Lifting and shoring jack assembly

A lifting and shoring jack assembly includes a main support assembly having a main column, a jack screw slidably mounted within the main column, and a jack nut engaged with the jack screw and bearing on the end of the main column. A load plate mounted at the free end of the jack screw facilitates engagement of the jack assembly with a load to be supported. Extensible side braces are pivotally mounted on the main column, and also include load engaging plates for load-bearing attachment to the load to be supported.

FIELD OF THE INVENTION 
This invention relates to load bearing support columns, and in particular 
to an adjustable lifting and shoring jack assembly. 
BACKGROUND TO THE INVENTION 
Adjustable support posts or columns are well known in the art. Typically, 
conventional support columns, such as lifting jacks for lifting and 
supporting of various structures employ a single, threaded support rod 
disposed in a main column. Many of these assemblies comprise a main column 
composed of two or more telescoping elements which can be extended and 
locked at predetermined intervals, such that the column can be adjusted to 
a length which is slightly shorter than that which is actually required. 
The threaded support rod, which may either engage an internal screw in the 
main column or an adjusting nut which bears on the top of the column, is 
then extended as required to support and/or raise the structure in 
question. 
For example, U.S. Pat. No. 3,027,140 (Holzbach) discloses an adjustable 
element which is adapted to be quickly and removably fitted to a fixed 
length column. The disclosed adjustable element comprises an adjusting 
screw and nut, a bearing plate, and a base plate. The adjustable element 
is intended to be used in conjunction with a column or post which is 
obtained separately, and cut approximately to length, by the user, on 
site. 
However, in some cases it is necessary to raise the structure by a 
substantial distance. For example, when a house or other structure is 
jacked to permit moving of same, or to raise its foundation, it is 
frequently found to be necessary to raise the structure by one meter or 
more. However, conventional jack posts of the type disclosed in U.S. Pat. 
No. 3,027,140 tend to become unstable, and prone to buckling, due to the 
extreme length of the adjusting screw extending from the fixed length 
column portion. 
U.S. Pat. No. 4,872,634 (Gillaspy et al) discloses a brace assembly which 
consists of a main brace and a pair of side braces pivotally attached 
thereto. The length of the main brace is adjustable by means of threaded 
couplings mounted on the ends thereof. Each of the threaded couplings 
consists of a length of threaded rod slidably fitted within the hollow 
main brace, and a nut which bears against an end surface of the main 
brace. A mounting bracket is pivotally fitted to the free end of each of 
the side braces to permit the side braces to be attached to a portion of a 
member being supported (i.e. a wall), or to some other structure (such as 
a floor), so as to lend stability to the main brace. 
However, since the side braces are of fixed length, the extent to which the 
main brace can be extended after the side braces have been attached is 
severely limited. Accordingly, a supporting system such as that disclosed 
in U.S. Pat. No. 4,872,634 is of limited use in situations where a 
structure being supported must be lifted through a substantial distance. 
Finally, when used to support a structure of substantial weight, a jack 
post tends to be forced downwards into the earth. Typically, the base 
plates provided on conventional jack posts do not distribute the weight 
over sufficient surface area to prevent from undue sinking of the post 
into soft and/or unprepared earth. Thus the safe and effective use of 
conventional jack posts is often impossible under these conditions. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide an adjustable 
lifting and shoring jack assembly capable of lifting a load through a 
substantial distance, and which can be safely and effectively used on soft 
and/or unprepared earth. 
According to an aspect of the present invention, there is provided a 
lifting and shoring jack assembly comprising: baseplate means, said 
baseplate means being capable of distributing load forces over a 
sufficiently large surface area to substantially prevent said jack 
assembly from sinking into soft earth when subjected to a load; support 
column means removably disposed on said baseplate means; jack screw means 
slidably disposed within said support column means and at least partially 
extending therefrom; jack nut means operatively engaged with said screw 
means, and bearing on an end surface of said support column means; load 
plate means disposed on a free end of said screw means and capable of load 
bearing engagement with a load to be supported; and at least two side 
brace means pivotally connected to said column means, each of said side 
brace means comprising: a respective elongate brace arm pivotally 
connected at an end thereof to said support column means; respective 
length adjusting means disposed at a free end of each of said brace arms 
for adjusting the length of each of said brace arms; and respective load 
engaging means pivotally disposed on said respective adjusting means to 
facilitate load bearing engagement between the load to be supported and 
each of said side brace means. 
In a preferred embodiment, the column means is removable from the base 
plate means, thereby permitting the assembly to be disassembled for ease 
of storage and transportation. 
In a further preferred embodiment, the lifting and shoring jack assembly is 
further provided with a second supporting column comprising secondary 
support column means removably disposed on said baseplate means; extension 
screw means slidably disposed within said secondary support column means 
and at least partially extending therefrom; extension nut means 
operatively engaged with said extension screw means, and bearing on an end 
surface of said secondary support column means; and jack means disposed on 
a free end of said screw means and capable of load bearing engagement with 
a load to be supported. 
Preferably, the jack means is a hydraulic jack.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring to FIGS. 1 and 2, the jack assembly comprises a baseplate 1, and 
a main support assembly 2. The main support assembly 2 comprises a hollow 
main column 3 mounted on the baseplate 1, a jack screw 4 slidably disposed 
within the main column 3 and at least partially extending therefrom, a 
jack nut 5 in threaded engagement with the jack screw 4, and bearing on 
the end surface of the main column 3, and a load plate 6 mounted on the 
exposed free end of the jack screw 4. At least two side braces 7 (three 
are illustrated in FIG. 1) are pivotally mounted on the main column 3. 
Each of the side braces 7 is designed to be adjustable in length as the 
load to be supported (diagrammatical represented in FIG. 1 by beams 24) is 
raised by the main support assembly 2, and include a respective load plate 
6a which facilitates engagement with the load to be supported. 
Conveniently, the side braces 7 can have a construction similar to that of 
the main support assembly 2, in that they can comprise a hollow brace arm 
8 pivotally connected to the main column 3, a length of threaded rod 9 
slidably mounted within the brace arm 8, and an adjusting nut 10 in 
threaded engagement with the threaded rod and bearing on the end surface 
of the brace arm 8. 
The baseplate can have any desired configuration, provided that it offers a 
large "footprint", so that heavy loads can be securely supported by the 
jack assembly, even when used on soft and/or unprepared earth. 
Conveniently, the baseplate 1 will consist of a generally square or 
rectangular bottom plate 11, a centrally-located column seat 12 for 
receiving the main column 3, and a set of generally radially oriented 
stiffening ribs 13 for transferring load forces outward towards the 
periphery of the bottom plate 11. The bottom plate and stiffening ribs 13 
can conveniently be constructed of steel plate, and the column seat 12 
from hollow round structural steel, the entire baseplate 1 being fastened 
together by, for example, welding. A lifting handle 15 is located on each 
side of the bottom plate 11. 
The interior diameter of the column seat 12 is suitably sized with respect 
to the outside diameter of the main column 3, so that the main column 3 is 
held securely therein during use of the jack assembly, but can be readily 
removed therefrom for ease of transportation. However, the main column 3 
can be permanently fastened in the column seat 12, for example by means of 
welding, in cases where disassembly for ease of transportation is not a 
consideration. 
The main column 3 is conveniently constructed of hollow tubular steel, and 
will be sized appropriately according to the loads to be supported. 
Similarly, the jack screw 4 and jack nut 5 will be suitably sized 
according to the load to be supported. In addition, the outer diameter of 
the jack screw 4 will be selected to provide a clear sliding fit within 
the main column 3. However, the fit between the jack screw 4 and the 
interior of the main column 3 must be close enough to substantially 
prevent an angular offset between the main column 3 and the jack screw 4 
(with the attendant increased bending stresses and risk of buckling). The 
length of the jack screw 4 will be selected according to the desired 
distance through which the load is to be lifted, but can conveniently be 
approximately the same length as that of the main column 3, thereby 
allowing jack assembly to lift the load to be supported through a distance 
as close as possible to the height of the main column 3. 
Each of the side braces 7 is pivotally attached to the main column 3 by 
means of respective pins or bolts and support lugs 14 attached to the 
exterior of the main column 3 (for example by means of welding) so as to 
not interfere with movement of the jack screw within the main column 3. 
In use, the jack assembly is located under a load to be supported (see FIG. 
4), and the load plates 6 and 6a of the main support assembly 2 and side 
braces 7, respectively, are attached to the load to be supported, such as 
a building 25 and/or temporary support beams 24 located under the building 
25 to facilitate the jacking thereof (note that in FIG. 4, only one side 
brace 7 is shown for clarity.). If desired, the base plate 1 can be 
secured against lateral (sliding) movement by the use of stakes 26 driven 
into the ground. The jack screw is then turned in a direction to extend 
the jack screw 4, from the main column 3, so as to raise the load to be 
supported, through a desired distance. As the load to be supported is 
raised by the main support assembly 2, the threaded rods 10 of the side 
braces 7 are pulled outwards from their respective brace arms 8. As this 
occurs, the adjusting nuts 9 are turned in order to maintain each of the 
side braces in compression, so that at least some of the weight of the 
load being supported is transferred to the main column 3 through the side 
braces 7. The maintenance of a compressive loading in each of the side 
braces 7 serves two purposes. First, it reduces the load forces acting on 
the jack screw 4 and jack nut 5, thereby making the jack nut 5 easier to 
turn. Second, the forces exerted by the side braces on the main column 3 
tend to brace the main column 3 against bucking, thereby increasing the 
effective load carrying capacity of the jack assembly of the invention. 
FIG. 3 illustrates a second embodiment of the jack assembly of the present 
invention. This second embodiment retains the base plate 1, main support 
assembly 2, and side braces 7 described in respect of the first 
embodiment. Accordingly, these elements will not be further discussed in 
detail. The lifting and shoring jack assembly, according to the second 
embodiment of the invention, is provided with a secondary support assembly 
16 comprising a secondary support column 17 mounted on the baseplate 1; an 
extension screw 18 slidably disposed within the secondary support column 
17 and at least partially extending therefrom; an extension nut 19 engaged 
with the extension screw 18 and bearing on an end surface of the secondary 
support column 17; and a lifting jack 20 mounted at the top of the 
extension screw 18. 
The secondary support column 17 is preferably mounted on the baseplate 1, 
by means of a secondary support column seat 21 in essentially the same 
manner as the main column 3. In addition, the secondary support column 17 
is removably coupled to the main column 3, at least during use, by means 
of a bolt (or the like) and lugs 22 affixed near the top of secondary 
support column 17 and the main column 3. 
The operation of the jack assembly according to the second embodiment of 
the invention is essentially the same as that of the first embodiment, 
except that in this case, the lifting jack 20 (which preferably comprises 
a conventional hydraulic or pneumatic jack) is used to lift the load being 
supported through a small distance; the jack nut 5, and adjusting nuts 9 
are then tightened so that the main support assembly 2 and side braces 7 
carry the weight of the load being supported; the lifting jack 20 is 
thereby released so that the extension nut 19 can be turned to extend the 
extension screw 18, thereby raising the lifting jack 20 without lifting 
the load being carried. By this means, the load being supported can be 
raised through a series of comparatively small incremental steps, thereby 
ensuring safe operation of the jack assembly. 
As a further safety measure, additional side support lugs 23 can be 
provided near the top of the main column 3. These additional lugs permit a 
further set of side braces 7 to be mounted on the main column 3, thereby 
increasing the buckling resistance of the main support assembly 2. In 
addition, the baseplate 1 can be modified as desired to provide additional 
reinforcement to the central portion of the bottom plate 11, particularly 
under the main support assembly 2 and the secondary support assembly 16. 
FIGS. 4 and 5 illustrate the use of the jack assembly according to the 
present invention for supporting and raising a building 25. FIG. 4 
presents an elevation view of a jack assembly being used, while FIG. 5 
presents a plan view showing the general locations of each of the jack 
assemblies used, along with supplementary supporting beams or timbers 24 
and bracing stakes 26 in relation to the building 25 being supported and 
lifted. 
In order to ensure adequate support of the building 25, while it is being 
lifted, a set of lateral and longitudinal support beams (or timbers) 24 
are preferably provided under the building 25. A number of jack assemblies 
(in the present example, six are employed) are then installed such that 
the main support assemblies 2 thereof are positioned under the respective 
intersection points of the beams 24. At this point, side braces 7 are 
mounted on each of the respective main support columns 3, and attached to 
the beams 24, generally as illustrated in FIGS. 1, 4 and 5. Following the 
installation of the beams 24 and jack assemblies, in this manner, the 
building 25 can be raised by operating each of the jack assemblies in the 
manner described above in connections with FIGS. 1-3. In tests performed 
by the inventor, two houses (one measuring approximately 30' by 40') were 
successfully raised by this method. During one of these tests, the house 
in question was subjected to winds in excess of 100 km/hr without ill 
effect. 
FIG. 6a is a perspective view illustrating a third embodiment of the 
present invention. This third embodiment can be considered as a 
modification of the embodiment of the invention described above in 
connection with FIG. 3. In this case, however, only two side braces 7 are 
pivotally attached to the main column 3 by means of respective pins or 
bolts and support lugs 14 attached to the exterior of the main column 3. A 
hook assembly 30 is mounted on the main support assembly 2, opposite the 
secondary support assembly 16, and is designed to engage (and lift) a load 
disposed near the ground. 
The hook assembly 30 comprises a pressure plate 31 capable of being bolted 
to the load plate 6 of the main support assembly 2. A suspender 32 is 
affixed to the pressure plate 31, for example by means of welding. In 
addition, reinforcing plates 33 can be provided to reinforce the pressure 
plate and strengthen the connection between the pressure plate 31 and the 
suspender 32. At the base of the suspender 32, a lifting hook 34 is 
provided for engaging a load. The length of the suspender 32 is preferably 
determined so that, when the main support assembly 2 is lowered to it 
greatest extent, the lifting hook 34 is capable of being operatively 
positioned beneath a load which is close (for example, less than 
approximately 200 mm) to the ground. 
In order to brace the lifting hook 34 against undesired movement, a roller 
35 is conveniently mounted on the suspender 32, preferably in the vicinity 
of the lifting hook 34, so as to bear against the main column 3. 
Preferably, the roller is provided with an hour-glass profile, as 
illustrated in FIG. 6b, which allows the roller 35 to operatively engage 
the side of the main column 3 in such a manner as to resist lateral (i.e. 
side-to-side) motion of the lifting hook 34. In order to permit the roller 
35 an unobstructed path along the length of the main column 3, no lugs 14, 
23 (see FIG. 3) are provided for the installation of side braces 7 on that 
side of the main column 3. However, if it is desired to remove the hook 
assembly 30, mounting brackets 36 can be installed as illustrated in FIG. 
6c. The mounting brackets 36 are conveniently designed to be supported on 
the lugs 14, 23 welded on opposite sides of the main column 3. By means of 
the mounting brackets 36, a third side brace 7 can be mounted on the main 
column 3, and the jacking assembly used in the same manner as the 
embodiment illustrated in FIG. 3. 
It will be appreciated that, while the present invention has been described 
in connection with three of its embodiments, it is by no means limited to 
same, but may instead by varied within the scope of the appended claims. 
INDUSTRIAL APPLICABILITY 
As will be clear from the forgoing description, the present invention can 
be used singly or in combination to support and lift heavy loads, and is 
particularly suited to lifting heavy loads while standing on uneven or 
unprepared soil. As such, in addition to the specific application 
described in detail above, the present invention is applicable (but is by 
no means limited) to such diverse areas as emergency supports (e.g. in an 
earthquake disaster area), lifting heavy equipment (e.g. construction 
equipment) for carrying out hard-to-reach maintenance or repair work, and 
in mining industries.