Abstract:
Disclosed herein is a ratcheting, self-aligning load-lifting device featuring a ram, responsive to a pressurized medium, having at least one rack of teeth and a keyway slot, and a ratchet mechanism encircling the ram. The ratchet mechanism has at least one pawl for engagement with the rack of teeth during elevation of the ram, a set screw extending into the keyway to maintain proper alignment of the mechanism, a spring plunger radially positioned for engagement with the keyway slot after the ratchet mechanism has been rotated and the pawl has been released from the elevated rack of teeth, and a biasing means positioned within and attached to rotate the ratchet mechanism thereby urging the re-engagement of the pawl with the lowered rack of teeth.

Description:
CROSS-REFERENCE TO A RELATED APPLICATION 
       [0001]    This application claims the benefit of Provisional Patent Application Ser. No. 61/923,711 filed Jan. 5, 2014, which is hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This disclosure relates generally to a load support device and more particularly to a ratcheting, self-aligning load-support device with safety features to prevent the unintended collapse or failure of the device when it is in the load support mode. 
       BACKGROUND OF THE INVENTION 
       [0003]    Hydraulic jacks are well-known mechanical devices and are generally used to raise and lower various types of loads, typically automobiles, off the ground. However, hydraulic fluid, the medium for raising and lowering the ram, may, over a period of time, leak past internal seals and allow the load or burden to unintentionally descend. In some instances, seal failure may cause the load to descend spontaneously without warning presenting an unacceptable risk to anyone in proximity to the jack and load. 
         [0004]    When using a typical jack to facilitate an automobile repair, it is common practice to eliminate the risk of spontaneous jack (ram) collapse by placing one or more safety stands under the elevated load and then lowering and removing the jack. This practice is problematic and inconvenient, especially with unibody vehicles, which typically have only a limited number of reinforced areas suitable for lifting the vehicle and supporting its weight. Thus, if the operator has used a jack on one of the provided lift points, there is generally limited space for placing a safety stand adjacent to the jack, and the operator must be judicious in selecting an area for the safety stand that will support the vehicle&#39;s weight because improper positioning introduces the possibility of damage to the vehicle&#39;s frame, or even more serious damage may result from the improvidently positioned safety stand punching through the floorboard allowing the vehicle to suddenly fall to the ground with possible injury to the operator. 
         [0005]    There is a need for a device that functions both as a jack and as a safety stand, and the disclosed ratcheting, self-aligning load-support device functions in that manner and meets that need. It eliminates the use of a separate jack and safety stand and thereby saves time, effort and avoids possible damage to the vehicle and injury to anyone in the event of jack failure and collapse. Efforts have been made in the past to address the need of a jack and safety stand combination. The following patent documents are representative of efforts made in that regard. 
       DESCRIPTION OF THE PRIOR ART 
       [0006]    U.S. Pat. No. 5,000,424, which issued to Inoue on Mar. 19, 1991, discloses a jack having the means to lock an elevated piston (ram) in place by employing a threaded annular stopper, or ring, affixed to threads cut into the surface of the piston. After raising the load, the operator spins the ring repeatedly to move it upwards on the piston, thereby locking the piston in position at the desired height. This approach is time and labor intensive and unacceptable. It requires the operator to spin the stopper repeatedly over a substantial distance once the load has been raised to the desired height, and then reverse the process by spinning the stopper back to the original position before being able to lower the load. Inoue discloses an alternate embodiment utilizing a rudimentary rack and pawl arrangement but fails to elaborate on how it could function safely in actual practice because the mechanism to release the pawl is exposed and subject to accidental disengagement. 
         [0007]    U.S. Pat. No. 6,902,148, which issued to C. Spencer on Jun. 7, 2005, describes a jack having what is referred to as a “prop” extending parallel to an elevated piston extending out of a bottle jack housing and containing receptacles in which to place pins to restrict lowering the elevated piston. Requiring the placement of pins to insure the elevation of the extended piston is commendable but manipulating the pins discourages their use and complicates the use of the device. 
         [0008]    U.S. Pat. No. 7,147,211, which issued to R. Porter on Dec. 12, 2006, describes an integrated jack and stand having a locking mechanism with pivoting teeth installed on a shaft that is pushed from below as the piston is raised. While rising, each tooth compresses into the shaft as needed to pass through a hole, but expanding outward again on the other side. The expanded teeth prevent the shaft from lowering back through the hole. Porter also discloses a mechanism designed to be selectively disengaged to open a passageway so that the jack can be lowered. 
         [0009]    U.S. Pat. No. 8,333,365, which issued to Z. Dai on Dec. 18, 2012, describes a jack having a slit nut collar that can be selectively engaged against threads cut into the surface of the jack piston. The operator disengages the locking mechanism before raising the load and then engages the lock after the intended height has been reached. The locking mechanism employs a slit nut collar with a trapezoidal cross-section that compresses against the piston as it is lowered causing threads on the collar to engage with threads on the piston. This device requires the operator to disengage the safety mechanism prior to use and requires that it be manually reengaged after the load has been raised. 
         [0010]    Unlike devices known in the prior art, the device described and claimed herein provides a jack having an automatic and reliable locking mechanism capable of supporting a heavy load indefinitely without requiring the operator to account for additional parts or manually engage a safety mechanism while raising or lowering the load. 
       SUMMARY OF THE INVENTION 
       [0011]    The invention described herein is a jack with an integrated ratchet mechanism for raising, lowering and maintaining positive locking engagement with a pressurized ram capable of supporting a load even if the pressurized medium supporting the ram were to fail. The disclosed device features a conventional jack having a modified ram and a ratchet load-support mechanism which is unique in its design and function. The device functions as a jack while simultaneously supporting its load regardless of seal damage or failure. Furthermore, the device defaults to a locked load-support position. Manual intervention by the operator is required only to release the load-support mechanism before lowering the load. When lowered, the mechanism automatically resets back to the default position when the jack reaches a fully retracted (lowered) position. 
         [0012]    Essentially and more specifically, the ratcheting, self-aligning load-support device described herein comprises a housing having a base for the stable placement of the device. The housing contains a ram having a plurality of rack teeth along its length as well as a keyway slot, offset from the rack teeth, also extending a predetermined length along the ram. The housing also has an apical opening for the vertical extension of the ram. Additionally, the disclosed device has a reservoir for the containment of a medium in communication with the housing and a means attached to the reservoir for pressurizing the medium. 
         [0013]    Attached to the apical opening in the housing are upper and lower ring assemblies, mated to allow rotation between the assemblies. Preferably, the lower ring assembly is threadably attached to the apical opening in the housing. Within the upper ring assembly is at least one pawl biased to engage with the rack teeth, and within the lower ring assembly is a set screw radially positioned for continuous engagement with the keyway slot to maintain the alignment of the teeth on the ram with the pawl on the upper ring assembly. 
         [0014]    Also positioned within the upper ring assembly is a plunger for engagement with the keyway slot after the ring assemblies have been rotated to disengage the pawl from the rack teeth, thus permitting the lowering of the ram. 
         [0015]    And finally, a biasing means is attached to and positioned between the upper and lower ring assemblies, biased to urge the upper ring assembly to rotate when the ram has been fully lowered, thereby re-engaging the pawl with the rack teeth. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0016]      FIG. 1  depicts a conventional bottle jack. 
           [0017]      FIG. 2  is a perspective view of the disclosed device. 
           [0018]      FIG. 3  is an exploded view of the device of  FIG. 2  with all the elements of the disclosed device depicted. 
           [0019]      FIG. 3 a    is an isolated view of the ram showing rack teeth and a keyway slot. 
           [0020]      FIG. 4  is an exploded view of the upper and lower ring assemblies. 
           [0021]      FIG. 4 a    is a top plan view of the assembled device showing the position of section line A-A. 
           [0022]      FIG. 4 b    shows an exploded, cross-sectional view of the upper and lower ring assemblies taken along line A-A of  FIG. 4   a.    
           [0023]      FIG. 5  is an elevated side view of the disclosed device showing the position of the plane section line B-B. 
           [0024]      FIG. 5 a    is a partial, enlarged cross-sectional view of the disclosed device taken along line B-B of  FIG. 5 . 
           [0025]      FIG. 6  is a top plan view of the disclosed device showing the plane of section line C-C. 
           [0026]      FIG. 6 a    is a partial, enlarged cross-sectional view of the disclosed device taken along line C-C of  FIG. 6  showing the set screw disposed into the keyway slot. 
           [0027]      FIG. 7 a    is a perspective view of the disclosed device in the default position, as it would appear after the load has been lifted, with the ram retracted (lowered) and pawls engaged. 
           [0028]      FIG. 7 b    is a perspective view of the disclosed device in the default position, as it would appear after the load has been lifted, with the ram extended (raised) and pawls engaged. 
           [0029]      FIG. 7 c    is a perspective view of the disclosed device in the secondary position, as it would appear prior to lowering the load, with the ram extended (raised) and pawls released, after having spun the upper ring assembly in the direction indicated. 
           [0030]      FIG. 7 d    is a perspective view of the disclosed device in the secondary position, as it would appear once the rack reaches full retraction, with the ram retracted (lowered) and the upper ring assembly poised to automatically rotate in the direction indicated. 
           [0031]      FIG. 8  is a top plan view of the disclosed device showing the plane of section line D-D. 
           [0032]      FIG. 8 a    is an isolated, enlarged cross-sectional view, taken along line D-D of  FIG. 8 , of the upper and lower ring assemblies in the secondary position shown in  FIG. 7   c.    
           [0033]      FIG. 8 b    is an elevated side view of the disclosed device in cross-section showing the isolated enlarged area depicted in  FIG. 8 a      
           [0034]      FIG. 9  is a top plan view of the disclosed device showing the plane of section line E-E. 
           [0035]      FIG. 9 a    is an isolated, enlarged cross-sectional view, taken along line E-E of  FIG. 9 , of the upper and lower ring assemblies in the secondary position shown in  FIG. 7   d.    
           [0036]      FIG. 9 b    is an elevated side view of the disclosed device in cross-section showing the isolated enlarged area depicted in  FIG. 9   a.    
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0037]    An appreciation of the disclosed ratcheting, self-aligning, load-support device described herein begins appropriately with the prior art  FIG. 1  depicts a conventional hydraulic bottle jack, which has many of the external features of the disclosed device. Common shared elements include the jack assembly  50  comprising a housing  502 , supported by a base  501 . There are a reservoir  505  and a handle receptacle  503  receiving a handle  510  for pressurizing the hydraulic fluid, or any other suitable medium, thus extending the ram or piston  506  to effect the lifting of the load. Additionally, a threaded saddle  507  is typically positioned within the conventional ram  506  to provide secure contact with the load. 
         [0038]    The primary external distinguishing features between the conventional bottle jack and the disclosed lifting device are depicted in  FIG. 2 . Those features consist of the modified ram  400  and the ratchet mechanical assembly  10 . The modified ram  400  is fully depicted in  FIG. 3 a   . Readily apparent are the rack of teeth  401  positioned along the length of the ram and a keyway slot  402 , offset from the rack of teeth, but also extending partway along the length of the ram. The ratchet mechanical assembly  10  comprises the upper  20  and lower  30  ring assemblies, depicted in their entirety in  FIG. 3 , an exploded view of the key elements of the disclosed device. Also depicted are the jack assembly  50  resting on its base  501  for stable placement or positioning of the device and its housing  502  for the containment of the ram  400 . As mentioned supra, the ram is modified to include racked teeth  401  and a keyway slot  402 . 
         [0039]    When the gas or fluid medium within the reservoir  505  of the jack assembly  50  is pressurized, typically by the manual action of a handle  510  inserted into the handle receptacle  503  attached to the reservoir, the ram is urged to extend vertically through the apical opening  509  in the jack housing  502 . 
         [0040]    Attached to the jack housing  502  at the apical opening  509  are the upper and lower ring assemblies  20  and  30 . These assemblies are mated, preferably threaded, to allow and permit rotation between the two assemblies. The lower ring assembly  30  is attached directly to the apical opening  509  in the jack housing  502 , preferably via mated threads.  FIG. 4  provides an exploded view of the upper and lower ring assemblies  20  and  30 . The lower ring assembly  30  comprises a lower ring body  301 , annular in shape and having an inner opening suitably sized to accommodate the extended ram  400  to pass through its center, an internal, annular alignment slot  302  and a radially positioned set screw  306 . 
         [0041]    Also apparent in  FIG. 4  are the elements of the upper ring assembly  20 . The upper ring assembly comprises an upper ring body  201  annular in shape and having an inner opening suitably sized to accommodate the extended ram  400  to pass through its center, and attached, preferably by threaded means, to the top of the lower ring body  301 . Positioned within the upper ring body  201  is a pawl socket  202  for the placement of a pawl  207  biased to make contact and engage with the rack teeth  401  on the ram  400  as it extends, when pressured, upwardly from the jack housing  502  through the mated upper and lower ring assemblies  20  and  30 . 
         [0042]    The pawl  207 , positioned in the pawl socket  202  within the upper ring body  20  and biased by a pawl torsion spring  210  to engage the rack teeth  401  on the ram  400 , is allowed to rotate slightly away from the rack teeth to permit extension of the ram  400  by dint of its placement on pivot pin  209 , which allows the pawl  207  to rotate within the pawl socket  202 . The pivot pin extends chord-like through the upper ring assembly body  201  with the benefit of a pivot pin hole  208 . At this juncture, it is helpful to note that while the pawl  207 , the pawl socket  202 , the pawl torsion spring  210  and the pawl pivot pin  209  are described in the singular, the preferred embodiment of the disclosed load support device  50  will feature the foregoing elements in pairs as depicted in  FIGS. 4 and 5   a.    
         [0043]    Further apparent in  FIG. 4 , and an element of the upper ring assembly  20 , is a spring plunger  206 . The plunger is radially positioned in the upper ring body  201 , extends through the spring plunger aperture  205 , and is spring-biased to be compressed against the surface of the extended ram  400 . 
         [0044]    Situated externally on the body  201  of the upper ring assembly  20  is a pair of alignment flanges  203  (one depicted) to mate with the corresponding annular alignment slots  302  on the inner surface of the lower ring assembly  30 . The proper mating of the alignment flanges within the alignment slots assures the proper range of rotation of the upper ring assembly  20  in relation to the lower ring assembly  30 . 
         [0045]    Positioned between and attached to the upper and lower ring assemblies  20  and  30  is a mechanism torsion spring  307 . One end of the torsion spring  307  is connected to the upper ring body  201  by disposition into torsion spring upper socket  204  ( FIG. 4 b   ) while the other end is disposed into torsion spring lower socket  304  of the lower ring body  301 . The main body of spring  307  nests in torsion spring raceway  303  of the lower ring body  301 . 
         [0046]    In operation, the disclosed ratcheting load-support device has two positions: the “default” position wherein the ram  400  is able to be raised, (i.e., extended but not lowered) and the “secondary” position where lowering, (i.e., retracting the ram) is possible. 
         [0047]    In a preferred embodiment and as depicted in  FIGS. 5 a  and 7 a   , at the fully-retracted default position, ratchet pawls  207  are biased against ram  400  and engage with rack teeth  401  on the surface of the ram  400 . As the operator pumps the jack handle  510 , pressurizing the medium and causing the ram  400  to rise, pawl torsion springs  210  urge pawls  207  to maintain continuous contact against ram  400  but allow pawls  207  to pivot back and forth on pivot pins  209 , while following the contour of the rack teeth  401 . This back and forth, pivoting, rocking action results in a constant locking engagement between the ram and the pawls thus preventing ram  400  from descending in the event of a pressure failure. See  FIG. 7 b    for a depiction of the disclosed device in raised ram default (locked) position. 
         [0048]    To lower the load, the operator must first release pawls  207  from their default locked position. To release the pawls  207 , the operator (after raising the load slightly to take its weight off the mechanism) rotates upper ring body  201  in a counter-clockwise direction, moving the device to the secondary position and disengaging pawls  207  from the rack teeth  401 . The turning of the upper ring body and disengagement of the pawls is depicted in  FIG. 7 c   . Rotating upper ring body  201  in a counter-clockwise direction causes spring plunger  206  to encounter keyway slot  402  extending along the length of ram  400  allowing the spring plunger to extend into the keyway slot. Positioning spring plunger  206  in keyway slot  402  prevents upper ring body  201  from returning to its default position. While in this secondary position, the ram is disengaged from the rack teeth  401  and free to descend without interference and in a controlled manner as the operator directs. 
         [0049]    As the ram  400  reaches the fully-lowered position ( FIG. 7 d   ), spring plunger  206  encounters the upper terminus of keyway slot  402  ( FIG. 9 ). As the slot terminates, spring plunger  206  is compressed once more against the cylindrical surface of ram  400 , thereby releasing upper ring body  201 . The torque force maintained by mechanism torsion spring  307  then causes upper ring body  201  to rotate on its axis in a clockwise direction ( FIG. 7 d   ) returning pawls  207  to their default (engaged) position with the rack teeth  401 . Thus, as ram  400  reaches its fully retracted position, ratchet mechanism  10  automatically resets to the default position shown in  FIG. 7 a    and the device  50  is ready for the next use. 
         [0050]    The ratcheting, self-aligning, load-lifting device  10  thus comprises a mechanism that functions simultaneously as a lifting jack and a safety stand. The locking mechanism integrated into the lifting capability of the jack eliminates the use of extraneous parts that can be lost, misplaced or misused. And, automatic engagement means that the operator need not take steps to engage the jack in order to benefit from its safety features. 
         [0051]    The device herein described is one embodiment of the invention, intended as explanation rather than limitation. The disclosed mechanism is easily adaptable to jack designs of varying shapes, sizes and load capabilities. For example, the ratcheting, self-aligning load-support mechanism could be deployed on either pneumatic or hydraulic jacks, or the design could be modified to have the mechanism spin in either direction for release. 
         [0052]    Additionally, the disclosed device could be manufactured from a variety of materials provided that they can be machined, fabricated or forged so as to perform the function required for the task at hand. Similarly, any and all pressure-receptive mediums could be used to move the ram, if suitable for the job requirements. 
         [0053]    While the foregoing is a detailed and complete description of the preferred embodiment of the disclosed ratcheting, self-aligning load-lifting device, it should be apparent that numerous variations and modifications could be made to the disclosed device and utilized to implement the overall purpose of the device without deviating or departing from the spirit of the invention, which is fairly defined by the appended claims.