Abstract:
A hybrid wedge jack/scissor lift device for lifting heavy loads is provided, the device having a horizontally-oriented actuator coupled to a wedge that acts on lower and upper rollers coupled to a scissor lift. In operation, the actuator can drive the wedge in between the rollers, spreading them apart to raise the scissor lift. When the actuator retracts, the wedge is removed and the scissor lift collapses under the weight of the load. The wedge can be shaped in such a way that the lift has one or more intrinsically safe positions in which the rollers on the scissor lift fit into seats on the wedge, preventing the scissor lift from collapsing in the event of an actuator failure. An optional restraint bar safety mechanism is also provided.

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present disclosure is related to the field of jacks and lifts for use in safely raising and lowering heavy objects, in particular, wedge jacks and scissor lifts operated by linear actuators and that incorporate integral safety features. 
     BACKGROUND OF THE INVENTION 
     Various types of jacks and lifting devices are used in a wide variety of industries for lifting many different types of loads. Each of the various designs of jacks and lifting devices possesses distinct advantages and disadvantages. Thus, it is important to choose a design that is suited to the specific lifting requirements of the task at hand. 
     Scissor lifts, which are well known, are very compact and possess low height profiles. These characteristics allow scissor lifts to function when limited clearance is available beneath a load. Scissor lifts are also advantageous because they are simple in design, and provide a stable and parallel movement of the load-bearing surface with respect to the base of the lift. However, scissor lifts that are driven by horizontally-oriented actuators are very inefficient, particularly during the initial stage of the lift. During this initial stage, a relatively large amount of horizontal force is required to raise the load on the scissor lift because only a small percentage of the horizontal force is translated into vertical force. 
     Another well-known lifting apparatus is the wedge jack. Wedge jacks are advantageous in that they are capable of lifting very heavy loads and are also very simple in design. Shortcomings of wedge jacks include difficulty in designing a jack such that the load-bearing surface remains horizontally stationary as it moves vertically; issues with friction between the moving surfaces in the jack; and design constraints with respect to the positioning of the linear actuator that drives the jack as well as the overall housing of the jack, which must contain moving and stationary wedges over the range of the lift. 
     Both scissor lifts and wedge jacks share a common deficiency: if the linear force actuator supplying the force to lift the load fails in some way, the load is uncontrollably dropped to the resting position of the scissor lift or wedge jack. This can be particularly problematic when multiple scissor lifts or wedge jacks are being used since the load being lifted may become unbalanced and shift or slide unpredictably. The failure of such a lifting apparatus creates a risk of serious property damage as well as a safety concern for people working in the same area as the load. While some devices and techniques for preventing scissor lifts and wedge jacks from failing in this way are taught in the prior art, most of the safety measures disclosed are not integral to the design of lifting apparatus itself. These safety measures may fail of their own accord or be intentionally or unintentionally disengaged by an operator. 
     One particular situation that arises frequently and presents a number of challenges is where the load to be lifted is very heavy and there is minimal space in which to position a lifting apparatus underneath said load. A common example of this situation is where heavy vehicles such as construction machinery or military equipment must be lifted for maintenance or transportation purposes. Scissor lifts are not feasible for this purpose due primarily to their inefficiencies in the initial portion of the lift. Wedge jacks are generally too large and unstable for such a task, and are often incapable of lifting the load to the required height. Devices using vertically-oriented actuators are often used for such tasks, but these devices do not have compact, low height profiles and are often unable to fit between the load and the surface underneath. Such devices also carry the same safety risks as scissor lifts and wedge jacks with respect to the failure of the actuators used to lift the load. 
     It is, therefore, desirable to provide a hybrid wedge jack/scissor lift device that overcomes the shortcomings of the prior art lifting apparatus designs. 
     SUMMARY OF THE INVENTION 
     A wedge jack/scissor lift hybrid lifting apparatus is provided. In some embodiments, the hybrid lifting apparatus can comprise a wedge driven by a linear actuator, with the linear actuator fixed to a central trunnion of a scissor lift assembly and the wedge oriented within the scissor lift such that extending the actuator causes the wedge to raise the scissor lift, and retracting the actuator causes the wedge to lower the scissor lift. 
     In some embodiments, the scissor lift assembly can comprise first and second sides connected by upper and lower fixed pins, upper and lower sliding pins and a central trunnion. The first and second sides can comprise a first scissor arm, a second scissor arm, an L-shaped upper frame member and an L-shaped lower frame member. The first and second scissor arms can each further comprise a fixed end having an end pin passage for receiving one of the fixed pins, a sliding end having an end pin passage for receiving one of the sliding pins and a central trunnion passage for receiving the central trunnion. The L-shaped upper frame member can comprise a downward-projecting main body having a fixed pin passage and a sliding pin slot and an outward-projecting flange. The L-shaped lower frame member can further comprise an upward-projecting main body having a fixed pin passage and a sliding pin slot and an outward-projecting flange. The upper fixed pin can pass through the fixed pin passage of the L-shaped upper frame member and the end pin passage of the fixed end of the first scissor arm of the first side of the scissor lift assembly, then through the end pin passage of the fixed end of the first scissor arm and the fixed pin passage of the L-shaped upper frame member of the second side of the scissor lift assembly, respectively. The lower fixed pin can pass through the fixed pin passage of the L-shaped lower frame member and the end pin passage of the fixed end of the second scissor arm of the first side of the scissor lift assembly, then through the end pin passage of the fixed end of the second scissor arm and the fixed pin passage of the L-shaped lower frame member of the second side of the scissor lift assembly, respectively. Both the upper fixed pin and the lower fixed pin can be fixed in place with respect to the upper frame members of both sides of the scissor lift assembly and the lower frame members of both sides of the scissor lift assembly, respectively. The first scissor arms of both sides of the scissor lift assembly and the second scissor arms of both sides of the scissor lift assembly can rotate freely about the upper fixed pin and the lower fixed pin, respectively. Both first scissor arms and both second scissor arms can be positioned coaxially about the central trunnion, which can pass through the central trunnion passages of the second scissor arm and the first scissor arm of the first side of the scissor lift assembly, then through the central trunnion passages of the first scissor arm and the second scissor arm of the of the second side of the scissor lift assembly, respectively. Both first scissor arms and both second scissor arms can rotate freely about the central trunnion. The upper sliding pin can pass through the sliding pin slot of the L-shaped upper frame member and the end pin passage of the sliding end of the second scissor arm of the first side of the scissor lift assembly, then through the end pin passage of the sliding end of the second scissor arm and the sliding pin slot of the L-shaped upper frame member of the second side of the scissor lift assembly, respectively. The lower sliding pin can pass through the sliding pin slot of the L-shaped lower frame member and the end pin passage of the sliding end of the first scissor arm of the first side of the scissor lift assembly, then through the end pin passage of the sliding end of the first scissor arm and the sliding pin slot of the L-shaped lower frame member of the second side of the scissor lift assembly, respectively. The second scissor arms of both sides of the scissor lift assembly and the first scissor arms of both sides of the scissor lift assembly can rotate freely about the upper sliding pin and the lower sliding pin, respectively. The upper sliding pin can be free to slide back and forth within the sliding pin slots of both L-shaped upper frame members, and the lower sliding pin can be free to slide back and forth within the sliding pin slots of both L-shaped lower frame members. 
     In some embodiments, the L-shaped upper frame members and the L-shaped lower frame members can further comprise flange bolt passages disposed through their respective flanges and a trunnion recess in each of the edges of their respective main bodies, with the trunnion recess positioned such that when the scissor lift is fully lowered, the trunnion recesses of the downward-projecting main bodies of the L-shaped upper frame members can sit over top of the central trunnion while the central trunnion rests in the trunnion recesses of the upwardly-projecting main bodies of the L-shaped lower frame members. 
     In some embodiments, the scissor lift assembly can further comprise an upper wedge roller and a lower wedge roller positioned coaxially with the upper and lower fixed pins, respectively. Both wedge rollers can be positioned between the two sides of the scissor lift assembly, with the upper fixed pin passing through the center of the upper wedge roller and the lower fixed pin passing through the center of the lower wedge roller. The diameter of the wedge rollers can be such that they extend beyond the edges of the main bodies of the L-shaped upper frame members and the L-shaped lower frame members. The scissor lift assembly can be at its lowest point when the bottom of the upper wedge roller rests on the top of the lower wedge roller. 
     In some embodiments, the hybrid lifting apparatus can further comprise a wedge attached to an actuator rod that can be extended and retracted by a linear actuator, with the linear actuator fixed in place by the central trunnion between the first and second sides of the scissor lift assembly. The wedge and linear actuator can be oriented such that the tip of the wedge points in the direction of the fixed pins of the scissor lift assembly. With the linear actuator fully retracted, the hybrid lifting apparatus can be at its lowest point, with the bottom of the upper wedge roller resting on the top of the lower wedge roller. As the linear actuator extends, the wedge can be driven between the two wedge rollers. The upper wedge surface can push on the upper wedge roller and the lower wedge surface pushes on the lower wedge roller. This can cause the scissor lift assembly to extend, with the upper and lower sliding pins moving towards the upper and lower fixed pins, respectively, the scissor arms rotating from a substantially horizontal position to an increasingly vertical position, and the L-shaped upper frame members moving straight up, away from the L-shaped lower frame members. When the linear actuator retracts, the process can reverse and the hybrid lifting apparatus can retract towards its resting position at its lowest point. 
     In some embodiments, one or both of the upper or lower wedge rollers can comprise a guided wedge roller. The guided wedge roller can comprise a main body with a length corresponding to the width of the wedge, and two disc-shaped wedge guides positioned at the ends of the main body, the wedge guides having a diameter greater than that of the main body. The wedge surface can rest on the main body while the wedge guides can resist lateral movement of the wedge. 
     In some embodiments, the wedge can further comprise one or more pairs of concave wedge roller seats. Each pair of wedge roller seats can comprise a wedge roller seat on the upper wedge surface, and a corresponding wedge roller seat on the lower wedge surface, the wedge roller seats situated directly opposite from one another. The concave shape of the wedge roller seats can be such that the when the wedge is in a position where the wedge rollers are sitting in a pair of wedge roller seats, the hybrid lift apparatus can be in an intrinsically safe position whereby the wedge cannot move and, thus, the scissor lift assembly cannot collapse unless a force sufficient to raise the load on the hybrid lifting apparatus acts on the wedge and removes the wedge rollers from the wedge roller seats. 
     In some embodiments, the hybrid lifting apparatus can further comprise a load plate with plate bolt passages. Bolts can pass through the plate bolt passages and the flange bolt passages of the L-shaped upper members, and can be fixed in place with plate nuts to secure the load plate to the hybrid lift assembly. 
     In some embodiments, the load plate can further comprise a cradle fixed to the top of the load plate. The cradle can be oriented and shaped to prevent loads from shifting atop the load plate. 
     In some embodiments, the hybrid lifting apparatus can further comprise a base plate with plate bolt passages. Bolts can pass through the plate bolt passages and the flange bolt passages of the L-shaped lower members, and can be fixed in place with plate nuts to secure the base plate to the hybrid lift assembly. 
     In some embodiments, the scissor lift assembly can further comprise support discs positioned coaxially with the upper and lower sliding pins, with the fixed pins passing through the center of the support discs. The diameter of the support discs can be such that they transfer the vertical forces exerted on the upper and lower sliding pins by the second and first scissor arms to the load plate and the base plate, respectively. 
     In some embodiments, the hybrid lifting apparatus can further comprise between one and four restraint bar safety systems, each restraint bar safety system comprising a restraint bar actuator and a restraint bar, each restraint bar having a restraint bar pin passage, one or more sliding pin seats and a restraint bar actuator attachment point. Each of the restraint bar safety systems can be associated with one of the L-shaped frame members, and the fixed and sliding pins associated with that L-shaped frame member. For each restraint bar safety system, a fixed pin can extend out through an L-shaped frame member and passes through a restraint bar&#39;s restraint bar pin passage. The restraint bar can be free to rotate about the associated fixed pin. The restraint bar can comprise a restraint bar actuator attachment point at the end opposite the restraint bar pin passage. This attachment point can be coupled to one end of the restraint bar safety system&#39;s restraint bar actuator. The other end of the restraint bar actuator can be fixed to a point on the associated L-shaped frame member. The restraint bar actuator can be oriented such that when the restraint bar actuator extends, the restraint bar can swing out and away from the flange of the associated L-shaped frame member. When the restraint bar actuator is extended far enough that the one or more sliding pin seats of the restraint bar are clear of the associated sliding pin, the hybrid lifting apparatus can be free to operate normally. When restraint bar actuator is retracted such that the restraint bar is in a position where the associated sliding pin can rest in one of the one or more sliding pin seats, the restraint bar safety system can be engaged. The hybrid lifting apparatus can be lowered into a position where the associated sliding pin rests in the one of one or more sliding pin seats and the hybrid lifting apparatus is secured in place in that position. 
     In some embodiments, a vertical tandem hybrid lifting apparatus is provided, the vertical tandem hybrid lifting apparatus comprising lower and upper hybrid lifting apparatuses attached by joining the L-shaped upper frame members of the lower hybrid lifting apparatus to the corresponding L-shaped lower frame members of the upper hybrid lifting apparatus. 
     In some embodiments, a simplified hybrid lifting apparatus is provided, the simplified hybrid lifting apparatus comprising a simplified scissor lift assembly having a compact load plate assembly and first and second sides connected by upper and lower fixed pins, a lower sliding pin and a central trunnion. The compact load plate assembly can further comprise a compact load plate having plate bolt passages and first and second load plate flanges, with each on one side of the compact load plate and each having a flange pin passage. The first and second sides can further comprise a first scissor arm, a first lever arm and an L-shaped lower frame member. The first scissor arm can further comprise a fixed end having an end pin passage for receiving one of the fixed pins, a sliding end having an end pin passage for receiving the sliding pin and a central trunnion passage for receiving the central trunnion. The first lever arm can further comprise a fixed end having an end pin passage for receiving the lower fixed pin and a rotatable end having an end trunnion passage for receiving the central trunnion. The L-shaped lower frame member can further comprise an upward-projecting main body having a fixed pin passage and a sliding pin slot and an outward-projecting flange. The lower fixed pin passes through the fixed pin passage of the L-shaped lower frame member and the end pin passage of the fixed end of the first lever arm of the first side of the simplified scissor lift assembly, then through the end pin passage of the fixed end of the first lever arm and the fixed pin passage of the L-shaped lower frame member of the second side of the scissor lift assembly, respectively. The upper fixed pin passes through the flange pin passage of the first flange and the end pin passage of the fixed end of the first scissor arm of the first side of the simplified scissor lift assembly, then through the end pin passage of the fixed end of the first scissor arm of the second side of the simplified scissor lift assembly and the flange pin passage of the second flange, respectively. The upper fixed pin may be fixed in place with respect to the first and second flanges and the lower fixed pin may be fixed in place with respect to the L-shaped lower frame members. The first lever arms of both sides of the simplified scissor lift assembly are free to rotate about the lower fixed pin. The first scissor arms of both sides of the simplified scissor lift are free to rotate about the upper fixed pin. The central trunnion passes through the central trunnion passage of the first scissor arm and the end trunnion passage of the first lever arm of the first side of the simplified scissor lift assembly, then through the end trunnion passage of the first lever arm and the central trunnion passage of the first scissor arm of the second side of the simplified scissor lift assembly, respectively. Both first lever arms and both first scissor arms rotate freely about the central trunnion. The lower sliding pin passes through the sliding pin slot of the L-shaped lower frame member and the end pin passage of the sliding end of the first scissor arm of the first side of the simplified scissor lift assembly, then through the end pin passage of the sliding end of the first scissor arm and the sliding pin slot of the L-shaped lower frame member of the second side of the simplified scissor lift assembly, respectively. The first scissor arms of both sides of the simplified scissor lift assembly rotate freely about the lower sliding pin. The lower sliding pin is free to slide back and forth within the sliding pin slots of the L-shaped lower frame member. 
     In some embodiments, the simplified hybrid lifting apparatus can further comprise one or two restraint bar safety systems. Each of the restraint bar safety systems is associated with one of the L-shaped lower frame members and the fixed and sliding pins associated with that L-shaped lower frame member. 
     In some embodiments, a horizontal tandem simplified hybrid lifting apparatus is provided, the horizontal tandem simplified hybrid lifting apparatus comprising first and second simplified hybrid lifting apparatuses attached together in an end-to-end configuration such that the linear actuators of the first and second simplified hybrid lifting apparatuses oppose one another. The first and second hybrid lifting apparatuses may be joined together by using common L-shaped lower frame members and a common base plate. The common L-shaped lower frame members are formed by attaching two L-shaped lower frame members in an end-to-end configuration, with the sliding pin slots of each L-shaped lower frame member adjacent to one another. The common base plate further comprises plate bolt passages. Bolts pass through the plate bolt passages and the flange bolt passages of the common L-shaped lower members and are fixed in place with plate nuts to secure the common base plate. 
     In some embodiments, a centrally-controlled hybrid lifting apparatus array is provided, the centrally-controlled hybrid lifting apparatus array comprising two or more hybrid lifting apparatuses controlled by a controller connected to each of the hybrid lifting apparatuses in the array by a control cable. 
     Broadly stated, in some embodiments, a lifting apparatus is provided, comprising: a scissor lift assembly, further comprising: an upper frame operatively disposed above a lower frame, a pair of scissor braces operatively disposed between the upper frame and the lower frame, each brace further comprising first and second arms pivotally attached to each other, each arm further comprising a first end and a second end, a first fixed pin pivotally attaching the first end of the first arms to the upper frame, and a second fixed pin pivotally attaching the first end of the second arms to the lower frame, a first sliding pin disposed in a first slot disposed in the upper frame, the first sliding pin further disposed through the second end of the second arms wherein the first sliding pin can move along the first slot, and a second sliding pin disposed in a second slot disposed in the lower frame, the second sliding pin further disposed through the second end of the first arms wherein the second sliding pin can move along the second slot; a linear actuator disposed between the upper frame and the lower frame, the linear actuator configured to extend and retract; and a wedge comprising upper and lower wedge surfaces, the wedge operatively coupled to the linear actuator, the wedge configured to extend between the first fixed pin and the second fixed pin when the linear actuator is extended wherein the upper frame can be raised relative to the lower frame when the linear actuator is extended, and wherein the upper frame can be lowered relative to the lower frame when the linear actuator is retracted. 
     Broadly stated, in some embodiments, the scissor lift assembly can further comprise a first roller rotatably disposed about the first fixed pin, and a second roller rotatably disposed about the second fixed pin, wherein the wedge extends between the rollers when the linear actuator is extended. 
     Broadly stated, in some embodiments, the wedge can further comprise at least one first concave indentation disposed on the upper wedge surface, and at least one second concave indentation disposed on the lower wedge surface, the at least one first and second concave indentations shaped to receive the first roller and the second roller, respectively, wherein retracting the wedge from a position where the rollers are resting in the first and second at least one concave indentations requires sufficient force to raise the upper frame slightly upward. 
     Broadly stated, in some embodiments, the lower frame can further comprise a base plate, the base plate configured to improve the structural integrity of the lower frame. 
     Broadly stated, in some embodiments, the lifting apparatus can further comprise at least one first support disc disposed about the second sliding pin, the at least one first support disc configured to transfer forces from the second sliding pin to the base plate. 
     Broadly stated, in some embodiments, the upper frame can further comprise a load plate, the load plate configured to improve the structural integrity of the upper frame and to facilitate the placement of loads thereon. 
     Broadly stated, in some embodiments, the lifting apparatus can further comprise at least one second support disc disposed about the first sliding pin, the at least one second support disc configured to transfer forces from the first sliding pin to the load plate. 
     Broadly stated, in some embodiments, the lifting apparatus can further comprise at least one restraint bar safety system, the at least one restraint bar safety system comprising a restraint bar capable of being engaged and disengaged by a restraint bar actuator, wherein the restraint bar is configured to engage the second sliding pin to prevent the apparatus from collapsing. 
     Broadly stated, in some embodiments, a vertical tandem lift system is provided, comprising two or more lifting apparatuses stacked one on top of the other. 
     Broadly stated, in some embodiments, a horizontal tandem lift system is provided, comprising two lifting apparatuses arranged end to end such that the linear actuators of the apparatuses extend away from each other. 
     Broadly stated, in some embodiments, a hybrid lifting system array is provided, comprising: two or more lifting apparatuses; and a central controller operatively coupled to the two or more lifting apparatuses, the central controller configured for controlling the two or more lifting apparatuses. 
     Broadly stated, in some embodiments, an actuator system is provided, comprising: a wedge comprising upper and lower wedge surfaces, the wedge operatively coupled to a linear actuator; two sets of a pair of lever arms, each pair of lever arms comprising a first lever arm and a second lever arm, each lever arm comprising a trunnion end and a pin end, the trunnion ends of one set of lever arms pivotally coupled to one side of the linear actuator about a central axis, the trunnion ends of the other set of lever arms pivotally coupled to an opposing side of the linear actuator about the central axis; a first lever pin operatively coupling the pin end of the first lever arm of one of the pair of lever arms to the pin end of the first lever arm of the other of the pair of lever arms; a second lever pin operatively coupling the pin end of the second lever of one of the pair of lever arms to the pin end of the second lever arm of the other of the pair of lever arms; a first roller rotatably disposed about the first lever pin between the two sets of lever arms, with each roller positioned coaxially with a lever pin between a set of lever arms; and a first roller rotatably disposed about the first lever pin between the two sets of lever arms, with each roller positioned coaxially with a lever pin between a set of lever arms wherein the linear actuator and wedge are oriented such that the linear actuator can extend the wedge to spread the rollers apart, causing the first and second lever arms to rotate about the central axis. 
     Broadly stated, in some embodiments, the wedge can further comprise at least one first concave indentation disposed on the upper wedge surface, and at least one second concave indentation disposed on the lower wedge surface, the at least one first and second concave indentations shaped to receive the first roller and the second roller, respectively. 
     Broadly stated, in some embodiments, a lifting apparatus is provided, comprising: a scissor lift assembly, further comprising: an upper frame operatively disposed above a lower frame, a pair of first arms operatively disposed between the upper frame and the lower frame, each first arm further comprising a first end and a second end, a second arm comprising a first end and a second, the first end of the second arm pivotally attached to the first arm, a first fixed pin pivotally attaching the first end of the first arms to the upper frame, and a second fixed pin pivotally attaching the second end of the second arms to the lower frame, and a sliding pin disposed in a slot disposed in the lower frame, the sliding pin further disposed through second end of the first arms wherein the sliding pin can move along the slot, a linear actuator disposed between the upper frame and the lower frame, the linear actuator configured to extend and to retract; and a wedge comprising upper and lower wedge surfaces, the wedge operatively coupled to the linear actuator, the wedge configured to extend between the first fixed pin and the second fixed pin when the linear actuator is extended wherein the upper frame can be raised relative to the lower frame when the linear actuator is extended, and wherein the upper frame can be lowered relative to the lower frame when the linear actuator is retracted. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevation view depicting a scissor lift assembly in a collapsed position. 
         FIG. 2  is a side elevation view depicting a scissor lift assembly in an extended position. 
         FIG. 3  is a perspective view depicting the scissor lift assembly of  FIG. 2 . 
         FIG. 4  is a side elevation view depicting a first embodiment of a hybrid wedge jack/scissor lift lifting apparatus in a collapsed position. 
         FIG. 5  is a side elevation view depicting the hybrid wedge jack/scissor lift lifting apparatus of  FIG. 4  in an extended position. 
         FIG. 6  is a perspective view depicting the hybrid wedge jack/scissor lift lifting apparatus of  FIG. 5 . 
         FIG. 7  is a side elevation view depicting a first embodiment of an actuator/wedge assembly. 
         FIG. 8  is a perspective view depicting the actuator/wedge assembly of  FIG. 7 . 
         FIG. 9  is a side elevation view depicting a second embodiment of a hybrid wedge jack/scissor lift lifting apparatus in a partially extended position. 
         FIG. 10  is a perspective view depicting the hybrid wedge jack/scissor lift lifting apparatus of  FIG. 9 . 
         FIG. 11  is a side elevation view depicting a third embodiment of a hybrid wedge jack/scissor lift lifting apparatus in a fully extended position. 
         FIG. 12  is a perspective view depicting the hybrid wedge jack/scissor lift lifting apparatus of  FIG. 11 . 
         FIG. 13  is a perspective view depicting a vertical tandem hybrid wedge jack/scissor lift lifting apparatus. 
         FIG. 14  is a perspective view depicting a horizontal tandem hybrid wedge jack/scissor lift lifting apparatus. 
         FIG. 15  is a side elevation view depicting a second embodiment of an actuator/wedge assembly. 
         FIG. 16  is a perspective view depicting the actuator/wedge assembly of  FIG. 15 . 
         FIG. 17  is a block diagram depicting a centrally-controlled hybrid wedge jack/scissor lift lifting apparatus array. 
         FIG. 18  is a side elevation view depicting an assembly comprising a lever arm and the actuator/wedge assembly of  FIG. 7 . 
         FIG. 19  is a perspective view depicting the assembly of  FIG. 18 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1 through 3 , one embodiment of a scissor lift assembly is shown. In this embodiment, scissor lift assembly  400  can comprise first side  402  and second side  404  connected by upper fixed pin  80  and lower fixed pin  82 , upper sliding pin  90  and lower sliding pin  91  and central trunnion  100 . First side  402  and second side  404  can further comprise first scissor arm  20 , second scissor arm  30 , L-shaped upper frame member  40  and L-shaped lower frame member  60 . First scissor arm  20  can further comprise fixed end  26  having end pin passage  22  for receiving upper fixed pin  80 , sliding end  28  having end pin passage  22  for receiving lower sliding pin  91  and central trunnion passage  24  for receiving central trunnion  100 . Second scissor arm  30  can further comprise fixed end  36  having end pin passage  32  for receiving lower fixed pin  82 , sliding end  38  having end pin passage  32  for receiving upper sliding pin  90  and central trunnion passage  34  for receiving central trunnion  100 . L-shaped upper frame member  40  can further comprise main body  42  having fixed pin passage  44  and sliding pin slot  48  and flange  52  having flange bolt passages  54 . L-shaped lower frame member  60  can further comprise main body  62  having fixed pin passage  64  and sliding pin slot  68  and flange  72  having flange bolt passages  74 . Upper fixed pin  80  can pass through fixed pin passage  44  of L-shaped upper frame member  40  and end pin passage  22  of fixed end  26  of first scissor arm  20  of scissor lift assembly first side  402 , then through end pin passage  22  of fixed end  26  of first scissor arm  20  and fixed pin passage  44  of L-shaped upper frame member  40  of scissor lift assembly second side  404 , respectively. Upper fixed pin  80  can be fixed in place with respect to both L-shaped upper frame members  40 , while both first scissor arms  20  can be free to rotate about upper fixed pin  80 . Lower fixed pin  82  can pass through fixed pin passage  64  of L-shaped lower frame member  60  and end pin passage  32  of fixed end  36  of second scissor arm  30  of scissor lift assembly first side  402 , then through end pin passage  32  of fixed end  36  of second scissor arm  30  and fixed pin passage  64  of L-shaped lower frame member  60  of scissor lift assembly second side  404 , respectively. Lower fixed pin  82  can be fixed in place with respect to both L-shaped lower frame members  60  while both second scissor arms  30  can be free to rotate about lower fixed pin  82 . Central trunnion  100  can pass through central trunnion passage  34  of second scissor arm  30  and central trunnion passage  24  of first scissor arm  20  of scissor lift assembly first side  402 , then through central trunnion passage  24  of first scissor arm  20  and central trunnion passage  34  of second scissor arm  30  of scissor lift assembly second side  404 , respectively. Both first scissor arms  20  and both second scissor arms  30  can be free to rotate about central trunnion  100 . Upper sliding pin  90  can pass through sliding pin slot  48  of L-shaped upper member  40  and end pin passage  32  of sliding end  38  of second scissor arm  30  of scissor lift assembly first side  402 , then through end pin passage  32  of sliding end  38  of second scissor arm  30  and sliding pin slot  48  of L-shaped upper frame member  40  of scissor lift assembly second side  404 . Upper sliding pin  90  can be free to slide back and forth within sliding pin slots  48  of L-shaped upper frame members  40 . Lower sliding pin  91  can pass through sliding pin slot  68  of L-shaped lower frame member  60  and end pin passage  22  of sliding end  28  of first scissor arm  20  of scissor lift assembly first side  402 , then through end pin passage  22  of sliding end  28  of first scissor arm  20  and sliding pin slot  68  of L-shaped lower frame member  60  of scissor lift assembly second side  404 . Lower sliding pin  91  can be free to slide back and forth within sliding pin slots  68  of L-shaped lower frame members  60 . When scissor lift assembly  400  is in a fully-collapsed position as seen in  FIG. 1 , first scissor arms  20  and second scissor arms  30  can be oriented substantially horizontal, wherein upper sliding pin  90  and lower sliding pin  91  can be a maximum distance away from upper fixed pin  80  and lower fixed pin  82 , respectively, and central trunnion  100  can rest in trunnion recesses  66  of L-shaped lower frame members  60  while trunnion recesses  46  of L-shaped upper frame members  40  can rest on central trunnion  100 . As scissor lift assembly  400  is raised to a fully extended position as seen in  FIGS. 2 and 3 , L-shaped upper frame members  40  can move vertically away from L-shaped lower frame members  60  as first scissor arms  20  rotate clockwise and second scissor arms  30  rotate counter-clockwise and upper sliding pin  90  and lower sliding pin  91  slide towards upper fixed pin  80  and lower fixed pin  82 , respectively. 
     In some embodiments, L-shaped upper frame members  40  can further comprise trunnion recess  46 , and L-shaped lower frame members  60  can further comprise trunnion recess  66 . Trunnion recesses  46  and  66  can be positioned on main bodies  42  and  62 , respectively, such that when scissor lift assembly  400  is fully collapsed, trunnion recess  46  can sit over top of central trunnion  100 , while central trunnion  100  can rest in trunnion recess  66 . 
     Referring to  FIGS. 4 through 8 , one embodiment of an actuator/wedge assembly  300 , can be disposed in scissor lift assembly  400  at central trunnion  100  to form one embodiment of hybrid wedge jack/scissor lift lifting apparatus  410 . Central trunnion  100  can fix linear actuator  110  in place with respect to scissor lift assembly  400 . Wedge  120  can be attached to actuator rod  112 , which can be extended and retracted by linear actuator  110 . Actuator/wedge assembly  300  can be oriented such that wedge  120  can point toward upper fixed pin  80  and lower fixed pin  82 . 
     In some embodiments, scissor lift assembly  400  can further comprise wedge roller  83  positioned coaxially with upper fixed pin  80  and guided wedge roller  84  positioned coaxially with lower fixed pin  82 . Wedge roller  83  and guided wedge roller  84  can be positioned between scissor lift assembly first side  402  and scissor lift assembly second side  404 . Upper fixed pin  80  can pass through the center of wedge roller  83 , and lower fixed pin  82  can pass through the center of guided wedge roller  84 . Guided wedge roller  84  can further comprise guided wedge roller main body  85  with wedge guides  86  disposed at each end. The diameter of wedge guides  86  can be greater than that of guided wedge roller body  85 , and the spacing between wedge guides  86  can be such that wedge  120  can rest on guided roller main body  85  while wedge guides  86  can prevent lateral movement of wedge  120 . Scissor lift assembly  400  can be at its lowest point when wedge roller  83  rests against guided wedge roller  84 . 
     In some embodiments, hybrid wedge jack/scissor lift lifting apparatus  410  can be at its lowest point with linear actuator  110  and actuator rod  112  fully retracted and wedge roller  83  resting against guided wedge roller  84 . As linear actuator  110  extends actuator rod  112 , wedge  120  can be driven between wedge roller  83  and guided wedge roller  84 . Wedge surface  122  can push up on wedge roller  83  and down on guided wedge roller main body  85 , spreading upper fixed pin  80  and lower fixed pin  82  and causing scissor lift assembly  400  to extend. The process can be reversed when linear actuator  110  retracts actuator rod  112 , removing wedge  120  from between wedge roller  83  and guided wedge roller main body  85 , allowing scissor lift assembly  400  to collapse due to gravity. 
     In some embodiments, wedge  120  can further comprise wedge roller seats  124 . Wedge roller seats  124  can be disposed opposite one another on wedge surface  122  and can be concave in shape. When wedge  120  is fully extended such that scissor lift assembly  400  is fully extended, wedge roller  83  and guided wedge roller  84  can sit in wedge roller seats  124 , wherein hybrid wedge jack/scissor lift lifting apparatus  410  can be in an intrinsically safe position since hybrid wedge jack/scissor lift lifting apparatus  410  cannot collapse unless a force sufficient to remove wedge roller  83  and guided wedge roller  84  from wedge roller seats  124  acts on wedge  120 . 
     In some embodiments, wedge surface  122  can comprise a convex curvature. In further embodiments, the curvature of wedge surface  122  can follow a circular arc. In other embodiments, the curvature of wedge surface can follow an exponential curve. In yet further embodiments, the curvature of wedge surface  122  can comprise a rise to run ratio of approximately 4:3 until rollers  83  and  84  are seated in roller seats  124 , wherein the rise to the stroke of actuator rod  112  is approximately 1:1. In some embodiments, approximately 75% of the stroke of actuator rod  112  can be used to move rollers  83  and  84  along wedge surface  122  until the rollers reach roller seats  124 , wherein approximately 25% of the stroke of actuator rod  112  can be used to seat rollers  83  and  84  in roller seats  124 . In some embodiments, the curvature of wedge surface  122  can be selected wherein the same force can be exerted by actuator  110  throughout the entire stroke of actuator rod  112  to move rollers  83  and  84  along wedge surface  122  until roller seats  124 . If wedge surface  122  were straight or linear, then the force required to move rollers  83  and  84  thereon would vary throughout the stroke of actuator rod  112 , such that the force to be exerted by actuator  110  would range from a minimum value to a maximum value. This would require selecting an actuator cylinder that could provide the maximum force required. By selecting a curvature for wedge surface  122  such that the force exerted by actuator  110  is constant throughout the stroke of actuator rod  112 , a smaller actuator or cylinder can be used for actuator  110 . 
     In some embodiments, the apparatus can comprise rise to stroke ratios other than 1:1. In some embodiments, an actuator  110  having an actuator rod  112  stroke length of 11.5 inches can be used to achieve a lift of 14 inches. In these embodiments, a 100 ton force actuator can be used to lift a 50 ton load. In other embodiments, an actuator  110  having an actuator rod  112  stroke length of 20 inches can be used to achieve a lift of 14 inches. 
     Referring to  FIGS. 15 and 16 , in some embodiments, actuator/wedge assembly  300  can be replaced by a second embodiment of an actuator/wedge assembly  310 , which can comprise modified wedge  210  with first wedge roller seats  214  and second wedge roller seats  218  along wedge surface  212 . Replacing actuator/wedge assembly  300  with actuator/wedge assembly  310  in hybrid wedge jack/scissor lift lifting apparatus  410  or any other embodiment of the hybrid wedge jack/scissor lift lifting apparatus can provide a second intrinsically safe position due to the addition of first wedge roller seats  214 . 
     Referring to  FIGS. 18 and 19 , an embodiment of an actuator/wedge/lever arm assembly is shown. Actuator/wedge/lever arm assembly  320  can comprise first side  322  and second side  324  connected by lever pins  326  and central trunnion  100 . First side  322  and second side  324  can further comprise first lever arm  190  and second lever arm  200 . First lever arm  190  can further comprise end pin passage  192  for receiving lever pin  326  and end trunnion passage  194  for receiving central trunnion  100 . Second lever arm  200  can further comprise end pin passage  202  for receiving lever pin  326  and end trunnion passage  204  for receiving central trunnion  100 . Central trunnion  100  can fix linear actuator  110  in place with respect to first lever arms  190  and second lever arms  200 . Wedge  120  can be attached to actuator rod  112 , which can be extended and retracted by linear actuator  110 . Wedge  120  can be oriented such that it points toward lever pins  326 . Wedge rollers  83  are positioned coaxially with lever pins  326  between actuator/wedge/lever arm assembly first side  322  and actuator/wedge/lever arm assembly first side  324 . Lever arm pins  326  can pass through the centers of wedge rollers  83 . As linear actuator  110  extends actuator rod  112 , wedge  120  can be driven between wedge rollers  83 . Wedge surface  122  can spread wedge rollers  83  apart, causing first lever arms  190  to rotate counter-clockwise and second lever arms  200  to rotate clockwise. The process can be reversed when linear actuator  110  retracts actuator rod  112 , removing wedge  120  from between wedge rollers  83  and allowing wedge rollers  83  to move towards each other. 
     Referring to  FIGS. 9 through 12 , in some embodiments, variations of the wedge jack/scissor lift hybrid lifting apparatus can further comprise one or more restraint bar safety systems. Each restraint bar safety system can further comprise restraint bar  150 , having restraint bar pin passage  152 , sliding pin seats  154  and actuated end  156 , and restraint bar actuator  160 , having restraint bar actuator rod  161  attached to clevis  170 . Each of the restraint bar safety systems can be associated with either an L-shaped upper frame member  40 , upper fixed pin  80  and upper sliding pin  90 , or an L-shaped lower frame member  60 , lower fixed pin  82  and lower sliding pin  92 . 
     In some embodiments, the restraint bar safety system associated with L-shaped lower frame member  60  of scissor lift assembly first side  402 , lower fixed pin  82  and lower sliding pin  91 , lower fixed pin  82  can extend out through L-shaped lower frame member  60  and pass through restraint bar pin passage  152 . Restraint bar  150  can be free to rotate about the lower fixed pin  82 . Actuated end  156  of restraint bar  150  can be located at the end opposite restraint bar pin passage  152 . Actuated end  156  can be offset from clevis  170  by restraint bar spacer  166 . Actuated end  156 , restraint bar spacer  166  and clevis  170  can be fastened together by restraint bar bolt  168  and restraint bar nut  169 . Restraint bar actuator cylinder  159  can be offset from L-shaped lower frame member  60  by frame member spacer  162 . Restraint bar actuator cylinder  159 , frame member spacer  162  and lower frame member  60  can be fastened together by frame member bolt  164  and frame member nut  165 . Restraint bar actuator  160  can be oriented such that when restraint bar actuator rod  161  extends, actuated end  156  of restraint bar  150  can swing out and away from flange  72  L-shaped lower frame member  60 . When restraint bar actuator  160  is extended far enough that sliding pin seats  154  of the restraint bar  150  are clear of lower sliding pin  91 , hybrid wedge jack/scissor lift lifting apparatus  420  can be free to extend and collapse. When restraint bar actuator  160  is retracted such that restraint bar  150  is in a position where lower sliding pin  91  rests in one of the sliding pin seats  154 , such as the position shown in  FIG. 11 , the restraint bar safety system can be engaged. In this position, hybrid wedge jack/scissor lift lifting apparatus  420  is prevented from collapsing as lower fixed pin  91  presses into sliding pin seat  154  of restraint bar  150 . 
     Referring to  FIGS. 9 and 10 , an embodiment of a hybrid wedge jack/scissor lift lifting apparatus  420  is shown. Hybrid wedge jack/scissor lift lifting apparatus  420  can further comprise four restraint bar safety systems having restraint bars  150  and restraint bar actuators  160 , load plate  130  and base plate  140 . Load plate  130  can further comprise plate bolt passages  132  projecting through load plate  130  and aligning with flange bolt passages  54  and cradle  134  fixed to the surface of load plate  130 . Load plate  130  can be secured to L-shaped upper frame members  40  with plate bolts  131  inserted through plate bolt passages  132  and flange bolt passages  54 , respectively, with plate bolts  131  secured in place with plate nuts  133 . Cradle  134  can be oriented and shaped to prevent loads from shifting atop load plate  130 . Base plate  140  can further comprise plate bolt passages  142  projecting through base plate  140  and aligning with flange bolt passages  74 . Base plate  140  can be secured to L-shaped lower frame members  60  with plate bolts  131  inserted through plate bolt passages  142  and flange bolt passages  74 , respectively, with plate bolts  131  secured in place with plate nuts  133 . Load plate  130  and base plate  140  can improve the structural integrity or rigidity of top frame  40  and lower frame  60 , respectively, of scissor lift assembly  400  while load plate  130  and cradle  134  can allow hybrid wedge jack/scissor lift lifting apparatus  420  to better handle loads placed atop it. 
     In some embodiments, hybrid wedge jack/scissor lift lifting apparatus  420  can further comprise support discs  92  positioned coaxially with upper sliding pin  90  and lower sliding pin  91 . Upper sliding pin  90  and lower sliding pin  91  can each pass through the center of two support discs  92 , with support discs  92  associated with upper sliding pin  90  being positioned adjacent to second scissor arms  30  and support discs  92  associated with lower sliding pin  91  being positioned between first scissor arms  20  and L-shaped lower frame members  60 . 
     Referring to  FIGS. 11 and 12 , another embodiment, hybrid wedge jack/scissor lift lifting apparatus  430 , is shown. Hybrid wedge jack/scissor lift lifting apparatus  430  can comprise a scissor lift assembly having compact load plate  180  with load plate flanges  182 , and hybrid wedge jack/scissor lift lifting apparatus first side  432  and hybrid wedge jack/scissor lift lifting apparatus second side  434  connected by upper fixed pin  80 , lower fixed pin  82 , lower sliding pin  91  and central trunnion  100 . Hybrid wedge jack/scissor lift lifting apparatus first side  432  and hybrid wedge jack/scissor lift lifting apparatus second side  434  can further comprise first scissor arm  20 , first lever arm  190  and L-shaped lower frame member  60 . First scissor arm  20  can further comprise fixed end  26  having end pin passage  22  for receiving upper fixed pin  80 , sliding end  28  having end pin passage  22  for receiving sliding pin  91  and central trunnion passage  24  for receiving central trunnion  100 . First lever arm  190  can further comprise first lever arm fixed end  196  having end pin passage  192  for receiving lower fixed pin  82  and first lever arm rotating end  198  having end trunnion passage  194  for receiving central trunnion  100 . L-shaped lower frame member  60  can further comprise main body  62  having fixed pin passage  64 , sliding pin slot  68  and trunnion recess  66  and flange  72  having flange bolt passages  74 . Lower fixed pin  82  can pass through fixed pin passage  64  of L-shaped lower frame member  60  and end pin passage  192  of first lever arm fixed end  196  of hybrid wedge jack/scissor lift lifting apparatus first side  432 , then through end pin passage  192  of first lever arm fixed end  196  and fixed pin passage  64  of L-shaped lower frame member  60  of hybrid wedge jack/scissor lift lifting apparatus second side  434 , respectively. Upper fixed pin  80  can pass through flange pin passages  184  of load plate flanges  182  and end pin passages  22  of fixed ends  26  of first scissor arms  20 . Load plate flanges  182  can be spaced apart on compact load plate  180  such that load plate flanges  182  sit outside of first scissor arms  20 . Upper fixed pin  80  can be fixed in place with respect to the load plate flanges  182  and lower fixed pin  82  can be fixed in place with respect to L-shaped lower frame members  60 . First lever arms  190  can be free to rotate about lower fixed pin  82 . First scissor arms  20  can be free to rotate about upper fixed pin  80 . Central trunnion  100  can pass through central trunnion passage  24  of first scissor arm  20  and end trunnion passage  194  of first lever arm  190  of hybrid wedge jack/scissor lift lifting apparatus first side  432 , then through end trunnion passage  194  of first lever arm  190  and central trunnion passage  24  of first scissor arm  20  of hybrid wedge jack/scissor lift lifting apparatus second side  434 , respectively. First lever arms  190  and first scissor arms  20  can rotate freely about central trunnion  100 . Lower sliding pin  82  can pass through sliding pin slot  68  of L-shaped lower frame member  60  and end pin passage  22  of sliding end  28  of first scissor arm  20  of hybrid wedge jack/scissor lift lifting apparatus first side  432 , then through end pin passage  22  of sliding end  28  of first scissor arm  20  and sliding pin slot  68  of L-shaped lower frame member  60  of hybrid wedge jack/scissor lift lifting apparatus second side  434 , respectively. First scissor arms  20  can rotate freely about lower sliding pin  91 . Lower sliding pin  91  can be free to slide back and forth within the sliding pin slots  68  of L-shaped lower frame members  60 . 
     In some embodiments, hybrid wedge jack/scissor lift lifting apparatus  430  can further comprise wedge roller  83  positioned coaxially with lower fixed pin  82 , and guided wedge roller  84  positioned coaxially with upper fixed pin  80 . Wedge roller  83  and guided wedge roller  84  can be positioned between hybrid wedge jack/scissor lift lifting apparatus first side  432  and hybrid wedge jack/scissor lift lifting apparatus second side  434 . Upper fixed pin  80  can pass through the center of guided wedge roller  84 , and lower fixed pin  82  can pass through the center of wedge roller  83 . Hybrid wedge jack/scissor lift lifting apparatus  430  can be at its lowest point with linear actuator  110  and actuator rod  112  fully retracted and wedge roller  83  resting against guided wedge roller  84 . As linear actuator  110  extends actuator rod  112 , wedge  120  can be driven between wedge roller  83  and guided wedge roller  84 . Wedge surface  122  can push down on wedge roller  83  and up on guided wedge roller main body  85 , spreading upper fixed pin  80  and lower fixed pin  82  and causing compact load plate  180  to extend upward. The process can be reversed when linear actuator  110  retracts actuator rod  112 , removing wedge  120  from between wedge roller  83  and guided wedge roller main body  85 , allowing gravity to pull compact load plate  180  down. 
     In some embodiments, hybrid wedge jack/scissor lift lifting apparatus  430  can further comprise support discs  92  positioned coaxially with lower sliding pin  91 . Lower sliding pin  91  can pass through the center of two support discs  92 , with each support disc  92  being positioned between first scissor arms  20  and L-shaped lower frame members  60 . 
     Referring to  FIG. 13 , a vertical tandem hybrid wedge jack/scissor lift lifting apparatus  440  is shown. Vertical tandem hybrid wedge jack/scissor lift lifting apparatus  440  can comprise two hybrid wedge jack/scissor lift lifting apparatuses  420  stacked on top of one another, attached by joining L-shaped upper frame members  40  of the lower hybrid wedge jack/scissor lift lifting apparatus  420  to the corresponding L-shaped lower frame members  60  of the upper hybrid wedge jack/scissor lift lifting apparatus  420  by placing plate bolts  131  through flange bolt passages  74  on L-shaped lower frame members  60 , then through plate bolt passages  142  on base plate  140 , then through flange bolt passages  54  on L-shaped upper frame members  40  and securing them in place with plate nuts  133 . 
     Referring to  FIG. 14 , a horizontal tandem hybrid wedge jack/scissor lift lifting apparatus  450  is shown. Horizontal tandem hybrid wedge jack/scissor lift lifting apparatus  450  can comprise two hybrid wedge jack/scissor lift lifting apparatuses  430  attached together in an end-to-end configuration such that the linear actuators  110  of the two simplified wedge jack/scissor lift hybrids  430  oppose one another. Hybrid wedge jack/scissor lift lifting apparatuses  430  can be joined together by using common L-shaped lower frame members  452  and common base plate  454 . Common L-shaped lower frame member  452  can be formed by attaching two L-shaped lower frame members  60  in an end-to-end configuration, with sliding pin slots  68  of each L-shaped lower frame member  60  adjacent to one another. Common base plate  454  can further comprises plate bolt passages  142 . Plate bolts  131  pass through plate bolt passages  142  and flange bolt passages  74  of common L-shaped lower frame members  452  and can be fixed in place with plate nuts  133 . 
     Referring to  FIG. 17 , a centrally-controlled hybrid wedge jack/scissor lift lifting apparatus array  460  is shown, comprising four hybrid wedge jack/scissor lift lifting apparatuses  420  controlled by controller  470 . Controller  470  can be connected to each improved wedge jack/scissor lift hybrid  420  via control cables  480 . 
     Although a few embodiments have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications can be made to these embodiments without changing or departing from their scope, intent or functionality. The terms and expressions used in the preceding specification have been used herein as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding equivalents of the features shown and described or portions thereof, it being recognized that the invention is defined and limited only by the claims that follow.