Abstract:
The present invention is a safety jack having a propping mechanism comprised of a prop attached parallel to and jointly movable with the lifting arm, a storage well for receiving the prop in a retracted position, and a pin engagable with the prop to bias the prop and the body of the jack to prevent untimely lifting arm retraction.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     Not Applicable  
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002]     Not Applicable  
       BACKGROUND OF THE INVENTION  
       [0003]     1. Field of the Invention  
         [0004]     The invention is generally related to lifting jacks and more specifically to jacks having a safety mechanism to prevent unanticipated movement from an extended position to a retracted position.  
         [0005]     2. Description of the Related Art  
         [0006]     A great variety of jacks are known in the field. Jacks are employed to lift items of substantial weight to include vehicles. In some instances, once an item is lifted it may be desired to maintain the item in the elevated position for an extended period while activity is conducted about the item. In these instances, there exists a hazard that the particular jack may lose lifting force engagement, permitting the weighty item to unexpectedly lower. This presents a particularly serious hazard to activity being conducted underneath the item. For this reason the field of art practices placing rigid supports or jack stands under items to prevent the item from lowering in case the jack loses lifting force.  
         [0007]     The prior art possesses a variety of exemplary adjustable jacks and jack stands. The following are a few examples.  
         [0008]     U.S. Pat. No. 4,042,202 issued to D. Molinari on Aug. 16, 1977, discloses a jack stand with a safety-locking device whereby a pin is positioned through a plurality of alignable corresponding holes in the shaft and the housing locking these members with respect to each other longitudinally. The pin is keyed so as to prevent withdrawal of the pin until rotated into an aligned position.  
         [0009]     U.S. Pat. No. 4,479,634 issued to R. Blatz on Oct. 30, 1984, discloses a jackable stand comprising of a vertical post that projects upward normal to a base. A carriage is attached to the vertical post moveably along the length of the post. The post has receiver holes vertically spaced apart along a length of the post and extending through the post. The carriage and base are engageable by a jack that may employ mechanical advantage to progress the carriage along the length of the post. A pin is employed in a selected receiver hole to restrict movement of the carriage along the post.  
         [0010]     U.S. Pat. No. 6,027,102 issued to Krupa on Feb. 22, 2000, discloses a hydraulic jack stand having a hydraulic bottle jack positionable on an elongated jack support comprising a tubular outer housing, a moveable cylindrical member, and a pin. The outer housing has a pin anchor receiver, such that the pin may be inserted through the outer housing. The moveable member has a plurality of receiver holes vertically spaced apart along a length that, with the moveable member inserted into the outer housing, may be selectively alignable with the anchor receiver such that the pin may be inserted through both a receiver hole and the anchor hole, fixing the outer housing and moveable member longitudinally.  
         [0011]     U.S. Pat. No. 6,322,062 B1 issued to Conn et al. on Nov. 27, 2001, discloses a cabinet installation lifting system comprising a jack and a pair of extendable supports, wherein said supports each comprise a tubular outer housing having an pin anchor receiver, a moveable cylindrical member having a plurality of receiver holes vertically spaced apart along a length that, with the moveable member inserted into the outer housing, may be selectively alignable with the anchor receiver such that a pin may be inserted through both a receiver hole and the anchor hole, fixing the outer housing and moveable member longitudinally throughout the lifting range of the jack.  
         [0012]     U.S. Pat. No. 6,443,413 B1 issued to Hawkins et al. on Sep. 3, 2002, discloses an adjustable jack stand having a ratchet and pawl height maintenance mechanism with a pin and hole mechanism wherein the holes in the post coordinate with the teeth in the post so that any engagement between the pawl and a tooth ensures that a pair of holes in the base and the post are aligned to receive a pin.  
         [0013]     It would be an improvement to the art to provide a jack having a locking mechanism comprised of a prop exterior to the lifting arm, a storage well for receiving the prop in a retracted position, and a locking pin engagable with said prop to bias said prop and the body of the jack to selectively prevent lifting arm retraction.  
       BRIEF SUMMARY OF THE INVENTION  
       [0014]     My invention is a jack having a housing, a lifting arm or ram, and a prop. The prop may comprise at least one segment extending from said bottle housing parallel with said ram. Another embodiment of a prop may be integrated into a lifting arm. The bottle housing comprises a storage area designed to receive the prop from the face from which the ram extends. A suitable storage area may comprise a well positioned around the circumference of the ram, having a width and depth suitable to receive the prop as the prop moves with the ram from an extended position primarily out of the well to a retracted position primarily contained in the well. The prop comprises at least one pin receptacle for engagement with a pin such that the engagement of said pin with said receptacle positions said pin to restrict retraction of said ram to within said housing by biasing between the engaged pin receptacle and the bottle housing adjacent to the outer edge of the well. In this manner such an inventive hydraulic jack may mechanically support a weight in an extended position, even if said jack were to lose hydraulic support of said ram. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]      FIG. 1  is a partially cut-away perspective view of a bottle jack according to the present invention.  
         [0016]      FIG. 2  is a frontal view of the jack depicted in  FIG. 1 .  
         [0017]      FIG. 3  is a partially cut-away frontal view of a bottle jack according to an alternate exemplary embodiment of the present invention.  
         [0018]      FIG. 3A  is a cross-sectional view of the device in  FIG. 3 , cut at line A-A.  
         [0019]      FIG. 3B  is a cross-sectional view of the device in  FIG. 3 , cut at line B-B.  
         [0020]      FIG. 3C  is a top view of a pin for use with the device depicted in  FIG. 3 .  
         [0021]      FIG. 4  is a perspective view of a bottle jack according to an alternate exemplary embodiment of the present invention.  
         [0022]      FIG. 4A  is a cross-sectional view of the device in  FIG. 4 , cut at line A-A.  
         [0023]      FIG. 4B  is a cross-sectional view of the device in  FIG. 4 , cut at line B-B.  
     
    
     DESCRIPTION OF THE INVENTION  
       [0024]     Referring to  FIGS. 1 and 2 , an exemplary jack  10  is shown. Exemplary jack  10  may be a hydraulic bottle jack having a generally cylindrical jack housing  12  fixedly attached to a solid jack base  18  at one end, generally considered the bottom of jack  10 . Other types of jacks known in the art may employ the inventive device. In the exemplary embodiment, jacking mechanism  16  is adjacent and operably linked to jack housing  12 . Operation of jacking mechanism  16  creates hydraulic pressure from mechanical leverage through hydraulic fluid (not shown) within a fluid reservoir  24  contained in jack housing  12 ; a device and process known to the art. Also known to the art is the employment of this pressurized hydraulic fluid to work against the one end of ram  14  recessed into jack housing  12  causing ram  14  to controllably extend away from and retract toward jack housing  12  with substantial force F having substantial lifting capacity. In this fashion ram  14  may be described as being telescopically attached to jack housing  12 . A jack shoe  17  is provided on the opposite end of ram  14  from jack housing  12 , generally considered the top of jack  10 , to provide an interface surface to an item to be jacked (not shown), as known in the art.  
         [0025]     Prop  40  is attached to travel jointly with ram  14 . Referring to  FIGS. 1 and 2 , exemplary jack  10  has a pair of elongated rigid members comprising prop  40  that are disposed on opposite sides of ram  14 , oriented generally parallel to ram  14 . As controlled by jacking mechanism  16 , in lifting operation or lowering operation, the individual components of prop  40  correspondingly fit into storage wells  22  in jack housing  12 , such that prop  40  and ram  14  may similarly and correspondingly both extend from in jacking mechanism  16  lifting operation and recess into jack housing  12  in jacking mechanism lowering operation.  
         [0026]     Prop  40  possesses a series of pin receptacles  42  arranged spaced apart along the length of each component of prop  40  from the end recessed in housing  12  to the end adjacent to jack shoe  17 . Pin receptacles  42  are disposed in prop  40  to permit the engagement of pin  50 . In the exemplary embodiment, pin receptacles  42  are transverses perforations in prop  40 . In the exemplary embodiment pin  50  is comprised of a pair of pin shafts  52  that extend in one direction with a pin handle  54  extending in the opposite direction. Pin  50  possesses a corresponding shape suited to engage corresponding pin receptacles  42  on prop  40 . In the exemplary embodiment a pin receptacle  42  in one component of prop  40  and a corresponding pin receptacle  42  in the other component of prop  40  are positioned along prop  40  in order to extend a similar distance above housing upper surface  20  such that each of the pair of pin receptacles  42  may receive a corresponding pin shaft  52 . In the exemplary embodiment, each pin shaft  52  is of sufficient length to extend completely through respective pin receptacle  42 , and may be inserted from either end of pin receptacle  42 .  
         [0027]     In regard to lifting operation, jack  10  operates as prior art jacks where mechanical reciprocation of jacking mechanism  16  caused pressurized hydraulic fluid (not shown) to create extending force F on ram  14 . As force F becomes greater than weight force W of an item to be lifted (not shown) applied to jack shoe  17 , ram  14  moves incrementally from a recessed position substantially within housing  12  and jack shoe  17  is close to housing upper surface  20 , to an extended position where distance D, between jack shoe  17  and housing upper surface  20 , is greater. As ram  14  extends from housing  12 , prop  40  extends from storage wells  22 , exposing pin receptacles  42 . As the desired distance D is reached jacking is continued until the next corresponding pair of pin receptacles  42  is completely accessible to pin shafts  52 . At this point jacking may be halted and pin  50  may be inserted into pin receptacles  42  adjacent to housing upper surface  20 . Slight lowering operation of jacking mechanism  16  results in a slight retraction of lifting arm  14  and prop  40 . Properly engaged in pin receptacles  42 , pin  50  disables lowering operation of jacking mechanism  16 , which prevents significant retraction of ram  14  by biasing between prop  40  and housing upper surface  20 , restricting the decrease in distance D. In this fashion, if lifting force F on ram  14  decreases to less than the force W of the weight of the lifted item (not shown), retractive motion and recessing travel of ram  14  is prohibited by the biasing of pin  50  in prop  40  against housing upper surface  20 .  
         [0028]     To affect lowering of jack  10 , lifting operation in jacking mechanism  16  may need to be actuated to increase lifting force F on ram  14  to be greater or equal to the force W of the weight of the lifted item (not shown) in order to ensure pin  50  is no longer biased between pin receptacles  42  of prop  40  and housing upper surface  20 . In the absence of biasing, pin  50  may be removed from prop  40  by withdrawing pin shafts  52  from pin receptacles  42 . With pin  50  removed, jack  10  may be lowered by an appropriate manner, as known to the prior art.  
         [0029]     Referring to  FIGS. 3, 3A , and  3 B, an alternate exemplary jack  110  may have prop  140  attached to ram  14  proximate jack shoe interface  19 . Prop  140  is attached to ram  14  and positioned to travel between a retracted position and an extended position in conjunction with ram  14 . In  FIGS. 3, 3A , and  3 B, exemplary prop  140  has a generally cylindrical shape, with ram  14  interior to prop  140 , and prop  140  oriented generally parallel to the sides of ram  14 . The connection of prop  140  to jack shoe interface  19  may rotate in order to permit prop  140  rotational movement about ram  14  independent of movement of ram  14  or jack shoe  17 . Prop  140  may be correspondingly recessable into storage well  122  in jack housing  12 , such that prop  140  and ram  14  may similarly and correspondingly both extend from and recess into jack housing  12 .  
         [0030]     Prop  140  possesses a series of pin receptacles  142  arranged spaced apart along the length of each component of prop  140  from the end recessed in housing  12  to the end adjacent jack shoe  17 . Referring to  FIGS. 3, 3B , and  3 C, exemplary receptacles  142  are configured to permit the engagement with pin  150 . In the exemplary embodiment pin  150  is comprised of a pair of pin shafts  152  that extend in one direction with a pin handle  154  extending in the opposite direction. Pin  150  possesses a corresponding shape suited to engage corresponding pin receptacles  142  on prop  140 . In the exemplary embodiment a pin receptacle  142  in one side of prop  140  and a corresponding pin receptacle  142  in the other side of prop  140  are coordinatingly positioned along prop  140  in order to extend a similar distance above housing upper surface  20  such that each of the pair of pin receptacles  142  may receive a corresponding pin shaft  152 . In the exemplary embodiment, each pin shaft  152  is of sufficient length to extend completely through respective pin receptacle  142 , and may be inserted from either end of pin receptacle  142 .  
         [0031]     In an exemplary embodiment having a pivotal connection at jack shoe interface  19 , prop  140  may be rotated around internal ram  14  while weight in on jack shoe  17 , in order to make insertion of pin  150  into pin receptacle  142  more convenient for an operator.  
         [0032]     Referring to  FIGS. 4, 4A , and  4 B, additional alternate exemplary jack  210  may have prop  240  integrated with ram  14 . As known in the field, one end of ram  14  may be recessed into jack housing  12 , while the other end of ram  14  and a length of ram  14  may extend from jack housing  12 . The length of ram  14  that may extend from jack housing  12  may be referred to as prop  240 .  
         [0033]     Prop  240  contains at least one pin receptacle  242 . In the exemplary embodiment multiple pin receptacles  242  are spaced apart along the length of ram  14  that may extend from housing  12 . Pin receptacles  242  may be configured to permit selective insertion of pin  250 . In the exemplary embodiment pin  250  is comprised of a single of pin shafts  252  that extend in one direction with a pin handle  254  extending in the opposite direction. Pin  250  possesses a corresponding shape suited to engage corresponding pin receptacles  242  on prop  240 , and may be inserted from either end of pin receptacle  242 .  
         [0034]     The foregoing disclosure and description of the invention is illustrative and explanatory thereof. Various changes in the details of the illustrated construction may be made within the scope of the appended claims without departing from the spirit of the invention. The present invention should only be limited by the following claims and their legal equivalents.