Abstract:
The present invention provides a method for lifting and lowering equipment. In a preferred embodiment, the equipment is lifted by attaching a plurality of equipment adapters to the equipment, attaching a jack assembly to each of the plurality of equipment adapters, lifting the equipment by simultaneously raising the jack assemblies, moving the transport under the equipment and lowering the equipment onto the transport. The inventive method may be modified to include an additional process of weighing the equipment before lowering the equipment by measuring the amount of force required to hold the equipment in an elevated position. To practice the inventive method, the present invention also provides an apparatus that includes a plurality of equipment adapters and a plurality of jack assemblies, wherein each of the plurality of jack adapter assemblies is configured for removable connection to a corresponding equipment adapter.

Description:
RELATED APPLICATIONS  
       [0001]    This application claims priority to Provisional Patent Application No. 60/265,254 filed Jan. 31, 2001. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention provides a method and apparatus for raising and lowering equipment to and from a transport vehicle. The present invention optionally provides a method of weighing the equipment during the raising or lowering operation.  
         BACKGROUND OF THE INVENTION  
         [0003]    For many years, skids have been used as mounts for a variety of industrial devices, such as, for example, natural gas compressors, packaged natural gas processing plants and generator packages. Typically, the device is mounted on the skid at the manufacturing facility. Because skids often bear devices that must be positioned at remote locations, skids are designed for durability and portability.  
           [0004]    The combined weight of the skid and device requires special handling while loading, transporting and unloading the skid. In the past, a crane or other hoist machine was used to load the skid onto a suitable transport for cartage to the remote destination. Once at the destination, the skid and accompanying device are unloaded from the transport onto a suitable pad or platform through use of a crane. Once the skid has been placed on the pad, the crane and transport are removed from the site. Over the life of the device, the skid and device may be moved several times to various remote locations.  
           [0005]    Although effective, the conventional method for loading, transporting and unloading the skid suffers several drawbacks. The use of a crane during the loading and unloading of the skid requires that the crane accompany the transport to the remote location. Over the life of the device, it becomes cost prohibitive to employ a crane each time the skid is moved to a new location. Additionally, prior art methods for handling skids have made it difficult or impossible to accurately weigh the skid during the loading or unloading process. Because cargo weight is a crucial factor to be considered during transportation, especially in marine applications, the weight of the skid must be accurately determined.  
           [0006]    In light of the foregoing deficiencies in the prior art, there exists a pressing need to develop an efficient and cost-effective means for loading, transporting, unloading and determining the weight of a skid-mounted device.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention provides a method for lifting and lowering equipment. In a preferred embodiment, the equipment is lifted by attaching a plurality of equipment adapters to the equipment, attaching a jack assembly to each of the plurality of equipment adapters, lifting the equipment by simultaneously raising the jack assemblies, moving the transport under the equipment and lowering the equipment onto the transport. The inventive method may be optionally modified to include an additional step of weighing the equipment before lowering the equipment by measuring the amount of force required to hold the equipment in an elevated position.  
           [0008]    To practice the inventive method, the present invention also provides an apparatus that includes a plurality of equipment adapters and a plurality of jack assemblies, wherein each of the plurality of jack assemblies is configured for removable connection to a corresponding equipment adapter. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 is a top perspective view of a skid and equipment adapters constructed in accordance with the present invention.  
         [0010]    [0010]FIG. 2 is a side elevational view of the equipment adapter and I-beam constructed in accordance with a preferred embodiment of the present invention.  
         [0011]    [0011]FIG. 3 is a front elevational view of the equipment adapter of FIG. 2.  
         [0012]    [0012]FIG. 4 is a front perspective view of the jack assembly constructed in accordance with the present invention.  
         [0013]    [0013]FIG. 5 is a perspective view of the upper and lower cylinder cases of FIG. 4.  
         [0014]    [0014]FIG. 6 is a top perspective view of a skid and attached jack assemblies constructed and operated in accordance with a presently preferred embodiment of the present invention.  
         [0015]    [0015]FIG. 7 is a front elevational view of a shackle assembly constructed in accordance with a preferred embodiment of the present invention.  
         [0016]    [0016]FIG. 8 is a side elevational view of a shackle assembly constructed in accordance with a preferred embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0017]    Because the present invention may be practiced in multiple ways, it is necessary to use certain terms to define multiple embodiments. For example, as used herein, the term “device” will be used to denote machinery or objects that are independent from a skid. The term “equipment” will be used to broadly define a skid, a device or the combination of a skid-mounted device. Furthermore, unless otherwise noted, all components disclosed herein are preferably fabricated from a deformation resistant material, such as steel or other suitable metal.  
         [0018]    Referring now to FIG. 1, shown therein is a top perspective view of a skid  100  constructed in accordance with a preferred embodiment of the present invention. Although a variety of skids may be successfully used with the present invention, for purposes of the present disclosure the skid  100  is shown having a structural framework that includes a plurality of I-beams  102 . Typically, the I-beams  102  are longitudinally oriented about the periphery of the skid  100 . The I-beams  102  include an upper flange  104  and a lower flange  106  that extend longitudinally along the length of the I-beams  102 . The I-beams  102  support an upper surface  108  and rest upon a lower surface  110 .  
         [0019]    A plurality of equipment adapters  112  are rigidly affixed between the upper flange  104  and lower flange  106  at specified distances along the length of the I-beams  102 . Although two equipment adapters  112  are shown along the I-beams  102 , it will be understood by those skilled in the art that, in certain applications of the present invention, additional or fewer equipment adapters  112  may be provided on the skid  100 .  
         [0020]    With continued reference to FIG. 1 but now also referring to FIGS. 2 and 3, shown therein are side and front elevational views, respectively, of the equipment adapter  112  constructed in accordance with a preferred embodiment of the present invention. In FIG. 2, the equipment adapter  112  is shown connected to an I-beam  102 . The I-beam  102  is not shown in FIG. 3.  
         [0021]    The equipment adapter  112  includes two vertical members  114  that are maintained in vertical alignment by an upper brace  116 . The combined vertical height of the vertical members  114  and upper brace  116  is preferably the same as the vertical distance between the lower flange  106  and the upper flange  104  of the I-beam  102 .  
         [0022]    The vertical members  114  are substantially rectangular but preferably include an area in relief toward the bottom of each vertical member  114 . The outward face of each area in relief forms a lower contact surface  118 . A connection pin bore  120  is located in about the center of each vertical member  114 . A connection pin guide  122  is located between the vertical members  114  such that the connection pin guide  122  is centered with the connection pin bores  120 . Preferably, the connection pin guide  122  has a diameter that is slightly larger than that of the connection pin bore  120 . Additionally, each vertical member  114  includes an upper contact surface  124  located above the connection pin bore  120 .  
         [0023]    Preferably, the equipment adapters  112  are pre-fabricated and installed onto the I-beams  102  of the skid  100  in a retrofit process. Alternatively, the equipment adapters  112  may be constructed as an integrated part during the manufacture of the skid  100 . In both cases, it is preferred that the equipment adapters  112  be constructed from a deformation resistant material, such as high strength steel.  
         [0024]    It will be noted that the present invention can also be used to move devices that are not supported by a skid or similar platform. In such applications, the equipment adapters  112  can be affixed directly to suitable, load-bearing portions of the device.  
         [0025]    Turning now to FIG. 4, shown therein is a front perspective view of a jack assembly  126  constructed in accordance with a preferred embodiment of the present invention. The jack assembly  126  includes a lower cylinder case  128  and an upper cylinder case  130 . The lower cylinder case  128  is an open-ended rectangular box that includes four rectangular sides and a rectangular base (not numerically designated). Similarly, the upper cylinder case  130  is an open-ended rectangular box that includes four rectangular sides and a top (not numerically designated).  
         [0026]    With continued reference to FIG. 4 but referring also to FIG. 5, the upper and lower cylinder cases  130 ,  128  are preferably dimensioned to enable telescopic, sliding engagement with one another. To reduce the amount of friction between the upper cylinder case  130  and lower cylinder cases  128 , a plurality of oil impregnated bearings  132  are preferably included on the outer surfaces of the lower cylinder case  128  and along the inner surfaces of the upper cylinder case  130 . Preferably the bearings  132  are fabricated from a durable polymer, such as nylon, that absorbs and retains the applied lubricant. It is also preferred that the tolerances between the lower cylinder case  128  and the upper cylinder case  130  substantially eliminate all non-vertical movement between the two cases, thereby minimizing the application of sheer stress on components internal to the cylinder cases.  
         [0027]    A jack base  134  is located at the bottom of the lower cylinder case  128  and provides stable footing for the jack assembly  126 . A handle  136  is provided on the top of the upper cylinder case  130  and is used to lift and position the jack assembly  126  for attachment to the equipment adapter  112 . The handle  136  can also used while moving the jack assembly  126  when not in use.  
         [0028]    A hydraulic cylinder  138  is contained within the upper and lower cylinder cases  130 ,  128 . At its terminal ends, the hydraulic cylinder  138  abuts a lower cylinder stop  140  and an upper cylinder stop  142 . Preferably, the hydraulic cylinder  138  fits closely within the upper and lower cylinder cases  128 ,  130 , thereby limiting the presence of extraneous lateral movement. Hydraulic connectors  144  located on the upper cylinder case  130  provide fluid communication between the hydraulic generator (not shown) and the hydraulic cylinder  138 . Preferably, the hydraulic cylinder is “rifle-bored” to minimize the amount of hydraulic plumbing contained within the lower and upper cylinder cases  128 ,  130 .  
         [0029]    A jack adapter assembly  146  is secured to the bottom of the upper cylinder case  130  and includes two side portions  148  that are rigidly affixed to opposing sides of the upper cylinder case  130  through a suitable method, such as welding. Each side portion  148  includes a load bearing surface  150  and a connection pin bore  152 . A lower jack adapter brace  154  and an upper jack adapter brace  156  are positioned between the side portions  148  at the bottom and top of the jack adapter assembly  146 , respectively. The outer edge of the lower jack adapter brace  154  forms a lower jack adapter contact surface  158 . The outer face of the upper jack adapter brace  156  forms an upper jack adapter contact surface  160 .  
         [0030]    The jack adapter assembly  146  is designed to engage the equipment adapter  112 . When engaged, the connection pin bore  120  should align with the connection pin bore  152  to enable passage of a connection pin  162 . During engagement, the lower jack adapter contact surface  158  meets the lower contact faces  118 . Similarly, the upper jack adapter contact surface  160  meets the outward edge of the upper flange  104  of the I-beam  102 . The combined engagement of these contact surfaces assures that the jack assembly  126  maintains a perpendicular relationship with the skid  100  during operation.  
         [0031]    It should be noted that, when properly engaged, the exertion of vertical and horizontal forces about the connection pin  162  should be minimal. Ideally, the totality of the vertical force exerted by the jack adapter assembly  112  on the skid  100  is borne by the load bearing surfaces  150 . Horizontal forces resulting from the moment created by the application of vertical forces about the jack adapter assembly  146  will be primarily opposed by the upper and lower jack adapter contact surfaces  160 ,  158 , respectively.  
         [0032]    Turning now to FIG. 6, shown therein is a perspective view of the skid  100  with four attached jack assemblies  126  in a partially raised (or lowered) position. It should be noted that, although four jack assemblies  126  and corresponding equipment adapters  112  are shown, it will be recognized, that additional or fewer jack assemblies  126  and equipment adapters  112  can also be used.  
         [0033]    Turning now to FIGS. 7 and 8, shown therein are a front elevational view and a side elevational view, respectively, of a shackle assembly  164 . The shackle assembly  164  is designed to be attached to the equipment adapter  112  and serves to allow the equipment adapter  112  to be used with conventional hoist mechanisms. In some applications, it may be desirable to use shackle assemblies  164  and jack adapter assemblies  146  in combination while moving equipment.  
         [0034]    The shackle assembly  164  includes a body portion  166  on which a lifting bore  168  is located. The lifting bore  168  is useable to connect the shackle assembly  164  with a crane or other hoist machine (not shown). Also included in the shackle assembly  164  are two attachment flanges  170 . The attachment flanges  170  should fit tightly around the outside of the two vertical members  114  of the equipment adapter  112 . The attachment flanges  170  also include connection pin bores  172  that have a diameter no less than the corresponding connection pin bores  120  of the vertical members  114 . When aligned, the connection pin  162  should pass completely through the two vertical members  114  and the two attachment flanges  170 .  
         [0035]    The following text describes a method for practicing the present invention in accordance with a preferred embodiment of the present invention. If the equipment was not manufactured with equipment adapters  112 , it is necessary to affix the equipment adapters  112  to the equipment before beginning the lifting operation. If the equipment is a skid, such as skid  100 , the equipment adapters  112  are preferably attached to external frame members, such as the I-beams  102 . If the equipment is an independent device that is not mounted on a skid, the equipment adapters  112  are preferably attached to a suitable load-bearing member on the device. The equipment adapters  112  are preferably welded to the equipment. It will be noted that, in some cases, it may be desirable to attach the equipment adapters  112  to a device that is mounted on a skid. Such attachment of the equipment adapters  112  is also encompassed within the scope of the present invention.  
         [0036]    To begin a lifting operation, the jack assemblies  126  are secured to the equipment through engagement of the equipment adapters  112  and the jack adapter assemblies  146 . The jack adapter assemblies  146  are secured to the equipment adapters  112  by inserting the connection pin  162  through the connection pin bores  120  and connection pin guides  122 .  
         [0037]    When all four jack assemblies  126  have been secured to the equipment, hydraulic lines (not shown) are used to connect a hydraulic generator (not shown) to the hydraulic connectors  144 . Once connected, hydraulic pressure is transferred from the hydraulic generator to the hydraulic cylinders  138 , thereby increasing the internal pressure of the hydraulic cylinders  138 . At such time that the combined upward force generated by the hydraulic cylinders  138  exceeds the weight of the equipment, the hydraulic cylinders  138  will telescopically extend, thereby forcing the upper cylinder cases  130  to rise. As the upper cylinder cases  130  are forced upward, the jack assembly adapters  146  impart the upward force through the load bearing members to the equipment, such as the load bearing surfaces  150  of the skid  100 .  
         [0038]    To adjust the attitude of the equipment during the lifting process, the hydraulic pressure applied to each jack assembly  126  is individually controlled through use of a plurality of control valves (not shown). If automated level control is desired, a closed-loop feedback control system can be used to adjust the attitude of the skid during operation. Such automated level control systems are generally known in the art and could include, for example, mercury switches or gyroscopic components.  
         [0039]    Once the equipment has been raised to a sufficient height, a suitable trailer or other transport (not shown) is positioned beneath the raised equipment. Next, the equipment is slowly lowered onto the transport surface (not shown) by gradually reducing the hydraulic pressure in each hydraulic cylinder  138 . During the lowering process, the attitude of the equipment is controlled through use of the control valves (not shown). After transport, the aforementioned process is repeated to lower the equipment onto a suitable pad. In certain applications, it may be desirable to disconnect the jack assemblies  126  from the equipment after loading the equipment on the transport. In other applications, the jack assemblies  126  can be maintained in connection with the equipment during transportation.  
         [0040]    It may be desirable to use a hoist or crane to lift the equipment either alone or in combination with the jack assemblies  126 . If so, the shackle assembly  164  is attached to the equipment adapter  112  by inserting the connection pin  162  through the two vertical members  114  and the two attachment flanges  170 . A suitable hoist or crane is then connected to the lifting bore  168  and an upward vertical force is applied to the equipment.  
         [0041]    The loading and unloading procedures described above can also be used to determine the weight of the equipment. When the hydraulic jack assemblies  126  are static and under load, the hydraulic cylinders  138  become load cells under a relatively constant pressure. The weight of the equipment can be determined by measuring and summing the force exerted by each cylinder  138  that supports the equipment. The force exerted by the each cylinder  138  is calculated by multiplying the pressure in each hydraulic cylinder  138  by the cross-sectional area of each cylinder  138 .  
         [0042]    The basic weight equation can be expressed as follows: 
           W= (Σ i=1   n   P   i   ·A )· c   (1) 
         [0043]    where P represents the pressure in each cylinder, A represents the area of each hydraulic cylinder and c is a unitless correction factor that accounts for inefficiencies in the system.  
         [0044]    As shown in equation (1), the force exerted by each static hydraulic cylinder is summed together for all cylinders (n). The pressure (P) in each cylinder is determined by attaching conventional, liquid filled pressure gauges to gauge ports located immediately out of each cylinder&#39;s pressure ports. The area (A) of each hydraulic cylinder  138  is measured during manufacture.  
         [0045]    The correction factor (c) is determined through a conventional calibration routine using a test skid (not shown) and a suitable scale. The jack assemblies  126  are attached to the test skid and the test skid is raised to a specified height. Once the test skid reaches the specified height, the hydraulic cylinders  138  are held static and a pressure reading is taken from each hydraulic cylinder  138 . Ideally, the pressure readings from each hydraulic cylinders  138  should be the same. However, an offset in the center of gravity for the test skid could cause an unequal distribution of weight across the skid.  
         [0046]    Once the total force exerted by all of the hydraulic cylinders  138  has been determined, the correction factor c can be calculated as the quotient of the known weight of the test skid to the total force exerted by the hydraulic cylinders  138 . To ensure the accurate determination of the correction factor c, the above stated calibration routine is preferably repeated over a broad range of skid loads by adding test weights of known mass to the test skid.  
         [0047]    It is clear that the present invention is well adapted to carry out its objectives and attain the ends and advantages mentioned above. While presently preferred embodiments of the invention have been described in varying detail for the purposes of this disclosure, it will be understood that numerous changes may be made which will readily suggest themselves to those skilled in the art and which are encompassed within the spirit of the invention disclosed and as defined in the above text and in the accompanying drawings.