rack and pinion drive, or other suitable mechanical or electro-mechanical, hydraulic or pneumatic drive mechanism. The mechanics of the linkage system allow for a simple form linear actuator to provide the motive force for the rotational drive mechanism as well as a simplified feedback system whereby the actuation position of the actuator is directly related to the rotational position of the steering mechanism facilitating automatic or semi-automatic control. 
         [0056]    The displaced position of the linear actuator may be detected by a linear transducer or similar instrument for devices similar to hydraulic or pneumatic cylinders or by a rotary encoder for linear actuators with a hydraulic, pneumatic, or electrically driven motor. 
         [0057]    The linear actuators may be controlled via a closed loop feedback system such as via a central processor that monitors and adjusts the displaced position of each linear actuator. A program within or otherwise running the central processor, relates linear actuator displacement to rotational orientation of the roller/foot assembly. 
         [0058]    The two bar linkage  200  comprises a first linkage including top and bottom (first) linkage elements  230 ,  220 , and a second linkage  210 . The second linkage comprises a curved linkage body. The top and bottom first linkage elements  230 ,  220  each comprises a curved body section  232 ,  222  and a central extending portion  231 ,  224 . Holes  235 ,  225  are provided in the extending sections  231 ,  224  through which a pin connector  236  is passed through each of the holes and through the hole  258  in the end connector  257  of the actuator  250 . The pin  236  is secured in place by an attachment bracket and screw/bolt element  236   a  which passes through the hole in the upper first linkage portion  230 , through a spacer  236   b  into a threaded  connection within the lower first linkage section  220  thereby securing the first linkage  220 / 230  in a rotatable fashion to the end connector  257  of the actuator  250 . 
         [0059]    The first linkage  230 / 220  is then connected via pivoting connection to the second linkage  210  by a pin connector  234  passing through a hole  233  in the upper first linkage portion  230  through hole  214  in the second linkage  212  through a bushing  213  and then through a hole  226  in the end of the lower first linkage portion  220 . The pin  234  is secured in place via screw  234   a  attached to a connecting bracket, the screw  234   a  passing through a hole in the upper first linkage portion  230  through a spacer  234   b  and then secured to the bottom first linkage portion  220  in the threaded connection therein. 
         [0060]    The steering ring assembly  150  is best shown in  FIGS. 15-18  and in the exploded view in  FIG. 18 . The steering ring assembly  150  comprises a bottom retaining ring  152 , a top retaining ring  190 , a torsion ring assembly  160  disposed between the bottom retaining ring  152  and the top retaining ring  190 , a bottom wear ring  180  disposed between the a bottom retaining ring  152  and the torsion ring assembly  160 , and an upper wear ring  170  disposed between the top retaining ring  190  and the torsion ring assembly  160 . 
         [0061]    The bottom retaining ring  152  is a flat washer-like shaped structure with four tabs  154  for attaching the steering assembly to the walking foot assembly. The bottom retaining ring  152  includes a pin connection lug  158  on the outside of the ring for connection to the linkage  212 . The bottom retaining ring  152  also includes eight threaded holes  156  for fastening the steering assembly rings  190 ,  152  together with the wear ring  180 . Rotation of the steering rings or collars  152 ,  190  are operative for rotation of the lower support structure (rolling assembly  400  and foot pad  110 ) via connection to the lift plates  380 ,  370 . 
         [0062]    The top retaining ring  190  is a flat washer-like shaped structure  192 . The top retaining ring  190  includes eight countersunk, threaded through holes  195  for fastening the assembly via screws/bolts  194 . The top retaining ring  190  also includes a pin connection lug  196  disposed on the outside of the ring for connection to the linkage  212 . The top retaining ring rotates with the walking foot assembly. 
         [0063]    The bottom wear ring  180  comprises a flat washer-like shaped outer lip  181  with a raised center portion  182 . The bottom wear ring  180  may be made out of  nylon or other a suitable material having superior wear resistance and low friction properties such as Nylatron® nylon available from DSM Engineering Plastic Products, Inc. of Reading, Pa. 
         [0064]    The upper wear ring  170  is disposed between the top retaining ring  190  and the torsion ring assembly  160  and is free to rotate. The upper wear ring  170  may also be made of nylon or other a suitable material having superior wear resistance and low friction properties such as Nylatron® nylon. 
         [0065]    The torsion ring assembly  160  remains in a fixed position and does not rotate with the walking foot assembly. The torsion ring assembly  160  includes a flat washer-like shaped central portion  161 , a trunnion or extension arm section  162 , and mounting tabs  163   a,    163   b  for connection to the steering actuator  250 . The central portion  161  of the torsion ring assembly  160  is disposed against the outer lip  181  and outside of the raised center portion  182  of the bottom wear ring  180 . The extension arm  162  includes the mounting brackets or tabs  163   a,    163   b,  the top bracket  163   a  being removably attached by screws  164   a  to mounting plate  165 . The steering actuator  250  is pivotally mounted to the extension arm  162  via hinge pins disposed within the holes  164  in the mounting tabs  163   a,    163   b.    
         [0066]    The steering ring assembly  150  is assembled via screws/bolts  194  passing through the countersunk through holes  195  in the top retaining ring  190 , passing through the interiors of the upper wear ring  170  and the torsion ring assembly  160 , through the spacers  184 , through the holes  183  in the bottom wear ring  180 , and then secured to the threaded holes  156  of the bottom retaining ring  152 . The spacers  184  may relieve the wear rings  170 ,  180  of the clamping force enacted by the screws  194 . The spacers  184  may include flat ends that bear on the retaining rings  190 ,  152  providing a metal to metal interface that may help avoid over-compression of the wear rings  170 ,  180 . 
         [0067]    The screws/bolts  194  are arranged in a spaced, circular pattern to provide equal amounts of adherence throughout the layout. The screws/bolts  194  are flat head elements that allow clearance between the lift cylinder and the top retaining plate  190  of the steering ring assembly. 
         [0068]    The second linkage  210  includes a hole  216  in the end distal from the first linkage  230 / 220 . The hole  216  is aligned with the holes in lugs  196 ,  158  and disposed therebetween and rotationally secured via a pin  198  passed through the hole in lug  196 , through hole  216 , through bushing  218  and then secured into hole  159  within lug  158 . 
         [0069]    The second end of the first linkage  230 / 220  is rotationally connected to the torsion ring  160 . The second end of the first linkage  230 / 220  includes holes  237 ,  228  which are aligned on opposite sides of the hole  168  of the torsion ring  160  proximate the arm section  162 . A pin  238  is disposed through the hole  237  in the upper first link portion  230 , through the hole  168  in the torsion ring  160 , and into the hole  228  in the lower first link portion  220 . The pin  238  is secured in place by a positioning bracket secured by a screw/bolt  238   a  which is passed through a hole in the end of the upper first link portion  230 , through spacer  238   b,  and into a threaded hole in the lower first link portion  220 . 
         [0070]    Low friction washers (such as washers  213   a,    214   a,    218   a,    216   a,    228   a ,  237   a ), which may be constructed or coated with low friction material, such as a nylon material, are provided between rubbing surfaces to reduce friction. 
         [0071]    A mounting tab  169  is attached or included with the central portion  161  of the torsion ring  160 . An indicator plate  510  is mounted to the mounting tab and includes a pointer for indicating the rotational position of the steering mechanism relative to the indicator  510  which remains fixed (rotationally) relative to the lifting mechanism  120  and the load/rig. A decal or label  500  is provided in a visible location on the top surface of the top retaining ring  190 , the label  500  bearing markings or readouts for indicating the rotational position of the steering mechanism as pointed to by the indicator  510 . Alternately, the markings may be drawn or etched directly onto the top retaining ring.  FIG. 26  is an enlarged view of the label  500  showing the rotational measurement markings according to an embodiment, further details of which will be described later. 
         [0072]    The steering ring assembly  150 / 200  is supported by support assembly  130  while also providing some freedom of motion. The support assembly  130  (as best shown in  FIGS. 10, 15, 19 and 20 ) comprises three plates sections: a first plate  142  which is attached to the lower lifting cylinder flange  121  (via bolts), a U-shaped central plate section  132  which is pivotally connected (via hinges  144 ,  146  and hinge pins  145 ) to the first plate  142 , and a third plate  138  which is pivotally connected (via hinges  134 ,  136  and hinge pins  135 ) to the central plate  132 . Since the support assembly  130  is attached to the lift mechanism  120 , it remains rotationally stationary during steering operation. The third plate  138  then is pivotally connected to the torsion assembly  150  via hinges  139 ,  166 ,  167  and hinge pin  140 . The support assembly thus allows the steering assembly  200  to travel vertically with the piston cylinder  126  as shown in  FIGS. 19, 20 . 
         [0073]      FIG. 19  illustrates a right side elevation view, slightly rotated relative to the view in  FIG. 10 , of the walking machine unit of  FIG. 9  with the piston cylinder  126  in the extended position whereby the load/rig would be in the lifted condition. 
         [0074]      FIG. 20  is a right side elevation view of the walking machine unit as in  FIG. 19  with the piston cylinder  126  of the lifting cylinder  120  in the retracted position. 
         [0075]      FIG. 21  is an isometric view of the walking machine unit of  FIG. 20  with the lift cylinder in the retracted position and the steering actuation cylinder  250  in the retracted position. 
         [0076]    Once in the retracted lifting position with the walking assembly lifted off the ground, the actuator  250  may be actuated to rotate the walking assembly to the desired steering position.  FIGS. 22-25  are each top plan views of the walking machine unit of  FIG. 21  with the top mounting flange removed to make lower components visible, these figures illustrating four different actuation positions of the steering actuation cylinder  250 , and thus four rotational steering positions. It is noted that the torsion arm  160  (the position shown by line “A”) and the attached indicator  510  remain stationary in the figures as being fixed relative to the lifting cylinder and load.  FIGS. 22-25  show four rotational steering position as follows:
       In  FIG. 22 , the steering actuation cylinder  250  is in a first position, fully retracted, the indicator  510  pointing to the gauge  500  at a first mark.   In  FIG. 23  the steering actuation cylinder is in a second position, partially extended, the indicator  510  pointing to the gauge  500  at a second mark, having rotated from the first position by an angle Θ of about 30°.   In  FIG. 24  the steering actuation cylinder is in a third position, partially extended, the indicator  510  pointing to the gauge  500  at a third mark, having rotated from the first position by an angle Θ of about 120°.   In  FIG. 25  the steering actuation cylinder is in a fourth position, fully extended, the indicator  510  pointing to the gauge  500  at a third mark, having rotated from the first position by an angle Θ of about 185°. Thus the geometry of the multi-linkage connector, comprising the first linkage  230 / 220  and the second linkage  210 , is operative for rotating the steering ring at least 179°, or somewhat larger. A larger angle in excess of 185° is not required because the travel mechanism  305  may be operated in either direction.       
 
         [0081]      FIG. 26  is a top plan view of the torsion ring  160  and  FIG. 27  is a graph of the rotational position of the steering assembly relative to the actuation position of the steering actuator. With reference to  FIG. 26 , the torsion ring  160  includes a gauge  500  and indicator  510  shown on an enlarged scale, with the gauge  500  bearing scale markings from −30° to −20°. In  FIG. 26 , the indicator  510  is shown at −27.7° at zero stroke length (see  FIG. 27 ), which would occur when the actuator is fully retracted. With reference to the graph on  FIG. 27 , when the actuator is fully extended, that is at an approximately 23.5 inch stroke length, the indicator  510  on the gauge  500  would be at −7° in the other direction, thus indicating that the steering assembly could provide a range for the steering angle somewhat in excess of 180° (for example 185°). It should be noted that both the −27.7° and the −7° may be extreme positions of the assembly if the actuator were allowed to fully retract or fully extend without limitation. However, it may be beneficial to establish a deadband at the ends of the stroke to avoid having the cylinder bottom out (particularly when fully extended), which could potentially bind up the mechanism. For example, in one embodiment, the deadband may be established between −27.7° and −25° on the extend portion of the cylinder stroke and between −7° and −25° coming back the other way on the retract portion. Accordingly, in this example, the controls would essentially limit the actual stroke performed to a range of 180° between −25° and −25° while keeping a cushion to aid in activating the rod of the cylinder. To provide for automatic operation control, the following equation (1) has been formulated to relate the actuator position y to the steering angle x: 
         [0000]        y=− 0.0405 x   2 +2.1265 x −3.6237  (1)
 
         [0082]    Additional operating details of the load lifting mechanism are shown with respect to  FIGS. 28-31 .  FIG. 28  illustrates the lifting piston  126  in the fully extended position, wherein the rolling assembly  400  is in contact with the foot pad  110  and the load/rig is supported/raised by the lift mechanism. In this position, there is a gap B between the rods  314 ,  316  (which are attached to the pad  110  via plates  310 ,  312 ) and the saddles  358 ,  357  in plate  356 , as well as saddles in plate  350 ). Also in this position, the concave surface  129  of the piston cylinder  126  is in contact with the dome plate  372  of the lifting plates  370 / 380 . There is also a gap E between the shoulder  127  of the lifting cylinder  126  and the lifting plate  382 , the gap E allowing articulation of the foot with respect to the cylinder rod  126 . 
         [0083]      FIG. 29  illustrates the lifting device with the lift mechanism in a first retracted position, with the rolling mechanism  400  still in contact with the pad  110 , but the piston cylinder  126  (and the concave surface  129 ) is separated by a gap A from the dome plate  372  of the lifting plates  370 / 380 , and the shoulder  127  of the piston cylinder  126  is contact with the lifting plate  382  and is ready to commence lifting the rolling mechanism. There remains the gap B between the rods  314 / 316  and the saddles  358 ,  356 . 
         [0084]      FIG. 30  illustrates the lifting device with the lift mechanism in a second retracted position, with the foot pad  110  still on the ground  5 , and with the rolling mechanism  400  lifted off the foot pad  110  by a gap C. There is no gap between the rods  314 / 316  and the saddles  357 ,  356  and with the gap, the system is ready to commence lifting the entire foot assembly off the ground. 
         [0085]      FIG. 31  illustrates the lifting device with the lift mechanism in a third retracted position, with the foot pad lifted off the ground. With the rods  314 ,  316  engaged in the saddles  358 ,  357 , the foot pad  110  is lifted off the ground as the piston cylinder  126  continues to retract creating a gap D between the pad  110  and the ground  5 . 
         [0086]      FIG. 32  is a diagram of a control system  600  according to an embodiment. The system controls four steering assemblies (# 1 , # 2 , # 3  and # 4 ). The system includes a hydraulic power unit  618  which provides hydraulic power to a control valve system  620  comprised of a plurality of control valves  621 ,  622 ,  623 ,  624 . The operation of the control valves is controlled by a central processor  610  which receives control signals via a transmitter/receiver  615  from a remote transmitter/receiver  680 . The connection may comprise a wired connection or may comprise a wireless connection via antenna  616  on the transmitter  615  and antenna  682  on the remote transmitter/receiver. 
         [0087]    The first steering assembly includes a linear actuator  630  hydraulically connected to control valve  621 , and a linear transducer  632  electrically connected to the central processor  610 . The second steering assembly includes a linear actuator  640  hydraulically connected to control vave  622 , and a linear transducer  642  electrically connected to the central processor  610 . The third steering assembly includes a linear actuator  650  hydraulically connected to control valve  623 , and a linear transducer  652  electrically connected to the central processor  610 . The fourth steering assembly includes a linear actuator  660  hydraulically connected to control valve  624 , and a linear transducer  662  electrically connected to the central processor  610 . The displaced position of the respective linear actuator ( 630 ,  640 ,  650 ,  660 ) is detected by the respective linear transducer ( 632 ,  642 ,  652 ,  662 ) (or similar instrument for devices similar to hydraulic or pneumatic cylinders or by a rotary encoder for linear actuators with a hydraulic, pneumatic, or electrically driven motor). 
         [0088]    The linear actuators may be controlled via a closed loop feedback system such as via a central processor  610  that monitors and adjusts the displaced position of each linear actuator. A program within or otherwise running the central processor  610 , relates linear actuator displacement to rotational orientation of the roller/foot assembly. 
         [0089]    The hydraulic linear actuators may be operated by directional control valves which receive their signals from the central processor via electricity (electric over hydraulic), compressed air (air over hydraulic), or hydraulic fluid (oil over hydraulic). Motor driven linear actuators  630 ,  640 ,  650 ,  660  may be controlled via the central processor  610  via electrical signals, compressed air or hydraulic power. 
         [0090]    Operation of the steering functions and the walking system functions may be controlled through the central processor  610  by remote control  680 . The remote control  680  may be connected to the central processor  610  via a wireless connection (and thus comprising a wireless remote control) or a wired connection (such as connected via a tether cable), or other suitable connection mechanism.  FIG. 33  illustrates an interface  700  for the remote control  680 . A closed loop feedback from the central processor  610  is displayed on the remote control display  715 . Indicated feedback includes but is not limited to: steering angle set position, steering angle current position, steering system in motion, fault codes, and other suitable feedback. 
         [0091]    The remote interface may be provided with a plurality of factory preset standard steering modes which may be selected by selector switch  705 . The operation of the standard steering modes are illustrated in  FIGS. 34-39 . The steering mode selection may set the orientations for aligning the walking system:
       to move the load along the longitudinal axis of the structure (straight ahead, longitudinal travel mode as in  FIG. 34 ). For straight ahead travel, the steering angles are set at 0° (all angles must be the same). In straight ahead travel, travel cylinders # 1  and # 2  retract while travel cylinders # 3  and # 4  extend.   to control any two adjacent jack assemblies, the effect would produce a basic or simple steering mode similar to that of an automobile (simple steering mode as in  FIG. 35 ), the steering angle would be set by actuating the second switch  710 . The steering angles of the lead lift/transport assemblies (Jack # 1  and Jack # 2 ) must match and are set in increments of 5° with a maximum of 15° (a steering angle of 15° is shown in  FIG. 35 ) and the steering angles of the trailing lift/transport assemblies (Jack # 3  and Jack # 4 ) are set at  0 ° . In simple steering mode, travel cylinders # 1  and # 2  retract while travel cylinders # 3  and # 4  extend.   to control all four jack assemblies steering the front jack assemblies (Jack # 1  and Jack # 2 ) by an angle in a first direction and the rear jack assemblies (Jack # 3  and Jack # 4 ) at the same angle in the opposite direction (complementary steering mode as in  FIG. 36 ), the steering angle would be set by actuating the second switch  710 . The steering angles of all the lift/transport assemblies must match, and are set in increments of 5° with a maximum of 15° (a steering angle of 15° is shown in  FIG. 36 ). In complementary steering mode, travel cylinders # 1  and # 2  retract while travel cylinders # 3  and # 4  extend.   to move the load diagonally in any direction (diagonal travel steering mode as in  FIG. 37 ), the steering angle would be set by actuating the second switch  710 . It is noted that the steering angle numbers do not match for some directions. In diagonal steering mode, all travel cylinders retract together and extend together.   to move the load along the lateral axis (lateral travel, lateral steering mode as in  FIG. 38 ). In lateral steering mode, all travel cylinders retract together and extend together.   to spin the load about a central vertical axis of the structure (spin steering mode as in  FIG. 39 ), the steering angle would be set by actuating the second switch  710 .  FIG. 39  illustrates the steering plates in a circular steering position. In circular/spin steering mode the some jack assemblies may need to retract while others extend. The steering angle for spin mode is based on the geometry of each individual load/rig and therefore varies with each load/rig. The angle is one of the design outputs for each walking system application. The steering angle will be input into the Central Processor  610  during its initial setup and will be unique to that load/rig. By way of example, the steering angle positions shown in  FIG. 39  are set at Jack # 1  70°; Jack # 2  110°, Jack # 3  110°; and Jack # 4  70°.       
 
         [0098]    The selector switch  705  selects the appropriate preset direction. For example, when switched to diagonal mode, the second switch  710  is operated to define the desired angle of travel. Other preset modes are achievable. Another example steering mode would control two separate sets of two adjacent jack assemblies. Each set of two would turn in the opposite direction of the other set. The steering effect would be similar to the steering method of an articulated loader. 
         [0099]      FIG. 40  is a flow diagram of an example operating process  900  for the central processor  610  of  FIG. 32 , comprising the following steps. 
         [0100]    Step  902 —receiving steering mode input from the remote control  680 . 
         [0101]    Step  904 —upon receiving input (from Input Source  910 ) from steering actuators (via signals from the linear transducers  632 ,  642 ,  652 ,  662 ), determining whether all steering actuators are in the correct position with respect to desired orientation. If Yes proceed to Step  920 , if No proceed to Step  906 . 
         [0102]    Step  906 —push the “Initiate Steering Movement” button  720  on remote control  680  to actuate steering repositioning. Proceed to Step  908 . 
         [0103]    Step  908 —upon receiving input (from Input Source  910 ) from steering actuators (via signals from the linear transducers  632 ,  642 ,  652 ,  662 ), determining whether all steering actuators  630 ,  640 ,  650 ,  660  are in the correct position with respect to desired orientation. If Yes proceed to Step  920 , if No proceed to Step  912 . 
         [0104]    Step  920 —activating “System Ready” illumination on the display  715  of the interface  700  of the remote control  680 . Then proceed to Step  922 . 
         [0105]    Step  922 —system is ready to perform walking functions. 
         [0106]    Step  912 —determining if attempt to move duration exceeds time limit. If No, return to Step  908 , if Yes, proceed to Step  914 . The time limit is an amount (e.g., about one minute) that will provide the actuators adequate time to be moved to the desired orientation(s). 
         [0107]    Step  914 —activate fault light on the remote control  680 , list the fault codes/indications on the display screen  715 . Proceed to Step  916 . 
         [0108]    Step  916 —Manually diagnose and attempt to resolve the fault issue. 
         [0109]    Other embodiments are envisioned. Although the description above contains certain specific details, these details should not be construed as limiting the scope of the invention, but as merely providing illustrations of some embodiments/examples. It should be understood that subject matter disclosed in one portion herein can be combined with the subject matter of one or more of other portions herein as long as such combinations are not mutually exclusive or inoperable. 
         [0110]    The terms and descriptions used herein are set forth by way of illustration only and not meant as limitations. It will be obvious to those having skill in the art that many changes may be made to the details of the above-described embodiments without departing from the underlying principles of the invention.