Abstract:
A jack for lifting an object includes a base assembly and a jacking assembly. The base assembly has a frame with a base member having a nesting chamber, lifting arms pivotably connected to the base member, and a support member for supporting the object. The support member is pivotably connected to the lifting arms and is disposed parallel to the base member. The support member and the lifting arms pivot with respect to the base member into positions including a fully raised position wherein the support member is lifted away from the base member and a fully lowered position wherein the support members and the lifting arms are at least partly nested within the nesting chamber. The jacking assembly is connected to the base assembly for moving the support members and the lifting arms from the fully lowered position towards the fully raised position.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 60/243,923 , filed Oct. 27, 2000. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention lies in the field of lifting equipment. The invention relates to a lifting device used to lift motorcycles or other suitable loads, especially suitable for loads having a low ground clearance. The lifting device of the present invention provides additional stability and improved safety. Also provided is an adjustable stabilizing element that can be used with the lifting device of the present invention or with conventional jacks, particularly jacks for motorcycles and/or all-terrain vehicles. 
     2. Description of the Related Art 
     Generally, different types of jacks exist in the prior art for lifting motorcycles or similar loads, such as hydraulic jacks, articulated jacks, and screw operated jacks. 
     U.S. Pat. No. 6,168,138 to Dhein describes a universal lift system for use in combination with a conventional hydraulic floor jack. The universal lift system replaces the mounting bracket on the floor jack with a substantially H-shaped attachment device having a kingpin that fits into a hole on the conventional jack. The lift system also includes a separate stabilizing device that attaches to the bottom of the floor jack. The lift system has a third separate part called an adjustable support device. The lift system is particularly suitable for lifting and supporting two-wheeled motorized vehicles. The universal lift system, however, is not configured to lift and support objects having a small floor-to-object clearance. 
     U.S. Pat. No. 4,457,492 to Lahti discloses a lifting apparatus for lifting a load, such as a motorcycle. The Lahti apparatus uses a lever operable cam to raise or lower the load. The Lahti apparatus, however, is not suitable for lifting and supporting objects having a small floor-to-object clearance. In fact, the clearance must be greater than the overall height of the Lahti apparatus, to wit, from the casters to the top of the load support. 
     U.S. Pat. No. 5,588,639 to Holman teaches a single-person operable support structure for lifting a motorcycle in combination with a common hydraulic floor jack. The support structure can support a motorcycle on the common jack in a variety of angular orientations. The Holman structure is limited to objects having a floor-to-bottom clearance that is greater than the sum of the height of the Holman retrofit structure plus the height of the common floor jack. 
     U.S. Pat. No. 5,601,277 to Larson is drawn to a two-piece jacking system for two-wheeled vehicles including a jacking mechanism and an adjustable separate support stand. Both the jacking mechanism and the stand have adjustable threaded bolts for adjusting the devices when they are placed on uneven surfaces. Again, the Larson structure is limited to objects having a floor-to-bottom clearance that is greater than the height of the Larson jacking mechanism. 
     U.S. Pat. No. 5,769,396 to Tischendorf discloses a multi-purpose motorcycle lift somewhat similar to the Lahti apparatus. A foot-operated stirrup is directly connected to one, of a pair of lifting beams connected to support bars. When the stirrup is pressed downwards, the lifting beams are forced to pivot and raise the support bars, with the motorcycle, until the lifting beams are moved past the vertical. Again, the Tischendorf structure is limited to raising objects having a floor-to-bottom clearance that is greater than the height of the entire Tischendorf structure before it is rotated to raise the lifting beams. The lifting beams are individually adjustable to correspond to lifting points on the motorcycle that are uneven with respect to ground. 
     U.S. Pat. No. 4,077,607 to Lovelady describes a complex service rack for motorcycles, the rack having a platform to support the motorcycle wheels including a ramp and a clamp for holding one of the motorcycle wheels therein. The servicing rack is almost as large as the motorcycle and is not configured to fit under objects having a small floor-to-object bottom clearance. 
     Some common problems exist among these prior art jacks. One problem is that the minimum required clearance height between the ground and the load is five inches or more. Newly-manufactured motorcycles, however, may only have two or three inches of ground clearance. Therefore, to utilize commonly available lifting devices, the user is required to drive or push the motorcycle onto supporting planks or blocks to artificially create the necessary minimum clearance for the prior art lifting device. Such an operation can be difficult and dangerous. It is, therefore, desirable to provide a low-profile lifting device that can accommodate the required low clearance without any extra lifting operation. 
     Additionally, the considerable extension of a load over a jack very often causes the problem of load instability. It is, therefore, desirable to provide additional stability when lifting the load. Additional stability is especially necessary for a small profile jack that is used on motorcycles having a low ground clearance. 
     Conventional jacks typically have flat lifting surfaces. Some motorcycles, however, do not have uniformly flat lower surfaces. Alternatively, the lifting surfaces may not exist below the center of gravity of the motorcycle. It is, therefore, necessary to provide a supporting device that is adjustable according to different lower surfaces of the motorcycle. 
     In general, hydraulic jacks may be subjected to unexpected loss of hydraulic pressure. Such loss of pressure may be dangerous, and could cause damage or injury. Some of the existing jacks on the market have employed safety devices to reduce pressure loss hazards. Such safety devices are generally of the nature of pawls that engage fixed “teeth” on the jack frame. However, such devices suffer from the drawback that the user must remember to engage the safety device. 
     Another drawback of these devices lies in the release of the safety devices. Due to the symmetrical nature of these jacks, it is common practice to employ a safety pawl on either side of the device. When releasing such a safety device, therefore, the user must retract one pawl on each side of the jack while simultaneously rotating the release valve to lower the jack. The great difficulty in performing three operations simultaneously, without assistance from another person, leads to non-use of the safety device. It is, therefore, very important to provide a safety device that can be released easily by a single operator. 
     It is accordingly an object of the present invention to provide a low profile lifting device that is useful for raising motorcycles or other suitable loads with a low ground clearance and without any extra operation. 
     Another object of the present invention is to provide a lifting device with improved safety measures, particularly, a safety device that engages automatically and can be released by a single person in a single operation. 
     It is still another object of the present invention to provide an adjustable receiving element that may be used to lift loads that may not be conveniently lifted by a lifting device with a typical flat lifting surface. The adjustable receiving element can be used either as an attachment to an existing lifting device or incorporated into a lifting device. 
     It is yet still another object of the present invention to provide a lifting device with a stabilizing element for providing additional stability to the lifting device and where the stabilizing element may be adjusted according to the needs of the user. 
     SUMMARY OF THE INVENTION 
     With the foregoing and other objects in view there is provided, in accordance with the invention, a motorcycle jack, which has a lower profile to be placed underneath motorcycles and other work pieces having a low ground to work piece profile. The preferred embodiment for implementing these principles comprises a frame having a support member for supporting a motorcycle to be lifted and a base member in connection with a support surface, the frame being convertible between a fully lowered position and a fully raised position, and wherein a height of the support member over the support surface in the fully lowered position is less than 3-4 inches and is 2.5 inches in the preferred embodiment of the present invention. 
     In a further principle of the present invention, a motorcycle jack includes a means for providing a wider profile than the base once the jack is in place to support the motorcycle. In the preferred embodiment for implementing this inventive principle, the motorcycle jack, comprises a frame having a support member for supporting a motorcycle to be lifted and a base member in connection with a support surface, the frame being convertible between a lowered position and a raised position, the base member having a length dimension and a width dimension, and at least one extending foot connected to the base member, the connecting foot being extendible away from the base member to expand the width dimension of the base member. 
     In a further principle of the present invention, a motorcycle jack includes a means for engaging a safety mechanism limiting the lowering of the jack and a means for easily disengaging the safety mechanism in conjunction with the interaction of a means for lowering the jack away from the raised position. In the preferred embodiment for implementing this inventive principle, the motorcycle jack comprises a frame having a support member for supporting a motorcycle to be lifted and a base member in connection with a support surface, the frame being convertible between a lowered position and a raised position, safety pawls connected to the frame to engage the frame as the frame is raised and to prevent the lowering of the frame without being released by a releasing member, the releasing member releasing the safety pawls and causing the frame to be lowered. 
     In the preferred embodiment of the present invention, a jack is provided for lifting an object and the jack contains a base assembly. The base assembly includes a frame having a base member with a nesting chamber, lifting arms pivotably connected to the base member, and a support member for supporting the object to be lifted. The support member is pivotably connected to the lifting arms and is disposed parallel to the base member. The support member and the lifting arms pivoting with respect to the base members into different positions. The different positions include a fully raised position wherein the support member is lifted away from the base member, and a fully lowered position wherein the support members and the lifting arms are at least partly nested within the nesting chamber. The jack further contains a jacking assembly connected to the base assembly for moving the support members and the lifting arms from the fully lowered position towards the fully raised position. 
     In accordance with an added feature of the preferred embodiment of the present invention, the base member is two base members disposed parallel to one another in a base plane, and each of the two base members has a nesting chamber. 
     In accordance with another feature of the preferred embodiment of the present invention, each of the two base members has a U-shaped cross-section defining the nesting chamber 
     In accordance with an additional feature of the preferred embodiment of the present invention, the support member has a second nesting chamber, and at least one of the lifting arms is at least partly nested within the second nesting chamber when in the fully lowered position. 
     In accordance with a further feature of the preferred embodiment of the present invention, the base member is two base members disposed parallel to one another in a base plane. Each of the two base members has a nesting chamber. The support member is two support members disposed parallel to one another in a support member plane and the support member plane is disposed parallel to the base plane. Each of the two support members has a second nesting chamber, the two support members and the lifting arms are at least partly nested within the nesting chamber when in the fully lowered position. At least one of the lifting arms is at least partly nested within the second nesting chamber of each of the two support members when in the fully lowered position. 
     In accordance with another added feature of the preferred embodiment of the present invention, each of the two base members has a series of ratchet openings disposed in the nesting chamber. 
     In accordance with another additional feature of the preferred embodiment of the present invention, the frame includes cross-beams fixedly connecting the two base members to one another. 
     In accordance with another further feature of the preferred embodiment of the present invention, the cross-beams include a first cross-beam and a second cross-beam, and the frame includes a jack platform fixedly connected to the first and second cross-beams. 
     In accordance with a further added feature of the preferred embodiment of the present invention, the jack platform has a first leg attached to the first cross-beam, and a second leg connected to the first leg and to the second cross-beam. 
     In accordance with a further additional feature of the preferred embodiment of the present invention, the lifting arms are four lifting arms. Each of the four lifting arms has a substantially same given arm length. 
     In accordance with an added feature of the preferred embodiment of the present invention, the base member is two base members disposed parallel to one another in a base plane, and a pair of the four lifting arms is pivotably connected to each of the two base members. 
     In accordance with an additional feature of the preferred embodiment of the present invention, the support member is two support members and are disposed parallel to one another and parallel to the two base members. Each of the two support members is pivotably connected to the pair of the four lifting arms. 
     In accordance with another feature of the preferred embodiment of the present invention, the two support members and the four lifting arms pivot with respect to the two base members into different positions. The positions include a fully raised position wherein the two support members are lifted away from the two base members; and a fully lowered position wherein one of the two support members and two of the four lifting arms are each at least partly nested within a nesting chamber of a respective one of the base members. 
     In accordance with a further feature of the preferred embodiment of the present invention, a ram support is pivotably connected to the lifting arms, and a removable hydraulic jack is removably connected to the ram support and to the base assembly. The jack moves the support member and the lifting arms from the fully lowered position towards the fully raised position through the ram support. 
     In accordance with the preferred embodiment of the present invention, the lifting arms are four lifting arms, and two of the four lifting arms are disposed closer to the jacking assembly than two other arms of the four lifting arms. Each of the two lifting arms disposed closer to the jacking assembly has a pivot, and the ram support is pivotably connected to a respective one of the two lifting arms disposed closer to the jacking assembly at the pivot. 
     In accordance with yet another feature of the preferred embodiment of the present invention, the frame includes a jack platform fixedly connected to the base member, and the jack platform has an attachment clamp removably connecting the jack to the jack platform. 
     In accordance with yet a further feature of the preferred embodiment of the present invention, the base member is two base members disposed parallel to one another in a base plane. The frame includes cross-beams fixedly connecting the two base members to one another. The cross-beams include a first cross-beam and a second cross-beam. The frame includes a jack platform fixedly connected to the first and second cross-beams, and the jack platform has an attachment clamp removably connecting the jack to the jack platform. 
     In accordance with another feature of the preferred embodiment of the present invention, the jack platform is disposed in a plane at an angle from the base plane. 
     In accordance with a further feature of the preferred embodiment of the present invention, the base member is disposed in a base plane, and the attachment clamp removably connects the jack to the jack platform in a plane at an angle from the base plane. 
     In accordance with an added feature of the preferred embodiment of the present invention, the base member is disposed in a base plane, and the attachment clamp removably connects the jack to the jack platform in a plane at an angle from the base plane. 
     In accordance with an additional feature of the preferred embodiment of the present invention, the frame includes a jack platform fixedly connected to the base member and the jack platform has an attachment clamp. The hydraulic jack has a base housing a hydraulic fluid, and a lifting piston is moveably disposed in the base. The lifting piston has a piston end and a cap disposed at the piston end. The attachment clamp of the jack platform removably connects the base to the jack platform such that the lifting piston has an axis inclined with respect to the base plane. A pumping piston is moveably connected to the base for exerting pressure upon the hydraulic fluid when moved into a downward position and correspondingly raising the lifting piston out of the base along the axis. A return spring is connected to the pumping piston for returning the pumping piston to a raised position. A pedal flange is pivotably connected to the base. A pedal is pivotably connected to the pedal flange, pivotably connected to the pumping piston, and connected to the return spring such that, when the pedal is depressed from an initial position, the pedal depresses the pumping piston, and, when pressure is released from the pedal, the return spring returns the pedal to the initial position. A pressure release valve is connected to the base for releasing pressure upon the hydraulic fluid. 
     In accordance with another feature of the preferred embodiment of the present invention, the front ram support has an upper span having two ends and a bracket removably connected to the cap of the lifting piston, and two side spans each having an upper end and a lower end. The upper end of each of the two side spans is fixedly connected to a respective one of the two ends of the upper span to form a U-shape. The lifting arms include two lifting arms disposed closer to the jacking assembly than other arms of the lifting arms. Each of the two lifting arms have a pivot, and the lower end of each of the two side spans is pivotably connected to a respective one of the two lifting arms at the pivot. 
     In accordance with a further feature of the preferred embodiment of the present invention, a locking assembly is connected to the base assembly for locking the base assembly in one of the positions. The locking assembly can be connected to the lifting arms. 
     In accordance with the preferred embodiment of the present invention, the lifting arms include two lifting arms, and the locking assembly is connected to the two lifting arms. 
     In accordance with a further added feature of the preferred embodiment of the present invention, each of the two lifting arms has a pivot. The locking assembly has two locking pawls each having a ratchet portion and an actuating portion. Each of the two locking pawls is pivotably connected to a respective one of the two lifting arms at the pivot for holding the two lifting arms in one of the positions. 
     In accordance with a further additional feature of the preferred embodiment of the present invention, a lowering assembly is connected to the base assembly and to the jacking assembly for lowering the support member and the lifting arms toward the fully lowered position and for lowering the jacking assembly. 
     In accordance with another further feature of the preferred embodiment of the present invention, the lowering assembly has a lowering pedal pivotably connected to the jacking assembly. In addition, a release bar is pivotably connected to the base assembly. 
     In accordance with another added feature of the preferred embodiment of the present invention, the lifting arms include two lifting arms each having a pivot. A locking assembly is connected to the base assembly and has two locking pawls each with a ratchet portion and an actuating portion. Each of the two locking pawls is pivotably connected to a respective one of the two lifting arms at the pivot. The ratchet portion has a locking end. The base member has ratchet openings, and the jack has a pressure release valve. A lowering assembly is provided and has a lowering pedal with a pressure release flange, and the lowering pedal is pivotably connected to the jack. A release bar is pivotably connected to each of the two locking pawls at the actuating portion and is connected to the lowering pedal such that, when the lowering pedal is initially depressed, the release bar pivots both of the two locking pawls to disconnect the locking end from a respective one of the ratchet openings. And, when the lowering pedal is further depressed, the pressure release flange contacts and moves the pressure release valve to release pressure in the jack thereby lowering the lifting arms and the support member towards the fully lowered position. 
     According to a concomitant feature of the preferred embodiment of the present invention, there is provided a stabilizing member pivotably connected to the base member. Preferably, the stabilizing member has an extendable foot having a foot part, a knob, and a threaded part connecting the foot part to the knob. 
     Other features that are considered as characteristic for the invention are set forth in the appended claims. 
     Although the invention is illustrated and described herein as embodied in a lifting device assembly, it is, nevertheless, not intended to be limited to the details shown because various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
     The construction and method of operation of the invention, however, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view from above the disassembled lifting device assembly and removable adapter assembly according to the preferred embodiment of the present invention; 
     FIG. 2 is a perspective view from above the assembled lifting device assembly according to the preferred embodiment of the present invention with a support frame in a lifted position; 
     FIG. 3 is a side view of the hydraulic ram assembly and the foot pedal assembly of the lifting device assembly of FIGS. 1 and 2; 
     FIG. 4 is a perspective view of the base assembly of the lifting device assembly of FIGS. 1 and 2 showing that a front ram support has been lifted; 
     FIG. 5 is a partial perspective view from above the lifting device assembly of FIG. 1 showing the hydraulic ram assembly and the base assembly in an installed state; 
     FIG. 6 is a partial perspective view from above the lifting device assembly of FIG. 1 showing the stabilizer arms; 
     FIG. 7 is a partial perspective view from above the lifting device assembly of FIG. 1 showing the releasing assembly; 
     FIG. 8 is a partial perspective view from above the lifting device assembly of FIG. 1 showing the pulling handle; 
     FIG. 9 is a perspective view from above the lifting device assembly of FIG. 1 showing the removable adapter assembly; and 
     FIG. 10 is a side elevational view of a safety pawl of the lifting device assembly of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Before explaining the preferred embodiment of the present invention in detail, it is to be understood that this invention is not limited in its application to the details of construction and configuration of parts illustrated in the accompanying drawings or described in the description. The terminology employed in this description is utilized to explain the invention to persons skilled in the art and is not intended to be limiting as to the embodiments described. 
     Referring now to the figures of the drawings in detail, and first particularly to FIG. 1, there is shown the lifting device assembly according to the preferred embodiment of the present invention in a disassembled state. The lifting device assembly  1  includes a base assembly  100 , a hydraulic ram assembly  300 , a foot pedal assembly  500 , a removable adapter assembly  700 , and a pulling handle  900 . 
     The hydraulic ram assembly  300  includes a pump piston  310 , a housing  320 , and a ram base  321 . The pump piston  310  has a piston  311  with a pinhole  315  formed in the top end thereof and a return spring  313  mounted surrounding the piston  311 . The housing  320  has a cylinder  322 , a plunger  325  (see FIG. 2) movable within the cylinder  322  and a cap  323  mounted on the top end of the plunger  325 . 
     As can be better seen from FIG. 3, a pinhole  317  is formed in a protrusion  324  on the ram base  321 . Another pinhole  327  is formed in another protrusion  328  located on the top of an air exit cylinder  326  connected to the cylinder  322  at the bottom end thereof. An air leak button  329  fits in the opening of the air exit cylinder  326 . 
     The foot pedal assembly  500  includes a pump lever  510  with two brackets  511  at one end of the pump lever  510 , a foot pedal  512  mounted at the other end of the pump lever  510 , and a linkage  520 . The linkage  520  is pivotably connected to the pump lever  510  at the end close to the two brackets  511  through a pivot pin and a cotter pin. Through-holes  515  are formed in the two brackets  511 . Another through-hole  521  is formed at the free end of the linkage  520 . 
     FIG. 3 shows the assembling relationship between the foot pedal assembly  500  and the hydraulic ram assembly  300 . The foot pedal assembly  500 , including the pump lever  510  pivotally coupled to the linkage  520 , is first connected to the ram base  312  by a first pin passed through pinholes  317 ,  521  of the base  321  and the linkage  520  and secured with a cotter pin. Second and third pins are inserted, respectively, through the first bracket  511  of the pump lever  500  and the upper through-hole of the linkage  520 , and through the second bracket  511  of the pump lever  500  and the through-hole of the piston  311 , and are secured with a cotter pin. The jacking assembly  400  is, thus, formed. 
     As shown in FIGS. 1 and 2, the base assembly  100  has a base frame  120 , a front ram support  140 , and a parallelogram support frame  160  for carrying a load. The base frame  120  is formed from parallel base members  121 ,  121 ′ with casters  110 ,  110 ′ at one end of each base member  121 ,  121 ′ to facilitate the transportation of the lifting device  1 . The parallel base members  121 ,  121 ′ define a base plane. 
     The casters  110 ,  110 ′ can be fixed by locking devices  111 ,  111 ′, referred to as loop straps. The parallel base members  121 ,  121 ′ are each formed with a recess  123 ,  123 ′ (as best seen from FIG. 2) to allow the parallelogram support frame  160  to nest therein when the lifting device assembly  1  is in a down or lowered position. Thus, in cross-section, the base members  121 ,  121 ′ each have a substantially U-shape. 
     A plurality of ratchet slots  130  are formed in bottom surfaces  135 ,  135 ′ of each of the parallel base members  121 ,  121 ′. Two center beams  124 ,  124 ′ and two end beams  124 ″,  124 ′″ fixedly connect the parallel base members  121 ,  121 ′ to one another. The two end beams  124 ″,  124 ′″ respectively connect each of the ends of the support members  121 ,  121 ′. 
     In addition to the base members  121 ,  121 ′, the support members  161 ,  161 ′ and the lifting arms  162   a ,  162   b ,  162   c ,  162   d  all employ “open” shapes so that they can nest within each other, and, therefore, reduce the overall height of the lifting device assembly  1  in its lowered position. Preferably, the overall height in the lowered position is less than five inches, and, particularly, approximately three inches or less. 
     A jack assembly base  125  is formed between the two center beams  124 ,  124 ′ and fixedly connected thereto. The jack assembly base  125  includes a first, sloped guide surface  126  and a second, substantially upright surface  128 . The sloped guide surface  126  extends in a plane at an angle to a base plane. Attachment clamps  127  are formed on the slope guide surface  126  to hold the jacking assembly  400  thereon. 
     A release pedal  187  is pivotably connected to one of the center beam  124 , the guide surface  126 , or the ram base  321  after the hydraulic ram assembly  300  has been connected to the base assembly  100 . Preferably, the release pedal  187  is pivotably connected to the ram base  321 . 
     A loop  131  can be formed on one or both of the end beams  124 ″,  124 ′″ for engaging with a pulling handle  900  to facilitate the transportation of the lifting device  1 . FIG. 8 illustrates the pulling handle  900  engaged with loop  131  for moving the lifting device  1 . Additional loops  132   a ,  132   b ,  132   c  and  132   d  can be formed at various portions of the base frame  120  to facilitate adjusting a position of the lifting device assembly  1  under a load. 
     As can be seen in FIG. 2, the parallelogram support frame  160  has two parallel, horizontal support members  161 ,  161 ′ pivotally connected to and supported by the top ends of four lifting arms  162   a ,  162   b ,  162   c ,  162   d . The bottom ends of these four lifting arms  162   a ,  162   b ,  162   c ,  162   d  are pivotably connected to the two horizontal base members  161 ,  161 ′ through bolts  136   a ,  136   b ,  136   c ,  136   d  ( 136   d  cannot be seen in the drawings). The bolts  136   a ,  136   b ,  136   c ,  136   d  are supported through holes formed in the U-shape of the side surfaces  137   a ,  137   b ,  137   c ,  137   d  of the support members  121 ,  121 ′ and fixed to the side surfaces by nuts. 
     A support bar  163  is fixedly connected, preferably by welding, between the two parallel support members  161 ,  161 ′ to increase the strength of the support frame  160 . A connecting beam  170  is fixedly attached, preferably by welding, on the two front lifting arms  162   a ,  162   d.    
     The front ram support  140  includes a lifting beam  141  with a bracket  142  formed on the bottom surface thereof, and two lifting legs  143 ,  143 ′. Together, the lifting beam  141  and two lifting legs  143 ,  143 ′ form an upside down, substantially U-shape. The bracket  142  is constructed to removably receive the cap  323  of the housing  320  when the hydraulic ram assembly  300  is connected to the lifting device assembly  1 . The lifting legs  143 ,  143 ′ are pivotably connected to the front lifting arms  162   a ,  162   d  on a pivot shaft at a pivot point lower on the front lifting arms  162   a ,  162   d  than the attachment point of the connecting beam  170 . Preferably, the pivot point of the lifting legs  143 ,  143 ′ is in the bottom one-third of the lifting legs  143 ,  143 ′. 
     Safety pawls  171 ,  171 ′ are pivotally connected on the respective pivot shaft of the lifting legs  143 ,  143 ′. FIG. 10 illustrates one of the safety pawls  171 , which has a locking part  172  with a locking point  176 , a pivot hole  175  for receiving the pivot shaft, and a release part  173  with a long slot  174  formed therein. Alternatively, the slot  174  can also be the pivot hole. 
     Springs  180 ,  180 ′ are connected between one end of the release part  173  of each safety pawl  171 ,  171 ′ and a portion of the parallelogram support frame  160 . Preferably, the springs  180 ,  180 ′ are connected to an end of each support member  161 ,  161 ′. Alternatively, springs  180 ,  180 ′ may also connect the safety pawls  171 ,  171 ′ to the ends of the connecting beam  170 . 
     As shown in FIG. 10, a hook hole  177  is formed in the end of the release part  173  of the safety pawl  171  to connect with a hook formed at one end of the spring  180 . The locking point  176  of the locking part  172  of the safety pawl  171  engages within one of the slots  130  in the bottom surface  135  of the base member  121 . 
     A release bar  185  is provided for substantially simultaneously releasing both of the safety pawls  171  from the slots  130 . The release bar  185  is movably inserted in the long slot  174 , preferably with a non-removable pin. Alternatively, the release bar  185  can also be pivotably fixed in the release part  173 . Although only one of the safety pawl  171  is described above, it is to be understood that the other safety pawl  171 ′ has the corresponding structure and is mounted on the other side of the lifting device  1 . 
     FIGS. 4 and 5 illustrate how the jacking assembly  400  is connected to the base assembly  100 . As shown in FIG. 4, the front ram support  140  is placed in a raised position. As shown in FIG. 5, with the foot pedal  512  of the foot pedal assembly  500  oriented toward the back (with respect to FIG.  5 ), the ram cap  323  is placed inside the bracket  142  of the front ram support  140  and the ram base  321  is aligned with at least one attachment clamp  127  attached to the slope guide surface  126 , preferably, attached by welding. The entire jacking assembly  400  is secured to the guide surface  126  by tightening a bolt  129  of the clamp  127 . 
     As shown in FIG. 6, the base assembly  100  can have stabilizer arms  190 ,  190 ′, preferably two in number, pivotably mounted at a side of the two base members  121 ,  121 ′. The stabilizer arms  190 ,  190 ′ provide additional stability for the lifting device assembly  1  by extending the so-called “footprint” of the lifting device assembly  1  to a wider geography. 
     The lifting device assembly  1  has a length and a width, with the width being smaller than the length. Therefore, the lifting device assembly  1  is less stable along an extent of the width, than along the extent of the length. As such, it is desireable to extend the effective width of the device and/or extend the length of the device, depending on the orientation of the object to be lifted and balanced thereupon. To effectuate such an extension, stabilizer arms  190 ,  190 ′ are provided. 
     In a preferred embodiment, the stabilizer arms  190 ,  190 ′ extend the width of the device&#39;s footprint to at least two times the width of the device  1 , as measured without such stabilizer arms  190 ,  190 ′. The stabilizer arms  190 ,  190 ′ can be retracted or extended according to the needs of the user. 
     The stabilizer arms  190 ,  190 ′ may be adjusted to provide side-to-side stability (width) or to enhance end-to-end stability (length) because they may be placed in one of many, separate, intermediate positions. If placed on the side of a base member  121 ,  121 ′, for example, the stabilizer arms  190 ,  190 ′ can rotate approximately through a 180 degree arc. Alternatively, if placed on a corner of a base member  121 ,  121 ′, for example, the stabilizer arms  190 ,  190 ′ can rotate approximately through a 270 degree arc. 
     Adjustment feet  191 ,  191 ′ can be provided at the furthest end of the stabilizing arms  190 ,  190 ′ to provide even contact with potentially uneven ground or pavement surfaces. Preferably, the adjustment feet  191 ,  191 ′ each have a disk-shaped foot, a height-adjustment knob, and a threaded rod connecting the foot to the knob. Thus, when the knob is turned clockwise, for example, the foot moves lower with respect to the base members  121 ,  121 ′, and when the knob is turned counter-clockwise, for example, the foot raises from that lowered position. Preferably, the feet can be raised slightly above the bottom of the base members  121 ,  121 ′ so that varying terrain can be accommodated. 
     FIG. 7 illustrates the lowering device of the preferred embodiment of the present invention. As set forth above, depressing the pedal  187  begins the process of lowering the load on the lifting device assembly  1 . 
     In an initial portion of the lowering movement, the pedal  187  presses down a first portion of the release bar  185  under the pedal  187 . The downward movement of the first portion of the release bar  185  causes a corresponding pulling movement on the second portions of the release bar  185  that are connected to each of the two safety pawls  171 ,  171 ′. The pulling movement pivots the pawls  171 ,  171 ′ such that a locking point  176  is removed from one of the slots  130  in the base members  121 ,  121 ′. 
     When the removal is complete, the safety pawls  171 ,  171 ′ no longer prevent the support frame  160  from lowering, but the pressure existing within the ram assembly  300  does continue to prevent the support frame  160  from lowering. As such, pressing of the pedal  187  is continued to a second position in which a flange of the pedal  187  presses in the air leak button  329  of the ram assembly  300  to release the internal pressure within the housing  320 . 
     Accordingly, the weight of the object and/or the support frame  160  causes the support frame  160  to lower towards a lowermost position nested within the base members  121 ,  121 ′. Because the release bar  185  is symmetrical with respect to the either side of the pressing point of the pedal  187 , the safety pawls  171 ,  171 ′ are substantially simultaneously released from the slots  130 . 
     FIG. 8 illustrates an embodiment of the pulling handle  900  engaging the loop  131  at a side of the lifting device assembly  1  that is closest to the casters  110 ,  110 ′. It is to be understood that the pulling handle  900  may also engage with any other loop on the lifting device assembly  1  for moving the lifting device assembly  1  in different directions. 
     As shown in FIGS. 1 and 9, the removable adapter assembly  700  includes a substantially square adapter frame  710  having four screw holes  712   a ,  712   b ,  712   c ,  712   d  formed therein. The frame  710  also has four threaded adapter arms  715   a ,  715   b ,  715   c ,  715   d  that can be rotatably inserted in a respective screw hole  712   a ,  712   b ,  712   c ,  712   d  for raising and lowering each of the arms  715   a ,  715   b ,  715   c ,  715   d.    
     The adapter frame  710  has another set of four through-holes  711   a ,  711   b ,  711   c ,  711   d  formed at each corner thereof for fixing the adapter frame  710  onto the support frame  160 . Accordingly, the support members  161 ,  161 ′ have four corresponding securing holes  711   a ′,  711   b ′,  711   c ′,  711   d ′. The through-holes  711   a ,  711   b ,  711   c ,  711   d  and securing holes  711   a ′,  711   b ′,  711   c ′,  711   d ′ are aligned so that the frame  710  can be removably attached to the lifting device assembly  1  using, for example, screws or nuts and bolts. 
     Preferably, one of the two sets of four holes is threaded so that a single threaded bolt with a head larger than a diameter of the other hole can be used to secure the frame  710 . In one preferred embodiment, the head has wing extensions so that a user can tighten the bolt without using a separate tool. 
     Preferably, the adapter frame  710  is rectangular or square. Each adapter arm  715   a ,  715   b ,  715   c ,  715   d  includes a vertical portion  717   a ,  717   b ,  717   c ,  717   d  formed with a thread and a horizontal head portion  718   a ,  718   b ,  718   c ,  718   d  having a lengthened slot  719   a ,  719   b ,  719   c ,  719   d  (see FIG.  8 ). 
     A respective padded rotating receiver  716   a ,  716   b ,  716   c ,  716   d  is movably mounted within the slot. By moving the respective padded receiver  716   a ,  716   b ,  716   c ,  716   d  within the slot and turning the thread into the respective screw hole  712   a ,  712   b ,  712   c ,  712   d , the height, rotation and extension of each padded receivers  716   a ,  716   b ,  716   c ,  716   d  can be adjusted individually so as to provide stable support for non-flat or irregular surfaces. Thus, each of the adapter arms  715   a ,  715   b ,  715   c ,  715   d  has a full three degrees of movement. The adapter frame assembly  700  can be used either as a retrofitted attachment to an existing lifting device or incorporated into the lifting device assembly  1  of the preferred embodiment of the present invention. 
     The following paragraphs describe the operation of the lifting device of the preferred embodiment of the present invention. 
     First, the lifting device assembly  1  is placed under a load to be lifted. If desired, the pulling handle  900  can be used to place the lifting device assembly  1 . When the lifting device assembly  1  is located in the right position under the load, the foot pedal  512  is depressed. If desired, to provide additional stability, the stabilizer arms  190 ,  190 ′ may be extended to a suitable position prior to depressing the foot pedal  512 . 
     The return spring  313  provides the return action of each depression of the foot pedal  512 . The plunger  325  of the ram assembly  300  lifts during each pumping action. Such lifting, in turn, raises the lifting beam  141  with respect to the base members  121 ,  121 ′. Because the bottom of the lifting beam  141  is connected to the two lifting arms  162   a ,  162   d , a raising of the lifting beam  141  causes a corresponding counter-clockwise rotation (with respect to FIG. 2) of the lifting arms  162   a ,  162   d  about their pivot axis, which are within the recess  123 ,  123 ′ of each base member  121 ,  121 ′. Because lifting arms  162   b ,  162   c  are connected to lifting arms  162   a ,  162   d  through the support members  161 ,  161 ′, the entire support frame  160  raises with respect to the base members  121 ,  121 ′. 
     In the mean time, the springs  180 ,  180 ′ provide a lifting force upon the end of each safety pawl  171 ,  171 ′. Thus, the locking point  176  of each safety pawl  171 ,  171 ′ engages one of the slots  130  in the bottom surface  135  of the base members  121 ,  121 ′ in the manner of a ratchet as the ram assembly  300  lifts. The lock prevents the support frame  160  from unintentionally lowering should the pressure in the ram assembly  300  be unexpectedly lost. 
     To lower the support frame  160 , the release pedal  187  is pressed into an initial position whereby the release bar  185  under the release pedal  187  moves downward and, correspondingly, simultaneously pivots both of the safety pawls  171 ,  171 ′ out of their respective slots  130 . Specifically, the release bar  185  pulls down the end of the release part  173  of the locking pawl  171 ,  171 ′ and disengages the locking point  176  from the slot  130 . 
     The release pedal  187  is pressed further down to a final position where a flange on the pedal  187  contacts and presses in the air leak button  329 . The air in the ram cylinder  322  slowly leaks out from the air exit cylinder  326 . The plunger  325  and the parallelogram support frame  160  slowly lower down under the weight of the load. 
     While the manner, operation and principles of the present invention has been illustrated and described by a specific preferred embodiment, it is to be understood that numerous changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.