Patent Abstract:
A hydraulic jack comprising a hydraulically actuated saddle movable from a first lowered position to a second raised position, the jack having a handle which, when pumped up and down, hydraulically raises the saddle, lowering control means associated with the jack for preventing premature lowering of the saddle upon malfunction of the hydraulic actuation during raising of the saddle and a release lever engaging the lowering control means adapted to release the same and permit lowering of the saddle when the handle is pumped up and down.

Full Description:
BACKGROUND 
     1. Field 
     This disclosure relates to relates to hydraulic jacks; and, more particularly, to hydraulic jacks that are used to raise and lower loads. 
     2. General Background 
     Hydraulic jacks used to raise and lower loads are well known in the art. Such jacks are usually rolled or otherwise placed under a load that it is desired to lift, such as a vehicle, then a lever is activated to raise the saddle of the jack that engages the load placed thereon. When it is desired to lower the load, the lever is used to release the jack and lower the saddle and thus the load placed thereon. However, should the hydraulic mechanism used to raise and lower the jack malfunction, then the jack may drop the load too quickly possibly resulting in injury to the operator. 
     There is need for an hydraulic jack that has lowering control means for preventing the jack from being lowered out of control while lifting the load placed thereon due to malfunction or the like. 
     SUMMARY 
     It is an object of this invention to provide a hydraulic jack having means for controlling the lowering of the jack during lifting in case of a malfunction or the like. 
     It is a further object of this invention to carry out the foregoing objects wherein the means for controlling lowering of the jack during lifting includes a mechanism built into the spaced side plates of the jack. 
     These and other objects are preferably accomplished by providing a hydraulically activated jack having a pair of spaced interconnected side plates, a lift arm assembly pivotally mounted between the side plates, and a saddle mounted at top of the lift arm assembly adapted to be placed under the load to be lifted. The jack includes an hydraulically activated power assembly coupled to the lift assembly for raising and lowering the same. Means for limiting the lowering of the jack during lifting of the lift assembly is provided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-mentioned features and objects of the present disclosure will become more apparent with reference to the following description taken in conjunction with the accompanying drawings wherein like reference numerals denote like elements and in which: 
         FIG. 1  is perspective view of a jack in accordance with the teachings of the invention; 
         FIG. 2  is a side view, partly in section, illustrating the inner mechanism of the jack of  FIG. 1 ; and 
         FIGS. 3 to 7  are views similar to  FIG. 2  showing further steps in the operation of the jack of  FIG. 1 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A jack  10  in accordance with the teachings of the invention is shown in  FIG. 1 . Jack  10  has a pair of spaced side plates  11 ,  12  with integral outwardly extending flanges  13  on each side plate  11 ,  12  (only plate  13  on side plate  12  shown in  FIG. 1 ). Block members  14 ,  15  may be provided on the outside of each side of plate  11 ,  12  to add weight and stability to jack  10 . 
     Front axle  16  extends between plates  11 ,  12  terminating on the outside of plates  11 ,  12  in roller ends  17  having wheels  18 ,  19  rotatably mounted thereon as is well known in the art. Ends  17  are threaded at their terminal ends receiving a suitable nut  20  and washer  21  thereon to retain the wheels  18 ,  19  in place. 
     A pair of L-shaped flanges  22  are provided on side plates  11 ,  12  at the rear of jack  10 . Each flange  22  holds a castor housing  23  comprised of a downwardly extending U-shaped yoke  24  having a wheel  24 ′ secured to housing  23  by a nut  25 . 
     A saddle  26  is rotatably mounted to a U-shaped flange  27  in any suitable manner, as, for example, by a downwardly extending pin  27 ′ (shown in dotted lines) fixed on the bottom of saddle  27  loosely and rotatably mounted in a saddle receiver hole  26 ′ (shown in dotted lines in  FIG. 2 ) in flange  27 . 
     Flange  27  is fixedly mounted to a pin  28  extending between a pair of spaced guide links  29 . Links  29  are rotatably mounted at the rear on bolts  30  extending through each side wall  11 ,  12 . 
     A lift arm assembly  31  having spaced downwardly extending side plates  100  is mounted between links  29  pivotally secured at one end to flange  27  and pivotally mounted by means of pin  42  to plates  11 ,  12 . 
     A guide flange plate  43  is mounted on the inner wall  32  of each side wall  11 ,  12 . Guide flange plate  43  has an elongated opening  32  therein aligned with a series of grooves  33  formed on inner wall  32 ′. A stop  34  is provided on the inner wall  32 ′. Flange plate  43  has an elongated slot  35  with a pin  36  extending from wall  32 ′ riding therein. Pin  36  may be spring biased, if desired. A roller  37  is mounted between a pair of spaced links  38  with a pin portion  39  ( FIG. 2 ), extending from roller  37 , riding in grooves  33  as will be discussed. Links  38  are rotatably mounted on pin  40  at their rear ends. 
     A release plate  101  ( FIG. 2 ) has spaced grooves  45 ,  46  receiving pins  47 ,  48 , respectively, thereon. Release plate  102  has a rearwardly extending extension portion  83  A cylindrical member  49  ( FIG. 1 ) is mounted between spaced links  50  (only one visible in  FIG. 1 ) which links  50  are mounted at the rear to pin  40 . 
     As is well known in the jack art, a conventional hydraulic cylinder  51  is fixed to cylindrical member  49  and moves the same back and forth when cylinder  51  is activated. 
     Cylindrical member  49  may be spring biased, if desired, in any suitable manner so as to return the same to the initial starting position. 
     Hydraulic cylinder  51  is activated by means of a handle  52  removably mounted in a handle housing  53  mounted at the front of jack  10  having a socket  54  receiving handle  52  therein. Handle housing  53  is rotatably mounted in any suitable manner and may abut against resilient spacer rollers  55 ,  56  mounted between side plates  11 ,  12 . 
     It is to be understood that jack  10  includes a conventional power unit assembly (not shown) of which hydraulic cylinder  51  is a part thereof. Handle  52 , at its lower end, engages the power unit assembly to move cylinder  49  back and forth when pumped up and down. That is, turning handle  52  clockwise and pumping handle  52  raises the saddle  26 . Turning handle  52  counterclockwise lowers saddle  26 , as will be discussed. 
     As the saddle  26  is lifted, starting from the  FIG. 2  position, roller  39  rolls along plate  43  up over the ridges  60  into a respective groove  33 . Thus, saddle  26 , shown in the rest or down position in  FIG. 2 , moves upwardly in the direction of arrow  61  in  FIG. 3  as handle  52  is moved up and down as indicated by arrow  62 . Roller  39  is shown as rolling in the direction of arrow  63  over ridge  60  and is shown as about to enter a groove  33 . The final “up” position for saddle  26  is shown with roller  39  disposed in one of the forward grooves  33  ( FIG. 4 ). 
     It should be understood that the rollers  39  entering sequential grooves  33  as handle  52  is activated prevent the saddle  26  from falling prematurely if there is a failure in the power lift system possibly damaging the operator or equipment being lifted. 
     In order to release roller  39  from groove  33 , a quick release lever  64  is provided. Lever  64  ( FIG. 1 ) is rotatably mounted on a shaft  65 ′ extending between side plates  11 ,  12 . Lever  64  is stopped in its forward movement by engagement with a spring biased stop plate  66  ( FIG. 2 ) rotatably mounted on shaft  67  which extends between side plates  11 ,  12 . Plate  66  is spring biased by coil spring  68  engaging the bottom of lever  64  encircling pin  69  ( FIG. 2 ) mounted on side plate  12 . A release latch  70  (see  FIG. 3 ) is mounted to side plate  12  biased by coil spring  71  (see also  FIG. 5 ). Shaft  65 ′ has a downwardly extending extension portion  72  (see also  FIG. 6 ) on each end adjacent the inner walls  32 ′ of each side plate  11 ,  12 . Link  81  is pivotally connected at  74 ′ to the lower end of each plate  43  and extends to and is fixed to extension portion  72  at point  74 . As will be discussed, pulling link  81  in the direction of arrow  75  ( FIG. 6 ) pulls plates  43  rearwardly in the direction of arrow  75 . A suitable stop  65  may be provided on the inner wall  32 ′ engaged by an extension  77  on extension portion  72 . 
     When plate  66  is rotated, it rotates shaft  65 ′, extending between side walls  11 ,  12 . 
     Release lever  70  rotates shaft  67  ( FIG. 2 ) which is spaced from shaft  65 ′ and has an extension portion  78  ( FIG. 2 ) adapted to engage release spring biased lever  79  when activated. Lever  79  abuts at one end against hub  80  ( FIG. 2 ) of extension portion  72  having a shoulder  81  thereon. Lever  79  is notched at notch  82  to hold hub  80  in locked position and thus hold guide flange plates  43  in position. When released, notch  82  disengages from shoulder  81  moving the lower end of lever  79  ( FIG. 5 ) against link  83  which has a guide slot  84  therein with pin  83  movable therein. Links  83  extend from plates  102  and are adapted to lift plates  43  upwardly along with pins  39  when lever  79  is released, thus lifting rollers  39  out of slots  33 . Link  83  ( FIG. 4 ) also has spaced guide slots  86 ,  87  with pins  88 ,  89 , respectively, adapted to ride thereon. Pin  89  also moves along slots  90  in plates  43 . 
     Thus, in operation, handle  52  is rotated clockwise, as previously discussed, and handle  52  is pumped to raise the jack. At this stage, release lever  64  is in the forward or  FIG. 2  position. This is also the stored position of lever  64 , safely out of the way. As previously discussed, rollers  39  move from the  FIG. 2  to the  FIG. 3 , then to the  FIG. 4  position. Lever  64  is then moved rearwardly in the direction of arrow  91  ( FIG. 4 ) and pressed downwardly again in the direction of arrow  91 . As can be appreciated by comparing  FIG. 2 to 4 , as lever  64  is moved in the direction of arrow  91 , the lower end of extension portion  78  abuts against the rear end of link  83  moving plates  43  forwardly and raising the same. That is, plates  43  are raised upwardly as indicated by arrow  93  in  FIG. 5  thus also moving rollers  39  out of grooves  33 . As rollers  39  moves rearwardly in the direction of arrow  76  ( FIG. 6 ), saddle  26  moves downwardly and rollers  39  move along guide slot  32 . The final position is shown in  FIG. 7  and lever  64  can now be raised in the direction of arrow  94  back to the rear or stored position releasing  82  from engagement with shoulder  84  thus returning guide plates  43  to the position shown. Notch  82  thus engages the shoulder  84  in hub  80  holding the hub  80 , and thus spring biased lever  64 , in the  FIG. 4  position prior to release. 
     In summary, lever  64  is in the forward or stored position of  FIG. 2 . Saddle  26  is in the lower position shown and the jack  10  may be placed under a vehicle or the like to lift the same. Handle  52  is now rotated clockwise and pumped up and down to raise saddle  26  and thus the vehicle. As the vehicle is lifted, rollers  39  move along grooves  33 , thus preventing a quick full downward drop of jack  10  should a malfunction of the power unit take place. Rollers  39  thus move forwardly into a forward groove as shown in  FIGS. 3 to 5 . 
     When it is desired to lower jack  10 , the operator merely taps lever  64  with his or her foot moving it from the  FIG. 1  position to the  FIG. 4  position, then pressing it downwardly to lift plates  43  as heretofore discussed this lifting rollers  39  out of grooves  33 . Handle  52  is now rotated counterclockwise lowering jack  10  to the  FIG. 2  position. 
     Although a particular embodiment of the invention is discussed, variations thereof may occur to an artisan and the scope of the invention should only be limited by the scope of the appended claims.

Technology Classification (CPC): 1