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BACKGROUND 
       [0001]    1. Field 
         [0002]    The present disclosure relates to lifting mechanisms for use with oilfield machines. More particularly, the present disclosure relates to lifting apparatus and methods for using the same in conjunction with oilfield shaking separators. 
         [0003]    2. Background Art 
         [0004]    Rotary drilling methods employing a drill bit and drill stems have long been used to drill wellbores in subterranean formations. Drilling fluids or muds are commonly circulated in the well during such drilling to cool and lubricate the drilling apparatus, lift drilling cuttings out of the wellbore, and counterbalance the subterranean formation pressure encountered. The recirculation of the drilling mud requires the fast and efficient removal of the drilling cuttings and other entrained solids from the drilling mud prior to reuse. Shaker separators are commonly used to remove the bulk solids from the drilling mud. 
         [0005]    A shaker separator consists of an elongated, box-like, rigid bed and a screen attached to, and extending across, the bed. The bed is vibrated as the material to be separated is introduced to the screen which moves the relatively large size material along the screen and off the end of the bed. The liquid and/or relatively small sized material is passed into a pan. The bed can be vibrated by pneumatic, hydraulic, or rotary vibrators, in a conventional manner. 
         [0006]    Various solids are brought up from the wellbore with the mud, including drill cuttings, clay, and debris. Sometimes clay that is directed into the shaker separator with the drilling fluid is sticky and heavy. Such solids risk causing screen breakage because they stick to the screen and are not transported to the discharge end of the shaker in an efficient manner. In such cases, it is desirable to lower the discharge end of the shaker bed to assist in the removal of the sticky solids from the screen. 
         [0007]    At other times, coarse solids are easily conveyed along the top of the screen by the vibratory motion of the shaker. In order to preserve the drilling mud and increase the volume flow rate of the mud being directed into the separator, it is desirable to raise the discharge end of the shaker bed. When the discharge end is raised, the mud flow rate may be maximized while mud loss over the screen is minimized. 
         [0008]    Some shaker separators have been built with systems to elevate the discharge end of the shaker bed. Many of these systems have employed manual operation techniques, such as hand wheels or jacks, to raise and lower the end of the bed. Other systems have included hydraulic lifts that are independently actuated, often requiring time and finesse by the operator to laterally level the discharge end of the shaker bed. Further, these systems have also included solenoids, which may be undesirable in the hazardous locations in which shaker separators are often used, particularly when separating drill cuttings from drilling mud. Thus, there is a need for a system to raise the discharge end of the shaker bed quickly and safely while keeping it level from side to side. 
       SUMMARY 
       [0009]    In one aspect, the present disclosure relates to an apparatus to lift an oilfield machine including at least one lifting bellows, an alignment assembly extending between at least one lifting bellows and an adapter plate of the oilfield machine, the alignment assembly comprising an inner cylinder to reciprocate within a sleeve of the oilfield machine, and the alignment assembly comprising a top plate at an upper end of the inner cylinder, the top plate configured to transfer forces from the at least one lifting bellows and the inner cylinder to the adapter plate, wherein the sleeve is configured to restrict the inner cylinder to a substantially linear displacements therethrough. 
         [0010]    In another aspect, the present disclosure relates to a method to lift an oilfield machine including positioning at least one lifting bellows beneath a component of the oilfield machine to be raised, positioning an alignment assembly between the at least one lifting bellows and an adapter plate of the component, wherein the alignment assembly comprises an inner cylinder and a top plate, wherein the inner cylinder is configured to reciprocate within a sleeve of the oilfield machine, inflating the lifting bellows beneath to raise the component with the inner cylinder, and restricting the inner cylinder to a substantially linear displacements with the sleeve. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0011]      FIG. 1  is a perspective view of a shaker assembly. 
           [0012]      FIG. 2  is a perspective view of an embodiment of a shaker lift system. 
           [0013]      FIG. 3  is a perspective view of a lift control assembly for the shaker lift system. 
           [0014]      FIG. 4  is a piping and instrumentation diagram of an embodiment of the shaker lift system. 
           [0015]      FIG. 5  is a perspective view of a control panel. 
           [0016]      FIG. 6  is a perspective view of an angle indicator. 
           [0017]      FIG. 7  is a piping and instrumentation diagram of an embodiment of the shaker lift system. 
           [0018]      FIG. 8  is a perspective view of an alternative lifting mechanism in accordance with embodiments of the present disclosure. 
           [0019]      FIG. 9  is a cross-sectional view of the alternative lifting mechanism of  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    Referring initially to  FIG. 1 , the reference numeral  10  refers, in general, to a vibrating screen separator assembly that includes a frame, or bed  12 , that includes a bottom wall  14  having an opening (not shown), a pair of side walls  18  and  20 , and a cross support member  24  coupled between the walls  18 ,  20 . Actuator  34  and  36 , respectively for imparting motion to the bed  12  are also coupled to the support member  24 . 
         [0021]    A flow box  16  is located at a feed end  22  of the shaker bed  12  to direct solid-bearing drilling mud to the screens  26 , located therein. A slide  28  may be located at the discharge end  30  of the shaker bed  12  to direct separated solids to a collection area (not shown). The shaker  10  may be mounted to a skid  32  to facilitate transport of the shaker  10  to the drill site as well as to aid in the positioning and relocation of the shaker  10  within the drill site. 
         [0022]    Referring to  FIG. 2 , the lift system  40  includes a lift control assembly  42 , a hydraulic tank  44 , a first bellow  46 , and a second bellow  48 . The first and second bellows  46 ,  48  are located near opposing corners  50 ,  52  of the discharge end  30  of the shaker bed  12  (shown in  FIG. 1 ). A shroud  54  is mounted to each of the first and second bellows  46 ,  48  to help protect them from damage. An adapter plate  56  mounted to each shroud  54  attaches to an adjacent side wall  18 ,  20  near the discharge end  30  of the shaker separator  10 . 
         [0023]    In one embodiment, shown in  FIG. 2 , the lift control assembly  42  is located at the discharge end  30  of the shaker bed  12  and the hydraulic tank  44  is shown to be at the feed end  22  of the shaker bed  12 . However the location of the lift control assembly  42  and the hydraulic tank  44  may be varied such that the lift control assembly  42  is located anywhere along the perimeter of the shaker assembly  10  where it is reachable by an operator and the hydraulic tank  44  is located in such proximity to first and second bellows  46  and  48  that fluid communication may reasonably be maintained between the hydraulic tank  44  and the bellows  46 ,  48 . 
         [0024]    The lift control assembly  42  is operable to control pressurized air to and from the hydraulic tank  44  as well as to control communication of fluid between the hydraulic tank  44  and each of the bellows  46 ,  48 . As will be described, the lifting system  40  utilizes an air over fluid hydraulic system to raise and lower the discharge end  30  of the shaker bed  12 , thereby providing a range of incline to the bed  12  of the shaker separator  10 . 
         [0025]    The hydraulic tank  44  is provided with a predetermined amount of liquid. In one embodiment, the liquid is water, such as when the shaker separator  10  is to be operated in temperatures where the water will not freeze. In one embodiment, the liquid is a fluid having an hydraulic fluid having a freezing point low enough for use in cold climates. A pneumatic line  72  directs air into the hydraulic tank  44  from the lift control assembly  42 . A first hydraulic line  80  directs the liquid to the bellows  46 ,  48 . The flow through the first hydraulic line  80  is controlled by the lift control assembly  42 . Thus, there is not a continuously open flow line between the hydraulic tank  44  and the bellows  46 ,  48 . 
         [0026]    Referring to  FIGS. 3 and 4 , the lift control assembly  42  includes an air inlet  62  into which pressurized air is fed. The pressurized air is provided to a first valve  64  via a first pneumatic line  66  and to a second valve  68  via a first pilot line  70 . The first valve  64  is connected to a second pneumatic line  72  leading to the hydraulic tank  44 . A third valve  74  has an actuator  76  that is connected via a second pilot line  78  to the second valve  68 . The third valve  74  opens and closes a pathway between a first hydraulic line  80  from the hydraulic tank  44  and a hydraulic junction  82  providing liquid to second and third hydraulic lines  84 ,  86  leading to the first and second bellows  46 ,  48 . The lift control assembly  42  is discussed in further detail below. 
         [0027]    Fluid to the first bellow  46  is provided through second hydraulic line  84  while fluid to the second bellow  48  is provided through third hydraulic line  86 . The second and third hydraulic lines  84 ,  86  are connected to the hydraulic junction  82  in parallel such that, when the third valve  74  is open, liquid is communicated to the first and second bellows  46 ,  48  simultaneously. Further, when the third valve  74  is closed, the liquid may be communicated between the first bellow  46  and the second bellow  48  via the second and third hydraulic lines  84 ,  86 . 
         [0028]    Continuing to refer to  FIGS. 2-4 , air from a pressurized air supply  88  enters the lift control system  40  through the air inlet  62 . A pressure regulator  90  is preferably included at the inlet  62  to provide an air stream at a predetermined pressure to the system. The preferred pressure will depend upon the weight to be lifted and the physical properties of the liquid to be communicated between the hydraulic tank  44  and the first and second bellows  46 ,  48  at within the anticipated ambient operating conditions. A pressure gauge  92  is preferably included along the second pneumatic line  72  between the first valve  64  and the hydraulic tank  44  to use in the adjustment of the pressure regulator  90 . 
         [0029]    Air from the pressure regulator  90  is provided to the first valve  64  through the first pneumatic line  66  and to the second valve  68  through the first pilot line  70 . The first valve  64  can be toggled between two positions, corresponding to raising and lowering the discharge end  30  of the shaker bed  12 . Further, the first valve  64  is a three-way valve, that is there are three ports into or out of which air may be directed. In a first position, corresponding to the operation of raising the discharge end  30 , the pressurized air from the regulator  90  enters one port of the first valve  64  and exits a second port of the first valve  64 , which port directs the air to the second pneumatic line  72  and the hydraulic tank  44 . In a second position of the first valve  64 , corresponding to the operation of lowering the discharge end  30 , air, displaced by fluid forced back into the hydraulic tank  44 , is forced from the hydraulic tank  44  through the second pneumatic line  72  to the first valve  64  is vented through a third port of the first valve  64 . In one embodiment, the first valve  64  is a three-way, two position ball valve. 
         [0030]    In one embodiment, the second valve  68  is biased to a closed position such that the pressurized air from the first pilot line  70  is not directed to the second pilot line  78  unless the second valve  68  is manually actuated. While in the normally closed position, the second valve  68  provides a vent for air in the second pilot line  78 . Upon actuation of the second valve  68 , the pressurized air from the first pilot line  70  is directed to the second pilot line  78 . Air directed through the second pilot line  78  provides communication to the actuator of the third valve  74 , thereby actuating the third valve  74  when the second valve  68  is actuated. In one embodiment, the second valve  68  is a signal valve. 
         [0031]    The third valve  74  is biased to a closed position thereby preventing communication of liquid through the first hydraulic line  80  to the hydraulic junction  82 . As previously explained, when the third valve  74  is actuated, fluid flow between the hydraulic tank  44  and the first and second bellows  46 ,  48  is open. In one embodiment, the third valve  74  is a two-way ball valve. 
         [0032]    Referring to  FIGS. 2 ,  3 , and  6 , to operate the lifting system  40 , an operator will position the first valve  64  in a desired position corresponding to whether the shaker discharge end  30  will be raised or lowered. To lift the discharge end  30  of the shaker separator  10 , the operator will place the first valve  64  in a corresponding position using a handle, knob, or other such operator interface. Air from the air supply  88  as regulated by the pressure regulator  90  is directed through the first valve  64  to the hydraulic tank  44 . So long as the third valve  74  is closed, communication of fluid from the hydraulic tank  44  to the first and second bellows  46 ,  48  is prevented and the shaker  10  will maintain its initial incline. 
         [0033]    To raise or lower the discharge end  30 , the operator actuates the second valve  68  thereby providing pressurized air to the actuator  76  of the third valve  74 . Actuation of the third valve  74  opens the passage between the first hydraulic line  80  and the hydraulic junction  82 . The pressurized air fed into the hydraulic tank  44  as a result of positioning the first valve  64  in the desired position, forces the liquid in the tank  44  through the first hydraulic line  80  to the hydraulic junction  82 . From the hydraulic junction  82 , the fluid is directed through the second and third hydraulic lines  84 ,  86  to the first and second bellows  46 ,  48  respectively. As the fluid fills the first and second bellows  46 ,  48 , each bellow  46 ,  48  expands to raise the discharge end  30  of the shaker separator  10 . 
         [0034]    Once the desired incline of the bed  12  is achieved, the operator releases the second valve  68 , thereby closing it and releasing the actuator  76  of the third valve  74 . When the actuator  76  is released, the third valve  74  returns to a closed position. Thus, the fluid transferred to the first and second bellows  46 ,  48  and the second and third hydraulic lines  84 ,  86  is confined. If the first bellow  46  contains more fluid than the second bellow  48  or vice versa, the weight of the shaker separator  10  will force the fluid to equalize between the first bellow  46  and the second bellow  48 , thereby leveling the discharge end  30  from side to side. 
         [0035]    To lower the discharge end  30  of the shaker separator  10 , an operator places the first valve  64  to a second position corresponding to lowering the discharge end  30 , again using a handle, knob, or other such interface device. When the first valve  64  is placed into the second position, any air under pressure in the second pneumatic line  72  and the hydraulic tank  44  may be vented. So long as the third valve  74  remains closed, only a minimal amount of air will be vented and the discharge end  30  will remain in the raised position. 
         [0036]    The operator actuates the second valve  68  to open fluid communication from the air supply  88  to the actuator  76  of the third valve  74 . When the air through the second pilot line  78  actuates the third valve  74 , the third valve  74  opens to provide fluid communication of the liquid between the first and second bellows  46 ,  48  and the hydraulic tank  44 . With pressure on the fluid released, the fluid moves back into the hydraulic tank  44  while the third valve  74  is open. The weight of the shaker separator  10  on the first and second bellows  46 ,  48  forces the liquid back into the hydraulic tank  44 . Air from the hydraulic tank  44 , displaced by the liquid, is forced back through the second pneumatic line  72  and vented through the first valve  64 . 
         [0037]    When the bed  12  of the shaker separator  10  has reached the desired declination angle, the operator releases the second valve  68  to stop the flow of liquid from the first and second bellows  46 ,  48  to the hydraulic tank  44 . This again confines the fluid in the first and second bellows  46 ,  48  and the second and third hydraulic lines  84 ,  86  and freezes the discharge end  30  in the desired position. 
         [0038]    Referring to  FIGS. 1 ,  2 , and  6 , to assist the operator in adjusting the discharge end  30  of the shaker separator  10 , a means for indicating a position of the discharge end  60  may be coupled between the shaker bed  12  and the floor or skid on which the shaker  10  is located. Indicator plates  94  may be located adjacent to one or both of the bellows  46 ,  48 . The indicator plates  94  may include graduation lines corresponding desired positions of the discharge end  30 . Graduation lines may correspond to a height of the discharge end  30  above the skid or the floor. Graduation lines may correspond to an angle of the shaker bed  12  with respect to the skid or the floor. A marker  96 , or pointer, such as piece of formed sheet metal coupled to the bed  12  of the shaker separator  10  may be used to mark the angle of incline of the discharge end  30  of the shaker separator  10  relative to the skid  32  or floor to which the shaker separator  10  is mounted. 
         [0039]    Referring to  FIG. 2 , a track system  98  may be provided to guide the vertical movement of each of the first and second bellows  46 ,  48 . The track system  98  includes upright plates  100 ,  102  located on opposing sides of each bellow  46 ,  48 . The inner upright plate  100  for the first bellow  46  is shown in  FIG. 2 , while the corresponding outer upright plate  102  may be seen in  FIG. 1 . Each upright plate  100 ,  102  has a vertical track  104  along its inner surface  106 . Each shroud  54  is provided with rollers  108 , which roll along the track  104 . A wall  110  extending from each upright plate  100 ,  102  helps keep the rollers  108  in a confined area near the track  104 . 
         [0040]    One of skill in the art will appreciate that some variation of the components described are possible. For example the first and second bellows  46 ,  48  may be replaced with other types of hydraulic lifters. Another variation includes replacing the first and second bellows  46 ,  48  with a single lifter centrally located along the discharge end  30  of the shaker bed  12 . 
         [0041]    In one embodiment of the lifting system  40 ′, depicted in  FIG. 7 , the lift control assembly  42 ′ includes a tank control valve  64 ′, a pair of pilot control valves  68 ′,  68 ″, a shuttle valve  112 , and a skinner fluid valve  74 ′. The pilot control valves  68 ′,  68 ″ and the skinner fluid valve  74 ′ are biased to a closed position. Air from an air supply (not shown) is split, with a first stream directed through a pressure regulator  90  to the tank control valve  64 ′ and a second stream split again into a first sub-stream and a second sub-stream. The first sub-stream is directed to the first pilot control valve  68 ′ and the second sub-stream is directed to the second pilot control valve  68 ″. 
         [0042]    A pneumatic line  72  connects the tank control valve  64 ′ to the hydraulic tank  44 . A first pilot line  70 ′ connects the first pilot valve  68 ′ to the shuttle valve  112  and a second pilot line  70 ″ connects the second pilot valve  68 ″ to the shuttle valve  112 . A third pilot line  78 ′ connects the shuttle valve  112  to an actuator  76 ′ on the skinner fluid valve  74 ′. A first hydraulic line  80 ′ connects the hydraulic tank  44  to the skinner fluid valve  74 ′. A second hydraulic line  114  splits into two sub-hydraulic lines  84 ′,  86 ′ going to each of the bellows  46 ,  48 , which are coupled to the shaker separator  10  near the discharge end  30 . 
         [0043]    To raise the discharge end  30  of the shaker separator  10 , an operator actuates the first pilot valve  68 ′. Air flows through the first pilot valve  68 ′ to the shuttle valve  112  and to a pilot port of the tank control valve  64 ′. The shuttle valve  112  directs the air to the third pilot line  78 ′ and actuates the skinner fluid valve  74 ′. Actuation of the skinner fluid valve  74 ′ opens fluid communication between the hydraulic tank  44  and the bellows  46 ,  48  through the first hydraulic line  80 ′ and the second hydraulic line  114 . The air flow to the pilot port of the tank control valve  64 ′ actuates the tank control valve  64 ′ to provide pressure regulated air to the hydraulic tank  44 . 
         [0044]    The pressure regulated air displaces fluid in the hydraulic tank  44 , causing the fluid to exit the tank  44  through the first hydraulic line  80 ′. The fluid is forced from the tank  44  through the skinner fluid valve  74 ′ into the bellows  46 ,  48 , causing them to expand and raise the discharge end  30  of the shaker separator  10 . When the first pilot valve  68 ′ is released by the operator, air pressure through the first pilot line  70 ′ to the shuttle valve  112  and air pressure to the pilot port of the tank control valve  64 ′ drops. The drop in air pressure on the shuttle valve  112  releases the actuation of the skinner fluid valve  74 ′, returning it to its normally closed position and terminating fluid communication between the hydraulic tank  44  and the bellows  46 ,  48 . The drop in air pressure to the tank control valve  64 ′ releases it to its normal position wherein air in the hydraulic tank  44  and the pneumatic line  72  is vented and air flow into the hydraulic tank  44  from the air supply is stopped. 
         [0045]    To lower the discharge end  30  of the shaker separator  10 , the operator actuates the second pilot valve  68 ″. When the second pilot valve  68 ″ is actuated, air is directed to the shuttle valve  112 . The pilot signal to the shuttle valve  112  causes it to open and provide air flow to the third pilot line  78 ′, thereby actuating the skinner fluid valve  74 ′. Upon actuation of the skinner fluid valve  74 ′, the first and second hydraulic lines  80 ′,  114  are in fluid communication, providing fluid communication between the bellows  80 ′,  114  and the hydraulic tank  44 . The tank control valve  64 ′ remains in its biased position wherein air from the hydraulic tank  44  is vented therethrough. 
         [0046]    The bellows  46 ,  48  are compressed by the weight of the shaker separator  10  causing the fluid therein to flow back to the hydraulic tank  44 . Air displaced by the fluid is vented through the tank control valve  64 ′. When the bed  12  has reached the desired angle, the operator releases the second pilot valve  68 ″, forcing the cessation of the pilot signal to the shuttle valve  112  and the return of the skinner fluid valve  74 ′ to its biased, closed position. The closure of the skinner fluid valve  74 ′ stops flow from the bellows  46 ,  48  to the hydraulic tank  44  and the bed  12  is maintained at the desired angle. 
         [0047]    In one embodiment, an electrical interlock solenoid valve  116  is included in parallel with the skinner fluid valve  74 ′ between the first and second hydraulic lines  80 ′,  114 . In one embodiment, a needle valve  118  and silencer  120  is included at the venting port of the tank control valve  64 ′. In one embodiment, a filter  122  is included at the inlet to the lift control assembly  42 ′. 
         [0048]    Referring now to  FIGS. 8 and 9 , an alternative mechanism for lifting and guiding vertical movement of a shaker separator (e.g.,  10  of  FIG. 1 ) may be described. In particular, each bellows ( 46 ,  48  of  FIGS. 1-7 ) may be replaced with a lifting mechanism  200  that includes a lifting apparatus  202  and a vertical alignment apparatus  204 . Lifting apparatus  202  includes two hydraulic bellows  206 ,  208  sandwiched between a bottom plate  210  and a top plate  212  for transmitting hydraulic energy from a hydraulic line  214  (similar to  84  and  86  of  FIG. 4 ) to lift either a free end or a discharge end of a separator shaker assembly. While lifting apparatus  202  is shown having two bellows  206  and  208 , it should be understood that fewer or more bellows may be used without departing from the scope of the present disclosure. Further, dual bellows  206  and  208  may be replaced with a single, larger bellows if desired. 
         [0049]    Vertical alignment apparatus  204  extends between top plate  212  of lifting apparatus  202  and an adapter plate  216  (similar to  56  of  FIG. 2 ) of the shaker separator. In selected embodiments, vertical alignment apparatus  204  is designed to ensure the displacement and forces transmitted from bellows  206  and  208  are substantially linear and vertical as would be desired by those having ordinary skill in the art. Alternatively, it should be understood that vertical alignment apparatus  204  may be angled such that displacement and forces are transmitted in a substantially linear, but not necessarily vertical orientation, if desired. 
         [0050]    As such, vertical alignment apparatus  204  includes an actuated cylinder assembly  218  configured to reciprocate within a sleeve  220  affixed to a frame  222  of the shaker separator. Sleeve  220  may be affixed to frame  222  by any mechanism known to those having ordinary skill including, but not limited to, welding, bolting, press fitting, brazing, and the like. With sleeve  220  rigidly affixed to frame  222 , cylinder assembly  218  is able to linearly displace therethrough when actuated by top plate  212 . Further, by selecting the length and relative position of sleeve  220  within frame  222 , the top and bottom ends of sleeve  220  may be used to limit a maximum and a minimum amount of stroke of cylinder assembly  218 , described below in more detail. 
         [0051]    Furthermore, cylinder assembly  218  includes an inner cylinder  224 , an outer cylinder  226 , and a top plate  228 . As such, an outer diameter of inner cylinder  224  is sized to engage through an inner diameter of sleeve  220  so that top plate  228  may be raised and lowered as bellows  206  and  208  of lifting apparatus  202  are inflated and deflated. An alignment ring  230  having an outer profile approximate to an inner diameter of inner cylinder  224  is rigidly affixed to top plate  212  so that cylinder assembly  218  is maintained in proper alignment at all times during the stroke of lifting apparatus  204 . 
         [0052]    Additionally, outer cylinder  226  of cylinder assembly  218  extends downward from top plate  228  and includes an inner diameter larger than an outer diameter of sleeve  220 . Thus, outer cylinder  226  may act as a cap to prevent fluids and debris from entering the annular gap formed between sleeve  220  and inner cylinder  228 . Advantageously, by preventing fluids and debris from entering the annular gap between sleeve  220  and inner cylinder  228 , the same fluids and debris may be prevented from entering a compartment  232  within frame where lifting apparatus  202 , bellows  206  and  208 , and various other components are housed. 
         [0053]    Furthermore, because shaker separator will experience to a large amount of vibration, a spring  234  may be mounted between top plate  228  of cylinder assembly  218  and adapter plate  216  to isolate lifting apparatus  202  and alignment apparatus  204  from vibrations. As such, a spring mount  236  may retain a bottom portion of spring  234  to top plate  228 , and a corresponding upper spring mount  238  may be mounted under adapter plate  216 . Furthermore, while only spring  234  is shown, it should be understood that a viscous coupling or other form of vibration dampener may be use in conjunction with or in place of spring  234 . Furthermore, one of ordinary skill in the art will appreciate that bellows  206  and  208  will also have inherent spring and dampening characteristics also. 
         [0054]    Advantageously, lifting mechanism  200  enables hydraulic bellows  206  and  208  to be positioned below (e.g., in compartment  232  of frame  222 ) a shaking separator deck to be raised and/or lowered. Further, alignment apparatus  204  enables any lifting force from bellows  206  and  208  to be applied substantially linearly in a desired direction so that damage from long term vibratory side, or translational, loading is minimized. Furthermore, by locating lifting bellows  206  and  208  beneath the shaker deck, torsional loads to the deck resulting from the lifting forces may be reduced. Further, lifting mechanisms in accordance with embodiments disclosed herein may be positioned at either a free end of a shaking separator, a discharge end of the shaking separator, or at both ends (i.e., all four corners) control the amount and direction of relative shaker screen tilt desired. 
         [0055]    While the claimed subject matter has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the claimed subject matter as disclosed herein. Accordingly, the scope of the claimed subject matter should be limited only by the attached claims.

Summary:
An apparatus to lift an oilfield machine includes at least one lifting bellows, an alignment assembly extending between at least one lifting bellows and an adapter plate of the oilfield machine, the alignment assembly comprising an inner cylinder to reciprocate within a sleeve of the oilfield machine, and the alignment assembly comprising a top plate at an upper end of the inner cylinder, the top plate configured to transfer forces from the at least one lifting bellows and the inner cylinder to the adapter plate, wherein the sleeve is configured to restrict the inner cylinder to a substantially linear displacements therethrough.