Safety jack

[0001] Not Applicable.

[0002] Not Applicable.

[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.

[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.

[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 3B, 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 3B, 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 3C, 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 4B, 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.