JP5580564B2 - How to remove slack when lifting with a jack - Google Patents

Description

In the present invention, when a long heavy object is lifted using a large number of suspension cables, for example, 12 lifting jacks each having eight suspension cables as one unit are installed and one long heavy object is removed. a slack Installing way method during lifting jack type to be used when lifting up a higher position more than a few 100 m, in particular, rapidly, and performed safely slack eliminating lifting work early plurality of suspension cables It is for the purpose.

  Various types of lifting devices using jacks are known. One of them is a multi-wire system using a number of PC steel suspension cables 11 as shown in FIG. In this apparatus, a jack chair 13 is placed on a fixed base 12, and a center hole jack 21 through which a plurality of suspension cables 11 are inserted is fixedly installed on the jack chair 13. In the jack chair 13, a repositioning side holding device 16 comprising an anchor head 14 and a plurality of lower grippers 15 divided in three is installed, and the ram 17 is moved up and down in the cylinder 20 of the center hole jack 21. A pull-in side holding device 24 composed of a plurality of upper grippers 23 divided into a pooling head 22 and a trimmer is attached to the upper end of the ram 17.

  In such a configuration, one suspension cable 11 is inserted into each upper gripper 23 of the pull-in side holding device 24 and each lower gripper 15 of the refilling side holding device 16, and the lower end is suspended from the load 10. It sticks to. When pressure oil is sent to the feed side hydraulic port 18 in this state, the ram 17 rises and the oil is returned from the return side hydraulic port 19 side, so that the pooling head 22 of the pull-in side holding device 24 is pushed up. Then, the suspension cable 11 is gripped by the upper gripper 23 and the suspended load 10 is lifted.

  Here, when the lifting distance L from the gantry 12 to the suspended load 10 is several hundreds of meters, different slacks are generated in each of the plurality of suspended cables 11. The load is applied. This means that when the suspended load 10 is to be lifted by a plurality of pieces, the entire load is lifted only by the slack cable 11 without slack immediately after the start of work, and a load exceeding the limit is applied, which is in a dangerous state.

  In order to avoid this, there is known a device that adds an equalizer device to the pull-in side holding device and averages the load (Patent Document 1). In FIG. 9, one cylinder 26 a and the other cylinder 26 b are arranged side by side on the left and right sides of the main body of the equalizer device 25, and communicate with each other through a communication passage 27 and filled with hydraulic oil. In the one cylinder 26a and the other cylinder 26b, one pull-in side holding device 24a composed of a pooling head 22a and a gripper 23a and the other pull-in side holding device 24b composed of a pooling head 22b and a gripper 23b are movable up and down. It is mated. The suspension cable 11a is inserted into the one drawing-side holding device 24a, the suspension cable 11b is inserted into the other drawing-side holding device 24b, and a piston 29 is inserted into the cylinder 28 at the center of the equalizer device 25. And a pooling head pull-in plate 30 is provided at the end of the piston 29 to constitute a return means.

In FIG. 9, when the main body of the equalizer device 25 is pushed up by the ram 17 of the center hole jack 21 of FIG. 10, tension is applied to the suspension cables 11a and 11b. At this time, the load 10 is loaded on one pull-side holding device 24a that bites the suspension cable 11a with little slack, for example, and the pooling head 22a is held in the same position, but the body of the equalizer device 25 is raised. As a result, the hydraulic oil inside one cylinder 26a flows into the other cylinder 26b via the communication path 27, the pooling head 22b rises from the body of the equalizer device 25, pushes up the slack suspension cable 11b, and tension Becomes even, the slack of the suspension cables 11a and 11b is absorbed.
In the case where the slack of the suspension cables 11a and 11b cannot be removed by a single balancing action, for example, the suspended load is changed to the change-side holding device 16 shown in FIG. The other pulling side holding device 24b is lowered and returned to the original state by the pooling head pulling plate 30, and the same operation is repeated again until the slack is eliminated.

JP-A-3-3894.

The apparatus having the equalizer device 25 shown in FIG. 9 has the following problems.
(1) Since the equalizer device 25 as shown in FIG. 9 must be mounted on the lifting center hole jack, there is a problem that the device becomes expensive.
(2) Since this type of equalizer device 25 is for fine adjustment with a slack removal distance of 20 to 30 mm at most, when the lifting distance L is several hundred meters and the slack removal distance is several meters, The number of slack removal operations for keeping the initial tension in the suspension cable constant is extremely large, and the efficiency of the lifting operation is not good.
(3) The work of removing the slack and keeping the initial tension constant is a manual operation by visual inspection, which causes troubles such as oversight and oversight of whether or not the suspension cable is fully extended. In addition, when the number of suspension cables increases, it becomes difficult to perform accurate adjustment one by one and it takes a long time.
(4) Since the suspension load 10 is actually lifted, the entire load of the suspension load 10 is supported by a specific suspension cable 11 having no slack, and a large safety cable having a large safety factor must be used. As a result, the apparatus itself was upsized. Moreover, since the entire load of the suspended load 10 is supported only by the specific suspension cable 11, there is a problem that it involves a danger.

The object of the present invention is as follows.
(1) To provide a jack type lifting and slack eliminating device that is easy to set up and inexpensive.
(2) In order to safely lift a heavy suspended load in a confined area, the loads of all the suspended cables should be equalized quickly and all the suspended cables should be used effectively.
(3) Do not directly apply a heavy suspended load to the suspension cable before removing the slack, and equalize the suspended load before it leaves the ground with a load smaller than the suspended load.
(4) To control equalization automatically, not manually.

In order to achieve the above object, the slack removal method at the time of jack type lifting according to the present invention solves the problem by the following means.
A repositioning side holding device, a center hole jack, and a pulling side holding device are sequentially stacked, and a single wire type center hole jack device is constructed by inserting a single suspension cable into the center of these holding devices. in the slack eliminating method at the time of lifting jack type do the work lifting the suspended load by pushing up the pull-side holding device by the center hole jack in the jack device,
A step of sending pressure oil from a lifting electric pump unit by communicating all the cylinders of the center hole jack in a plurality of single wire type center hole jack devices mounted on the same pedestal by one feed pipe;
Raising the respective retracting side holding devices with the rams of the respective center hole jacks;
A step of detecting with a stroke sensor the lifting distance of each pull-in side holding device as a slack removal distance of the suspension cable;
When the slack removal distance of any suspension cable reaches the set value, pressure oil is sent to all cylinders from one return pipe, and the load of all suspension cables is redistributed to the reshuffling side holding device. And returning the retracting side holding device to the original position;
A step of lifting all the pulling side holding devices, a step of detecting a slack removing distance with a stroke sensor, and a step of returning the pulling side holding device to the original position to remove all slack cables.
Consists of
At the initial stage where the difference in slack between the suspension cables is greatly different, the slack removal stroke amount is set to be large within the range of the center hole jack and the hydraulic pressure is set small, so that the difference in slack between the suspension cables is reduced. Then, control is performed by setting the amount of slack removal stroke small and setting the hydraulic pressure value to a large value close to the suspended load.

According to the first aspect of the present invention, the repositioning side holding device, the center hole jack, and the pulling side holding device are sequentially laminated, and a single suspension cable is inserted into the center portion of these, so that the single wire type center hole jack device is provided. in the structure, and the slack eliminating method at the time of lifting jack type to perform lifting operations of the suspended load by pushing up the pull-side holding device by the center hole jack in center hole jack device of the single-wire scheme,
A step of sending pressure oil from a lifting electric pump unit by communicating all the cylinders of the center hole jack in a plurality of single wire type center hole jack devices mounted on the same pedestal by one feed pipe;
Raising the respective retracting side holding devices with the rams of the respective center hole jacks;
A step of detecting with a stroke sensor the lifting distance of each pull-in side holding device as a slack removal distance of the suspension cable;
When the slack removal distance of any suspension cable reaches the set value, pressure oil is sent to all cylinders from one return pipe, and the load of all suspension cables is redistributed to the reshuffling side holding device. And returning the retracting side holding device to the original position;
It consists of a step of raising the pull-in side holding device, a step of detecting a slack removal distance by a stroke sensor, and a step of removing all slack cables by repeating the step of returning the pull-in side holding device to its original position. ,
At the initial stage where the difference in slack between the suspension cables is greatly different, the slack removal stroke amount is set to be large within the range of the center hole jack and the hydraulic pressure is set small, so that the difference in slack between the suspension cables is reduced. Then, the slack removal stroke amount is set to a small value and the hydraulic pressure is set to a large value close to that of the suspended load. Therefore, the slack removal work for keeping the initial tension constant when the lifting distance is several hundred meters is small. The number of times can be increased, and the efficiency of the lifting work can be improved. In addition, the operation of making the initial tension constant can be automatically controlled, and trouble can be eliminated. Also, it can be adjusted extremely safely and accurately.

FIG. 6 is a partially cutaway front view showing an embodiment of a jack type lifting and slack eliminating device 9 in which a plurality of single-wire center hole jack devices 37 according to the present invention are used as one unit. FIG. 2 is a detailed cross-sectional view of a single-wire center hole jack device 37 in FIG. 1. FIG. 3 is a side view of a state in which a jack-type lifting / loosening device 9 including a plurality of single-wire-type center hole jack devices 37 in FIG. 2 is installed on a first jack stage 34. FIG. 4 is a plan view of the jack type lifting / loosening device 9 in FIG. 3. (A)-(e) is process drawing of the operation | work which lifts the antenna 10 using the jack type lifting and slack removal apparatus 9 by this invention, constructing the steel tower 32. FIG. FIG. 6 is an enlarged view of a state where the antenna 10 is lifted by the jack type lifting and slack eliminating device 9. It is horizontal direction sectional drawing of the steel tower 32 in FIG. It is the hydraulic piping and electric circuit diagram of the operation | work which lifts the antenna 10 using the several jack type lifting and slack removal apparatus 9 by this invention. It is sectional drawing of the conventional equalizer apparatus 25. FIG. It is sectional drawing of the conventional jack lifting apparatus of a multi wire system.

The slack removal method at the time of jack type lifting according to the present invention is as follows:
A repositioning side holding device, a center hole jack, and a pulling side holding device are sequentially stacked, and a single wire type center hole jack device is constructed by inserting a single suspension cable into the center of these holding devices. in the slack eliminating method at the time of lifting jack type do the work lifting the suspended load by pushing up the pull-side holding device by the center hole jack in the jack device,
A step of sending pressure oil from a lifting electric pump unit by communicating all the cylinders of the center hole jack in a plurality of single wire type center hole jack devices mounted on the same pedestal by one feed pipe;
Raising the respective retracting side holding devices with the rams of the respective center hole jacks;
A step of detecting with a stroke sensor the lifting distance of each pull-in side holding device as a slack removal distance of the suspension cable;
When the slack removal distance of any suspension cable reaches the set value, pressure oil is sent to all cylinders from one return pipe, and the load of all suspension cables is redistributed to the reshuffling side holding device. And returning the retracting side holding device to the original position;
It consists of a step of raising the pull-in side holding device, a step of detecting a slack removal distance by a stroke sensor, and a step of removing all slack cables by repeating the step of returning the pull-in side holding device to its original position. ,
At the initial stage where the difference in slack between the suspension cables is greatly different, the slack removal stroke amount is set to be large within the range of the center hole jack and the hydraulic pressure is set small, so that the difference in slack between the suspension cables is reduced. Then, control is performed by setting the slack removal stroke amount small and the hydraulic pressure value to a large value close to the suspended load.

  The internal pressure of each cylinder is detected by a valve with a pressure sensor provided between the feed pipe and each cylinder and a valve with a pressure sensor provided between the return pipe and each cylinder.

Embodiment 1 of the present invention will be described below with reference to the drawings.
FIG. 5 shows an example in which the jack type lifting and slack eliminating device 9 according to the present invention is used when lifting a suspended load 10 such as an antenna of a steel tower 32. The suspended load 10 such as an antenna is further added to a 500 m steel tower 32. In this example, the total height is 610 m by extending 110 m. Hereinafter, as the suspended load 10, for example, an antenna having a length of 250 m and a weight of 4000 tons is taken as an example.

  As shown in FIGS. 6 and 7, the steel tower 32 has a hollow portion 33 formed therein, and the antenna 10 is assembled in the hollow portion 33, and the inside of the hollow portion 33 is lifted by the jack type of the present invention. It is lifted by the slack eliminating device 9 and attached to the top of the steel tower 32. The hollow portion 33 is formed to the minimum necessary as a lifting space for the antenna 10. Therefore, the first jack stage 34 (for example, 250 m), the second jack stage 35 (for example, 375 m), and the third jack stage 36 (for example, 485 m) for installing the jack type lifting and slack eliminating device 9 are provided in the middle of the tower 32. A plurality of, for example, twelve transverse girders 58 are formed so as to protrude slightly toward the hollow portion 33 radially toward the center, and a plurality of units (for example, as shown in FIG. 8 units) 12-unit jack type lifting and slack eliminating devices 9a to 9n, each unit comprising a single-wire center hole jack device 37, lift-up electric pump units 55a to 55n, and chuck fixing / opening The electric pump units 56a to 57a are mounted.

  Before the lifting operation of the antenna 10 by the 12-unit jack-type lifting / loosening device 9, the suspension cable 11 for each unit is fixed to the cable so that the refilling device provided at the lower end of the antenna 10 is turned upside down. It is fixedly attached to the frame 51 at the cable binding end 52.

Next, a specific structure of the jack type lifting / loosening device 9 will be described with reference to FIGS.
In FIG. 4, one jack type lifting and slack eliminating device 9 includes a single pedestal type center hole jack device 37 mounted on a jack pedestal 50 in a ring shape. Yes.
As shown in FIG. 2, the general single-wire-type center hole jack device 37 has a jack chair 13 provided with a remounting side holding device 16 and a release hydraulic jack 43 on a jack base 50. On the chair 13, the center hole jack 21, the release hydraulic jack 42, and the pull-in side holding device 24 are sequentially stacked and attached.
In the pull-in side holding device 24, an inverted conical upper gripper 23 that is vertically divided into three is fitted in the center of the pooling head 22, and the suspension cable 11 is engaged in the center of the upper gripper 23. Hold it. The pooling head 22 is covered with a cover 48, and a coil spring 49 is interposed between the cover 48 and the upper gripper 23.
In the release hydraulic jack 42, when a piston 44 is fitted inside a cylinder 45 having a feed port 46 and a return port 47, the piston 44 is pushed up by the hydraulic pressure from the feed port 46 to open the retracting side holding device 24. used. The release hydraulic jack 42 operates mainly when suspended.
The refill-side holding device 16 has the same configuration as that of the pull-in side holding device 24, and the release hydraulic jack 43 has the same configuration as that of the release hydraulic jack 42.

In a specific embodiment of the present invention, a single wire type center hole jack device 37 shown in FIG. 2 is used, which is further provided with two replacement side holding devices as shown in FIG. The That is, the jack pedestal 50b with the change-side holding device 16b attached under the jack pedestal 50a and the jack pedestal 50c with the change-side holding device 16c attached therebelow are stacked and attached.
In the first jack stage 34, all the jack type lifting / loosening devices 9 shown in FIG. 3 are installed. When the lifting work on the first jack stage 34 is completed, the antenna 10 is replaced and supported while the rear-side holding device 16c and the jack base 50c remain on the first jack stage 34, and the upper part including the jack base 50b is supported. It is moved to the second jack stage 35 and lifted. When the lifting work on the second jack stage 35 is completed, the antenna 10 is replaced and supported while the rear-side holding device 16b and the jack base 50b remain on the second jack stage 35, and the upper part including the jack base 50a. Is moved to the third jack stage 36 to perform the lifting work.

The eight single-wire-type center hole jack devices 37 shown in FIG. 4 are arranged in a ring shape, but in FIG. 1, they are arranged in a horizontal row for convenience of explanation. Further, FIG. 1 illustrates the action of load equalization during the lifting work unique to the present invention, and the release hydraulic jack 42 and the release hydraulic jack 43 in FIG. 2 are omitted.
In the eight single-wire center hole jack devices 37, stroke sensors 59 are attached to all the center hole jacks 21, and the wires 60 drawn from the stroke sensors 59 are connected to the pulling head 22 of the upper drawing side holding device 24. The rising distance of the ram 17 is measured, and the distance is output as an electric signal from the output signal line 61. All the feed side hydraulic ports 18 communicate with each other through a feed pipe 38 with a pressure sensor valve 40 interposed therebetween, and all the return side hydraulic ports 19 have a return pipe with a pressure sensor valve 41 interposed therebetween. Communicate at 39.

  FIG. 8 shows a hydraulic control circuit. A centralized operation panel 53 for commanding overall control is connected to a control box 54. The control box 54 includes stroke control units 62a to 62n and a lifting electric pump unit 55a. The center hole jack 21 of the twelve jack-type lifting / loosening devices 9 connected to ˜55n and unitized is controlled. The control box 54 is connected to the chuck fixing / releasing electric pump units 56a to 56n and the chuck fixing / releasing electric pump units 57a to 57n, and is twelve jack types that are unitized when mainly hanging. The pulling side holding device 24 and the refilling side holding device 16 of the lifting and slack eliminating device 9 are controlled.

The oil feed ports in the lifting electric pump units 55a to 55n are connected to the feed pipe 38 of the unitized 12 jack-type lifting / loosening device 9 and are connected to the return pipe 39 on the return oil port side. Has been.
The feed oil port and the return oil port side of the electric pump units 56a to 56n for fixing and releasing the chuck are connected to the pull-in side holding device 24 of 12 jack type lifting / loosening devices 9 unitized, The chucking and releasing electric pump units 57a to 57n are connected to the refilling side holding device 16 of 12 jack type lifting / loosening devices 9 on the side of the feed oil port and the return oil port. .

Next, the action of slackening each suspension cable 11 according to the present invention and adjusting the tension and the lifting force at each lifting point to be constant will be described.
6 and 7, 12 units of jack type lifting and slack eliminating devices 9 comprising eight single-wire center hole jack devices 37 shown in FIG. 4 are installed on 12 cross beams 58 of the first jack stage 34. It is done. The lower end portion of the suspension cable 11 for each unit is coupled to the cable binding end 52 of the cable fixing frame 51 of the antenna 10. In this example, the total number of the suspension cables 11 is 96, and in the initial state of the lifting work, the slacks are different. At this time, the antenna 10 is placed on the ground.
In the centralized operation panel 53, a stroke amount and a load for loosening of the suspension cable 11 in each single-wire center hole jack device 37 are set, and the set value is sent to the control box 54. The stroke amount to be set is within 18 cm of the drive stroke of the ram 17 in the center hole jack 21, for example, 18 cm when the drive stroke is 20 cm, and the set load of the suspension cable 11 is, for example, when lifting About 50 to 60% of the maximum load of the suspension cable 11 per one cable. With these signals from the control box 54, the lifting electric pump units 55a to 55n send pressure oil to the jack type lifting and slack eliminating device 9 for each unit via the feed pipe 38. Then, pressure oil is sent from the feed pipe 38 to the feed side hydraulic port 18 of the center hole jack 21 in each center wire jack device 37 through the valve 40 with a pressure sensor, and the ram 17 of each center hole jack 21 is pushed up. The oil in the cylinder 20 is returned to the lifting electric pump unit 55 through the return side hydraulic port 19, the pressure sensor valve 41, and the return pipe 39.

Here, the pressure sensor-equipped valve 40 for each suspension cable 11 detects different pressures depending on the applied load. Since the same pressure oil is sent from the lifting electric pump units 55a to 55n, the ram 17 of the center hole jack 21 of the suspension cable 11 having a small pressure (large slackness) is pushed up more and the wire 60 is extended. On the contrary, the ram 17 of the center hole jack 21 of the suspension cable 11 having a large pressure (small slack) is less pushed up and the wire 60 is less stretched. The pushed distance of each ram 17 is sent from the stroke sensor 59 to the stroke control unit 62 via the output signal line 61.
The ram 17 of each center hole jack 21 is pushed up until the detection value of any one of all the stroke sensors 59 reaches a set value (18 cm), and as shown in FIG. The holding device 24 stops at positions that are separated from each other.

When stopped at the position where the upper and lower parts are separated, the pressure oil is sent from the lifting electric pump unit 55 to the return side hydraulic port 19 of each center hole jack 21 through the return pipe 39 and the pressure sensor valve 41, and the center hole jack 21 is sent. When the side hydraulic port 18 is switched to the return side, the load is changed to the change-side holding device 16, and all the drawing-side holding devices 24 are returned to the original lower end position together with the ram 17 with no load.
In response to the signal from the control box 54, the lifting electric pump units 55a to 55n send pressure oil to the jack type lifting and slack eliminating device 9 for each unit via the feed pipe 38, and detect the stroke to remove the slack. The same operation is repeated until the position of the retracting side holding device 24 in each center hole jack 21 becomes the same.

In the process of removing the slack of each suspension cable 11 described above, in the initial stage where the difference in slack between the suspension cables 11 is greatly different, the slack removal stroke amount is large within the range of the center hole jack 21 and the hydraulic pressure value is increased. the set small, small slack eliminating stroke When the difference between the slack is reduced, and, by the control set with a value close to the suspended load oil pressure value, What can be adjusted safe accurately.

Next, an operation process for constructing a tower having an overall height of 610 m by extending the antenna 10 by 110 m on the 500 m steel tower 32 will be described with reference to FIGS.
FIG. 5A: First, a ground foundation 31 is constructed, and a 300 m steel tower 32 is constructed thereon. In this steel tower 32, the antenna 10 is lifted, and then a hollow portion 33 having a diameter of about 10 m is formed at the center for providing an elevator or the like. Twelve units of the jack-type lifting and slack eliminating device 9 according to the present invention are installed on the first jack stage 34 around the hollow portion 33 at 250 m of the steel tower 32. At the lower part of the hollow portion 33, the upper end of the antenna 10 is sequentially assembled while being lifted by the lifting cable 11 of the jack type lifting / loosening device 9.

  FIG. 5B: Assembling while lifting with the suspension cable 11 by the jack type lifting and slack eliminating device 9 of the first jack stage 34 until the antenna 10 becomes a predetermined length (for example, 250 m).

  FIG. 5C: Assembling the antenna 10 while constructing the steel tower 32 upward, and when the assembled antenna 10 reaches a predetermined length (for example, 250 m), the suspension cable 11 is lowered from the upper end of the antenna 10 to the lower end. Re-hang on the part. The antenna 10 replaces the total load on the jack pedestal 50c and the change-side holding device 16c shown in FIG. 3 for the first jack stage 34, leaving these jack pedestals 50c and the change-side holding device 16c, as shown in FIG. The jack type lifting and slack eliminating device 9 for the second jack stage 35 shown in FIG. 2 is transferred to the second jack stage 35 of 375 m. Then, the load is changed to the jack pedestal 50b for the second jack stage 35 and the changing side holding device 16b. The jack pedestal 50c for the first jack stage 34 and the replacement side holding device 16c are disassembled. The antenna 10 is lifted by the jack type lifting / loosening device 9 and the suspension cable 11 for the second jack stage 35.

  FIG. 5 (d): When the steel tower 32 is constructed facing upward, the antenna 10 is lifted up to 375 m by the jack type lifting / loosening device 9 for the second jack stage 35 and the suspension cable 11, and then the second jack stage 35. The total load is changed in the jack pedestal 50b and the change-side holding device 16b, and the jack type lifting / loosening device 9 for the third jack stage 36 shown in FIG. 3 is transferred to the third jack stage 36 of 485 m.

  FIG. 5 (e): The entire load of the suspension cable 11 is changed to the transferred jack pedestal 50a for the third jack stage 36 and the changing side holding device 16a, and the jack pedestal 50b for the second jack stage 35 is changed to the changing side. The holding device 16b is disassembled. The antenna 10 is lifted and fixed to the hollow portion 33 of the tower 32 by the jack type lifting and slack eliminating device 9 of the third jack stage 36 until the upper end of the antenna 10 reaches a target height (for example, 610 m). After fixing, the jack type lifting / loosening device 9 of the third jack stage 36 is disassembled.

  The feed-side hydraulic port 18 of each single-wire center hole jack device 37 is connected to the feed pipe 38 via a valve 40 with a pressure sensor, and the return-side hydraulic port 19 is returned via a valve 41 with a pressure sensor. By connecting to the piping 39, even if one of the eight single-wire-type center hole jack devices 37 fails, if the failed valve 40 with pressure sensor and the valve 41 with pressure sensor are closed, the remaining 7 Can be lifted normally on the table.

DESCRIPTION OF SYMBOLS 9 ... Jack type lifting and slack removal apparatus, 10 ... Hanging load, such as an antenna, 11 ... Suspension cable, 12 ... Mount, 13 ... Jack chair, 14 ... Anchor head, 15 ... Lower gripper, 16 ... Replacement side holding device, 17 ... Ram, 18 ... Feed side hydraulic port, 19 ... Return side hydraulic port, 20 ... Cylinder, 21 ... Center hole jack, 22 ... Pooling head, 23 ... Upper gripper, 24 ... Retracting side holding device, 25 ... Equalizer device, 26a, 26b ... Cylinder, 27 ... Communication path, 28 ... Cylinder, 29 ... Piston, 30 ... Pulling head retracting plate, 31 ... Ground foundation, 32 ... Steel tower, 33 ... Hollow part, 34 ... First jack stage, 35 ... First 2 jack stages, 36 ... third jack stage, 37 ... single wire center hole jack, 38 ... feed piping, DESCRIPTION OF SYMBOLS 9 ... Return piping, 40 ... Valve with pressure sensor, 41 ... Valve with pressure sensor, 42 ... Release hydraulic jack, 43 ... Release hydraulic jack, 44 ... Piston, 45 ... Cylinder, 46 ... Feed port, 47 ... Return port, 48 DESCRIPTION OF SYMBOLS ... Cover, 49 ... Coil spring, 50 ... Jack base, 51 ... Cable fixing frame, 52 ... Cable binding end, 53 ... Centralized operation panel, 54 ... Control box, 55 ... Electric pump unit for lifting, 56 ... Fixation of chuck Electric pump unit for opening, 57... Electric pump unit for fixing and releasing chuck, 58... Cross beam, 59... Stroke sensor, 60.

Claims (1)

A repositioning side holding device, a center hole jack, and a pulling side holding device are sequentially stacked, and a single wire type center hole jack device is constructed by inserting a single suspension cable into the center of these holding devices. in the slack eliminating method at the time of lifting jack type do the work lifting the suspended load by pushing up the pull-side holding device by the center hole jack in the jack device,
A step of sending pressure oil from a lifting electric pump unit by communicating all the cylinders of the center hole jack in a plurality of single wire type center hole jack devices mounted on the same pedestal by one feed pipe;
Raising the respective retracting side holding devices with the rams of the respective center hole jacks;
A step of detecting with a stroke sensor the lifting distance of each pull-in side holding device as a slack removal distance of the suspension cable;
When the slack removal distance of any suspension cable reaches the set value, pressure oil is sent to all cylinders from one return pipe, and the load of all suspension cables is redistributed to the reshuffling side holding device. And returning the retracting side holding device to the original position;
It consists of a step of raising the pull-in side holding device, a step of detecting a slack removal distance by a stroke sensor, and a step of removing all slack cables by repeating the step of returning the pull-in side holding device to its original position. ,
At the initial stage where the difference in slack between the suspension cables is greatly different, the slack removal stroke amount is set to be large within the range of the center hole jack and the hydraulic pressure is set small, so that the difference in slack between the suspension cables is reduced. A slack removal method at the time of jack type lifting, characterized in that the slack removal stroke amount is reduced and the hydraulic pressure value is set to a large value close to the suspended load .

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