JPH07257878A - Safety device of tower crane - Google Patents

Abstract

PURPOSE:To prevent breakage of a tower crane in its operations of raising the tower, its falling, swing-out of a jib, and embracing it, enhance the easiness in operation of changing over from the working condition with them to the normal working condition and vice versa, and prevent breakage in the condition that a safety device is out of function. CONSTITUTION:A safety device for a tower crane is equipped with a means to sense the jib raise/fall rope tension Tj, a means to store T1, T2, T3, T4, theta, and a means which judges the working condition from So, thetab, theta, S1, S2, S3, S4, compares Tj with T1, T2, T3, T4, and emits a stop signal or stop it, and also a means which receives the stop signal and stops the operation of raising a boom, falling, winding up and down, and raising a jib, falling, winding up and down. Furthermore, the arrangement includes a means to sense the boom angle thetab, a means to automatically judge if the operation is in the normal mode or the tower raising mode, and a means to sense in which position a boom raise/fall lever and a jib raise/fall lever are set, i.e., in wind-up, neutral, and wind-down position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety device for a tower crane.

[0002]

2. Description of the Related Art FIG. 1 shows an overall view of a tower crane.
In FIG. 1, 1 is a boom and 2 is a jib. 3 is a boom elevation loop, and 4 is a jib elevation loop. Further, 5 is a tension detector of the jib depression / raise rope 4, and 6 is an angle detector of the boom. 7 holds jib 2 when boom 2 is held in boom 1.
Jib catch for holding on the 1st, 8 for the jib 2
It is a jib wrapping detector that detects a state of being held in the camera 1.

[0003] In the conventional tower crane, the tower raising, tower tilting, jib swinging, and jib wrapping operations (hereinafter referred to as tower raising mode) are not normal operations (hereinafter referred to as normal mode). Therefore, the controller had to be set so that various safety devices would not operate. Therefore, in the normal mode, if the controller is forgotten to set the various safety devices to operate, or if the various safety devices are intentionally set to not operate, a damage accident may occur. In addition, it was troublesome to change the setting each time. Further, the raising and lowering work of the tower is performed by the boom elevation loop 3 of FIG. 1, but at the same time, the jib elevation rope is used.
The operator was operating the tension so that the cable No. 4 was not too loose or too tight. For this reason, there is a risk that excessive tension will be applied to the jib raising and lowering rope 4 due to a mistake in operation, resulting in a damage accident of the tower attachment. Further, the jib swing-out work is performed by removing the jib catch 7 and releasing the jib 2 from the boom 1 and then using the jib elevation rope 4, but at this time, forgetting to remove the jib catch 7 and holding the jib on the boom 1. When trying to swing out the jib 2 without doing so, an excessive tension was applied to the jib lowering rope 4, which also caused a damage accident of the tower attachment.

[0004]

Problems to be Solved by the Invention
Provide a safety device that can prevent damage during tilting, jib swinging out, and juggling operations, improve operability when switching between these working states and normal working states, and prevent damage when the safety device is not operating. The purpose is to

[0005]

[Means for Solving the Problem] Jib depression / rope tension Tj
The tension detector 9 for detecting the height of the jib and the rope, and the automatic stop release jib tension T ₁ at the time of raising and lowering the tower.
Automatic stop to prevent damage during work to pull up / tow down Jib tension T ₂ , automatic stop for jib swing out / hold in jib Release jib tension T ₃ , automatic stop to prevent damage during swing out / jib hold Output from the jib squeeze detector 11 and the memory 21 for storing the boom angle θ for determining the jib tension T ₄ , the work for raising and lowering the work, the work for tilting the jib, and the work for swinging the jib and holding the jib. Jib entrainment signal S ₀ , boom angle signal θb output from boom angle detector 10
, Boom angle θ for discriminating between work raising / jib wrapping work and jib swinging / jib wrapping work, boom elevation lever winding boom output from the hoisting detector 12 The upper signal S ₁ , the boom lowering / lowering signal S ₂ output from the boom lowering / lowering detector 13, the jib lowering / lowering signal S ₃ output from the jib lowering / lowering detector 14. , The jib depression / reverse unwinding detector 15 outputs the jib depression / lowering signal S ₄ to determine the working state, and the jib tension detector 9
The tension signal Tj of the jib elevation rope output from the
Automatic stop release jib tension T ₁ when pulling up / towing down, automatic damage stop jib tension T ₂ when tower pulling / towing down, automatic stop release jib during jib feeding / jib hugging work The tension T ₃ and the automatic stop jib tension T ₄ for preventing damage during jib swing-out and jib wrapping work are compared, and the solenoid valve 16 for boom and hoisting up cutoff and the solenoid valve 17 for boom and hoisting down cutoff are compared. Solenoid valve for cut-off on jib depression
8 and a comparative calculation device 22 for outputting or canceling a stop signal to the solenoid valve 19 for cutting down the jib depression and elevation, and a boom angle θ.
A boom angle detector 10 for detecting b, a means for automatically distinguishing between the normal mode and the tower raising mode, and a boom raising / lowering operation lever and a jib raising / lowering operation lever. By means of detecting whether it is in neutral or under winding,
Configured the safety device for the crane.

[0006]

[Action]

(1) It is possible to discriminate between the normal mode and the tower-raising mode by the signal S ₀ of the jib embedding detector mounted so that it can be judged whether or not the jib is held in the boom. It is possible. (2) The signal .theta. Of the boom angle detector 10 is used for the tower raising / tower tilting operation area and the jib squeezing / jib holding operation area.
b and the comparison of θ is stored in the memory 21, Bed - arm elevation lever - hoist the detector 12 signals S ₁ and Bed - arm elevation lever -
The determination can be made based on the two conditions of the position of the boom / elevation lever determined from the signal S ₂ of the unwinding detector 13. That is,
If the boom angle is θ b ≧ θ and the boom depression lever neutrality is established, it can be determined as the jib swinging / jib hugging operation area, and if it is not established, it can be determined as the tower raising / twering operation area.

(3) To distinguish between the power-up operation and the power-down operation, if the signal S _{1 of the} boom / elevation / rewinding detector 12 is input to the comparison operation unit 22, the power-up operation is performed. If the signal S _{2 from the} boom / reverse lever unwinding detector 13 is input to the comparison operation device 22, it can be determined that the operation is a power down operation. (4) The signal S ₃ of the jib elevation / rewinding detector 14 is used to determine whether the jib swing-out operation or the jib wrapping operation is performed.
If the signal S ₄ from the jib depression / elevation lowering detector 15 is input to the comparison operation device 22, it can be determined as the jib wrapping operation.

(5) Regarding the processing at the time of raising and lowering the tower, first, when the boom raising / lowering lever is wound, that is, in the case of the tower raising / lowering operation, the jib raising / lowering lever is used. The tension of the jib elevation rope increases when the is being wound. Therefore, the boom elevation lever hoisting detector 12
When the signal S ₁ of the jib tension detector 5 is input to the comparison calculation device 22 and the signal Tj of the jib tension detector 5 becomes larger than T ₂ stored in the memory, the jib depression / elevation stop signal is output. Output to the cut-off solenoid valve 18 to stop the hoisting of the jib. Once the stop is applied, the stop cannot be released unless the signal Tj of the jib tension detector 5 becomes smaller than T ₁ .

(6) Next, when the boom raising / lowering operation lever is in the lowering position, that is, in the case of the tilting operation, when the jib lowering / elevating operation lever is in the neutral position or in the winding position, the jib lowering / lowering position is lowered. The tension of the pump increases. Therefore, when the signal S _{2 of the} boom / elevation / rewinding detector 13 is input to the comparison operation device 22 and the signal Tj of the jib tension detector 9 becomes larger than T ₂ stored in the memory. In addition, the boom depression / lowering stop signal is sent to the boom depression / lowering cut-off solenoid valve 17.
Then, a jib depression / elevation winding stop signal is output to the jib depression / elevation winding cutoff solenoid valve 18 to stop the boom depression / elevation winding and the jib depression / elevation winding. Once the stop is applied, the stop cannot be released unless the signal Tj of the jib tension detector 9 becomes smaller than T ₁ .
Next, as an erroneous operation, the tension of the jib depression / elevation rope increases when the boom / elevation operation lever is in the neutral position and the jib depression / elevation lever is put on the hoist. Therefore, the boom elevation lever hoisting detector 1
Neither the signal S _{1 of No. 2} nor the signal S _{2 of the} boom-depression lever unwinding detector 13 is inputted to the comparison operation device 22, and the signal Tj of the jib tension detector 9 is stored in the memory. When it becomes larger than T ₂ , a jib depression / elevation hoisting stop signal is output to the jib depression / elevation hoisting cutoff solenoid valve 18 to stop the jib depression / elevation hoisting. Once the stop is applied, the stop cannot be released unless the signal Tj of the jib tension detector 9 becomes smaller than T ₁ .

(7) Regarding the processing at the time of jib swing-out operation / jib-holding operation, in the jib swing-out / jib-holding operation area, the signal S ₃ of the jib elevation / rewinding detector 14 is sent to the comparison arithmetic unit 22. have been entered, and outputs the jib tension detector 9 signals Tj is the jib derricking winding the jib derricking hoist stop signal when it is larger than T _4, which is stored in the memory cutoff solenoid valve 18, Stop the jib depression roll. Once stopped, the signal T from the jib tension detector 9
The stop cannot be released unless j becomes smaller than T ₃ .

[0011]

FIG. 2 shows the construction of a safety device for a tower crane. In FIG. 2, reference numeral 9 is a tension detector for the jib elevation rope 4, 10 is an angle detector for the boom 1, and 11 is a jib inclusion detector for detecting a state in which the jib 2 is caught in the boom 1. Is. 12 is a boom elevation lever hoisting detector that operates when the boom elevation lever is in the winding position, and 13 is a boot that operates when the boom elevation lever is in the winding position. -Mu-San-Lever-Unwinding detector. Reference numeral 14 is a jib elevation / reverse-winding detector that operates when the jib elevation / reverse lever is in the winding position, and reference numeral 15 is a jib / depression-reverse-winding detection that operates when the jib elevation / lowering lever is in the lowering position. It is a vessel. Reference numeral 16 is a solenoid valve for a boom depression / elevation hoisting cutoff, which operates when a boom depression / elevation hoisting stop signal is received. It is a solenoid valve for. Reference numeral 18 is a solenoid valve for jib depression / elevation stop cutoff that operates when a jib depression / elevation stop signal is received. Reference numeral 19 is a solenoid valve for jib depression / elevation cutoff that is activated when a jib depression / elevation stop signal is received. -La.

[0012] Inside the controller 20, T ₁ is a jib tension for automatic stop release when the work is pulled up and tilted, and T ₂ is an automatic stop jib for preventing damage when the work is pulled up and tilted. Tension (T ₂ > T ₁ ). T ₃ is the tension of the automatic stop release jib during the jib swing-out / jib squeezing work, and T ₄ is the automatic stop jib tension (T ₄ > T ₃ ) for preventing breakage during the jib swing-out / jib squeezing work. θ is a boom angle for discriminating between the work for raising and tilting the work, the work for swinging out the jib, and the work for holding the jib, and 21 is for storing T ₁ , T ₂ , T ₃ , T ₄ , and θ. It is a memory.

Tj is a jib tension signal output from the jib tension detector 9, and θb is a boom angle signal output from the boom angle detector 10. S ₀ is the jib inclusion detector 11
The jib envelopment signal output from S, S ₁ is the boom elevation lift signal output from the boom elevation lift winding detector 12,
S ₂ is a boom depression / winding signal output from the boom depression / rewinding detector 13, S ₃ is a jib depression / winding signal output from the jib depression / lever winding detector 14, S ₄ Is a jib depression / rewinding signal output from the jib depression / rewinding detector 15. 22 determines the working state by S ₀ , θb, θ, S ₁ , S ₂ , S ₃ , S ₄ , and Tj and T ₁ , T ₂ , T ₃ , T ₄
And cut-off solenoid valves 16, 17, 18, 19
It is a comparison operation device that outputs and cancels a stop signal.

FIG. 3 shows an example of a hydraulic circuit when the boom elevation pump and the jib elevation pump are the same. In addition to this, the boom elevation pump and the jib elevation pump may of course be different. In FIG. 3, reference numeral 23 is a variable hydraulic pump for boom elevation / jib elevation, 24a is a hydraulic motor for boom elevation, 24b is a hydraulic motor for jib elevation, and 25a is a rotation direction of the hydraulic motor 24a. 25b is a directional control valve that controls the rotational direction of the hydraulic motor 24b, 26a is a boom-elevation operating lever that determines the spool position of the directional control valve 25a, and 26b is a directional control valve. The jib-depression operation lever that determines the spool position of the switching valve 25b, 27a is a boom-depression hoisting detector that operates when the operation lever 26a enters the hoisting position, and 28a is 26a when the hoisting position is lowered. A boom-down / down-winding detector that operates when the power is turned on, and 27b is an operation lever 26.
A jib-and-elevation hoist detector that operates when b enters the hoist,
28b is a jib depression and elevation lowering detector that operates when the operation lever 26b enters the lowering position, and 29a is a boom depression and hoisting up cut that operates when a boom depression and elevation winding stop signal is received from the comparison processing unit 22. Solenoid valve for OFF, 30a is a solenoid valve for boom-down and down-winding cutoff which operates by receiving a boom-down and down-winding stop signal from the comparison processing unit 22, 29b is a jib-down and up-winding stop signal from the comparison processing unit 22 A solenoid valve for jib-up / down-winding cut-off, which is operated in response to the jib-down / down-winding, is a solenoid valve for jib-down / down-winding cut-off, which is operated in response to a jib-down / down-winding stop signal from the comparison operation device 22.

[0015]

[Operation] The basic operation will be described below with reference to FIGS. 1, 2 and 3. When operating the boom elevation lever 26a to the side of the pilot pipe 31a, the pilot oil passes through the boom elevation cutoff solenoid valve 29a, and the pilot port 3
Pilot pressure is applied to 3a, and the boom-elevation direction switching valve 25
The spool of a moves from the position of 25a _{1 to} the position of 25a ₂ .
At the same time, the contact point of the boom / elevator winding detector 27a is 27a ₁
It switched to 27a ₂ from Bed - arm elevation hoist signal S ₁ is inputted to the comparison operation unit 22, Bed - arm elevation manipulation lever -26a is detected to have entered the hoisting. At this time, the oil discharged from the hydraulic pump 23 flows from the pipe 35 to the hydraulic motor 24a,
The hydraulic motor 24a rotates in the normal direction, the boom raising / lowering rope 3 (FIG. 1) is wound up, and the boom 1 is raised. Control here
When a boom / elevation hoisting stop signal is output from the comparison operation device 22 inside the laser 20, a current flows through the solenoid 36a, and the spool of the boom / elevation hoisting cutoff solenoid valve 29a is switched. The pilot oil is shut off and the pilot pressure is no longer applied to the pilot port 33a. Then Bed - beam elevation of directional control valve 25a spool - Le is the position of 25a _1, oil discharged from the hydraulic pump 23 is a hydraulic motor - not flow to the motor 24a, the hydraulic motor - motor stops. In other words, boom boom winding stops.

The same applies to the case where the boom is lowered, the jib is raised, and the jib is lowered. Next, the discrimination between the normal mode and the power-inducing mode will be described with reference to FIGS. When performing normal power-up and power-down operations, the jib 2 is held in the boom 1 by the jib catch 7. Further, when the jib swinging operation is performed, the boom 1 is raised up to near the vertical position, and then the jib catch 7 is removed to release the jib 2 from the boom 1 when the jib swinging is started. When carrying out the jib hugging work, the jib 2 is moved to the boom 1 by the jib catch 7 at the end of the jib hugging.
Hold on. Therefore, it is possible to discriminate between the normal mode and the power-inducing mode by the signal S _{0 of} the jib entrapment detector 8 mounted so that it can be judged whether or not the jib 2 is held in the boom ₁ . Is possible (see FIG. 4).

Next, with reference to FIG. 2 and FIG. 4, a description will be given of the discrimination between the tower raising / tower tilting operation area and the jib feeding / jib holding operation area. For normal jib swing-out / jib-holding operations, with the boom 1 upright, the boom raising / lowering operation lever 26a is set to the neutral position, and jib raising is performed by hoisting the jib / elevation operation lever 26b. To hang it up, put the jib-down operation lever 26b underneath. Therefore, the signal .theta.b of the boom angle detector 10 is compared with .theta. Stored in the memory 21, and the signal S of the boom elevation lever hoisting detector 12 is compared.
_It can be discriminated from two conditions of the position of the boom elevation lever and the position of the boom elevation lever which is determined from ₁ and the signal S _{2 of the} boom elevation lever unwinding detector 13. That is, if the boom angle is θ b ≧ θ and the boom elevation lever neutrality is established, it is a jib swinging / jib hugging operation area, and if it is not established, it can be determined as a tower raising / twering operation area. (Figure 4).

Next, the distinction between the power-up operation and the power-down operation will be described. Normally, the boom raising / lowering operation lever 26a is hoisted for raising the tower and the boom lowering operation lever 26a is put for lowering the tower lowering operation. In each case, the jib raising / lowering rope 4 is used. In order to prevent the tension from being too tight or too loose, the jib depression / elevation operation lever 26b is placed at the top or the bottom of the jib while adjusting the tension of the jib elevation rope 3. Therefore, if the signal S _{1 of the} boom elevation lever hoisting detector 12 is input to the comparison arithmetic unit 22, a tower raising operation is carried out, and the signal S _{2 of the} boom elevation lever unwinding detector 13 is compared and calculated. If it is input to the device 22, it can be determined as a power-down operation.

Next, the discrimination between the jib swing-out operation and the jib holding operation will be described. In the normal jib swing-out / jib-holding operation area, the jib swing-out operation is performed by the operation lever for jib elevation.
26b is hoisted, and the operation to hold the jib is done by using the jib depression / elevation operation lever 26b.
Put in the bottom. Therefore, if the signal S _{3 of} the jib elevation / reverse roll-up detector 14 is input to the comparison calculation device 22, the jib output operation is performed, and the signal S _{4 of} the jib rise / reverse roll-down detector 15 is input to the comparison calculation device 22. If so, it can be determined as a jib holding operation.

Next, the processing at the time of the tower raising operation / tower tilting operation will be described. First of all, as the characteristics of the machine body,
Boom depression speed <jib depression rope speed
It is conceivable that the mode is boom, boom elevation speed> jib depression elevation speed. This is caused by the difference in the number of boom elevation loops, jib elevation loops, and the pump capacity (in the case of different pumps). Then, considering the operation for increasing the jib elevation rope tension in each of the above cases, the operation is as shown in FIG. Based on this, the processing in the above case will be described. First, when the boom-elevation operation lever is rolled up, that is, in the case of the tower raising operation,
The tension of the jib depression and elevation rope increases when the jib depression and elevation lever is in the winding position. Therefore, when the signal S _{1 from the} boom depression / reverse roll-up detector 12 is input to the comparison operation device 22 and the signal Tj from the jib tension detector 5 becomes larger than T ₂ stored in the memory. Then, a jib depression / elevation winding stop signal is output to the jib depression / elevation winding cutoff solenoid valve 18 to stop the jib depression / elevation winding. Once the stop is applied, the stop cannot be released unless the signal Tj of the jib tension detector 5 becomes smaller than T ₁ .

Next, when the boom raising / lowering lever is unwound,
That is, in the case of the tilting operation, the tension of the jib depression / elevation rope increases when the jib depression / elevation operation lever is in the neutral position or in the winding position. Therefore, the signal S _{2 from the} boom depression / reverse roll down detector 13 is input to the comparison operation device 22,
And when the signal Tj jib tension detector 9 is greater than T ₂ which is stored in the memory, blanking - the arm elevation winding under stop signal blanking - the arm elevation winding under the cutoff solenoid valve 17, the jib derricking Solenoid valve for hoisting cut-off signal
Output to 8 and stop boom lowering and jib lowering. Once the stop is applied, the stop cannot be released unless the signal Tj of the jib tension detector 9 becomes smaller than T ₁ .

Next, as an erroneous operation, when the boom raising / lowering operation lever is in the neutral position, the tension of the jib raising / lowering rope increases when the jib raising / lowering lever is put on the winding. Therefore, the boom depression lever
Neither the signal S ₁ of the hoisting detector 12 nor the signal S _{2 of the} boom-lowering lever lowering detector 13 is input to the comparison operation device 22, and the signal Tj of the jib tension detector 9 is stored in the memory. When it becomes larger than the stored T ₂ , a jib depression / elevation hoisting stop signal is output to the jib depression / elevation winding cutoff solenoid valve 18 to stop the jib depression / elevation winding. Once the stop is applied, the stop cannot be released unless the signal Tj of the jib tension detector 9 becomes smaller than T ₁ . In this case as well, a process of stopping the operation in which the jib depression / rope tension increases and a damage accident occurs during each operation may be performed.

Next, the processing at the time of the jib swing-out operation and the jib wrapping operation will be described. In the case of these operations, the operation that causes a breakage accident is when the jib depression / elevation lever is put on the hoist while the jib 2 is held in the boom 1 without removing the jib catch 7. Therefore, in the jib swing / jib wrapping operation area, the signal S _{3 from} the jib elevation / reverse hoisting detector 14 is input to the comparison operation device 22, and the signal Tj from the jib tension detector 9 is stored in the memory. When it becomes larger than T ₄ , the jib depression / elevation hoisting stop signal is output to the jib depression / elevation hoisting cutoff solenoid valve 18 to stop the jib depression / elevation hoisting. Once stopped, the signal T from the jib tension detector 9
The stop cannot be released unless j becomes smaller than T ₃ . The value of T ₄ is set to the normal mode from the power-up mode when the jib catch 7 is removed and the jib swing-out operation is performed normally, and the signal S ₀ of the jib entrapment detector 11 is no longer input to the comparison operation device 22. It is necessary to set a value larger than Tj that can be applied before switching to the negative mode so that the jib is not stopped when it is normally operated.

[0024]

[Effect] By performing the above processing, normal mode
The switching between the power supply mode and the power raising mode is automated, the time and effort required for the switching are reduced, the operability is improved, and the damage accident due to the setting error can be prevented. Also,
In the pull-up mode, it is possible to prevent a damage accident caused by an excessive tension applied to the jib elevation rope.

[Brief description of drawings]

FIG. 1 is an overall side view of a tower crane.

FIG. 2 is a block diagram of a safety device of a tower crane.

FIG. 3 is a hydraulic circuit diagram of a tower crane.

FIG. 4 is an explanatory view for discriminating between a normal mode and a tower raising mode.

FIG. 5 is an explanatory diagram of a jib tension increasing operation at the time of the tower raising operation and the tower tilting operation.

[Explanation of symbols]

1 boom 2 jib 3 boom elevation roll 4 jib elevation roll
Pitch 5 Jib Depression / Loop tension detector 6 Boom angle detector 7 Jib catch 8 Jib embrace detector 9 Jib tension detector 10 Boom angle detector 11 Jib embrace detector 12 boom Ascending lever winding detector 13 Boom Ascending lever winding detector 14 Jib Ascending lever winding detector 15 Jib Ascending lever winding detector 16 Boom Depression winding solenoid valve 17 b − Solenoid valve for lower / lower hoisting cutoff 18 Solenoid valve for jib lower / lower hoisting cutoff 19 Solenoid valve for jib lower / lower hoisting lower cutoff 20 Controller 21 Memory 22 Comparative arithmetic unit 23 Voom hoisting / jib lower / height variable Type hydraulic pump 24a Boom elevation hydraulic motor 24b Jib elevation hydraulic motor 25a Directional switching valve 25b for controlling the rotation direction of 24a 25b Directional switching valve for controlling the rotational direction of 24b 26a 25a spool position Boom Depression operation lever 26b Determine the spool position of 25b Boom depression / elevation operation lever 27a 26a is activated when the hoist goes up.Boom depression hoist detector 27b 26b is activated when the hoist goes up. Boom depression / lowering detector that operates when the robot enters 28b 26b Jib depression / lowering detector that operates when 26b enters the lower portion 29a boom depression / suspension boom Solenoid valve for hoisting cut-off 29b Jib / elevation hoisting stop stop solenoid valve for actuating 30a Boom for hoisting hoisting down stop signal Boom for hoisting lower cut-off Solenoid valve 30b Jib depression / down-winding stop signal operated solenoid valve for jib depression / down-down 31a Pilot piping 32 Pilot piping 33a, 33b Pilot port 34a Pilot piping 35 Piping 36a Solenoid

Claims (1)

[Claims] 1. A tension detector (9) for the jib elevation rope tension (Tj) for detecting the jib elevation rope tension (Tj), and an automatic stop release jib tension (T ₁ when the tower is pulled up and tilted down). ), Automatic stop jib tension to prevent damage during power-up / power-down work
(T ₂ ), Automatic stop release jib tension (T ₃ ) during jib swing-out / jib-holding work, Damage prevention automatic stop jib tension (T ₄ ) during jib swing-out / jib-holding work, Twist-raising / twirl -Memory (21) for storing the boom angle (θ) for distinguishing whether it is tilting work or jib swinging / jib wrapping work, and jib wrapping output from the jib wrapping detector (11) signal
(S ₀ ), the boom angle signal (θb) output from the boom angle detector (10), and for determining whether to raise the tower / jib hold work or jib swing / jib hold work. Boom angle
(θ), the boom depression / raise / winding detector (12), the boom depression / raise / winding signal (S ₁ ), and the boom depression / raising / winding detector (13) Boom depression / elevation signal (S ₂ ), output from jib depression / elevation winding detector (14) Jib depression / elevation winding signal (S ₃ ), output from jib depression / reverse detector (15) The work state is determined by the jib depression / lowering signal (S ₄ ) and the jib depression / rope tension signal (Tj) output from the jib tension detector (9) and the power-up / power-down operation. Automatic stop release jib tension (T ₁ ) when turning, raising and turning
Prevention of damage during tilting work Automatic stop jib tension (T ₂ ), Automatic stop release jib tension during jib swing-out / jib hold work
(T _3), compares the jib shaken jib engulfment working time prevent damage automatic stop jib tension (T _4), Bed - arm elevation hoist cutoff solenoid valve (16), Bed - arm elevation wound under cut Solenoid valve for turning off (1
7), a comparison calculation device (22) that outputs or cancels a stop signal to the solenoid valve (18) for the jib depression / elevation upper cutoff and the solenoid valve (19) for the jib depression / elevation lower cutoff, and the boom angle (θb ), A boom angle detector (10), a means for automatically distinguishing between the normal mode and the tower raising mode, and a boom raising / lowering lever and a jib raising / lowering lever. , A neutral feature or a means for detecting whether it is in the unwinding part
Crane safety device.