JP5823337B2 - Height limiting device for folding crane - Google Patents

Description

  The present invention relates to a height limiting device used for a folding crane having two booms of an inner boom and an outer boom.

  A folding crane of this type includes a base 2 provided on a chassis frame 23 and a column 3 erected on the base 2 so as to be horizontally rotatable like a folding crane 100 illustrated in FIG. The inner boom 4 is provided at the front end of the column 3 so that it can be raised and lowered, and the outer boom 10 is provided at the front end of the inner boom 4 so that it can be raised and lowered (see, for example, Patent Document 1).

  Here, this Patent Document 1 detects the height of the most advanced upper part (hereinafter also simply referred to as “the height of the tip of the outer tab”) among a plurality of booms constituting the telescopic mechanism of the outer tab. There is disclosed a height limiting device that regulates the height of the tip of the outer tab so as not to exceed a height (for example, a ceiling or an overhead wire).

JP 2000-335889 A

  However, although the height limiting device described in Patent Document 1 can detect the height of the tip of the outtabome, this type of folding crane has a boom compared to a crane having only one boom that can be raised and lowered. Makes complex movements. That is, this type of folding crane has a structure including two booms 4, 10 of an inner boom 4 and an extendable outer tab 10 as illustrated in FIG. Therefore, depending on the postures of the two booms 4, 10, not only the tip of the outer tab 10 but also other portions of the outer tab 10 may be positioned higher than the tip of the outer tab 10.

Specifically, as shown in FIG. 7, as in Patent Document 1, in addition to the case where the most advanced upper portion 13f of the plurality of booms constituting the telescopic mechanism of the outtabome 10 reaches a limit height R, As shown in FIG. 8, the rear end upper portion 11r of the outer tab 10 (first outer tab 11) may reach a limit height R.
Further, in this type of folding crane, the outtab 10 is constituted by a plurality of boom sets (in this example, the first to third outtabs 11, 12, and 13) as the telescopic structure of the outtab 10. That is, in this outer tab 10, the first outer tab 11 at the base end portion has a cylindrical shape, and other booms (in this example, the second and third outer tabs 12 and 13) can be expanded and contracted. It is fitted. And when the 2nd outer tab 12 is shrunk, the rear end of the second outer tab 12 protrudes from the rear end of the first outer tab 11.

  Therefore, in this type of folding crane, as shown in FIG. 9, the rear end upper portion 12t of the second outer tab 12 at the time of reduction may reach a limit height R, and further, as shown in FIG. 10. As described above, in a posture in which the outer tab 10 is bent toward the inner boom 4 at the time of reduction, the rear end lower portion 12b of the second outer tab 12 may reach a limit height R. Thus, the height limiting device described in Patent Document 1 still has room for examination as a height limiting device for this type of folding crane.

  Therefore, the present invention has been made paying attention to such problems, and in the folding crane having the two booms of the inner boom and the outtabome as described above, the outtabome can be used in any posture of the outtabome. It is an object of the present invention to provide a folding crane height limiting device capable of notifying an operator to prevent or prevent exceeding a limit height.

  In order to solve the above-described problems, a folding crane height limiting device according to an aspect of the present invention includes a base, a column erected on the base so as to be horizontally rotatable, and a undulation at a tip of the column. An inner boom that can be provided and an outer boom that can be raised and lowered at the tip of the inner boom, and the telescopic mechanism of the outer boom is composed of a plurality of booms, and the base end of the plurality of booms The first outer tab is formed in a cylindrical shape, and the second outer tab is telescopically fitted along the first outer tab. The rear end of the second outer tab is smaller than the rear end of the first outer tab when being reduced. Is a height limiting device used for a folding crane configured to protrude rearward, a first angle detector for detecting a ground inclination angle of the inner boom, Based on the detection information of the three detectors, the second angle detector for detecting the ground inclination angle of the Utaboom, the boom length detector for detecting the length of the outtabome, and the height of the boom of the folding crane. A height limiter for controlling the height, the height limiter based on the detection information of the three detectors, the most advanced upper part of the plurality of booms constituting the outtabome and the first The heights of the four upper portions of the upper end and the lower end of the second outer tab are monitored at the time of reduction, and the height of any one of the four monitoring portions is a limit. When a predetermined height lower than a certain height is exceeded, the movement to the height side that becomes the limit of the output of the alarm or the outtabome is restricted.

  Here, in the folding crane height limiting device according to one aspect of the present invention, the height limiting unit is configured such that any one of the four monitoring units has a predetermined height as the predetermined height. When the limit height is exceeded, a limit warning is output and at least the movement to the height side which is the limit of the outtabome is stopped, and when the warning height lower than the predetermined limit height is exceeded, the warning warning is issued. Is preferably output.

  According to the height limiting device for a folding crane according to one aspect of the present invention, in a folding crane having two booms of an inner boom and an outtabome, a first angle detection capable of detecting the ground inclination angle of the inner boom. , A second angle detector capable of detecting the ground inclination angle of the outer tab, and a boom length detector capable of detecting the length of the outer tab, and the height limiter is detected by the three detectors. Based on the information, the top 4 of the plurality of booms constituting the outtabome and the upper end of the rear end of the first outabum, and the upper end of the second outtab and the lower end of the back end of the second outtab when being contracted are monitored. When any of these monitoring units exceeds a predetermined height that is lower than the height at which the limit of the outtab is exceeded, an alarm output or the height at which the limit of the outtubum is reached Since it restricts the movement of the can Autabumu in any posture of Autabumu to notify the operator to prevent or prevented from exceeding the height the limit.

It is a figure explaining one Embodiment of a folding crane provided with the height limiting device concerning one mode of the present invention. It is a flowchart of the height restriction | limiting process performed with a controller. It is a schematic diagram for demonstrating four monitoring part AD monitored by a height restriction | limiting process. For constants required for calculation of height h _A to h _D of the monitoring unit A~D of places 4 is a schematic diagram for explaining. Monitoring section A~D of places 4 the height h _A to h _D variables required for the operation of a schematic diagram for explaining. It is a figure explaining an example of a folding crane which has two booms of an inner boom and an outtabome. It is a figure explaining the attitude | position (1st example) where the outtab boom (the most upper part of the some boom which comprises an outtabome) exceeds a limit height of a folding crane. It is a figure explaining the attitude | position (2nd example) in which the outtab boom (back end upper part of the 1st outtab boom) of a folding crane exceeds restriction height. It is a figure explaining the attitude | position (3rd example) where the outtab boom (the rear end upper part of the 2nd outtabome at the time of reduction) of a folding crane exceeds a restriction height. It is a figure explaining the attitude | position (4th example) in which the outtab boom (the rear end lower part of the 2nd outtabome at the time of reduction | decrease) exceeds a limit height of a folding crane.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings as appropriate. Since the folding crane body other than the height limiting device has the same configuration as that of the folding crane described in the background art, the corresponding components will be described with the same reference numerals.
As shown in FIG. 1, the folding crane 1 is mounted on a vehicle 20 such as a truck, and is mounted at a position between a driver's seat 21 and a loading platform 22 of the vehicle 20. The base 2 is provided on the chassis frame 23 of the vehicle 20. The base 2 is provided with a pair of outriggers 9 projecting in the width direction of the vehicle 20.

  A column 3 is erected on the base 2 so as to be horizontally rotatable. An inner boom 4 is pivotally supported at the tip of the column 3, and a first hoisting cylinder 5 is provided at a substantially center between the column 3 and the inner boom 4. Are connected. Thereby, the inner boom 4 can be raised and lowered by the expansion and contraction drive of the first raising and lowering cylinder 5. Further, an outer tab 10 (first outer tab 11 to be described later) is pivotally supported at the tip of the inner boom 4 and connected to the inner boom 4 through a undulation link mechanism 7. Furthermore, the approximate center of the inner boom 4 and the undulation link mechanism 7 are connected by a second undulation cylinder 6. As a result, the outtab 10 can be raised and lowered by the expansion and contraction drive of the second raising and lowering cylinder 6.

  Further, the outer tab 10 has a stretchable structure. That is, the outer tab 10 is composed of a plurality of booms (in this example, the first to third outer tabs 11, 12, 13). In this autum 10, the first autum 11 at the base end has a cylindrical shape, a second autum 12 is fitted in the first autum 11, and a third autum 13 is fitted in the second autum 12. Has been. The booms are connected to each other by an expansion / contraction cylinder 8 so as to be extendable / contractible.

  In this example, the both ends of the cylinder tube of the expansion / contraction cylinder 8 are expansion rods, the distal end of the expansion / contraction rod at one end (the left end in the figure) is fixed to the rear end of the first autum 11, and the cylinder tube is The distal end of the telescopic rod at the other end (the right end in the figure) is fixed to the distal end of the third outer tab 12. Accordingly, the outer tab 10 has a configuration in which the rear end of the second outer tab 12 protrudes from the rear end of the first outer tab 11 when the second outer tab 12 is contracted by driving the telescopic cylinder 8 to the reduction side. It has become. In addition, operation of each crane operation | movement of the inner boom 4 and the outer boom 10 demonstrated above can be operated by the operating device (input device) provided in the base 2 vicinity.

  Here, in the folding crane 1, as shown in FIG. 1, a first angle detector 31 that detects an inclination angle of the inner boom 4 to the ground is attached to the inner boom 4. Further, the outer tab 10 is provided with a second angle detector 32 for detecting the ground inclination angle of the outer tab 10. As these angle detectors, a pendulum type inclination angle sensor (ground angle sensor) is suitable. Specifically, for example, a model number WR-7UH equivalent manufactured by Green Sokki Co., Ltd. can be employed.

  Further, a boom length detector 33 that can detect the length of the outer tab 10 is attached to the outer tab 10. And in the base 2, the controller 30 is provided as a height restriction | limiting part which controls the height of the outer tab 10 of this folding crane 1. As shown in FIG. The controller 30 can calculate the positions of four predetermined locations of the outtabome 10 based on signals (detection information) from the three detectors 31, 32, and 33 (described later). Then, from the result of the calculation, the operator is notified in advance so as to prevent and prevent the outtab 10 from exceeding the limit height.

Hereinafter, the controller 30 will be described in detail.
The controller 30 is provided in the base 2, and based on a predetermined control program, a CPU (not shown), a ROM that stores a CPU control program or the like in a predetermined area, and read from the ROM, etc. The controller 30 is provided with a RAM for storing data and calculation results required in the calculation process of the CPU, and the above three detectors 31, 32, 33, alarm buzzer (voice alarm device), height It has a limit setting indicator lamp, a warning lamp, a height limit setting release switch, a height limit alarm release switch, and the like.

Next, the height restriction process executed by the controller 30 will be described with reference to FIGS.
The height limit processing program is a timer interrupt process. When the program is started, as shown in FIG. 2, first, the process proceeds to step S1, and the three detectors 31, 32, 33 are moved. The detection information from is read, and the process proceeds to step S2.

In step S2, in order to monitor the four predetermined monitoring units A to D of the outtabome 10 based on the detection information of the three detectors 31, 32, 33, the plurality of booms 11, 12, 13, the height h _A of the top upper end 13 f of the third outer tab 13 located at the foremost position, the height h _B of the rear upper end 11 r of the first autum 12, and the height of the rear upper end 12 t of the second outer tab 12 and by calculating h _C and 4 positions of the height h _D of the rear lower portion 12b of the heights proceeds to step S3.

Here, the calculation contents of the respective heights h _A to h D of the four monitoring units A to _D will be described in detail.
As shown in a schematic diagram in FIG. 3, the above-described parts 13 f, 11 r, 12 t, and 12 b shown in FIGS. 7 to 10 correspond to the four monitoring units A to D of the outtabome 10. In other words, one point on the top surface of the third outer tab 13 that is the most distal boom of the outer tab 10 is monitored as one point (monitoring part A) in the upper end 13f of the upper tab 10. Also, one point on the top surface of the most proximal end of the first outer tab 11 that is the boom at the proximal end of the outer tab 10 is monitored as one point (monitoring part B) at the center of the upper rear end 11r of the outer tab 10.

  Further, as a telescopic structure of the outer tabome 10, when the second outer tab 12 is contracted with respect to the second outer tab 12 fitted inside the first outer tab 11, as shown in FIG. Since the rear end of the second outer tab 12 projects from the end, one central point (monitoring part C) of the rear end upper portion 12t of the second outer tab 12 is monitored. Further, as shown in FIG. 10, when the outer tab 10 is bent to the inner boom 4 side, the rear end lower portion 12b of the second outer tab 12 may reach the limit height R. One point (monitoring part D) in the center of the lower end 12b is monitored.

Then, in order to calculate the height h _A to h _D of the monitoring unit A~D described above, as shown in FIG. 3, the pin pivotally supporting the inner boom 4 in column 3 the inner boom pivot pin 14 The pins that pivot the outer tab 10 on the inner boom 4 are called the outer tab pivot pins 15, and the vertical heights of the pivot pins 14, 15 from the ground are h ₁ and h _{2 in} FIG. The heights in the vertical direction from the ground of ˜D are set as h _A to h _D , respectively, and the height restriction is controlled based on these heights.

  FIG. 4 shows the definition of constants used for this calculation. In the following description, “when fully contracted” means the time when the second outer tab 12 of the outer tab 10 is most contracted, and “long direction” means the length of the outer tab 10 in the long direction. Means. The “offset length” means the length in a direction orthogonal to the “long direction”.

Here, in the figure, L ₀ is the distance between the inner boom pivot pin 14 and the outer tab pivot pin 15,
L ₁ is the length in the longitudinal direction from the outtabome pivot pin 15 of the monitoring unit A at the time of the maximum contraction,
L ₂ is the length in the longitudinal direction from the outtabome pivot pin 15 of the monitoring unit B,
L ₃ is a longitudinal direction length from Autabumu pivot pin 15 of the monitoring unit C during most condensed,
L ₄ is the length in the longitudinal direction from the outtabome pivot pin 15 of the monitoring unit D at the time of the maximum contraction,
D _1, the monitoring unit offset length between Autabumu pivot pin 15 of the A,
D ₂ is the offset length between Autabumu pivot pin 15 of the monitoring unit B,
D ₃ is the offset length between Autabumu pivot pin 15 of the monitoring station C, a
D _4, the monitoring unit offset length between Autabumu pivot pin 15 and D,
H _out is the height of the upper surface of the outrigger with respect to the ground plane,
H _column is the height of the inner boom pivot pin 14 with respect to the upper surface of the outrigger.

FIG. 5 shows the definition of variables used for this calculation. Of the following variables, θ ₀ is measured by the first angle detector 31, θ ₁ is measured by the second angle detector 32, and d ₁ is a value measured by the boom length detector 33. (Detection information). That is, in the figure, θ ₀ is an angle (ground angle) formed by the inner boom 4 and the horizontal plane,
θ ₁ is an angle between the outer tab 10 and the horizontal plane (ground angle),
d ₁ is the distance in the longitudinal direction of the monitoring part A from the outer tab pivot pin 15;
d ₃ is the distance in the longitudinal direction of the Autabumu pivot pin 15 of the monitoring station C, a
d ₃ = L ₁ + L ₃ −d ₁ (Formula 1)
Moreover, d4 is the distance in the longitudinal direction of the monitoring part D and the outtabome pivot pin 15;
d ₄ = L ₁ + L ₄ −d ₁ (Formula 2)

Based on the above definition, the formulas representing the heights h _A to h D of the four monitoring units A to _D are as follows (Formula 3) to (Formula 8).
h ₁ = H _out + H _column (Formula 3)
h ₂ = h ₁ + L ₀ sin θ ₀ (Formula 4)
h _A = h ₂ + d ₁ sin θ ₁ + D ₁ cos θ ₁ (Formula 5)
h _B = h ₂ −L ₂ sin θ ₁ + D ₂ cos θ ₁ (Formula 6)
h _C = h ₂ −d ₃ sin θ ₁ + D ₃ cos θ ₁ (Expression 7)
h _D = h ₂ −d ₄ sin θ ₁ −D ₄ cos θ ₁ (Equation 8)

When the above (formula 5) to (formula 8) are expanded, the following (formula 9) to (formula 12) are obtained.
h _A = H _out + H _column + L ₀ sin θ ₀ + d ₁ sin θ ₁ + D ₁ cos θ ₁
(Formula 9)
h _B = H _out + H _column + L ₀ sin θ ₀ −L ₂ sin θ ₁ + D ₂ cos θ ₁
(Formula 10)
h _C = H _out + H _column + L ₀ sin θ ₀ − (L ₁ + L ₃ −d ₁ ) sin θ ₁ + D ₃ cos θ ₁ (Formula 11)
_{h D = H out + H column} + L 0 sinθ 0 - (L 1 + L4-d 1) sinθ 1 -D 4 cosθ 1 ( Equation 12)
As described above, the heights h _A to h D of the four monitoring units A to _D are obtained.

Then, the processing proceeds to step S3, the process proceeds to step S4 extracts the maximum value h _max is the height of the highest point of the height h _A to h _D of the monitoring unit A~D obtained above calculation. In step S4, the difference between the maximum value _{h max old} maximum value _{h max} and than this maximum value _{h max} is the maximum value _{h max} extracted before a predetermined time as an increase rate _{V h} of the height of the highest point Obtained (Formula 13 below).
V _h = h _max −h _{max old} (Equation 13),
In subsequent step S5, a process of replacing the current maximum value h _max with the maximum value h _{max old} extracted a predetermined time ago is performed, and the process _proceeds to step S6.

In step S6, whether or not the maximum value h _max exceeds a warning height (first predetermined height) H _pre that is a predetermined height lower than the limit height R, or the highest point It is determined whether or not a value obtained by multiplying the height increase rate Vh by a constant N and the maximum value h _max exceeds the notice height H _pre . In other words, if the maximum value h _max exceeds the notice height H _pre (Yes), or the value obtained by multiplying the maximum point height increase rate V _h by the constant N is added to the maximum value h _max. If it exceeds the height H _pre , the process proceeds to step S7. If not (No), the process proceeds to step S12.

In step S7, the maximum value h _max is set to a predetermined height (second predetermined height) H _lim that is a predetermined height lower than the limit height R and higher than the warning height. beyond and whether it, or the highest point whether or not the value obtained by adding the maximum value h _max is greater than the limit height H _lim height value obtained by multiplying the constant N to increase rate V _h of determining. That is, if the maximum value h _max exceeds the limit height H _lim (Yes), or the value obtained by multiplying the maximum rate _h increase rate V _h by the constant N is added to the maximum value h _max. If it exceeds the height H _lim , the process proceeds to step S8; otherwise (No), the process proceeds to step S11.

In step S8, it is determined whether or not an alarm release by the alarm release switch of the controller 30 has been input. That is, if alarm cancellation is not input (OFF), the process proceeds to step S9, and if alarm cancellation is input (ON), the process proceeds to step S10.
In step S9, the limit alarm is set to “ON” and the process returns to step S1. By turning on the limit alarm, the buzzer (sound alarm device) is continuously sounded and a crane stop command is output to stop the movement to the height side that is the limit of the outtab. In this stopping operation, an actuator (first hoisting cylinder 5, second hoisting cylinder 6, and telescopic cylinder 8) is operated by operating an unload valve of a hydraulic circuit (not shown) to operate the two booms 4, 10. ) Is stopped.

In step S10, the limit alarm is canceled and the process returns to step S1.
In step S11, the notice alarm is set to “ON” and the process returns to step S1. The buzzer sounds intermittently by setting the warning warning to “ON”. In step S12, the warning warning is canceled and the process returns to step S1. Here, in the example of the present embodiment, at the time of the warning, the crane operation itself is not restricted. However, at the time of the warning, for example, an operation speed control process for slowly operating the crane may be performed.

In the present embodiment, the notice height (first predetermined height) H _pre is set to be 0.2 m lower than the limit height (second predetermined height) H _lim. The limit height (second predetermined height) H _lim is set to 4.0 m as a height slightly lower than the limit height R. These set values of the predetermined height can be changed by a numerical input operation from the controller 30.

Next, the operation and effect of the height limiting device will be described.
According to the height limiting device for the folding crane 1 described above, in the folding crane 1 having the two booms 4 and 10 of the inner boom 4 and the outer boom 10, the inclination angle of the inner boom 4 to the ground can be detected. Three detectors 31, 32, 33, which are a single angle detector 31, a second angle detector 32 that can detect the ground inclination angle of the outtabome 10, and a boom length detector 33 that can detect the length of the outtabome 10, Based on the detection information θ ₀ , θ ₁ , d ₁ of the three detectors 31, 32, 33, the controller 30 detects the upper end 13 f (monitoring part A) and the rear upper part 11 r (monitoring part B) of the outtab 10. and a second Autabumu 12 rear top 12t of the (monitoring unit C) and the height _h a to h _D of the four positions of the lower rear end 12b (monitoring unit D) monitors, these monitoring unit A~D Either the height _h A to h _D is, when it exceeds the limit and becomes height lower predetermined height than the R of Autabumu 10 (predetermined limit height _{H lim,} notice the height _{H pre),} alarm (Limit alarm, warning warning) output or movement to the height R side that is the limit of the outtab 10 is restricted (crane stop at the limit alarm), so the outtab 10 is at the limit at any position The operator can be notified so as to prevent or prevent exceeding R.

In particular, in this height limiting device, the controller 30 issues a limit alarm when the height h _A to h D of any of the four monitoring units A to _D exceeds a predetermined limit height H _lim. When the output to the height R side that is the limit of the outtabome 10 is stopped and the warning height H _pre lower than the predetermined limit height H _lim is exceeded, a warning warning is output. The operator can be notified in advance, and a two-stage control is performed that can prevent the outtab 10 from exceeding the limit height R even if the movement to the limit height R side is performed thereafter. Therefore, it is suitable for notifying the operator to prevent or prevent the outtabome 10 from exceeding the limit height R in any posture.

The folding crane height limiting device according to one aspect of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above-described embodiment, the controller 30 has been described mainly with respect to an example in which control is performed to prevent the outtab 10 from exceeding the limit height R. However, the controller 30 is not limited to the height monitoring, and the calculation is further performed. It is also possible to avoid contact between the outtabome 10 and the ground by increasing the points.

  The controller 30 recognizes predetermined four positions of the outtabome 10 based on signals (detection information) from the three detectors 31, 32, and 33, and indicates that the outtabome 10 exceeds the limit height. Although the example in which the operator is notified to prevent and prevent the problem has been described, the present invention is not limited to this. For example, the warning notification is not issued, and the limit alarm is output and the height of the outer tab 10 is reached. It is also possible to prevent the outtab 10 from exceeding the limit height by stopping the movement of. Moreover, it is good also as a specification which issues an announcement only for an advance warning. In this case, the operator can be notified so as to prevent the outtabome 10 from exceeding the limit height.

  However, in order to notify the operator to prevent and prevent the outtubome 10 from exceeding the limit height R in any posture, as described in the above embodiment, the predetermined height is used. When a predetermined limit height is exceeded, a limit alarm is output, and at least the movement to the height side that is the limit of the outtabome is stopped, and when a warning height lower than the predetermined limit height is exceeded, It is preferable to have a configuration that outputs a warning warning.

1 Folding Crane 2 Base 3 Column 4 Inner Boom 5 First Hoisting Cylinder 6 Second Hoisting Cylinder 7 Hoisting Link Mechanism 8 Telescopic Cylinder 9 Outrigger 10 Autaboom 11 First Autaboom 12 Second Autaboom 13 Third Aubutamu 14 Inner Boom Pivot Support pin 15 Outtab boom support pin 20 Vehicle 21 Driver's seat 22 Loading platform 23 Chassis frame 30 Controller (height restriction part)
31 First angle detector 32 Second angle detector 33 Boom length detector R Height restriction target (limit height)

Claims (2)

A base, a column erected on the base so as to be horizontally rotatable, an inner boom provided to be able to undulate at the tip of the column, and an outtab to be provided to be able to undulate and extend at the tip of the inner boom The autum telescopic mechanism is composed of a plurality of booms, and among the plurality of booms, the base end side first autbum forms a cylindrical shape, and the second autbum can be expanded and contracted along the first autum. A height limiting device used for a folding crane that is internally fitted and has a configuration in which the rear end of the second autbum projects rearward from the rear end of the first autbum when reduced,
A first angle detector for detecting the ground inclination angle of the inner boom, a second angle detector for detecting the ground inclination angle of the outer boom, a boom length detector for detecting the length of the outer boom, and A height limiter for controlling the height of the boom of the folding crane based on detection information of the detector;
The height limiter is configured to, based on the detection information of the three detectors, the most advanced upper part of the plurality of booms constituting the outtabome, the rear end upper part of the first outtabome, and the first at the time of reduction. When the heights of the upper part of the rear end and the lower part of the rear end of the two outer tabs are monitored and the height of any of the four monitoring parts exceeds a predetermined height lower than the limit height Further, the height limit device for a folding crane is characterized by restricting the movement of the alarm to the height side that is the limit of the output or the alarm.   When the height of any of the four monitoring units exceeds the predetermined limit height as the predetermined height, the height limit unit outputs a limit alarm and at least the limit of the outtabome 2. The folding crane height according to claim 1, further comprising: a warning warning is output when a warning height that is lower than the predetermined limit height is exceeded and the movement to a certain height side is stopped. Restriction device.

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