US 3764109 A
A weld-free jack for the frame of a vehicle of the type to be trailed or pulled. The jack comprises an outer elongated body or tube having a telescoping jack stem therein. The upper end of the jack stem is provided with a jack nut through which a jack screw passes in threaded engagement. Axial movement of the jack stem is accomplished by means of the jack screw, the upper end of which extends above the jack body and is provided with handle means. At the upper end of the jack body, the jack screw is provided with a thrust washer and thrust bearing; these last mentioned elements, together with the jack screw, being supported in the jack body by a transverse key passing through diametrically opposed slots in the jack body. Finally, the jack body passes through a perforation in a plate on the vehicle frame and is affixed to the frame plate by a pair of diametrically opposed keys attached to the underside of the frame plate and entering diametrically opposed slots in the jack body.
Description (OCR text may contain errors)
llnite States Patent [191 Hollis, ,Br.
[ Oct. 9, 1973 JACK  Inventor: Russell E. Hollis, In, 502 Merrick Dr., Xenia, Ohio 45385  Filed: Nov. 29, 1971  Appl. No.: 202,966
Primary Examiner-Othell M. Simpson Assistant Examiner-Robert C. Watson Attorney-Jerome P. Bloom  ABSTRACT A weld-free jack for the frame of a vehicle of the type to be trailed or pulled. The jack comprises an outer elongated body or tube having a telescoping jack stem therein. The upper end of the jack stem is provided with a jack nut through which a jack screw passes in threaded engagement. Axial movement of the jack stem is accomplished by means of the jack screw, the upper end of which extends above the jack body and is provided with handle means. At the upper end of the jack body, the jack screw is provided with a thrust washer and thrust bearing; these last mentioned elements, together with the jack screw, being supported in the jack body by a transverse key passing through diametrically opposed slots in the jack body. Finally, the jack body passes through a perforation in a plate on the vehicle frame and is affixed to the frame plate by a pair of diametrically opposed keys attached to the underside of the frame plate and entering diametrically opposed slots in the jack body.
17 Claims, 8 Drawing Figures Patented Oct. 9, 1973 2 Sheets-Sheet 1 Patented Oct. 9, 1973 3,764,109
2 Sheets-Sheet 2 JACK BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a jack for the frame of a vehicle to be pulled or trailed, and more particularly to a jack of simple and weld-less construction and optimal strength for the parts involved.
2. Description of the Prior Art The jack of the present invention is substantially unlimited as to its use. Because of its heavy duty capacity, for purposes of an exemplary showing, it will be described with respect to its application to the frame of a vehicle to be .pulled or towed, such as a mobile home, a recreational vehicle, a boat trailer, a piece of heavy equipment, an off-the-road industrial trailer, or the like. Again, for purposes of an exemplary showing, it will be specifically described with respect to its use with a mobile home, wherein it would normally be affixed to the top frame surface of the conventional mobile home A-frame.
Experience has shown that a jack used with a mobile home or similar vehicle is subject to damage and must be readily replaceable. Prior art structures have generally been provided with a mounting flange welded to the outer tube or body of the jack. The jack body passes through a perforation in the upper plate of the A-frame and the mounting flange of the jack lies in abutting relationship to the upper surface of the plate. The mounting flange is affixed to the plate by bolts passing through both elements. It will be understood that such bolts are required to carry the full load supported by the jack. Thus, the safety and effectiveness of the jack has hitherto depended upon the integrity of the weld of the mounting flange to the jack body and the strength of the bolts.
Also, in prior art structures, the jack screw and thrust bearing therefor have generally been supported within the jack body by a thrust washer welded to the jack body at the top end thereof or held in place by a reduced diameter portion or a crimped portion of the jack body. Again, theeffectiveness and safety of the jack has depended upon the integrity of the means by which the thrust washer has been held in place.
In contrast, in preferred application the jack of the present invention is affixed to a plate bridging upper surface portions of the mobile home A-frame by means of a pair of keys affixed to the bottom surface of such plate. The keys are configured to enter diametrically opposed slots in the jack body. Thus the mounting load is entirely in shear on the keys and the forces impressed thereby are directed through the wall of the jack body. The safety and effectiveness of the jack does not depend upon welds or bolts.
Further, in the invention embodiment of the jack screw and the thrust washer and thrust bearing therefor are supported in the jack body by a key means extending transversely of the jack body and passing through diametrically opposed slots in the upper end of the jack body. This provides a safe and simple assembly eliminating expensive and time consuming welding, crimping or diameter reducing operations.
The jack of the present invention is also provided with simple means for preventing the jack stem from turning with the jack screw, a means which avoids inadvertent jamming of the stem during its adjustment in place. In addition, the fabricated parts of the jack of the present invention may be assembled directly, with no intermediate welding and the like. It can, in fact, be bench-assembled. Finally, the forward key affixing the jack body to the A-frame may be so configured as to serve as a means for properly locating the plate on the A-frame to which it is affixed, during assembly thereof.
SUMMARY OF THE INVENTION The jack of the present invention, in preferred embodiment, comprises an outer elongated body or tube, a jack stem having a telescoping fit within the outer tube and a jack screw for moving the jack stem axially. The screw has a threaded engagement with a jack nut affixed to the upper end of the stem by a pin. The upper end of the stem has a laterally projected, longitudinally extending rib-like formation adapted to ride in a channel provided by the formation of a longitudinal bead in the wall of the outer tube. This prevents the rotation of the stem by the jack screw in use.
A thrust washer and a thrust bearing are provided to seat about the jack screw at the upper end of the tube to sustain upward thrust of the jack stem through the screw. Upward movement of the thrust bearing, in turn, is prevented by a key means extending transversely of the outer tube through diametrically opposed slots therein.
The outer tube or body of the jack is affixed to a mounting plate, which in turn is appropriately mounted to a vehicle frame, for example to bridge upper surface portions of the A-frame of a mobile home. This mounting plate is provided with a perforation through which the jack extends. On its under side, the mounting plate has a forward and a rearward key affixed thereto. These keys are configured to extend into diametrically opposed slots in the jack body or outer tube.
The forward key on the mounting plate may be so configured as to render the jack and mounting plate self-locating on any conventional A-frame, as will be described hereinafter. Further, the parts of the jack may be quickly and easily assembled and the final as sembly may be produced directly, without any intervening welding steps or the like.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a perspective view of the jack of the present invention mounted on a conventional A-frame of a mobile home;
FIG. 2 is a side elevational view, partly in cross section, of the structure of the present invention, with the jack stern fully nested, while FIG. 2a is a fragment of a similar view wherein the jack stem is partially projected to elevate the supported structure;
FIG. 3 is a cross sectional view taken along the section line 33 of FIG. 2;
FIG. 4 is a cross sectional view taken along the section line 44 of FIG. 2;
FIG. 5 is a cross sectional view taken along the section line 55 of FIG. 2;
FIG. 6 is an exploded perspective view illustrating the upper frame plate or mounting plate, the forward key and the rearward key, as shown inassembly in FIG. 5; and
FIG. 7 is a bottom view of the structure of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning first to FIG. I, the jack of the present invention is illustrated in its fully assembled form and mounted on a conventional A-frame of a mobile home or the like. As indicated above, this is an exemplary showing only, the jack being capable of substantially unlimited application.
The jack, generally indicated at 1, includes an outer tube or body 2 and is actuated by handle means 3.
The forward convergent ends of the beams of a conventional A-frame are shown at 4 and 5. These forward ends meet at an angle and are joined together in any conventional and well known manner (not shown). While the beams 4 and 5 are illustrated as I beams, it will be understood that their cross sectional configuration does not constitute a limitation on the present invention. Thus the beams 4 and 5 could have an angle iron and channel-shaped cross sectional configuration.
In the present construction, the A-frame members 4 and 5 are bridged by and have affixed thereto an upper frame plate 6 and a lower frame plate 7 (see FIGS. 2 and 7). These plates are provided with perforations through which the jack 1 extends, and the jack may be affixed to either of them. For purposes of an exemplary showing, the jack will hereinafter be described as affixed to the upper frame plate 6. The frame plates 6 and 7 are, themselves, affixed to the beams 4 and 5 in any suitable and conventional manner such as welding or the like. It is also within the scope of the invention that either the upper or the lower frame plates may comprise an integral portion of a coupler body for use with a ball-type hitch or the like.
The construction of the jack itself is most clearly shown in FIG. 2. A jack stem, generally indicated at 8, is illustrated in its fully retracted position within the outer tube or body 2. The jack stem is so sized as to be longitudinally shiftable within the outer tube and comprises an elongated tubular body 9. Throughout the major portion of its length, the body 9 contains and has affixed thereto a reinforcing tube 10. At its upper end, the stem 8 terminates in ajack nut 11, the latter having a threaded perforation 12 through which a jack screw 13 extends to depend within the body 9 and tube 10. The jack nut 11 has a reduced diameter portion which nests within the upper end of the body 9 to which body it is fixed by means of a pin or dowel 14 extending through a perforation in the wall of body 9 and into a recess in the jack nut. The reduction of the nut 11 produces an annular shoulder which, in assembly, seats to the upper end of the body 9, while the nested portion of the nut is abutted by the upper end of the reinforcing tube 10. A short longitudinally extended bead 140 formed in the wall of body 9, at its upper end, provides a lateral projection serving a purpose to be further described.
The jack screw 13 has an upper shaft-like portion [3a of reduced diameter, forming thereon a shoulder 13b. The shaft-like portion 13a of reduced diameter passes through a central perforation in a thrust washer 15 against which the jack screw shoulder 13b abuts. The thrust washer 15 is surmounted by a thrust bearing 16 which may be of any suitable and conventional type. The upper end of the thrust bearing 16 abuts a key member 17. Referring both to FIGS. 2 and 3, it will be noted that the key 17 extends transversely of and through diametrically opposed slots 18 and 19 in the jack body or outer tube 2, the ends of the key 17 being engaged within such slots in the jack body. The key 17 is maintained in position by the passage of the portion 13a of the jack screw through a perforation 17a in the key.
The remainder of the portion l3a of the jack screw, which extends above the key 17, nests within one end of a sleeve 20 and is suitably fixed thereto by a pin, rivet, or the like, shown at 21. The lower end of the handle 3 is engaged in the upper end of sleeve 20 and affixed thereto by a similar pin, rivet, or the like, as indicated at 22. The upermost end of the handle 3 may be provided with a grasping means 23 rotatively, or nonrotatively, affixed thereto. A cap means 24 is applied about the sleeve to the top of the jack body or outer tube 2 to protect the jack parts from moisture, dirt, foreign material or the like.
It will be evident from FIG. 2 that the abutment of the sleeve 20 on the key 17 and the abutment of the thrust washer 15 on the jack screw shoulder 13b will keep these parts captively assembled and will prevent their downward movement to the tube 2. Similarly, the same arrangement will cause the key 17 and its engagement with the body or outer tube of the jack to support upward thrust forces on the jack stem, the jack screw, the thrust washer l5 and the thrust bearing 16.
The operation of the jack will be readily understood. Upon rotation of the jack handle 3 in one direction, the interaction of the jack screw 13 and the jack nut ll will cause the jack stem 8 to move downwardly in and from the jack body or outer tube 2. Similarly, rotation of the jack handle 3 in the opposite direction will cause the I jack stem 8 to move upwardly into the jack body toward its fully retracted position illustrated in FIG. 2.
In order for the jack screw 13 to properly operate the jack stem 8, means must be provided to prevent the jack stem from rotating within the jack body 2. To this end, the body 2 is provided with a longitudinally extending bead 25. The bead 25 provides a channel or key way on the inside surface of the body 2 in which the longitudinally extending bead 14a projected from the body 9 will ride. The engagement of the bead 14a in the bead 25 will obviously prevent rotation of the jack nut 11 and the jack stem 8 and will not interfere with the raising and lowering of the jack stem.
This construction has a number of advantages. For example, it will be understood that in order to obtain a smooth, easy and trouble free movement of the jack stem 8 within the body 2, it is desirable to perform on these elements the fewest possible steps which might tend to result in their distortion. In the assembly of the present invention, nothing need be done to the tubular body 9 of the jack stern other than to cut it to length and to provide the short bead on its upper end in a simple, stress free and obvious manner. The bead 25 in the outer tube or body 2 of the jack may be simply and easily formed by the insertion in the tube of an appropriately configured sizing mandrel. This requires little force and eliminates any dents, bumps or flash on the inside surface of the body 2. This construction eliminates the necessity for machining applications which might weaken the elements or distort them so as to invite malfunction.
From the above description, it will be evident that the jack of the present invention can be easily and quickly assembled and lends itself well even to a manual,
bench-type assembly. Thus, the jack screw 13 may be easily engaged in the nut in stem 8 and the thrust washer 15 and thrust bearing 16 may then be applied over the end 130 of the jack screw. The assembly so formed may then be shoved upwardly into the outer tube or jack body 2. With the insertion of key 17 through the slot 18 or 19 to bridge the tube 2 at its upper end the assembly is moved home to have the upper portion 13a of the jack screw extend through the perforation 17a in the key 17, whereupon the thrust bearing will abut the undersurface of the key. The sleeve 20 may then be applied to the upper extremity of portion 13a of the jack screw, and receive in its upper end the handle 3 following the application of the cap 24 in an obvious manner.
The attachment of the jack to its mounting plate 6 may be best understood from FIGS. 2, S and 6. Turning first to FIGS. 2 and 5, it will be noted that the body or outer tube 2 of the jack is provided with a pair of diametrically opposed slots at the position where it is affixed to the plate 6. The rearward slot is indicated at 26 and the forward slot is indicated at 27. As will be clear from FIG. 2, in the particular embodiment illustrated, the forward slot 27 has a larger vertical dimension that does the rearward slot 26.
Turning now to FIGS. 5 and 6, the plate 6 has a perforation 28 therein which is slightly larger than the outside diameter of the jack body or outer tube 2. A forward locator control key 29 is adapted to be affixed to the underside of the plate 6. While not so limited, for reasons of convenience and for additional reasons which will be evident hereinafter, the forward key 29 may be permanently affixed to the underside of the upper plate 6 by means of a rivet 30 or other suitable fastener. As seen in FIG. 5, the forward end of the control key 29 has convergent sides 29a and 29b the purpose of which will be further described. The rearward edge of the key 29 has a surface 31 thereon configured to conform to the inside surface of the outer tube 2. Thus, the surface 31 will have a radius equal to the radius of the inside surface of the outer tube 2. Also, the surface 31 will further have a notch 31a therein so that it will further conform to the inside surface of bead 25.
Referring to FIG. 6, the forward edge of the perforation 28 in the plate 6 has an inwardly extending tongue 32 formed with a rearward arcuate surface 33 including a notch 33a at its center. As will be evident from FIGS. 5 and 6, when the forward key 29 is affixed to the undersurface of plate 6, the rearward key surfaces 31 and 31a and the rearward tongue surfaces 33 and 33a will be in respective alignment.
When the jack is assembled to the plate 6, its upper end is inserted through the perforation 28 and moved forwardly therein so that the key 29 and the plate tongue 32 will extend into the slot 27 of the jack outer tube or body 2. Since the rearward edges 31 and 31a of the key 29 and the rearward edges 33 and 33a of the tongue 32 are configured as described, they will form a continuation of the inside surface of the outer jack tube 2 and will not interfere with the jack stem 8 or the bead 14a on the tube 9.
Once the jack has been so located, it is finally fixed in place by means of a rearward key 34. The rearward key is detachably affixed to the underside of the plate 6 by any suitable means. For purposes of illustration, the rearward key is shown to have a pair of threaded perforations 35 and 36 and plate 6 has a coaxial pair of unthreaded perforations 37 and 38. Bolts 39 and 40 extend through the perforations 37 and 38 in the upper plate 6 and threadedly engaged in the perforations 35 and 36 in the rearward key 34 to connect the same to the plate.
The rearward key 34 has a forward edge with portions 41 and 42 configured to conform to the exterior surface of the outer tube 2. The forward edge of the rearward key 34 also has a forwardly extending tongue 43 with an edge 44 adapted to conform to the inside surface of the outer tube 2. It will be evident from FIGS. 2 and S'that when the rearward key 34 has its tongue portion 43 inserted in the slot 26 of the outer tube 2, and when the rearward key is additionally detachably affixed to the plate 6 by bolts 39 and 40, the jack will be securely positioned in connection with the plate 6. The edge 44 of the tongue portion 33 of the rearward key 34, being configured as described above, forms a continuation of the inside surface of the outer tube 2.and does not interfere with the movement of the jack stem 8.
Since the forward key 29 and rearward key 34 are mounted on the underside of the plate 6, it will be noted that, in use of the jack, the forces on the keys and on the tongue 32 of the plate 6 are shear forces. The mounting load is entirely in shear and the rivet 30 and bolts 39 and 40 do not carry the load.
From the above description, it will be seen that the attachment of the jack to the plate 6 does not depend for its safety and effectiveness upon the integrity. of a weld or the strength of the rivet 30 and bolts 39 and 40. On the other hand, the jack is easily and readily removable and replaceable.
The integrity and nature of the attachment of the jack of the invention to the plate 6 is of importance since failure of the attachment of conventional jacks has resulted not only in serious personal injury, but also in considerable shock damage to the mobile home producing broken windows, cracked paneling, and the like. Such damage is time consuming and expensive to rep ir.
With respectto manufacturing, the nature of the attachment of the jack to the frame plate as here provided results in a considerable savings in materials, manufacturing steps and time. No attachment flange need be provided, nor is there any welding of an attachment flange to the jack. By the invention, only two small and simple keys are required. Note that the slots 26. and 27 in the outer tube 2 of the jack may be punched therein at the same time the. slots 18 and 19 are punched for the key 17. The simplicity of the manufacturing requirements is beneficial therefore not only from a safety standpoint but also from a cost standpoint.
It has been noted, from FIGS. 5 and 6, that the forward key 29 are here formed with side surfaces 29a and 29b angled toward each other. The included angle between surfaces 290 and 29b should preferably be chosen to be the same as the angle at which the A- frame beams 4 and 5 meet. While this angle may be varied, the usual A-frame beamsmeet at an angle of about 50. With the angle of the edges 29a and 29b made to conform to the angle between the beams 4 and 5, when the forward key is affixed to the plate 6 by means of the rivet 30, or the like, the forward key may be used to render the assembly self-locating on the A- frame. Thus, the forward key 29 may be affixed to the plate 6 and the upper frame plate may be placed upon the top surfaces of the beams 4 and 5 to bridge the same and moved forwardly until the forward key surfaces 29a and 29b abut the inside edge surfaces of the frame members 4 and 5. The plate 6 is then in position to be welded or otherwise affixed to the frame members and the plate 6 and correspondingly the jack will be properly oriented on the A-frame members 4 and 5 for optimal positioning of the jack.
The lower plate 7 may be similar in peripheral configuration to the upper frame plate 6 and is provided with a perforation 45 so configured and sized as to permit the outer tube 2 of the jack to pass therethrough in a sliding fit. Thus, the jack can be used to properly locate the lower plate 7, and on fixing thereof the lower frame plate 7 will serve as an additional stabilizing means for the jack. The self-locating feature of the assembly of the present invention can be applicable to any A-frame design and can further be used to properly locate a coupler device, particularly when the upper or lower plate comprises an integral portion of the coupler body. If it is desired to affix the jack to the lower plate, rather than the upper frame plate, the lower frame plate can be configured as described with respect to the upper frame plate 6 and provided with the keys 29 and 34 in an indentical manner.
Of course, modifications of the illustrated embodiment may be made without departing from the spirit of the invention. For example, the tongue 32 on the plate 6 may be eliminated so that the jack is affixed to the coupler plate by the forward and rearward keys only. In such a situation, the forward edge of the perforation 28 in the upper frame plate would simply be configured to conform to the peripheral surface of the outer tube 2 of the jack. Furthermore, the bead 25 may be located elsewhere about the periphery of the outer tube 2 of the jack, so that it need not be accommodated by the tongue 32 of the upper frame plate 6 and the rearward edge of the forward key 29. In such a situation the notches 33a and 31a, respectively, in these last named elements need not be provided.
From the above description it will be apparent that there is thus provided a device of the character described possessing the particular features of advantage before enumerated as desirable, but which obviously is susceptible of modification in its form, proportions, detail construction and arrangement of parts without departing from the principle involved or sacrificing any of its advantages.
It is of importance to realize that the reflection of the forces involved is substantially limited as to its directed path so as to be transmitted through the wall segment of the jack. The construction is such to minimize damage to and jamming of the jack parts and lend maximum stability and resistance to deformation.
While in order to comply with the statute the invention has been described in language more or less specific as to structural features, it is to be understood that the invention is not limited to the specific features shown, but that the means and construction herein disclosed comprise but one of several modes of putting the invention into effect and the invention is therefor claimed in any of its forms or modifications within the legitimate and valid scope of the appended claims.
Having thus described my invention, 1 claim:
1. A jack of the type to raise, lower and support a load comprising a portion of a structure such as a mobile home or like unit, said jack comprising an elongate hollow body having a side wall, top end and a bottom end, an elongated jack stem mounted within said body for movement axially thereof to be projected from and retracted in said body by way of its bottom end, means for moving said stem between said retracted and projected positions, insert means, said body being formed to receive said insert means in the said side wall thereof, to project therein in a sense transverse thereto, said insert means having in connection therewith means whereby to connect the same to the structure to be supported by said jack, said body being established by means of said insert means and said jack stem in a load accommodating position, wherein the load of the supported structure is applied thereto by way of the portion of said insert means which lies within the limits of its side wall, whereby to cause the stress of said load to be distributed in a sense longitudinally of said body side wall.
2. A jack as in claim 1 characterized by said insert means including key-like portions projected within the limits of said body side wall at diametrically opposite positions thereon.
3. A jack as in claim 1 characterized by key means bridging said hollow body adjacent its top end releasably lodged therein to have portions thereof project within diametrically opposite portions of said hollow body side wall and a jack screw constituting the means for moving said stem being suspended from and having one end thereof projected through said key means and screw portions thereof in threaded engagement with and projected internally of said jack stem, said jack screw being operable to project and retract said jack stem in reference to said hollow body, and means interrelating said hollow body and said jack stem to prevent rotation of said jack stem with said jack screw.
4. A jack as in claim 3 characterized by means defining a channel in the inner wall of said body and said jack stem including an outer tubeJike portion having a bead thereon moving in said channel to provide said means to prevent rotation of said jack stem with said jack screw.
5. A jack as in claim 3 characterized by thrust means interposed between a shoulder on said jack screw and said key means.
6. A jack as in claim 1 wherein said body side wall is formed with a pair of oppositely disposed slots to receive said insert means and said insert means includes plate-like key portions which are projected in each slot to abut a portion of the body side wall, within the transverse limits thereof, to transmit the supported load to said body side wall.
7. Jack apparatus as in claim 6 wherein said insert means comprises a pair of key elements and said body side wall is formed with diametrically opposite slots accommodating the projection therein of a portion of a respective one of said key elements, and plate means in combination with said insert means having an aperture accommodating the projection therethrough of said hollow body, said plate means being formed to mount to and bridge a space between relatively displaced portions of the structure to be supported and to mount said key elements in connection therewith to dispose said hollow body in an essentially right angle relation thereto by virtue of the projection of said key elements in said body slots.
8. A jack structure as set forth in claim 7 characterized by said plate means mounting a tongue element to extend inwardly of its said aperture to position in abutting relation to a portion of one of said key elements which projects into one of said body slots.
9. Apparatus as set forth in claim 8 characterized by said plate aperture having a greater cross sectional area than said hollow body and at least the other of said key elements being removably secured to said plate whereby said hollow body may be inserted through said aperture and said first key engaged in its respective slot and the jack established in the desired position by application of the second key to said plate means to project in the other said slot.
10. Apparatus as set forth in claim 6 characterized by said plate means including means in connection therewith which will nest precisely within an open area of the structure to which the jack is affixed and predetermine the position at which the jack is to be established in use.
11. Apparatus as set forth in claim 10 for application to the A-frame of a mobile structure such as a mobile home and the means which establishes the position of said jack having a configuration producing thereon convergent sides for precisely nesting in the A-frame and precisely insuring the proper application of the plate means and said jack to said structure.
12. A jack as in claim 1 characterized by diametrically opposite slots formed in the said side wall of said hollow body one of which accommodates the end of a first key constituting a portion of said insert means configured and positioned to form a continuation of the inside surface of said body and a second key constituting another portion of said insert means projects into the opposite slot to intersect the wall of said body, and both said keys being adapted to be secured to spaced portions of the structure to be supported by said jack whereby the load of the supported structure is specifically directed through the wall of said hollow body in use of the jack, and at least one of said keys having a releasable mount to facilitate the application of the jack to and the release thereof from a supported structure.
13. A jack as in claim 1' for application to the A- frame of a mobile unit such as a mobile home wherein the A-frame includes a pair of beams the free ends of which meet at an angle, characterized by said jack having in association therewith means whereby to connect the same to the A-frame including plate means arranged to span portions of said beams of said A-frame, said plate means having at a surface thereof a plate portion with convergent sides adapted to nest between the free ends of said beams which meet at an angle and thereby predetermine the position of said jack in precise reference to said A-frame, said plate means having an aperture therein and means defining a projection within said aperture at'an edge portion thereof, said hollow body being adapted to be inserted through said aperture and having a side wall portion formed to define a recess within the wall of said body accommodating the projection on said plate and a diametrically opposite side portion of said hollow body being formed to receive within the wall thereof an edge portion ofa key means which is releasably fixed to said plate means to position the said hollow body and maintain the required frame of reference of said jack to the supported structure in use.
14. Jack apparatus as in claim 13 characterized by said means to move said jack stem including a jack screw, a pair of slots being formed in said body adjacent the top end thereof having a plate-like element projected therethrough to bridge said top end and including therein an aperture through which the upper end of said jack screw projects, means on the upper end of said jack screw for rotation thereof and to suspend said jack screw in reference to said plate-like element, and the body of said jack stem having means thereon riding in a channel formed on the inner wall of said hollow body to prevent rotation of said stem and provide for axial movement thereof on rotation of said jack screw, and thrust means about said jack screw above said jack stem and below said plate-like element bridging the top end of said hollow body, and means on said jack screw containing said thrust means in reference to the plate-like element thereabove to transmit therethrough to said hollow body the forces involved in raising the structure supported by said jack through the medium of the projection of said jack stem.
15. A jack comprising an elongated hollow body having a top end and a bottom end, an elongated jack stem slidably mounted within said body for movement axially thereof to be projected from'and retracted in said body by way of its bottom end, said jack stem being a further hollow body having a jack nut in the interior thereof, a jack screw extending through said jack nut and axially of said jack stem, said jack stern having means in association with a portion of the wall of said hollow body to prevent rotation thereof, a key extending transversely of said hollow body having peripheral portions thereof lodged in the wall thereof above said jack stem, said jack screw having an upper end passing through an opening in said key and means thereon to establish a fixed relation of said jack screw to said key whereby on projection of said jack stem the resultant load is directed through said stem and said jack screw to said key and thereby to the wall of said hollow body.
16. The structure as set forth in claim 15 wherein a shoulder is formed on said jackiscrew below said key mounting in superposed relation a thrust washer and a thrust bearing confined thereby to said key and, to the opposite side of said key, said jack screw having fixed thereabout a collar to which is connected the operating handle for said jack screw.
17. The structure as set forth in claim 15 characterized by said jack stem comprising an outer tube, a jack nut mounted on the upper end of said outer tube and abutting the upper end of an inner tube fixed concentrically within the. outer tube of said jack stem and said wall of said hollow body to prevent rotation of said jack stem.
UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3 ?64109 Dated Ogtober 9, 1973 Invent0r(s) I'itissell Hollis Jr It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
Col. 1, line 56, "of" is deleted.
Col. 4, line 23, replace "to" by in Signed and sealed this 9th day of April 1971;.
(SEAL) Atte st:
EDWARD I-LFLETCHEIQJR C. MARSHALL DAI'IN Attesting Officer Commissioner of Patents USCOMM'DC 60376-P69 GOVERNMENT PRINTING OFFICE "l9 O-866-33l, g
F ORM PO-1050 (10-69)