A multistage wedge-shaped jack apparatus is provided for jacking up and maintaining a heavy structure for mounting and replacing bearing units interposed between the heavy structure and a lower base while considerably increasing the jack amount without increasing the overall length of the apparatus. A wedge-shaped drive member (1) and a wedge-shaped pressure receiving member (2) are laminated on a base plate (3) and brought into contact with each other with the respective slant surfaces (11) and (21). A push/pull drive device (6) is provided in cooperation with a reactive force receiving device (5) for limiting a movement of the wedge-shaped pressure receiving member. A single or a plurality of auxiliary wedge-shaped members (7) are provided to the wedge-shaped drive member to be detachably coupled with each other in order. Each auxiliary wedge-shaped member has a shorter length than a stroke length of the push/pull drive device and has a slant surface (11) at the same slant angle as that of the slant surface of the wedge-shaped drive member. The slant surfaces are continuous between the wedge-shaped drive member or the front stage wedge-shaped member and the rear stage wedge-shaped member. A drive rod (71) of the push/pull drive device and the wedge-shaped drive member/each auxiliary wedge-shaped member are detachably coupled with each other. A temporary engagement device (8) is provided for limiting a movement of the wedge-shaped drive member and the auxiliary wedge-shaped member after the jack-up operation.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a multistage wedge-shaped jack apparatus 
for lifting and supporting a structure in, for example, mounting bearing 
units to be interposed between heavy structures such as bridges and lower 
working space, and performing the replacement work. More particularly, the 
present invention relates to a multistage wedge-shaped jack apparatus that 
may considerably increase an amount of jack up without reducing a jack 
amplifying rate. 
2. Description of the Related Art 
As shown in FIG. 11, there are bearing units C in place between a heavy 
structure (hereinafter simply referred to as a structure) A such as a 
bridge girder supported by bearings for bridges or express ways and a 
lower support B for supporting the structure A, for positively 
transmitting, to the lower support B, vertical loads such as a dead load, 
an active load and the like of the structure A, and for enabling the 
horizontal movement of the structure A in consideration of the length of 
the horizontal movement due to expansion of the structure A caused by 
changes of temperature, vibrations or the like. In many cases, the bearing 
units which already have been laid (which units will be hereinafter 
referred to old bearing units C) are subjected to strains due to loads, 
vibrations and the like from the structure A and to damages due to the 
bending moment since the bearing units have been used long from the 
building time of the structure A. Also, in many cases, the old bearing 
units are damaged caused by corrosion due to rain water and sand dust, 
resulting in the reduction or suppression in the weight absorbing 
function. Therefore, the requirements to replace the damaged old bearing 
units to new ones arise one after another. 
A conventional replacement method is as follows: As shown in FIG. 12, plate 
members made of metal or saddle made of steel are piled up to 
substantially the same height as that of the old bearing units C in the 
vicinity of the old bearing units C to form a temporary bearing member D. 
A hydraulic jack E which may jack up with supporting the structure A (this 
operation will be hereinafter referred to as "jack") is installed in the 
vicinity of the bearing units C. Then, the jack up is effected by several 
millimeters to 10 mm to the condition that the old bearing units C are 
separated from the structure A. The structure A is temporarily supported 
by a temporary support tool F that is composed of piled metal plates or 
the like. Under this condition, the old bearing units C are removed, and 
the new bearing units are installed. Thereafter, the structure A is 
further jacked up once beyond the temporary bearing position by the 
above-described hydraulic jack E and the temporary support tool F is 
removed. Then, the structure is jacked down. The replacement work for the 
bearing units are thus performed. Also, in addition to the above-described 
replacement method for the bearing units C, a bracket method, a special 
base method and the like have been conventionally proposed depending upon 
the mounting condition of the bearing units C. 
According to these methods, it is impossible to smoothly jack up the heavy 
structure such as a bridge and an additional installation work for 
installing the temporary bearing members D and the like for jacking up is 
required, whereby since it takes a long working period, it causes not only 
to increase the repair cost but also to impose loads to the workers with a 
danger to induce an accident. Accordingly, the present inventors invented 
a jacking method for jacking the above-described structure A in safety and 
with ease and a wedge-shaped jack for use in such a method, granted in 
Japanese Examined Patent Publication No. Hei. 4-54002 and also matured 
into U.S. Pat. No. 4,944,492. Also, these inventions are now practiced. 
More specifically, as shown in FIGS. 13(I) to 13(III), a wedge-shaped 
drive member 201 having slant surfaces on its upper and lower surfaces is 
interposed between two upper and lower wedge-shaped pressure receiving 
members 202 and 203 in the vicinity of the old bearing unit C in relation 
with a pushing/retracting means 200, and the above-described wedge-shaped 
drive member 201 is pushed to a longitudinal direction by a hydraulic jack 
204. As a result, as shown in FIG. 13(II), the above-described 
wedge-shaped drive member 201 is moved upwardly in accordance with the 
sliding movement relative to the slant surface of the lower wedge-shaped 
bearing member 203. At the same time, the upper wedge-shaped pressure 
receiving member 202 is moved upwardly in accordance with the sliding 
movement relative to the slant surface of the wedge-shaped drive member 
201 to thereby jack up the structure A upwardly. Then, in order to 
maintain this condition, a suitable number of stop members 207 having a 
horseshoe-shape are inserted from above while embracing a drive rod 206 of 
the hydraulic jack 204 in the space between the pressure receiving plate 
205 of the hydraulic jack 204 and the above-described wedge-shaped drive 
member 201. As a result, the space between a reactive force receiving 
plate 205 and the wedge-shaped drive member 201 is filled to once limit 
the movement of the wedge-shaped drive member 201. In the meantime, the 
repair or replacement for the old bearing unit C is carried out and the 
new bearing unit (not shown) is installed. After the completion of this 
work, as shown in FIG. 13(III), the above-described wedge-shaped drive 
member 201 is pulled away in the longitudinal direction, and the structure 
A is jacked down for completing the repair or replacement. Incidentally, 
during the repair and replacement work for the old bearing unit C, various 
variable loads are applied to the structure A due to the passage of 
vehicles, and the shift and vibration are generated. The shift and 
vibration are however absorbed by a damper (not shown) and a slide plate 
208 disposed between the upper wedge-shaped pressure receiving member 202 
and the lower surface of the structure A. According to this method and the 
apparatus, for a short period of time and with ease, it becomes possible 
to perform the repair or replacement work for the old bearing unit C, 
which had been impossible or dangerous. This is highly appreciated in 
various engineering and construction fields. 
According to the jacking method and apparatus and further to a subsequent 
improvement in the apparatus, it is possible to attain the object to 
smoothly jack up with ease the structure such as a bridge for the repair 
and replacement work for the old bearing units in a normal condition. 
However, in the circumstances that the old bearing units are damaged so 
that the bridge girders are more lowered than expected, or the bearing 
units themselves are removed and fallen down so that the bridge is 
directly laid on the support legs due to the vibrations or quakes with 
unexpected vertical swings like a Hanshin Earthquake Disaster of a seismic 
intensity of seven, it would be impossible to cope with the accidents with 
the conventional wedge-shaped jack apparatus. Namely, in the conventional 
wedge-shaped jack apparatus, the height through which the structure may be 
jacked is 10 mm at best. However, in fact, the jack up that is much larger 
than 10 mm is required. More specifically, in order to maintain the jack 
amplification rate at about three or four times with the conventional 
wedge-shaped jack apparatus, a gradient of the slant surface is set at 
about 8% in view of the static frictional coefficient of the slant 
surfaces. In order to obtain the jack up of 10 mm with this gradient, a 
125 mm stroke of the wedge-shaped drive member is required, and a 
hydraulic jack (i.e., cylinder) having the stroke of 150 mm is practically 
used. Therefore, in order to obtain the further jack amount without 
reducing the jack amplification rate, it is considered that a large size 
hydraulic jack is used and the wedge-shaped drive member is elongated to 
increase the stroke. However, the hydraulic jack, the wedge-shaped drive 
member, and their peripheral equipment become large in size to increase 
the cost. In addition, the weight of the apparatus is increased, thereby 
making it difficult to handle the apparatus. Moreover, even if the stoke 
is doubled, the amount of the jack is just twice larger than ever. This 
never leads to the basic countermeasure. 
SUMMARY OF THE INVENTION 
Accordingly, the present inventors have found the countermeasure through 
vigorous studies as follows. In the jack-up operation, a plurality of 
auxiliary wedge-shaped members are coupled with each other in order at the 
thick end face of a wedge-shaped drive member. The wedge-shaped drive 
member or the front stage auxiliary wedge-shaped member which are not 
necessary for the operation is removed. In the jack-down operation, the 
front stage auxiliary wedge-shaped member or the final wedge-shaped drive 
member is coupled in order at the thin end face side of the rear stage 
auxiliary wedge-shaped member. The rear stage auxiliary wedge-shaped 
member which are not necessary for the operation is removed. A reactive 
force receiving means is devised. Then, the above-described tasks may be 
solved at once. The multistage wedge-shaped jack apparatus has been 
developed so that it is possible to jack up, smoothly in safety, the heavy 
weight structure such as a bridge girder in the same manner as in the 
conventional jack apparatus and also to considerably increase the jack 
amount of about 50 to 100 mm without increasing the overall length of the 
apparatus. 
According to the present invention, there is provided a multistage 
wedge-shaped jack apparatus wherein a longitudinally movable wedge-shaped 
drive member having a slant surface at least on an upper side and a 
wedge-shaped pressure receiving member having a slant surface at the same 
slant angle as that of the slant surface of the drive member and slidable 
on the slant surface of the wedge-shaped drive member, on one of its upper 
and lower sides, and having a horizontal surface on the other of its upper 
and lower side are laminated one on another on a base plate with the 
respective slant surfaces being in contact with each other; a plate-like 
pedal is laminated on the lamination; and the thick end face side of the 
wedge-shaped drive member is pushed or pulled by a push/pull drive means 
provided in cooperation with a reactive force receiving means for limiting 
a movement of the wedge-shaped pressure receiving member for jacking up 
and down a structure laid on the plate-like pedal, characterized in that: 
a single or a plurality of auxiliary wedge-shaped members are detachably 
coupled with each other in order at the thick end face side of the 
wedge-shaped drive member; each auxiliary wedge-shaped member has a 
shorter length than that of the stroke length of the push/pull drive 
means, and has a slant surface having the same slant angle as that of the 
slant surface of the wedge-shaped drive member; the slant surfaces of the 
wedge-shaped drive member or a front stage auxiliary wedge-shaped member 
and a rear stage auxiliary wedge-shaped member are continuous at the thick 
end face of the wedge-shaped drive member or the front stage auxiliary 
wedge-shaped member and the thin end face of the rear stage auxiliary 
wedge-shaped member; further, a tip end of a drive rod of the push/pull 
drive means and the thick end face of the wedge-shaped drive member and 
each wedge-shaped member are detachably coupled with each other; and a 
temporary engagement means is provided for limiting a movement of the 
wedge-shaped drive member and the auxiliary wedge-shaped members in 
engagement with side walls of the wedge-shaped drive member and the 
auxiliary wedge-shaped members after a jack-up operation through a 
predetermined height. 
More particularly, the wedge-shaped drive member and the auxiliary wedge 
shaped members have the slant surfaces on the upper side and horizontal 
surfaces on the lower side, and the wedge-shaped pressure receiving member 
located on the upper side has the slant surface on the lower side. In this 
case, it is preferable that the reactive force receiving means is provided 
for coupling, through links, both side portions of pressure receiving 
members to which a body portion of the push/pull drive means is fixed and 
both side portions of the wedge-shaped pressure receiving member at 
positions close to the thin end face thereof, and the reactive force 
receiving member is fixed to the base plate. 
Also, the wedge-shaped drive member and the auxiliary wedge shaped members 
have the slant surfaces on the upper and lower sides, the wedge-shaped 
pressure receiving member located on the lower side has the slant surface 
on the upper side, and the wedge-shaped pressure receiving member located 
on the upper side has the slant surface on the lower side. In this case, 
it is preferable that the reactive force receiving means is provided for 
coupling, through links, both side portions of pressure receiving members 
to which a body portion of the push/pull drive means is fixed and both 
side portions of the upper and lower wedge-shaped pressure receiving 
members at positions close to the thin end faces thereof. 
Then, it is practical that the wedge-shaped drive member and the auxiliary 
wedge-shaped member or the front stage and rear stage auxiliary 
wedge-shaped members are coupled with each other by inserting an H-shaped 
spill member into connection grooves having a T-shape in cross section and 
formed at the end faces of the wedge-shaped drive member and the auxiliary 
wedge-shaped member or the front stage and rear stage auxiliary 
wedge-shaped members. Guide linear recesses are formed along both sides of 
one of the slant surfaces that are slidingly moved relative to each other, 
and guide linear projections which are slidably contact with the guide 
linear recesses are formed on the other of the slant surfaces. A single or 
a plurality of stop plates are inserted between the reactive force 
receiving member and the thick end face of the wedge-shaped drive member 
or the auxiliary wedge-shaped member. 
Also, it is more practical that the wedge-shaped drive member is divided 
into a plurality of segments in a longitudinal direction, and the segments 
are detachably coupled with each other. 
In the multistage wedge-shaped jack apparatus having the structure as 
described above, the slant surface of the wedge-shaped drive member is 
brought into contact with the slant surface of the wedge-shaped pressure 
receiving member to be laminated on the base plate. At the same time, the 
plate-like pedal is laminated thereon. The thick end face side of the 
wedge-shaped drive member is pushed or pulled by the push/pull means 
provided in cooperation with the reactive force receiving means for 
limiting the movement of the wedge-shaped pressure receiving member. 
Therefore, the structure laid on the plate-like pedal is jacked up and 
down. In the case where the structure is jacked up, the thick end face 
side of the above-described wedge-shaped drive member is pushed by the tip 
end of the drive rod of the push/pull means, and the wedge-shaped drive 
member is slidingly moved relative to the wedge-shaped drive member to 
thereby jack up the upper wedge-shaped pressure receiving member and the 
plate-like pedal. Then, in the case where the structure is to be further 
jacked up, the engagement means is engaged with each side wall of the 
wedge-shaped drive member kept in this condition for limiting the movement 
thereof. Thereafter, the drive rod is withdrawn. The auxiliary 
wedge-shaped member which is shorter than the stroke length of the 
above-described push/pull drive means and which has the slant surface 
having the same slant angle as that of the slant surface of the 
wedge-shaped drive member is detachably coupled with the thick end face 
side of the wedge-shaped drive member between the wedge-shaped drive 
member and the drive rod so that the slant surfaces are continuous at the 
thick end face of the wedge-shaped drive member and at the thin end face 
of the auxiliary wedge-shaped member. Thereafter, the drive rod pushes the 
thick end face side of the auxiliary wedge-shaped member so that the 
wedge-shaped drive member is pushed with the sliding movement between the 
slant surface of the auxiliary wedge-shaped member and the slant surface 
of the wedge-shaped pressure receiving member to thereby jack up the 
plate-like pedal and the upper wedge-shaped pressure receiving member. In 
order to further jack up the structure under this condition, the side 
surfaces of the auxiliary wedge-shaped member are engaged with the 
engagement means to limit the movement. Thereafter, the drive rod is drawn 
and the thin end face side of the rear stage auxiliary wedge-shaped member 
is detachably coupled in the same manner with the thick end face side of 
the auxiliary wedge-shaped member between the auxiliary wedge-shape member 
and the drive rod. The thick end face of the rear stage auxiliary 
wedge-shaped member is pushed by the drive rod for the further jack-up 
operation. After that, the structure is jacked up stepwise by coupling the 
rear stage auxiliary wedge-shaped members in order. Finally, the large 
jack amount may be obtained. Then, the wedge-shaped drive member and the 
auxiliary wedge-shaped members which have passed through the thick end 
face side of the wedge-shaped pressure receiving member are removed in 
order by separating them at the connection portions. Thus, the overall 
length of the apparatus may be suppressed. 
Also, in the case where the structure which has been jacked up as described 
above is to be jacked down, the tip end of the drive rod of the push/pull 
drive means is coupled with the thick end face side of the final stage 
auxiliary wedge-shaped member. At the same time, under the condition that 
the thick end face of the one stage previous auxiliary wedge-shaped member 
is coupled to the thin end face of the front stage auxiliary wedge-shaped 
member that appears at the thick end face side of the wedge-shaped 
pressure receiving member, the drive rod is drawn to remove the final 
stage auxiliary wedge-shaped member. At the same time, the auxiliary 
wedge-shaped member connected on the front stage side is drawn below the 
wedge-shaped pressure receiving member, and the wedge-shaped pressure 
receiving member and the plate-like pedal are lowered. Then, this 
operation is performed in order and finally, the wedge-shaped drive member 
is coupled for the original condition. 
Also, in case of the wedge-shaped drive member and the auxiliary 
wedge-shaped member having the slant surfaces on the upper side and the 
horizontal surface on the lower side, the horizontal surface of the 
wedge-shaped drive member is slidingly moved along and on the base plate. 
The working line of the drive force of the push/pull drive means is not 
changed up and down. Accordingly, it is possible to fix the push/pull 
drive means to the base plate, and the structure of the reactive force 
receiving means may be simplified. The maintenance of the push/pull drive 
means is stable. Therefore, in this case, the reactive force receiving 
means is sufficient if the both side portions of the reactive force 
receiving member to which the body portion of the push/pull drive means is 
fixed is coupled, through links, with the both side portions of the upper 
wedge-shaped pressure receiving member at the position close to the thin 
end face thereof by the reactive force rods, and the reactive force 
receiving member is fixed to the base plate. 
On the other hand, in case of the wedge-shaped drive member and the 
auxiliary wedge-shaped member having the slant surface on the upper and 
lower sides, the lower wedge-shaped pressure receiving member having the 
slant surface on the upper side, and the upper-shaped pressure receiving 
member having the slant surface on the lower side, the jack amount may be 
doubled in comparison with the case described above. On the other hand, 
since the wedge-shaped drive member is fluctuated up and down relative to 
the lower wedge-shaped pressure receiving member, in order to transmit the 
drive force of the push/pull drive means always in the stable manner to 
the wedge-shaped drive member, it is necessary to use the reactive force 
receiving means that fluctuate the working line of the drive force of the 
push/pull drive means up and down relative to the base plate in accordance 
with the up and down movement of the wedge-shaped drive member. 
Accordingly, it is preferable that both side portions of the reactive 
receiving member to which the body portion of the push/pull drive means is 
fixed is coupled through links, i.e., reactive force receiving rods with 
the both side portions of the upper and lower wedge-shaped pressure 
receiving members at the thin end face sides. 
In the case where the wedge-shaped drive member and the auxiliary 
wedge-shaped member or the front stage and the rear stage auxiliary 
wedge-shaped members are coupled with each other by inserting the H-shaped 
spill member from the side into the connection grooves having the T-shape 
in cross section and formed at the end faces, it is possible to obtain a 
strong connection against the push/pull force, and to facilitate the 
detachment/attachment. Also, in this case, even if the space between the 
lower base and the structure is small, it is possible to readily attain 
the separation work. 
Also, in the case where the guide linear recesses are formed along both 
sides of one of the slant surfaces which are slidingly moved relative to 
each other, and the guide linear projections for engaging with the guide 
linear recesses are formed on the other of the slant surfaces, the 
wedge-shaped drive member or the auxiliary wedge-shaped member and the 
wedge-shaped pressure receiving member are not displaced in the lateral 
direction, and it is possible to stably slidingly move the components only 
in the predetermined longitudinal direction. 
Also, if a single or a plurality of stop plates are inserted between the 
reactive force receiving member and the thick end face of the wedge-shaped 
drive member or the auxiliary wedge-shaped member, it is possible to 
maintain the state in a stable manner after the structure has been jacked. 
Furthermore, if the wedge-shaped drive member is devided into a plurality 
of segments in a longitudinal direction, and the segments are detachably 
coupled with each other, it is possible to remove the unnecessary parts 
for the jack-up and -down working. Accordingly, it is possible to suppress 
the increase of the apparatus even if the jack amount is considerably 
increased by using the single or plural auxiliary wedge-shaped members.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention will now be described in detail with reference to the 
accompanying drawings. FIGS. 1 and 2 show a first embodiment of a 
multistage wedge-shaped jack apparatus according to the invention. FIGS. 3 
and 4 show a second embodiment of the multistage wedge-shaped jack 
apparatus according to the invention. In these figures, reference numeral 
1 denotes a wedge-shaped drive member; 2, a wedge-shaped pressure 
receiving member; 3, a base plate; 4, a plate-like pedal; 5, a reactive 
force receiving means; 6, a push/pull drive means; 7, an auxiliary 
wedge-shaped member; 8, a temporary engagement or stop means; and 9, a 
stop means. 
The basic structure of the multistage wedge-shaped jack according to the 
present invention includes a wedge-shaped drive member 1 which has a slant 
surface 11 at least on its upper side and which is movable in the 
longitudinal direction, and a wedge-shaped pressure receiving member 2 
which has, on its one side, a slant surface 21 at the same slant angle 
along with the slant surface 11 of the above-described wedge-shaped drive 
member 1 and which has, on the other side, a horizontal surface 22. The 
wedge-shaped drive member 1 and the wedge-shaped pressure receiving member 
2 are brought into contact with each other along the slant surfaces 11 and 
21 to form a laminate on a base plate 3. Furthermore, a plate-like pedal 4 
is laid on the laminate. A portion on the end face 12, with a larger 
thickness, of the above-described wedge-shaped drive member 1 is pushed 
and pulled by a push/pull drive means 6 which is provided in cooperation 
with a reactive pressure receiving means 5 for limiting a movement of the 
above-described wedge-shaped pressure receiving member 2. Thus, the 
structure A laid on the plate-like pedal 4 is jacked up and down. 
In addition, the basic structure includes a single or a plurality of 
auxiliary wedge-shaped members 7 which may be detachably connected in 
order with the portion having the larger thickness of the above-described 
drive member 1. Each auxiliary wedge-shaped member 7 has a slant surface 
71 having the same slant angle as that of the slant surface 11 of the 
above-described wedge-shaped drive member 1. The slant surface 11 of the 
wedge-shaped drive member 1 is continuous with the slant surface 71 of the 
auxiliary wedge-shaped member at the end face 12 having the larger 
thickness of the wedge-shaped drive member 1. Also, the slant surface 71 
of the auxiliary wedge-shaped member 7 is continuous with the slant 
surface 71 of the other auxiliary wedge-shaped member 7 at the end face 73 
of the auxiliary wedge-shaped member 7 on the rear side. Furthermore, a 
tip end of a drive rod 61 of the above-described push/pull drive means 6 
is connectable to the wedge-shaped drive member 1 and each of the 
wedge-shaped members 7 on its larger thickness end face. A temporary 
engagement means 8 is provided for engaging with side faces 13 and 74 of 
the wedge-shaped drive member 1 and the auxiliary members 7 for limiting 
the movement thereof through a predetermined jack height. 
In the following description, in the case where it is necessary to specify 
the order of the auxiliary wedge-shaped members 7, the auxiliary 
wedge-shaped members 7 are referred to by reference characters 7a, 7b, . . 
. in order from the front side to the rear side. Thus, in this case, 
suffixes a, b, . . . are added also to each component of the auxiliary 
wedge-shaped member 7. 
The first embodiment of the invention shown in FIGS. 1 and 2 is drawn to a 
structure in which the wedge-shaped pressure receiving member 2 is 
laminated on a top of the wedge-shaped drive member 1. The second 
embodiment of the invention shown in FIGS. 3 and 4 is drawn to another 
structure in which wedge-shaped pressure receiving members 2, 2 are 
laminated on an upper portion and a lower portion of the wedge-shaped 
drive member 1. In the latter case, the upper wedge-shaped pressure 
receiving member 2 is referenced by the upper wedge-shaped pressure 
receiving member 2a and the lower wedge-shaped pressure receiving member 2 
is referenced by the upper wedge-shaped pressure receiving member 2b for 
distinction. 
First of all, the first embodiment will be explained in detail. In this 
embodiment, the wedge-shaped drive member 1 has a slant surface 11 on its 
upper side and a horizontal surface 14 on its lower side. A connection 
hole 15 is formed on a central portion of a larger thickness end face 12. 
At the same time, a coupling groove 16 having substantially the T-shape in 
cross section extending in the lateral direction is formed thereat. 
Furthermore, guide linear recesses 17, 17 are formed along both sides of 
the above-described slant surface 11. A pair of stop holes 18, 18 each of 
which communicates with associated side of the above-described connection 
hole 15 are formed from the top surface of the wedge-shaped drive member 
1. A connection pin 19 may be threadedly engaged into the associated hole 
18 from above. 
The above-described wedge-shaped pressure receiving member 2 has a slant 
surface 21 having, on its lower side, the same slant angle as that of the 
slant surface 11, and has on its upper side, a horizontal surface 22. At 
the same time, guide linear projections 23, 23 are formed for engaging 
with the above-described guide recesses 17 along both sides of the 
above-described slant surface 21. 
Also, in order to facilitate the sliding movement of the wedge-shaped drive 
member 1 relative to the above-described wedge-shaped pressure receiving 
member 2, it is desirable to embed sliding plates made of stainless steel 
or a tetrofluoroethylene resin. In order to lay slidably the 
above-described plate-like pedal 4 slidably on the horizontal surface 22 
of the wedge-shaped pressure receiving member 2, it is also preferable to 
embed the sliding plates in the same manner. However, if the sliding 
movement would be easy between each slant surface and the component, it is 
possible to dispense with any sliding plate. 
Principally, the above-described wedge-shaped drive member 1 and the 
wedge-shaped pressure receiving member 2 may be made of steel. However, 
the work required for delivery and workability, it is of course preferable 
to use a material that is much lighter in weight. It is therefore possible 
to recommend to use a synthetic resin compound material, titanium and the 
like. As the synthetic resin compound material, it is more preferable to 
use a laminate made of special fiber impregnated with phenol resin because 
its strength and hardness are high. This laminate is made from a block 
which is produced by a basic material, made of cloth of special fiber, 
with resin liquid which is mixed and reacted with phenol, hormaldehyde and 
special additives within a reactive container, dried and then cut into a 
predetermined length, laminated and pressurized by a molding press. After 
the block has been formed a predetermined shape, its sliding surface is 
subjected to a paraffine process to form the above-described respective 
components. With respect to the physical property of the material, the 
specific weight is 1.39, and the hardness is 98 HRM. Also, with respect to 
the mechanical property, the compression strength is 25.3 kgf/mm.sup.2 in 
the laminate direction (hereinafter referred to as a vertical direction) 
and is 14.9 kgf/mm.sup.2 in the direction along the cloth (hereinafter 
referred to as a horizontal direction, the bending strength is 13.0 
kgf/mm.sup.2 in the vertical direction and 14.3 kgf/mm.sup.2 in the 
horizontal direction, the collision value is 45.2 kgf.cm.sup.2 in the 
vertical direction and the 24.9 kgf.cm/cm.sup.2 in the horizontal 
direction, and the amount of wear is 0.02 mm/hr (in case of the test 
condition of pressure P=60 kg/cm.sup.2 and sliding speed V=1 m/s). 
Incidentally, these characteristic parameters are at a temperature of 
20.degree. C. 
The above-described base plate 3 is made of stainless steel, and is used to 
support the horizontal surface of the above-described wedge-shaped drive 
member 1 and to allow the latter to move in the longitudinal direction. 
Also, in order to limit the lateral movement of the above-described wedge 
shaped drive member, it is possible to form projecting guide plates on 
both sides of the base plate 3. 
The above-described pedal plate 4 is composed of a top plate 41 made of 
metal and laid directly on a horizontal surface 22 of the wedge-shaped 
pressure receiving member 2 and a rubber pad 42 made of neoprene rubber, 
etc. laminated thereon in this embodiment. On the top surface of the 
rubber pad 42 is disposed the structure A. The rubber pad 42 serves as an 
absorber to any vibration and horizontal rotation of the structure A after 
the jack-up operation. 
The above-described reactive force receiving means 5 is formed as follows. 
Both side portions of a reactive force receiving member 51 to which a body 
portion 62 of the push/pull drive means 6 is connected are coupled by 
reactive force receiving rods 52, 52 with both side portions of the 
above-described wedge-shaped pressure receiving member 2 on the side of 
the thin side end face 24. The above-described reactive force receiving 
member 51 is fixed to one end portion in the longitudinal direction of the 
above-described base plate 3. In more detail, the reactive force receiving 
member 51 is so constructed that support plates 54, 54 are fixedly secured 
to both end portions of a fixed plate 53 arranged perpendicular to the 
longitudinal direction of the base plate 3, and a thread hole 55 is formed 
for mounting the body portion 62 of the push/pull drive means 6 on the 
above-described fixed plate 53. In addition, longitudinal holes 56, 56 are 
formed in the above-described support plates 54, 54. One end of each of 
the above-described reactive force receiving rods 52 is pivoted by a pivot 
pin 57 to be rotatable and movable up and down within the associated 
longitudinal hole 56. The other end of each of the reactive force 
receiving rod 52 is pivoted to be rotatable about a pivot pin 58 relative 
to the above-described wedge-shaped pressure receiving member. Then, the 
fixed plate 53 and the support plates 54, 54 are welded to the top surface 
of the above-described base plate 3. 
In this embodiment, the above-described push/pull drive means 6 is 
constituted by a hydraulic jack or cylinder. A male screw portion 63 
projecting from one end of the body portion 62 may be threadedly fixed to 
the thread hole 55 of the above-described fixed plate 53. The 
above-described drive rod 61 is projected from and retracted into the 
center of the male screw portion 63 by the hydraulic control. A connector 
64 is fixed to a tip end of the drive rod 61. In this embodiment, if the 
above-described male screw portion 63 is formed by a square screw and 
parts of the square screw are cut in an axial direction to form a 
plurality of longitudinal grooves, whereas the above-described thread hole 
55 is formed in the same manner and screw portions are left only to the 
parts corresponding to the longitudinal grooves, it is very practically 
convenient because the screw portions may readily be engaged with each 
other through a small amount of rotation after the male screw 63 is 
inserted into the thread hole 55. The connector 64 has a shape such that 
it may be inserted into the connection hole 15 of the above-described 
wedge-shaped drive member 1. An annular groove 65 is formed in an outer 
circumference of the connector 64. As shown in FIGS. 5(I) and 5(II), under 
the condition that the connector 64 is inserted into the connection hole 
15, if connection pins 19, 19 are inserted into the above-described stop 
holes 18, 18, parts of the connections pins 19 are engaged with the 
annular groove 65 so that the drive rod 61 is engaged with the 
wedge-shaped drive member 1 and prevented from being pulled away from the 
wedge-shaped drive member 1. In other words, in accordance with the 
push/pull movement of the drive rod 61, the wedge-shaped drive member 1 is 
moved integrally therewith. However, in the case where the drive rod 61 is 
pushed, it is unnecessary to connect the connector 64 with the 
wedge-shaped drive member 1 by the connection pins 19. This connection is 
effective for the pull operation thereof. 
Another connection structure for the above-described wedge-shaped drive 
member 1 and the drive rod 61 is shown in FIG. 6 and FIGS. 7(I) and 7(II). 
In this example, a slit hole 18a having a rectangular shape in plan view 
is formed from the top surface of the wedge-shaped drive member 1 so as to 
be perpendicular to the deep portions of the above-described connection 
hole 15 and the connection groove 16. With the connector 64 being inserted 
into the connection hole 15, a connection plate 19a having an rectangular 
outer appearance is inserted from above the slit hole 18a. A U-shaped 
groove 19a formed from a center to a lower end of the connection plate 19a 
is engaged with the above-described annular groove 65. Also, it is 
preferable that a projection 19c be formed at the top end of the 
connection plate 19a for the easy insertion into the slit hole 18a. 
Incidentally, the same connection structure may be used for the auxiliary 
wedge-shaped members 7. 
The above-described auxiliary wedge-shaped members 7 are made of the same 
material as the above-described wedge-shaped member 1. As described above, 
the single or plural auxiliary wedge-shaped members 7 may be detachably 
engaged with the thick end face 12 of the above-described wedge-shaped 
member 1 in order. A length of the auxiliary wedge-shaped members 7 is 
shorter than a stroke of the drive rod 61 of the above-described push/pull 
drive means 6. A width thereof is the same as the above-described 
wedge-shaped drive member 1. The auxiliary wedge-shaped members 7 have the 
top slant surface 71 at the same slant angle as that of the slant surface 
11 of the above-described wedge-shaped drive member 1, and the horizontal 
surface 75 at the bottom. Guide linear recesses 76, 76 to be engaged with 
the above-described guide linear projections 23, 23 are formed along both 
sides of the above-described slant surface 71. The thin end face 73 of the 
front stage auxiliary wedge-shaped member 7a has the same size in 
appearance as the thick end face 12 of the above-described wedge-shaped 
drive member 1. When the two members are coupled with each other, the 
respective slant surfaces 11 and 71 are made continuous with each other. 
On the other hand, the thin end face 73 of the next stage auxiliary 
wedge-shaped member 7b has the same size in appearance as the thick end 
face 72 of the front stage auxiliary wedge-shaped member 7a. When the two 
components are coupled with each other, the respective slant surfaces 71, 
71 are made continuous with each other. Also, a connection hole 77 having 
the same size as the above-described connection hole 15 is formed in the 
central portion of the thick end face 72 of the auxiliary wedge-shaped 
member 7. Stop holes 78, 78 are opened upwardly in the same manner as the 
above-described stop holes 18, 18. Connection grooves 79 are formed in the 
thick end face 72 and the thin end face 73 of the auxiliary wedge-shaped 
member 7, respectively, in the same manner as the connection groove 16. 
Then, in order to couple the above-described wedge-shaped drive member 1 
and the auxiliary wedge-shaped member 7a with each other, under the 
condition that the thin end face 73 of the auxiliary wedge-shaped member 
7a is brought into contact with the thick end face 12 of the wedge-shaped 
drive member 1, both edge portions of an H-shaped spill member 100 are 
inserted into the connection grooves 16 and 79 from the side. Also, in 
order to couple the front stage auxiliary wedge-shaped member 7a and the 
rear stage auxiliary wedge-shaped member 7b with each other, under the 
condition that the thin end face 73 of the rear stage auxiliary 
wedge-shaped member 7b is brought into contact with the thick end face 72 
of the front stage auxiliary wedge-shaped member 7a, both edge portions of 
an H-shaped spill member 100 are inserted into the connection grooves 79 
and 79 from the side. Then, as described above, the auxiliary wedge-shaped 
members 7, . . . are coupled in order one after another with the 
wedge-shaped drive member 1. The connector 64 fixed to the tip end of the 
drive rod 61 in the same manner is connected into the connection hole 77 
of the thick end face 72 of the rearmost stage auxiliary wedge-shaped 
member 7. 
The above-described temporary engagement means 8 is used to temporarily 
limit the rearward movement of the wedge-shaped drive member 1 when the 
next auxiliary wedge-shaped member 7a is connected thereto under the 
condition that a predetermined height of the jack up is attained by using 
the wedge-shaped drive member 1, and also to temporarily limit the 
rearward movement of the auxiliary wedge-shaped member 7a when the next 
wedge-shaped drive member 1b under the condition that a predetermined 
height of the jack up is attained by using the auxiliary wedge-shaped 
member 7a. Various types of the structures may be considered therefor. 
However, in this embodiment, as shown in FIGS. 1, 2 and 8, engagement 
grooves 81 consisting of vertical grooves are formed at positions at a 
predetermined length away from the thick end faces 12, 72 on both side 
surfaces 13, 13 of the wedge-shaped drive member 1 and on both side 
surfaces 74, 74 of the auxiliary wedge-shaped members 7, . . . , 
respectively. Cams 84 are rotatably projected from openings 83 formed at 
parts of side plates 82, 82 extending upwardly from both sides of the base 
plate 3 and are engaged with the above-described engagement grooves 81 for 
preventing the wedge-shaped drive member 1 and the auxiliary wedge-shaped 
member 7, . . . from returning back. The above-described cams 84 are 
pivoted about vertical shafts disposed within mount members 85 having a 
U-shape in cross section and having base ends fixed to the outer surfaces 
of the side plates 82. With the structure of the engagement grooves 81 and 
the cams 84, after the wedge-shaped drive member 1 or the auxiliary 
wedge-shaped member 7 is pushed so that the engagement grooves 81 are 
located to the cams 84, when the drive rod 61 is drawn so that the 
wedge-shaped drive member 1 or the auxiliary wedge-shaped member 7 is 
somewhat retracted, the cams 84 are automatically drawn inwardly by 
steeply stepped portions 81a of the front edges 81a of the engagement 
grooves 81 for engagement. Under this condition, when the drive rod 61 is 
pushed so that the wedge-shaped drive member 1 or the auxiliary 
wedge-shaped member 7 is advanced, the tip ends of the cams 84 are pushed 
by gently slant surfaces 81b of the engagement grooves 81 so that the cams 
84 are rotatably received outwardly automatically for disengagement. Of 
course, it is possible to normally urge the cams 84 in a direction to 
project for release. 
The above-described stop means 9 is used to prevent the wedge-shaped drive 
member 1 or the auxiliary wedge-shaped member 7 from returning back in 
order to stably maintain the condition after the structure A is jacked up 
at a predetermined height by using the wedge-shaped drive member 1 and the 
auxiliary wedge-shaped members 7, . . . . In this embodiment, the stop 
means 9 is composed of single or a plurality of stop plates 91, . . . to 
be interposed between the thick end face 12 of the wedge-shaped drive 
member 1 or the thick end face 72 of the most rear stage of the auxiliary 
wedge shaped member 7 and the fixed plate 53 of the reactive force 
receiving member 51. The stop plate 91 is in the form of a horseshoe with 
a cutaway portion 92 open downwardly in the central portion in order to be 
mounted to embrace the above-described drive rod 61. 
Also, in this embodiment, the wedge-shaped drive member 1 is divided into 
three segments in the longitudinal direction. Each segments 1a, 1b and 1c 
are detachably engaged with each other by using the H-shaped spill members 
101 in the same manner as described above. 
The operation for jacking up the structure A relative to the lower base B 
by using the multistage wedge-shaped jack apparatus according to the 
present invention will now be described. First of all, the wedge-shaped 
pressure receiving member 2 is laminated on the wedge-shaped drive member 
1 with the slant surface 21 in contact with the slant surface 11. At the 
same time, the horizontal surface 14 of the wedge-shaped drive member 1 is 
laid on the base plate 3. The reactive force receiving rods 52, 52 are 
pivoted on both sides of the wedge-shaped pressure receiving member 2. The 
male thread portion 63 of the body portion 62 of the push/pull drive means 
6 is threadedly engaged with the thread hole 55. At the same time, the 
connector 64 fixed to the tip end of the drive rod 61 is inserted into the 
connection hole 15 of the thick end face 12 of the wedge-shaped drive 
member 1. A condition is kept in that the wedge-shaped drive member 1 is 
closest to the fixed plate 53. Under the condition that the plate-like 
pedal 4 is laid on the horizontal surface 22 of the wedge-shaped pressure 
receiving member 2, the base plate 3 is set horizontally on the lower base 
B so that the structure A is positioned in a predetermined position. 
Then, the push/pull drive means 6 is hydraulically driven to push the 
wedge-shaped drive member 1 on the thick end face 12 to gradually enter 
below the wedge-shaped member 2 by the drive rod 61. In accordance with 
the sliding movement of the respective slant surfaces 11 and 21, the 
wedge-shaped pressure receiving member 2 and the plate-like pedal 4 are 
raised, thereby jacking up the structure A. In this case, since one side 
ends of the reactive force receiving rods 52 are pivoted at the 
longitudinal holes 56, the pivot pins 57 are raised along the longitudinal 
holes 56 in accordance with the elevation of the wedge-shaped pressure 
receiving member 2, and the reactive force receiving rods 52 are always 
kept in the horizontal position to stably receive the reactive forces to 
thereby limit the movement of the wedge-shaped pressure receiving member 
2. Thereafter, when the push movement of the wedge-shaped drive member 1 
reaches the final stage, the above-described cams 84 are located in the 
engagement grooves 81. Then, the drive rod 61 is retracted rearwardly so 
that the connector 64 is removed from the connection hole 15. Furthermore, 
the connector 64 is retracted rearwardly up to the position of the fixed 
plate 53. Under this condition, in the case where the wedge-shaped drive 
member 1 is abruptly moved rearwardly, the cams 84 are engaged with the 
engagement grooves 81 to prevent the wedge-shaped drive members 1 from 
returning back. Also, the engagement holes 18 are exposed on the thin end 
face 24 side of the wedge shaped pressure receiving member 2. Then, under 
the condition that the first stage auxiliary wedge-shaped member 7a is 
located on the base plate 3 between the thick end face 12 of the 
wedge-shaped drive member 1 and the connector 64, and the thick end face 
12 of the wedge-shaped drive member 1 is jointed with the thin end face 73 
of the auxiliary wedge-shaped member 7a, the H-shaped spill member 100 is 
inserted into the connection grooves 16 and 79. In this case, the segment 
1a of the wedge-shaped drive member 1 which has passed through the thick 
end face 25 of the wedge-shaped pressure receiving member 2 may be removed 
by removing the H-shaped spill member 101. 
When the drive rod 61 of the push/pull drive means 6 is advanced, after the 
connector 64 is inserted into the connection hole 77 of the auxiliary 
wedge-shaped member 7b, the auxiliary wedge-shaped member 7a is pushed 
below the wedge-shaped pressure receiving member 2, and the wedge-shaped 
pressure receiving member 2 is raised by the sliding movement of the 
respective slant surfaces 71 and 21 in the same way to thereby further 
jack up the structure A. Thereafter, almost all of the auxiliary 
wedge-shaped member 7a is pushed below the wedge-shaped pressure receiving 
member 2. When the cams 84 are located at the position corresponding to 
the engagement grooves 81 of the auxiliary wedge-shaped member 7a, the 
drive rod 61 is again moved rearwardly and the connector 64 is removed 
from the connection hole 77 and moved close to the fixed plate 53. In this 
case, the cams 84 are engaged with the engagement grooves 81 by the 
rearward movement of the auxiliary wedge-shaped member 7a in the same way. 
Under this condition, the next auxiliary wedge-shaped member 7b is laid 
between the thick end face 72 of the auxiliary wedge-shaped member 7a and 
the connector 64. Both components are coupled with each other by the 
H-shaped spill member 100. In this case, the segment 1b of the 
wedge-shaped drive member 1 which has passed through the thick end face 25 
of the wedge-shaped pressure receiving member 25 may be removed. 
When the drive rod 61 of the push/pull drive means 6 is advanced, after the 
connector 64 has been inserted into the connection hole 77 of the 
auxiliary wedge-shaped member 7a, the auxiliary wedge-shaped member 7b is 
pushed below the wedge-shaped pressure receiving member 2, and the 
wedge-shaped pressure receiving member 2 is raised in the same way to 
thereby raise the structure A. Thus, the auxiliary wedge-shaped members 7, 
. . . are fed one by one. The structure A is further jacked up. Each 
member which has passed through the thick end face 25 of the wedge-shaped 
pressure receiving member 2 is repeatedly removed. Finally, after the 
structure A is jacked up at a predetermined height, the stop members 91, . 
. . are inserted as the stop means between the thick end face 72 of the 
final stage auxiliary wedge-shaped member 7 and the fixed plate 53 of the 
pressure receiving member 51, and the complete rearward movement 
prevention is effected for the auxiliary wedge-shaped member 7 to maintain 
the jack-up condition. 
On the other hand, the structure A which has been jacked up at the 
predetermined height will be jacked down as follows. Under the condition 
that the connector 64 at the tip end of the drive rod 61 is engaged with 
the connection hole 77 of the final stage auxiliary wedge-shaped member 7, 
the connection pins 19 and 19 are threadedly engaged from above with the 
stop holes 78 and 78 of the auxiliary wedge-shaped member 7. The 
intermediate portions of the connection pins 19, 19 which project 
partially into the connection hole 77 are engaged with the annular groove 
65 of the connector 64 for preventing the connector 64 from pulling away. 
At the same time, the stop plates 91, . . . are removed. The H-shaped 
spill member 100 is inserted into the connection grooves 79, 79 from the 
side on the thin end face 73 side of the auxiliary wedge-shaped member 7 
of the front stage projecting from the thick end face 25 of the 
wedge-shaped pressure receiving member 2 and on the thick end face 72 of 
the wedge-shaped member 7 corresponding to its front stage, or the segment 
1c of the wedge-shaped drive member 1 is connected. Thereafter, while 
releasing the temporary engagement means 8, the drive rod 61 is retracted, 
and the final stage auxiliary wedge-shaped member 7 is pulled away from 
the thin end face 24 side of the wedge-shaped pressure receiving member 2 
to thereby jack down the structure A. Then, under the condition that the 
cams 84 of the temporary engagement means 8 are rotated and engaged with 
the engagement grooves 81, if necessary, the connection pins 19, 19 are 
removed, and the H-shaped spill member 100 is removed to keep a release 
condition. In this condition, the drive rod 61 is further retracted and 
the connector 64 is pulled away from the connection hole 77. The final 
stage auxiliary wedge-shaped member 7 is removed. These operations are 
repeated to thereby jack down gradually the structure A. 
A second embodiment of the present invention will now be described with 
reference to FIGS. 3 and 4. In this embodiment, the wedge-shaped drive 
member 1 is made symmetric up and down. Slant surfaces 11, 11 are formed 
on the top and bottom surfaces, and the guide linear recess 17, 17 are 
formed along both sides of each slant surface 11. In correspondence with 
this, also, the wedge-shaped pressure receiving member 2 is composed of a 
pair of upper wedge-shaped pressure receiving member 2a and the lower 
wedge-shaped pressure receiving member 2b. The upper wedge-shaped pressure 
receiving member 2a is substantially the same as that of the first 
embodiment. The lower wedge-shaped pressure receiving member 2b is made by 
forming it up side down. The slant surface 21 formed on the lower surface 
of the upper wedge-shaped pressure receiving member 2a is brought into 
contact with the upper slant surface 11 of the wedge-shaped drive member 
1, and the slant surface 21 formed on the upper surface of the lower 
wedge-shaped pressure receiving member 2b is brought into contact with the 
lower slant surface 11 of the wedge-shaped pressure receiving member 2. 
Under this condition, the horizontal surface 22 of the lower wedge-shaped 
pressure receiving member 2b is laid on the base plate 3, and the 
above-described plate-like pedal 4 is laid on the horizontal surface 22 of 
the upper surface of the upper wedge-shaped pressure receiving member 2a. 
Also, the following reactive force receiving means 5 is used in this 
embodiment. A reactive force receiving member 51 has support plates 54, 54 
fixed to a fixed plate 53 on both sides. A screw hole 55 is formed in a 
fixed plate 53. On end portions of similar four reactive force receiving 
rods 52 are pivoted about the upper and lower portions of each support 
plate 54 by pivot pins 57, 57, respectively. The other end portions are 
pivoted by pivot pins 58, . . . on both sides close to the thin end faces 
24 of the associated wedge-shaped pressure receiving members 2a, 2b. In 
this case, it is preferable that the reactive force receiving plate 51 is 
not fixed to the base plate 3. 
Also, the following temporary engagement means 8 is used in this 
embodiment. Vertical cutaway grooves 86 are formed at positions close to 
the thick end face 12 in the side wall 13 of the above-described 
wedge-shaped drive member 1. The similar cutaway grooves 87, 87 are formed 
in the side wall on the thin end face 24 side of the upper and lower 
wedge-shaped pressure receiving members 2a, 2b. Central portions of limit 
plates 88 are fixed to the above-described cutaway grooves 86 by suitable 
fastening means such as bolts 89. The upper and lower end portions of the 
limit plates 88 are engaged with the cutaway grooves 87, 87 of the upper 
and lower wedge-shaped pressure receiving members 2a, 2b to thereby limit 
the movement of the wedge-shaped drive member 1 relative to the upper and 
lower wedge-shaped pressure receiving members 2a, 2b. 
In this embodiment, the auxiliary wedge-shaped members 7, . . . are tapered 
with the slant surfaces 71, 71 on the upper and lower surfaces in the same 
manner as the above-described wedge-shaped drive member 1. The cutaway 
grooves 86, 86 are formed on both side surfaces 74, 74 on the thick end 
face 72 side in the same manner as described above. Accordingly, when the 
structure is jacked by using the wedge-shaped member 7, the 
above-described limit plates 88 are fixed to the cutaway grooves 86 of the 
auxiliary wedge-shaped member 7, and the upper and lower end portions 
thereof are engaged with the cutaway grooves 87, 87 of the upper and lower 
wedge-shaped pressure receiving members 2a, 2b for the temporary 
engagement. 
The other structure of the multistage jack apparatus according to the 
second embodiment is the same as that of the first embodiment. 
Accordingly, the same reference numerals are used to denote the same 
components. The duplication of explanation therefor will be avoided. The 
method for use is the same, and hence its operation will be omitted. 
However, if the slant angles of the slant surfaces 11, 21, 71 of the 
respective members are the same as that of the first embodiment, in this 
embodiment, even if the amount of shift of the wedge-shaped drive member 1 
by the push/pull drive means 6 is the same, the jack shift amount may be 
doubled. Also, in this embodiment, since the pressure receiving means 5 is 
not fixed to the base plate 3, if the horizontal drive force is applied to 
the structure A after the jack operation, it is possible to move the upper 
and lower wedge-shaped pressure receiving members 2a, 2b integrally 
together with the structure A along the upper surface of the base plate 3. 
Accordingly, this system may be used also to return, back to the original 
location, the structure A which has been replaced laterally due to 
earthquakes or the like. 
Another structure for the above-described temporary engagement means 8 may 
be used as shown in FIGS. 9 and 10. FIG. 9 shows a structure for 
preventing the return movement of the wedge-shaped drive member 1 and the 
auxiliary wedge-shaped members 7, . . . , in which engagement grooves 81 
are formed on both side surfaces 13, 13 of the wedge-shaped drive member 1 
and both side surfaces 74, 74 of each auxiliary wedge-shaped member 7, . . 
. . Engagement claws 84a are slidingly inwardly projected from openings 
83a formed in parts of the side plates 82, 82 formed upright on both sides 
of the base plate 3 and engaged with the engagement grooves 81. Here, the 
above-described engagement claws 84a are disposed to be slidable within a 
mount members 85 having a U-shape in cross section and having base 
portions fixed to the outer surfaces of the side plates 82. The structure 
of the engagement grooves 81 and the engagement claws 84a is as follows. 
After the wedge-shaped drive member 1 or the auxiliary wedge-shaped member 
7 is pushed by the drive rod 61 and the engagement grooves 81 reaches the 
position of the engagement claws 84a, the engagement claws 84a are 
projected by coil springs 84b interposed between the engagement claws 84a 
and the inner surfaces of the mount members 85. As a result, the 
engagement claws 84a are engaged with the engagement grooves 81. In this 
case, the steeply stepped portions 81a at the front edges of the 
engagement grooves 81a are retained at the engagement claws 84a. Also, in 
this condition, when the drive rod 61 is pushed to advance the 
wedge-shaped drive member 1 or the auxiliary wedge-shaped member 7, the 
tip ends of the engagement claws 84a are pushed outwardly by the gentle 
slant surfaces 81b of the engagement grooves 81 to thereby release the 
engagement. Inversely, in the case where the wedge-shaped drive member 1 
or the auxiliary wedge-shaped member 7 is withdrawn by the drive rod 61, 
operating shafts 84c which pass through the mount members 85 and which are 
fixed to the engagement claws 84a are withdrawn and the engagement claws 
84a are slidingly moved outwardly against the spring force of the coil 
springs 84b to attain the disengagement from the engagement grooves 81. 
In the temporary engagement means shown in FIG. 10, a through-hole 83b is 
formed in each of the above-described side plates 82, and an engagement 
pin 84d is detachably inserted from the outside into the through-hole 83b. 
The engagement pin 84d is inserted into one of single or a plurality of 
retainer holes 81c formed along the movement direction in the side wall of 
the wedge-shaped drive member 1 or the auxiliary wedge-shaped member 7 to 
thereby attain the prevention of return movement of the wedge-shaped drive 
member 1 or the auxiliary wedge-shaped member 7. 
With the thus explained multistage wedge-shaped jack apparatus according to 
the present invention, it is possible to jack up smoothly in safety, the 
heavy weight structure such as a bridge girder in the same manner through 
a small push/pull drive force as in the conventional jack apparatus and 
also to considerably increase the jack amount without increasing the 
overall length of the apparatus. 
Various details of the invention may be changed without departing from its 
spirit nor its scope. Furthermore, the foregoing description of the 
embodiments according to the present invention is provided for the purpose 
of illustration only, and not for the purpose of limiting the invention as 
defined by the appended claims nd their equivalents.