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Патент USA US3036826

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May 29, 1962
3,036,816
A. H._STUBBS ETAL
APPARATUS FOR LIFT-SLAB BUILDING CONSTRUCTION
Original Filed March 20, 1956
4 Sheets-Sheet 1
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May 29, 1962
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A. H. STU-BBS ETAL
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APPARATUS FOR LIFTWSLAB BUILDING CONSTRUCTION
Original Filed March 20, 1956
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4 Sheets-Sheet 2
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INVENTORS.
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May 29, 1962
A. H. STUBBS ETAL
3,036,816
APPARATUS FOR LIFT-SLAB BUILDING CONSTRUCTION
Original Filed March 20, 1956
4 Sheets-Sheet 3
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INVENTORS
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115mm 6. 117/250»;
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May 29, 1962
A. H.'STUBBS ETAL
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APPARATUS FOR LIFT~SLAB BUILDING CONSTRUCTION
Original Filed March 20. 1956
4 Sheets-Sheet 4
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4773211556;
United States Patent 0
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ICC
3,036,816
Patented May 29, 1962
1
2
3,036,816
bracing between successive slabs may be used to stiffen
the structure as the slabs are progressively lifted.
APPARATUS FOR LIFT-SLAB BUILDING
The foregoing and additional objects and advantages of
CONSTRUCTION
Allan H. Stubbs, 5543 Bradna Drive, Los Angeles 43,
the invention will be apparent from a consideration of the
Calif, and Howard G. Wilson, 2718 N. Beverly Glen 5 following detailed description of certain presently pre
Blvd., Los Angeles 24, Calif.
ferred embodiments thereof, such consideration being
Original application Mar. 20, 1956, Ser. No. 572,735.
given
also to the attached drawings in which:
Divided and this application Sept. 6, 1960, Ser. No.
FIGURES 1, 2, and 3 are sequential perspective views
53,938
illustrating successive stages of operation of the present
8 Claims. (Cl. 254-—89)
10
The present invention relates generally to building con—
struction and more particularly to a type of construc
tion known in the art as lift-slab construction.
method as employed in constructing a three-story build
mg;
FIGURE 4 is an enlarged elevational view taken
through one of the columns shown in FIGURES 1
This application is a divisional application of co-pend
through 3, the same being partially sectioned to show the
ing United States patent application, Serial No. 572,735, 15 method of connecting the lifting and bracing means to
entitled, “Method and Apparatus for Lift-Slab Building
the slabs;
Construction,” by Allan H. Stubbs, Edward K. Rice, and
FIGURE 5 is a bottom plan view taken on the line
Howard G. Wilson, ?led March 20, 1956, now aban
5-5 of FIGURE 4;
doned.
Lift-slab building construction is that in which a plu
rality of horizontal slabs forming the various ?oors and
the roof of a building are constructed of reinforced con
crete poured at ground level with one slab resting on top
of another and the slabs are thereafter lifted into their
FIGURE 6 is a top plan View taken on the line 6—6
of FIGURE 4;
FIGURE 7 is a fragmentary perspective view of a
clamping mechanism employed in the jack structure shown
in FIGURE 4;
FIGURE 8 is a semi-schematic diagram of a solenoid
appropriate positions in the ?nished building. The lifting 25 valve embodied in the lifting mechanism shown in FIG
of the slabs is customarily accomplished by placing an
URE 4;
hydraulic or other type of lifting jack on top of each of
FIGURE 9 is a semi-schematic elevational view of parts
a plurality of columns in the building structure, and pro
of the lifting jack shown in FIGURE 4;
viding each jack with a cross member and dependent ten
FIGURE 10 is a side elevational view of the parts taken
sion bars by which the slabs may be lifted by operating
on the line 10——10 in FIGURE 9; and
the jacks. This general method of construction is illus
FIGURE 11 is a semi-schematic circuit diagram illus
trated in Patent No. 1,006,436 to Pelzer.
trating the jack synchronizing system embodied in the
In practicing the lift-slab method of construction above
present invention.
described it is desirable that the operation of the various
Referring-?rst to FIGURES 1, 2, and 3, it will be
jacks, placed on top of the columns, be so synchronized 35 seen that the illustrated building construction includes a
It
foundation slab 20 poured at ground level, superimposed
is further desirable that means be provided in conjunction
with the tensile lifting members by which the same may
be held motionless while the jack is lowered to “take a
‘as to lift all portions of the slab at the same rate.
second and third floor slabs indicated at 21 and 22, re
spectively, and a roof slab illustrated at 23. The roof
slab may, if desired, be formed with integrally molded
40 beam portions shown ‘at 24. In accordance with con
new bite.”
' A still further desirable characteristic of the lift-slab
ventional practice, the slabs are separated by a bond
method is that in multiple stories where relatively tall
inhibiting layer such as tar paper.
EIn the present illustrative embodiment the slabs 21, 22,
for progressively stiffening the columns during the lifting
and 23 in the ?nished building are supported on four
45
and as the slabs are raised into place.
pipe columns 30, each of which is in turn supported on
With the foregoing general points in mind, it is a major
a subterranean pier 31 to which it is secured by means
object of the present invention to provide a system of
of a lower terminal ?ange 32 and studs 33 (see FIGURE
slab-lifting jacks which are synchronized to provide auto
4). The columns shown are conventional round pipe
matic operation at a uniform rate.
section,
although it will be realized that other cross-sec
It is a further object of the present invention to pro 50 tion shapes can be used as desired.
vide a system of the class described which does not re
A lifting collar 35 is embedded in each slab at each
quire continual manual adjustment of the various jacks
point where a colunm 30 passes therethrough. The collar
to provide the above-mentioned uniform and synchron
35 is provided with projecting ?anges 36 which are per
ous operation.
forated to receive tension members or lifting rods 38 and
It is a still further object of the present invention 55 39. The lifting rods 38 connect the uppermost slab 23 to
to provide in a system of the class described a plurality
the lifting jack to be described while the additional ten
of hydraulic jacks each of which is provided with its own
sion members 39 serve to interconnect sucessive slabs.
separate hydraulic system whereby a failure of the power
The interior openings are formed of such size as to provide
means leading from a central control point to the jack
substantial clearance around each column to avoid ‘fric
in question will not cause a failure of the jack itself. Such 60 tional resistance when the slab is later raised.
slender columns are employed, that means he provided
a system may be referred to as one which “fails safe.”
Yet a further object of the invention is to provide
a system of safety interlocks which prevent operation of
the lifting jacks in the event of a malfunction in the
holding or lifting means.
An additional object of the invention is to provide an
automatically operating tension member which is made
up of separable sections whereby the unused sections may
Additional diagonally ‘disposed interconnecting mem
bers 40 are employed to interconnect the spaced slabs.
The diagonal members 40 are temporary only and are
removed after the building has been completed, the tem
65 porary connection being effected by studs 41 embedded
at appropriate points in the slab.
In the case of the present illustration, additional tension
members to prevent sagging of the slabs at the points re
mote from the lifting columns are provided as shown at
be removed as the lifting progresses.
70 43.
A still further object of the invention is to provide a
The details of the lifting jack, designated generally at
lifting system of the class described wherein diagonal
49, are best seen in FIGURE 4. Here it will be seen that
3,036,816
4
3
Reciprocation of the jack piston 52 is accomplished by
a transversely extending jack base 50 is secured to the
upper end of each of the columns 30. On each base 50 is
means of a double-acting hydraulic pump comprising two
relatively small diameter pump cylinders 70 and 71 in
which pump plungers 72 and 73 operate (see FIGURES 4
and 10). The details of the hydraulic jack, per se, being
conventional, no further detailed description thereof is
deemed necessary herein.
Reciprocation of the pump plungers 72 and 73 is ef
mounted a conventional hydraulic jack cylinder 51, which
cylinder contains a vertical piston or ram 52 to the upper
end of which is secured a crosshead 53. The horizontal
extent of the crosshead 53 is such as to project well be
yond the sides of the column 30. The jack base 50 is in
parallel alignment with the crosshead 53 and of equal
fected by means of a rocker arm 74 fulcrumed at 75 on
horizontal extent.
Adjacent the outer ends of the crosshead 53 and the 10 an upstanding pillow block 76 and connected to the plung
ers 72 and '73 by connecting links 77 and 78. The rocker
jack base 50 are mounted gripping mechanisms 54, the
arm 74 is provided with an outwardly extending lever 80,
details of which may be seen in FIGURE 6. The oper
the outer end of which is pivotally secured to a piston rod
ative members of the gripping mechanisms comprise a
81 of a reciprocating air motor indicated generally at 82.
pair of jaws 55 and 56 which are urged toward each
other by compression springs 57. The jaw members 55
15 To provide for the swinging movement of the lever 80
and 56 are slidably supported in lateral track members 59
for transverse guided sliding movement on the top sur
face of the crosshead 53 (see FIGURE 7). The com
pression springs 57 are anchored against the rear edge of
about the fulcrum 75, the lower end of the air motor is
pivotally secured to the jack base 50 as indicated at 83.
The air motor 82 is of more or less conventional design
including a reciprocating piston 87 within the cylinder 84
which is driven back and forth between the ends of the
one of the jaws 55 and exert a closing force on the other
cylinder by air admitted alternatively to one end or the
jaw 56 by means of tension rods 58 which extend through
other of the cylinder under the control of an electrically
loosely ?tting transverse apertures in the jaw 55 and are
actuated valve 85. Air under pressure is supplied from
secured to the jaw 56.
a conventional source (not shown) by ?exible conduit 86
The jaws 55 and 56 are formed with adjoining semi
circular recesses which together form an oval-shaped aper— 25 and under the control of the valve 85 is admitted either
directly from the valve 85 at the lower end of the cylinder
ture 59a through which passes the lifting rod or tension
84 or through an interconnecting pipe 86 to the upper
member 38. Secured to the crosshead 53 and to the jack
end of the cylinder 84.
base 50 below each aperture 59a is a tubular guide 591;
While various types of electrically actuated valves are
which aligns the lifting rod 38 with the aperture 59a.
As can be seen in FIGURE 4, each of the lifting rods 30 suitable for controlling the operation of the air motor 82
one suitable form is illustrated schematically in FIGURE
38 is formed with a succession of spaced enlargements
8. Here it will be seen that air under pressure admitted
through a pressure manifold 90 is selectively directed to
either of two cylinder conduits 91 or 92 by the longitu
upwardly through the gripping mechanism 54 the jaws 55
and 56 are separated by the engagement of the frusto 35 dinal movement of a valve spool 93 mounted in the bore
60, the upper ends of which are frusto-conical as shown at
61. Thus it will be seen that as a lifting rod 38 is pulled
94 of the valve. The bore 94 extends beyond the ends
conical portion 61 to open the jaws and permit the passage
of the spool 93 whereby to form actuating chambers 95
of the largest diameter of the enlargements 60. As a
and 96 adjacent the opposite ends of the valve spool 93.
particular enlargement 60 passes the plane of the jaws
Air under pressure is delivered to the actuating cham~
55 and 56 the later are snapped together by the action of
the compression springs 57 and thus underlie the en 40 bers 95 and 96 through passageways 97 and 98, respec
tively, each of which is provided with a ?ow restrictor 99.
largement 60 to prevent relative downward movement
Air may be released from either of the actuating cham
of the lifting rod through the gripping mechanism.
bers 95 or 96 by opening a solenoid-operated pilot valve
From the foregoing description it will be appreciated
100 or 101, respectively. Release of air from either of
that as the crosshead 53 is moved upwardly by operation
of the jack piston 52 the gripping mechanisms 54 at the 45 the chambers 95 or 96 permits the pressure in the oppo
site chamber to move the valve toward the chamber from
ends of the crosshead 53 engage the overlying enlarge
which air is released.
The construction and operation of the spool 93 is con
ventional and is shown in full line position in which
mechanisms on the jack base 50 engage the rods 38 and
prevent downward movement thereof while the gripping 50 pressure is delivered to the cylinder port 92 while at the
same time the cylinder port 91 is connected to an exhaust
mechanisms on the crosshead 53, during the downward
port 102. Moving of the spool 93 to the position 93’,
movement thereof, will automatically open and pass over
shown in dotted line, reverses the operation, as shown by
the successive enlargements on the rods 38. Thus it will
be seen that vertical'reciprocation of the jack piston 52
the dotted arrows delivering pressure from the manifold
98 to the'cylinder port 91 and exhausting the cylinder
will automatically engage the rods 38 in a ratchet-like
ments on the rods 38 and exert tension on the rods. Con
versely, when the crosshead 53 is lowered, the gripping
operation and incrementally lift the slab 23 to which the
lower ends of the rods 38 are secured.
port 92 through the exhaust port 102.
It will ‘be appreciated that the construction of the valve
As the above-described operation continues and the slab
shown in FIGURE 7 is such that once the spool 93 has.
is lifted by the rods 38, it will be seen that the latter
been moved to one or the other of its alternate positions
extend a greater and greater distance above the jack 49 and 60 it will remain in such position until the appropriate pilot
that such upwardly projecting portion is unsupported
valve 100 or 101 is opened to cause movement of the
against bending. Where the structure in question is only
one or two stories in height the extended, unsupported
rods are stiff enough to stand without bending. Where
the rods exceed the length of two stories, however, they
may tend to bend when standing alone. Also, the greater
lengths are awkward to handle.
Accordingly, the rods 38 employed in the present illus
spool to its other position.
The air motor cylinder 84 is shown schematically in
FIGURE 8 and it will be seen that the opposite ends are
shown connected to the cylinder conduits 91 and 92
whereby the introduction of air under pressure at one
end or the other of this cylinder 84 causes the piston 87
therein to move in one ‘direction or the other, the air on
the opposite side of the piston being exhausted through
threaded joints formed by boring and internally thread 70 the appropriate port as previously described.
From the foregoing description it will be apparent that
ing a terminal enlargement 60 as shown at 39a and form
tration are each made up of several sections having
ing an externally threaded extension 3917 on the end of
the air motor piston 87 is reciprocated back and forth in
the adjoining rod section. Thus the portions of the rod
the cylinder 84 by alternatively opening the pilot valves
above the jack 49 may be unscrewed and removed as the
lifting proceeds, as may best be seen in FIGURES 7 and 9. "
opened only momentarily for a su?icient time to release
100 and 101.
It is to be noted that these valves are
5
3,036,816
air from the associated actuating chamber £95 or 96. Due
to the restriction 99 in the pressure delivery passages 97
and 98 air under pressure is not replaced in the actuating
chamber therein so long as the pilot valve of such cham
ber is open.
Once the valve spool 93 has moved to its appropriate
position and the pilot valve causing such motion is there
after closed, the building up of equal pressure in both of
6
ing stud 112 on which is mounted a multi-lobed cam 113
arranged parallel to the slot 111 and on the opposite side
of the plate 110 from the jack 49‘. A relatively short
guide stud 114 is mounted on the lower end of the cam
113 and extends into the slot 111 to maintain the cam
in a vertical position as it is moved by the jack piston 52
and the crosshead 53.
As can be seen in FIGURE 9, one edge of the cam 113
the actuating chambers causes no return movement of the
is provided with a plurality of sinusoidal cam lobes 115
spool 93. Thus, once the pilot valves 1011 or 101 is 10 which are of uniform height and are uniformally spaced
pulsed, the valve spool 93 moves to the appropriate posi
tion causing the motor piston 87 to move to one end of
the cylinder 84 where it remains until the valve spool 93
is actuated in the opposite direction.
As previously described, the air motor 82 is double
acting since it is connected to two alternately operating
pump plungers 72 and 73. Thus, each stroke of the pis
ton 87, irrespective of direction, causes a power stroke of
a pump plunger, thus raising the jack piston 52 by a small
increment. Due to the relatively high mechanical advan
tage of the jack employed herein, the incremental move
ment of the jack piston 52 in response to a single stroke
of the air motor 84 is on the order of %4 of an inch.
The total stroke of the jack piston 52 from its lower
most position to its uppermost is on the order of 6 inches.
along the length of the cam 113. A single pole, single
throw, snap-action switch 116 is mounted on the front
of the plate 110 and has an actuating lever 117 with a
terminal roller 118 in contact with the operative edge of
the cam 113.
The adjustment of the switch 116 is such that the
switch is changed from one of its positions to the other
each time the roller passes a. point halfway between the
lowest dwell and highest rise on the cam. In the present
illustrative embodiment the total jack stroke of 6 inches
is divided by the cam into 12 equal increments, each of
which is Well below the maximum difference in elevation
that can safely exist between adjacent lift points in the
slab during lifting.
Adjacent the upper end of the slot 111 is a single pole,
single throw, normally closed ‘limit switch 1151 having an
lifting rods 38 is somewhat less than the full stroke of the
actuating button 1211 positioned to be engaged by the
jack whereby proper engagement of the jack with one of
upper end of the cam 113 when the cam reaches the upper
the enlargements 60 at each stroke of the jack is assured.
of its travel, As will be described, the purpose of
From the foregoing description, it will be realized that 30 limit
the limit switch 119 is to render the jack inoperative upon
there is bound to be some variation in the speed with
reaching the upper end of its stroke.
which various air motors in any system operate. For
The jack synchronizing circuit is illustrated in FIG
example, the load to be lifted may vary from point to
URE 11, which is a schematic block diagram in which
point over the area of the slab or there may be variation
the location of parts on the drawing is not necessarily
in the friction losses in the compressed air conduits as 35 the actual physical arrangement of the parts in the system.
between jacks close to and remote from the pressure
Electric power to operate the system is provided in a
source.
conventional power supply 120, the main output of which
It is also apparent that a slab of concrete must be lifted
is a power bus ‘121 which in the present instance is at
at the same rate at all points if destructive stresses are
28 volts above ground, the other side of the power output
to be avoided. Accordingly, synchronized operation 40 being grounded as indicated at 122. Power from the
within relatively close tolerances of all jacks is essential
supply 120 is also delivered to a square wave generator
to successful operation of the lift-slab method
125. The square wave generator is of conventional de
Before proceeding to a detailed description of the cir
sign and circuitry, being adapted to deliver two square
cuit means by which the operation of the various jacks
Wave pulse signals denominated herein as the “odd” and
is synchronized, it is well to consider brie?y the general 4:5 “even” pulse signals which appear on output conductors
The longitudinal spacing of the enlargements 611 along the
principle employed. The total stroke of the jack piston
52 is divided into equal increments, in the present instance,
twelve. interconnecting means are provided in the con
trols of the various air motors 82 whereby each jack stops
upon reaching the end of the ?rst increment of upward
movement and remains stationary until all of the remain
ing jacks have reached the end of the ?rst increment of
motion, whereupon the air motors 82 automatically all
start operating again. The ?rst jack to complete the
second increment of motion again pauses until the re
maining jacks reach the end of the second increment,
whereupon all jacks again move into the third increment
and so on. The system is illustrated by showing only
four jacks, designated No. 1, No. 2, No. 3, and No. 4,
126 and 127, respectively.
The odd and even pulses are in 180° time displace
ment, as indicated graphically at 128 and 129‘ in the
‘ drawings. The odd and even pulse signals are delivered
to odd and even pulse relay coils 130‘ and 1311 so as to
energize the respective relay coils upon the occurence of
each pulse in the signal.
The actuating coils of the pilot valves 1410 and 161
previously described are indicated by those respective ref
erence characters in FIGURE 11. The coil of pilot valve
1120 is energized each time the pulse relay 13-1 is ener
gized, closing the contacts 132, thus to deliver power from
the bus 121 through a conductor 133 to the coil 100 and
thence to ground. It will be noted that except ‘as the
but it will be realized that any number of jacks can be 60 even pulse signal may be interrupted by opening the
synchroized by means of the system to be described.
For purposes of the discussion to follow the successive
strokes of each air motor are designated as “odd” and
limit switch 119, which is interposed in the conductor
133, even pulses are continuously delivered ‘to the coil
100.
'
“even” strokes, all those in a given direction being “odd”
As previously stated, it is desired to interrupt the
and all those in the opposite direction being “even.”
63 Or operation of each jack upon its reaching the end of a
The above-described synchronization is effected by a
given increment of motion (unless it is the last jack to
series of cam-operated switches, one operatively connected
reach the end of such increment). Such control is effected
to each of the jacks 49. The construction and arrange;
by interrupting the odd pulse signal delivered to. the
ment of these switches and their operating cams is illus
coil of the pilot valve 101. It will be appreciated that
trated semi-schematically in FIGURES 9 and l0.
70 all that is required to interrupt the operation of the air
On each of the jack bases 50 is secured an upstanding
motor is‘ to interrupt one of the two pulse signals de
?at plate 110, which plate is provided with a central slot
livered to the pilot valves associated with such jack.
111 which is parallel and co-extensive with the move
The continued even pulse signal, which is delivered to a
ment of the jack piston 52. Secured to the crosshead
given jack, will be ineitective to produce any operation
53, and extending through the slot 111, is a cam mount 75 unless the even pulses are interspersed with odd pulses
3,036,818
7
139 and a normally closed manual switch 154 to com—
cylinder 84.
plete a circuit from the power bus 121 through the pulse
bus selector relay coil 139 to ground.
Thus, it will be seen that as the jacks successively
reach the end of their ?rst increment of motion, actuat
ing their respective interlock switches 116, the contacts
145 are successively closed, completing the above-de
The cam-actuated interlock switch 116 is a single pole,
single throw switch which, as shown in FIGURE 11,
is arranged to interrupt a circuit from the power bus
121 through a relay coil 135 denominated herein the
“interlock relay.” As will be described, energization
of the interlock relay 135 or conversely, de-energization
thereof, serves to interrupt the operation of the air motor
by interrupting the odd pulse signal delivered to the pilot
scribed series circuit upon closure of the last pair of con
10
valve coil 101.
The odd pulse signal produced by closure of the con
tacts 136 each time the coil 130 is energized, is de
livered selectively through contacts 137 or 138 of a pulse
bus selector relay, the coil of which is shown at 139 in 15
FIGURE 11. Since one of the two pairs of contacts 137
and 138 is normally open and the other is normally closed,
it will be appreciated that when the coil 139 is energized,
the odd pulse signal is delivered through a conductor
8
normally closed pair of contacts 150 of the selector relay
so as to return the piston 87 to the other end of the
tacts. Completion of this circuit energizes the pulse bus
selector relay coil 139, which, as earlier described, op
erates the contact pairs 137 and 138 and switches the
odd pulse signal from the “B” pulse bus to the “A” pulse
bus. This operation, as previously described, serves to
re-start all of the air motors by switching the pulse signal
to the bus to which each coil 101 is now connected, (the
contact pairs 144 now being closed).
Energization of the pulse bus selector relay 139 also
serves to open its normally closed contacts 150 and close
140 to an “A” pulse bus 141 whereas when the coil 139 is 20 a pair of normally open contacts 151 to provide “look
ing” current, as will be described. Opening of the nor
de-energized, the odd pulse signal is delivered to a “B”
mally closed contacts 150 breaks the series circuit and
bus 142. Thus the odd pulse signal is present on only
thus momentarily interrupts the current to the pulse bus
one of the two buses 141 and 142, the selector relay
selector relay 139. In order to maintain the energization
139 alternately transferring the connection, as will be
of the coil 139 for a sufficient time to cause the contacts
25
described.
151 to become closed to lock the relay a condenser 15?.
The odd pulse present on one of the buses 141 or 142,
is connected across the coil 139.
for example the “A” bus 141, may reach the coil 101
only when the appropriate one of two pairs of contacts
143 and 144 of the interlock relay is closed.
As can be seen in FIGURE 11, the interlock relay is
alternately energized and de-energized by the operation
of the interlock switch 116 operated by the cam 113 as
the jack moves upwardly. Thus, the contacts 143 and
144 are each successively closed and opened in alternate
The respective contacts 146 of the several interlocking
relays 135 are, as shown in FIGURE 11, connected in
parallel and form with the locking contacts 151 a parallel
series circuit delivering power from the power bus 121
to the pulse bus selector relay coil 139. Thus, it will be
seen that so long as any one of the contacts 146 is closed,
current is delivered to the pulse bus selector relay and
time phase whereby to connect the coil 101 through the
the odd pulse signal remains connected to the “A” pulse
conductor 145 alternately to the “A” bus or the “B” bus.
It will be seen that assuming the signals to be reaching
bus.
Throughout the second increment of travel of any
particular jack, the parallel contacts 146 associated with
the coil 101 through the appropriate pulse bus 141 or
such jack remain closed. With a jack reaches the end
142 and the appropriate pair of contacts 143 or 144, a
change in the then condition of the interlock relay 135 40 of its second increment of travel the interlock switch 116
is again opened, de-energizing the relay 135 and, among
will interrupt the pulse signal to the coil 101 until the
other things, opening the associated contact pair 146.
pulse signal is again transferred from one of the buses
When all of the contacts 146 have been opened, the above
1411 and 142 to the other.
mentioned parallel-series circuit is broken and the pulse
The pulse bus selector relay 139 is operated in response
bus selector relay 139 is de-energized, transferring the odd
to the relative positions of the various jacks in respect
pulse
signal from the “A” bus back to the “B” bus.
to their movement in a particular increment of motion.
Therefore, as was the case in the ?rst increment of
As previously described, each of the jacks in a system
motion of the jacks, each jack pauses upon reaching the
embodying the present invention is provided with a cam
end of the second increment due to the fact that the
actuated switch 116 and its associated relay 135. Each
de~energization of the interlock relay 135 again transfers
of the relays 135 operates four pairs of contacts, to-wit:
the connection of the coil 101 to the pulse signal bus
the two signal selector pairs 143 and 144 previously de
upon which no signal is then present. By the time the
scribed and additionally two pairs of contacts for con
last jack has reached the end of its second increment
trolling the operation of the pulse bus selector relay, the
of travel, however, the signal is transferred to the bus to
latter two pairs being designated at 145 and 146, respec
which all coils ‘1011 are now connected, whereupon all
tively, in FIGURE 11.
jacks again start to operate. The sequence of operations
Inasmuch as many of the circuit elements associated
at the end of the third increment of jack travel correspond,
with a particular jack are merely duplicated with respect
of course, to those of the ?rst increment of travel where
to the other jacks, such duplicated circuit elements have
fore the jacks continue their synchronized movement until
not all been repeated in the drawings. The elements
included within the phantom outline 147 are all of those 60 they all reach the tops of their respective strokes.
When any jack reaches the uppermost limit of its stroke,
associated with jack number 1 of the four jacks illustrated
the cam 113 engages the normally closed limit switch 119,
in the present embodiment, and it will be understood that
breaking the circuit through the conductor ‘133 to the
the equivalent circuit arrangement containing the same
coil 100. Such jack then becomes inoperative until the
elements is duplicated for each of the other three jacks,
as indicated schematically by the phantom outline 148.
65 crosshead therein is lowered to its starting position, per
mitting the switch 119 to close.
Two of the pairs of contacts actuated by the interlock
During the initial adjustment of the jacks before the lift
relay 135 are concerned in the control of the pulse bus
ing operation starts, and also at the end of the lift, it may
selector relay 139 and for this reason these contacts for
be desirable to operate one or more of the jacks inde
each of the four jacks have all been shown in the draw
ings, are identi?ed by the reference characters 145 and 70 pendently of the others. In the course of such operation,
it is sometimes desirable to change the mode of the pulse
146, and additionally by the designation K-li, K-Z, K-3
bus
selector relay, that is, to change it from its then con
and K-4, identifying the same with jacks No. 1, No. 2,
dition to the opposite condition, whereby to transfer the
No. 3 and N0. 4, respectively.
signal from the “A” bus to the “B” bus, or vice versa.
The contact pairs 1415 for the respective jacks K-1,
K-2, K-3 and K-4 are all connected in series with a 75 To accomplish this result, the two manually operable
3,036,816
10
switches 153 and 154- »are provided. By opening the
normally closed switch 154, the pulse bus selector relay
coil is de-energized, permitting the contact pairs 1317, 138,
release valves (not shown), lowering the slab slightly onto
the just-mentioned abutments. The lifting operation iS
now complete and all tension members, jacks, etc. may
150 and 151 thereof to return to the position shown in
be removed.
full line in FIGURE 11. Conversely, closure of the nor C1
It will be realized that the just-described method is
mally open switch 153 energizes the coil 1391 and moves
particularly adapted for the lifting of multi-story slabs
the contact pairs 137, 138, 150 and 151 to the positions
in that the relatively long and slender columns 30 are
opposite those shown in FIGURE 11.
progressively stiffened as added load is applied thereto.
When all of the jacks have completed their full stroke,
This sti?ening is particularly effective, since the diagonal
conventional ?uid release valves in the jacks are opened 10 interbracing of the slabs at substantial spacing from each
to permit the jack piston 52 land the crosshead ~53 to
other provides an effective guide to prevent bowing or
descend to its starting position so ‘as to take a “new bite”
lateral bending of the columns 30.
on the lifting rods 33. As a safety feature, it is, of course,
While the method and apparatus hereinabove described
highly desirable that the jacks be prevented from descend
is illustrative of the invention is ‘fully capable of achiev
ing if the lower gripping mechanisms 54, mounted on the 15 ing the objects and providing the advantages hereinbe
ends of the jack base 50‘, are not properly closed. Accord
fore stated, it will ‘be realized that both the method and
ingly, the fluid release valves of the jacks 49‘ are sole
the apparatus are capable of considerable modi?cation
noid-operated under the control of a normally closed
withoutv departure from the spirit of the invention. For
safety switch 160, mounted adjacent the jaw 55 of the
this reason we do not mean to be limited to the forms
lower gripping mechanisms. Thus, if either of the jaws 20 shown and described, but rather to the scope of the ap
55 is opened, the circuit through the switches 160 is
pended claims.
broken and it is impossible to open the ?uid release valve
What is claimed is:
in the jack in question.
1. Apparatus for constructing lift-slab structures com
All of the foregoing control circuit elements, except
prising: a plurality of jacks adapted for connection to a
the cam-operated switches 116 and the limit switches 119, 25 lift-slab at horizontally spaced lift points therein; a motor
are located in a central console (not shown) from which
connected to each of said jacks to operate the same, each
three conductor signal cables radiate to each of the jacks.
motor ‘being adapted to operate in response to a signal and
The three conductors of each signal cable, it will be
stop when said signal is interrupted; a signal generator;
realized, are those shown in FIGURE 11 as connecting
a signal conductor for each motor connecting the same to
the elements in the upper part of the area 147 with 30 said signal generator; a signal interrupter interposed in
those in the lower part thereof.
each conductor; and an actuator ‘for each interrupter,
The details of construction and some of the operations
said actuator being carried by a moving portion of the
of the invention having been described, the overall op
jack operated by its corresponding motor, said actuators
eration of lifting the three slabs shown in FIGURE 1
being adapted to actuate their respective interrupters and
into their appropriate positions in the ?nished building 35 interrupt said signal and stop when said motor upon
may now be described. The initial steps of pouring the
said jack reaches the end of a given increment of lifting
slabs into their superimposed positions shown in FIG
movement, said increments for all of said jacks being
URE 1 are conventional and need not be described in
equal whereby to prevent any lift point in said slab be—
detail herein. Su?ice it to say that some separatory
ing lifted higher than another ‘by more than said incre
medium such as tar paper or lacquer is applied to the inter 40 ment.
.
faces between the successive slabs so that they may be
2. For use in raising lift-slabs, a system of synchro
separated during the lifting operation.
nized jacks comprising: a plurality of jacks adapted for
Also it will be noted that at the time the slabs 241,
connection to a lift-slab at a plurality of spaced lift
22, and 23 are poured, nuts or other similar fastening
points; a plurality of motors, one for each jack, and con
members 19 are embedded in the concrete under the aper 45 nected thereto to operate the same, each motor being
tures in the collars 35, so as to receive the threaded ends
adapted to operate in response to a signal and stop when
of the lifting rods I38 or other tension members 39'.
said signal is interrupted; a signal generator; a plurality
When the slabs have been cured to reach their full
of ?rst signal conductors, each connecting said generator
strength, the lifting operation is commenced by connect
with a different one of said motors; a plurality of ?rst
ing the lifting rods 3% to the roof slab 23‘- and to the 50 signal interrupters, one interposed in each of said ?rst
jacks 49 mounted on the top of the columns. The lift
conductors; a plurality of actuators for said ?rst inter
ing of the roof slab 23 then commences and continues
rupters, one carried by a moving portion of each of said
as previously described until the spacing between the two
jacks, each of said actuators being operatively associated
slabs 22 and 23‘ is equal to that which will be obtained
with the corresponding one of said interrupters to actuate
in the ?nished building. At this point, the lifting oper 55 the latter and interrupt said signal to stop said motor on
ation is interrupted and interconnecting rods 39' and t3
and diagonal braces 4,0 are secured between the slabs 22
and 26 as previously described. In this connection, it
will be noted that the tension members 43 are attached
to the upper slab at the apex of the inverted beam 24 60
said jack reaching the end of a given increment of lifting
movement, said increments for all of said jacks being
equal whereby to prevent any lift point in said slab from
being lifted higher than another by more than said in
crement; a plurality of second signal conductors, motors
to the slab 22.
and each being independent ofsaid ?rst interrupters; a
plurality of second interrupters, one interposed in each
whereby to transfer the stiffening effect of the beam 24
The interconnections having been made as just de
of said second conductors and in normally open condi
tion; and means connecting said actuators to said second
continued until the slab 22 is at its appropriate spacing 65 interrupters to close the same upon the associated jack
from the slab 21, at which time the lifting operation is
reaching the end of said increment whereby said motors
scribed, the lifting operation is again commenced and
again interrupted. Interconnecting members 39, 43 and
' are all connected to said second conductor when said
diagonal braces 40 are now connected between the slags Z1
jacks all reach the end of said ?rst increment; and signal
and 22 and the lifting operation reactivated until the
transfer means interposed between said generator and
slabs 21, 22 and 23 all reach their ?nal position. At this 70 said conductors and adapted to transfer said signal from
point the lifting operation is stopped with the slabs pref
said ?rst conductor to said second conductor when all
erably positioned slightly above their ?nal position in the
of said jacks have reached the end of said ?rst increment
building, and suitable abutments are welded to the col
of movement.
umns 30 ‘below each of the collars 35. Each of the jacks
3. Apparatus for constructing lift-slab structures com
may then be released through the operation of manual 75 prising: a plurality of slab-lifting jacks, each adapted to
3,036,816
11
be supported on top of a column in a lift-slab building
and having tension means adapted to be secured to a
slab to be lifted at a lift point adjacent the base of said
column; a plurality of motors, one for each jack and
connected thereto to operate the same, each motor be
ing adapted to operate in response to a signal and stop
when said signal is interrupted; a signal generator; a plu
rality of separate signal transmission means, each con
conductors whenever all of said jacks reach the end of
a particular increment of travel.
6. In a lift-slab apparatus of the type having a plu
rality of horizontally spaced jacks connected to a hori
zontal slab to lift the same by said jacks acting in unison,
control means for synchronizing the operation of said
jacks comprising in combination: a plurality of motors,
one connected to operate each jack, said motors each
being adapted to operate during the application of a
tors; a plurality of signal interrupters, one interposed in 10 signal thereto and to remain inoperative in the absence
of said signal; a plurality of separate actuator means each
each of said transmission means; and a plurality of actu
carried by one of said jacks and moved between alternate
ating means for said interrupters, one carried by a mov
?rst and second positions con-responding to alternate
ing portion of each of said jacks, each of said actuating
successive increments of lifting movement of said jacks,
means being operatively associated with a correspond
ing one of said interrupters to actuate the latter and in 15 said increments ‘as to all jacks corresponding in number
and size; a ?rst group of circuit interrupters, each actu
terrupt said signal to stop said motor upon said jack
ated by a respective one of said actuator means and nor
reaching the end of a given increment of lifting move
mallyrclosed when said actuator means is in said ?rst
ment, said increments for all of said jacks being equal
position open when the same is in said second position;
whereby to prevent any lift point in said slab being lifted
a second group of circuit interrupters, each actuated by
higher than another by more than said increment,
necting said generator with a different one of said mo
4. Apparatus for constructing lift-slab structures com
prising: a plurality of slab-lifting jacks, each adapted
to be supported on top of a column in a lift-slab building
and having tension means adapted to ‘be secured to a slab
to be lifted at a lift point adjacent the base of said
column; a plurality of motors, one for each jack and
connected thereto to operate the same, ach motor being
adapted to operate in response to a signal and stop when
said signal is interrupted; a signal generator; a plurality
a respective one of said actuator means and normally
open vwhen said actuator means is in said ?rst position
and closed when the same is in said second position; a
signal generator; a ?rst signal conductor connected to
all of said motors through the respective interrupters
of said ?rst group; a second signal conductor connected
to all of said motors through the respective interrupters
of said second group; and signal transfer means respon
sive to ‘the positions of said actuators to apply the signal
of separate signal transmission means, each connecting 30 from said generator to said ?rst conductor during said
?rst increment of motion and to transfer said signal to
the conductor to which it is not then applied each time
all of said jacks reach the end of a particular increment
of said transmission means; a plurality of actuating means
of motion.
for ‘said interrupters, one carried by a moving portion
of each of said jacks, each of said actuating means being 35 7. The apparatus of claim 6 further characterized in
that said signal transfer means includes: a third group
operatively associated with a corresponding one of said
of circuit interrupters, each actuated by a respective one
interrupters to actuate the latter and interrupt said signal
of said actuator means and normally open when said
to stop the associated motor upon the associated jack
actuator means is in, said ?rst position and closed when
reaching the end of a given increment of lifting move
ment, said increments for ‘all of said jacks being equal 40 the same is in said second position; a fourth group of
circuit interrupters each actuated by a respective one of
whereby to prevent ‘any lift point in said slab being lifted
said actuator means and normally open when said actu
higher than another by more than said increment; and
ator means is in said ?rst position and closed when the
lift reinst-ituting means comprising a plurality of ele
same is in said second position; relay means adapted
ments, one operatively associated with each of said actu
whene energized to effect transfer of said signal from
ating means to be actuated upon said associated jack
said ?rst conductor to said second conductor, a circuit
reaching the end of said increment, all said elements
including all of said third group of interrupters con
being interconnected to re-establish said transmission
nected in series to energize said relay means when all
means and start all of said motors when all of said jacks
interrupters in said third group are closed; and a holding
have reached the end of said increment.
5. For use in raising lift-slabs, a system of synchronized 50 circuit for said relay means including ‘all of the inter
rupters in said fourth group connected in parallel to
jacks comprising: a plurality of jacks adapted for con
maintain energization of said relay means until all inter
nection to a lift-slab at a plurality of spaced lift points;
rupters of said fourth group are opened.
a plurality of motors, one connected to each jack to
said generator with a different one of said motors; a
plurality of signal interrupters, one interposed in each
operate the same, each motor being ‘adapted to operate
its respective jack in response to a signal applied thereto
and to stop upon interruption of said signal; a signal
generator; a pair of signal conductors; ?rst signal trans
fer means adapted to apply said signal from said gen
8. In lift-slab apparatus of the type having a plurality
of horizontally spaced jacks connected to a horizontal slab
to lift the same by said jacks acting in unison, control
means ‘for synchronizing the operation of said jacks com
prislng in combination: a plurality of motors, one con
nected to operate each jack, said motors each being adapt
ductors; a plurality of second signal transfer means, one 60 ed to operate during the application thereto of an electric
signal and to remain inoperative in the absence of said
for each of said motors and each adapted to connect its
erator selectively to one or the other of said signal con
slgnal; a plurality of separate switch actuator means, each
carried by one of said jacks and moved between alternate
?rst and second positions corresponding to alternate suc
ments, one for the motor of each jack, each element being
connected to 1a respective one of said second transfer 65 cessive increments of lifting movement of such jacks, said
increments as to all jacks, corresponding in number and
means whereby to effect said transfer of said motor con
size; a ?rst group of single pole, two-position switches,
nection when said element is actuated; a plurality of
each actuated by a respective one of said actuator means
actuators, each carried by a moving portion of a respec~
and closed when said actuator means is in said ?rst posi
tive one of said jacks and adapted and connected to
actuate the respective synchronizing element of such 70 tion; a second group of single pole, two-position switches,
each actuated by a respective one of said actuator means
jack upon said respective jack reaching the end of a
and normally open when said actuator means is in said
given increment of lifting movement; and signal control
?rst position; a signal generator; a ?rst signal bus connect
means operatively connected to all of said actuators
‘and to said ?rst signal transfer means to actuate the
ed to all of said motors through the respective switches
latter to transfer said signal from one to the other of said 75 of said ?rst group; a second signal bus connected to all of
respective motor selectively to one or the other of said
conductors; a plurality of actuatable synchronizng ele
3,036,816
13
said motors through the respective switches of said second
group; and a signal transfer relay having an operating
coil and adapted to apply the output of said signal gen
erator to said ?rst signal bus when said operating coil
is de-energized and to said second signal bus when said 5
coil is energized; a third group of normally open switches
connected in series, each adapted to be closed by a respec—
tive one of said acutator means upon the corresponding
jack reaching the end of the ?rst increment of travel;
powered means for said relay coil ‘connected through said 10
third group of ‘switches whereby to energize said coil
when all of said jacks have reached the end of said ?rst
increment of travel; and locking means for said relay
coil comprising a pair of locking contacts closed by said
relay when energized and a plurality of switches connected 15
in parallel with each other and in series with said locking
14
contacts, each said last switch being adapted to be closed
by a respective one of said switch actuating means when
the latter is in said second position whereby to maintain
the signal in said second ‘bus until all jacks have reached
the end of the corresponding increment of travel.
References Cited in the ?le of this patent
UNITED STATES PATENTS
1,147,080
Dunlap et a1 ___________ __ July 20, 1915
1,327,611
1,398,822
1,454,088
2,655,223
2,758,467
2,867,111
2,975,560
Burns et a1. __________ __ Jan. 13,
Wilson ______________ __ Nov. 29,
Thrift ________________ __ May 8,
Villars ______________ __ Oct. 13,
Brown et a1 ___________ __ Aug. 14,
Youtz _________________ __ Jan. 6,
Leonard _____________ __ Mar. 21,
1920
1921
1923
1953
1956
1959
1961
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