Levelling device

A levelling apparatus for use between a structural frame member defining a first plane and a supporting member defining a second plane, vertically adjustable between raised and lowered positions, comprising a base section having first and second inclined surfaces, a top section having first and second inclined surfaces, and first and second pairs of half wedge members disposed intermediate the base and top section, the half wedge members having inclined faces mating with the complementary surfaces formed on the base and top section. A threaded rod is disposed longitudinally within the levelling device, passing through the pairs of half wedges members and brackets engaging the back sides of the half wedge members, with nuts threadingly engaging each end of the threaded rod. Rotation of one or both nuts causes longitudinal translation of the half wedge members and resulting vertical adjustment of the levelling device. The half wedge members are pivotable about lateral pivot pins, so that substantially constant contact is maintained between the top and base section when the base section is tilted due to an inclined support surface. Braces secured to the opposite ends of the pivot pins cooperate with the brackets to prevent lateral displacement of the components. The top section is angularly adjustable relative to the base section to compensate for an uneven support surface.

BACKGROUND OF THE INVENTION 
1. Field 
This invention relates to levelling devices and, more particularly, to such 
devices used for permanent installation between a structural frame member, 
such as in a mobile home, and the supporting foundation, especially when 
the foundation rests on uneven terrain. 
2. Description of the Prior Art 
Lifting and levelling devices utilizing a pair of slidable wedges are well 
known. U.S. Pat. No. 3,078,072 entitled "Levelling Device for Derricks", 
issued Feb. 19, 1963, for example, discloses a device having a pair of 
wedge members with oppositely threaded holes formed therethrough. A screw 
shaft passes through the wedge members and engages the threaded holes, so 
that rotation of the shaft causes the wedge members to diverge when turned 
in one direction, and converge when turned in the opposite direction. 
Movement of the wedge members causes the lift section to move upward or 
downward, depending upon the direction the shaft is rotated. The device 
shown in the '072 patent, however, does not include any provision for 
accommodating non-parallel surfaces. 
Russian Patent No. 623,819 published Aug. 2, 1978 to inventor Kurbatov 
discloses a lifting and centering device having top and base portions with 
inclined surfaces formed thereon, and wedge members slidably disposed 
therebetween. Each wedge member includes a central pivot pin having a 
threaded hole formed therethrough, one such hole having right hand screw 
threads and the other having left hand screw threads, interconnected by a 
central threaded shaft. As with the '072 levelling device mentioned above, 
rotation of the shaft causes the wedges to move in opposite directions, 
either converging or diverging, resulting in vertical adjustment of the 
device. The Russian device is also capable of accommodating misalignment 
between the supporting surface and structure being supported, as the top 
and base portions are angularly adjustable relative to one another. 
The use of a rotating shaft having both left and right hand screw threads, 
as with the above described devices, has been found to have certain 
disadvantages. First, threaded rods of this nature are relatively 
expensive when compared to a conventional threaded rod having only right 
hand screw threads. Second, this arrangement requires that both wedge 
members move concurrently, and does not allow the user to adjust the 
position of one wedge member without moving the other. Additionally, the 
threaded pivot pins in the Russian '819 device are susceptible to 
dislocation in either the longitudinal or lateral direction due to the 
forces generated by the wedges and the threaded rod. The wedges are also 
susceptible to dislocation, making the device unsafe for continuous usage 
in permanent installations, such as beneath a mobile home. 
BRIEF SUMMARY OF THE INVENTION 
It is an object of this invention to provide a levelling device for use 
between a structure and a support foundation which will compensate for 
angular misalignment therebetween. 
It is a further object of this invention to provide such a levelling device 
which is stable enough for use in permanent, or semi-permanent, 
installation. 
In order to achieve these and other objects, the present invention 
comprises substantially identical top and base sections having oppositely 
inclined surfaces formed on the inner portions thereof. A first and second 
pair of half wedge members are disposed intermediate the top and base 
sections, and include top and bottom inclined faces abutting the inclined 
surfaces of the top and base sections. Each pair of half wedge members has 
a pivot pin laterally disposed therein, and a bracket engaging the back 
sides of the half wedge members. A conventional threaded rod is disposed 
longitudinally through the levelling device, with opposite ends extending 
through holes formed in the brackets. A nut is threadingly engaged on each 
end of the threaded rod, bearing on each bracket. Tightening one or both 
of the nuts drives the half wedge members together, thereby extending the 
levelling device to its raised position. The top and base sections of the 
device are angularly adjustable relative to one another, with the half 
wedge members pivoting to maintain substantially constant contact with the 
top and base portions during angular adjustment thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
In the appended drawings, levelling device 10 is shown in use supporting a 
generic structural member 12 in the form of a conventional I-beam defining 
a first plane, on top of a concrete block 14 defining a second plane. In 
the preferred embodiment disclosed herein, structural member 12 is 
representative of the structural beam in a typical mobile home, which is 
ordinarily supported by concrete blocks. While levelling device 10 was 
developed primarily for use beneath the structure of a mobile home, its 
potential uses are clearly not so limited. It is to be understood that the 
advantages provided by levelling device 10 will be appreciated in a wide 
variety of situations requiring the support of a structural member. 
Referring now to FIGS. 1 and 2, levelling device 10 is seen to comprise a 
top section 16 and a base section 18, one being essentially identical to 
the other in an inverted orientation. Top section 16 includes a generally 
planar upper surface 20 adapted to support structural member 12, and a 
lower surface comprising oppositely inclined surfaces 22a and 22b. 
Similarly, base section 18 comprises a lower planar surface 24 adapted to 
rest on block 14, and an upper surface comprising oppositely inclined 
surfaces 26a and 26b. 
Disposed intermediate top section 16 and base section 18 are a first pair 
of half wedge members 28a and 30a, and a second pair comprising half wedge 
members 28b and 30b. In the preferred embodiment shown, half wedge members 
28a, 30a, 28b and 30b are identical, interchangeable components, as are 
top section 16 and base section 18 discussed above. Accordingly, it is to 
be understood that any feature discussed in connection with one half wedge 
member is generally applicable to all four half wedge members. 
Half wedge members 28a and 28b include inclined top faces 32a and 32b, 
configured to slidably engage inclined surfaces 22a and 22b, respectively. 
Similarly, half wedge members 30a and 30b include inclined bottom faces 
34a and 34b configured to slidably engage inclined surfaces 26a and 26b of 
base section 18. 
Each half wedge member is pivotable about an axis defined by pivot pins 36 
and 38, with pin 36 being disposed intermediate half wedge members 28a and 
30a, and pin 38 being disposed intermediate half wedge members 28b and 30b 
upon assembly of levelling device 10. Pivot pins 36 and 38 include a brace 
40 secured to each end thereof. Braces 40 extend vertically closely 
adjacent a side portion of half wedge members 28a, 28b, 30a and 30b, as 
well as top section 16 and base section 18, thereby preventing lateral 
displacement of the components during use. A threaded rod 42 is 
longitudinally disposed within levelling device 10, passing through 
clearance holes 44 and 46 and pivot pins 36 and 38. A pair of brackets 48 
and 50 engage a portion of the back and side surfaces of half wedge 
members 28a, 30a, and 28b and 30b, respectively, and are secured in 
position by nuts 52 and 54. The angled ends of brackets 48 and 50 provide 
additional resistance to lateral displacement of the half wedge members. 
It will be readily understood by those skilled in the art that vertical 
adjustment of levelling device 10 is effected upon rotation of one or both 
of nuts 52 and 54. In the embodiment shown, clockwise rotation of either 
nut 52 or nut 54 causes brackets 48 and 50 to converge, resulting in 
longitudinal translation of half wedge members 28a, 30a and 28b, 30b. The 
resulting force generated upon convergence of the pairs of half wedge 
members drives top section 16 upward relative to base section 18. 
Counterclockwise rotation of either nut 52 or nut 54 reverses the process, 
allowing top section 16 to be lowered as the pairs of half wedge members 
diverge. 
It should be noted that, in contrast with prior art levelling devices, 
vertical adjustment of levelling device 10 is accomplished with minimal 
horizontal load being placed on pivot pins 36 and 38. The longitudinal 
compressive load placed on the two pairs of half wedge members upon 
tightening nuts 52 an 54 is transmitted through brackets 48 and 50 onto 
the back sides of the half wedge members. By exposing pivot pins 36 and 38 
to vertical forces almost exclusively, levelling device 10 greatly reduces 
the risk that either pin 36 or pin 38 will become inadvertently dislodged 
during use. Furthermore, the angled end sections of brackets 48 and 50 
engage the sides of the half wedge members, and cooperate with braces 40 
to prevent lateral movement of the half wedge members. The structural 
rigidity provided by levelling device 10 provides enhanced safety, which 
is particularly important when used beneath a mobile home. 
One of the most beneficial aspects of levelling device 10 is seen in FIGS. 
3 and 4. FIG. 3 illustrates the configuration of levelling device 10 when 
the ground and concrete block 14 are substantially level. FIG. 4, on the 
other hand, illustrates the unique ability of levelling device 10 to 
compensate for sloping terrain, wherein concrete block 14 is disposed on 
an incline. When the plane defined by the top of concrete block 14 is not 
parallel to the plane defined by the bottom of structural member 12, base 
section 18 tilts accordingly so that lower surface 24 maintains a 
substantially constant contact surface with concrete block 14 to prevent 
inadvertent slipping. Under such circumstances, half wedge members 28a, 
28b, 30a and 30b pivot slightly about pivot pins 36 and 38 so that top 
faces 32a and 32b maintain substantially constant contact with inclined 
surfaces 22a and 22b, and bottom faces 34a and 34b maintain substantially 
constant contact with inclined surfaces 26a and 26b. By maximizing the 
surface contact between the inclined surfaces and the top and bottom faces 
of the half wedge pairs, the structural integrity of levelling device 10 
is insured, even when vertical adjustment is necessary on an uneven 
support surface. The structural integrity of levelling device 10 is 
further enhanced by the resistance to lateral dislocation effected by 
braces 40 and brackets 48 and 50, and by virtue of the fact that pivot 
pins 36 and 38 are subjected to minimal horizontal forces. 
While the principles of a levelling device specially adapted for use on an 
inclined surface have been made clear from the above detailed description, 
it will be apparent to those skilled in the art that numerous changes may 
be made in the preferred embodiment without departing from the spirit 
and/or scope of this invention. Accordingly, the scope of coverage 
provided by this patent is to be limited only by the following claims and 
the prior art: