JP3161674B2 - Crane safety equipment - Google Patents

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 crane which is used for lifting construction materials and the like and in which a lifting load can be arbitrarily selected by increasing or decreasing a counterweight.

[0002]

2. Description of the Related Art Self-propelled crawler cranes used for lifting construction materials and the like have different sizes and weights of the working machine body depending on the lifting weight. As the lifting weight increases, the winch hoisting torque and body weight increase. It is necessary to secure strength and a stable moment to be described later for preventing a fall.

This crawler crane is provided, for example, as shown in FIG. Boom 4 of the long structure and the upper swing body 2
And equipment such as a winch, a hydraulic motor, and an engine (not shown) for raising and lowering the boom 4 and hoisting / lowering the suspended load, and a rear portion of the upper swing body 2 (opposite the cab 3). It is roughly composed of a provided counterweight device 5 and an A frame 6 erected on the upper swing body 2 and supporting the boom 4 via a wire rope. The undercarriage 1 includes a track frame 7, a pair of left and right side frames 8 (only one is shown) provided on both sides of the track frame 7, a tumbler 9 provided at one end of the side frame 8, Traveling device 10 provided at the end and including a traveling motor (not shown)
And a plurality of rollers 1 provided on the side frame 8 for supporting the crawler belt 11 between the tumbler 9 and the traveling device 10.
2 and the like.

The above-mentioned counterweight device 5 is formed by stacking a plurality of rectangular blocks made of steel, and the number of blocks to be mounted is increased or decreased according to the load of the suspended load, so that the load that can be lifted according to the working condition. Can be changed.

As shown in FIG. 3 showing a view in the direction of arrow A in FIG. 1 and FIG. 4 showing a view in the direction of arrow B in FIG. A first counterweight 5a attached by a fixture and a second counterweight formed by stacking eight blocks 5b1 to 5b8 on both left and right sides of the first counterweight 5a so as to sandwich the rear leg 6a of the A frame 6.
Counter weight 5b and second counter weight 5
b, a plurality of third counterweights 5c formed by stacking three blocks on the first counterweight 5a, and two blocks stacked on the second counterweight 5b. And a fourth counterweight 5d to be formed. The first, second and fourth counterweights 5a, 5b and 5d are fixed to the first counterweight 5a by bolts 32 penetrating therethrough, and the third counterweight 5c is connected to the first counterweight 5a. And is fixed by a bolt (not shown) penetrating through.

As shown in detail in FIG. 2, a plurality of weights 13 are attached to the side frame 8 of the lower traveling body 1 by fasteners such as bolts (not shown) to increase a stable moment described later together with the counterweight device 5. ing.

The above-mentioned crane is provided with an overload prevention device required by law. This overload prevention device is for preventing the crane from falling over due to the work being performed beyond the allowable hanging load and working radius. In FIG. 1, Rt is the horizontal distance from the tip a of the boom 4 to the first roller 12 a of the lower traveling body 1, Ra is the horizontal distance from the first roller 12 a to the center of gravity Sa of the lower traveling body 1, and Rb is The horizontal distance from the first roller 12a to the center of gravity Sb of the upper swing body 2 is shown.

[0008] The overload prevention device is a product of the overturning moment Mt which is the product of the horizontal distance Rt and the load (Wt) of the suspended load, and the product of the horizontal distance Ra and the load (Wa) acting on the position of the center of gravity Sa. 1 which is the product of the stable moment Ma of the first and the load (Wb) acting on the horizontal distance Rb and the position of the center of gravity Sb.
Is related to the stable moment Mb of

It is monitored whether or not Mt <(Ma + Mb) × α (1) is satisfied. If the expression (1) is not satisfied, a warning is issued to the operator or the operation of the work machine is stopped. Or something. Here, α is a safety factor.

As described above, the allowable lifting load is determined by the above equation (1). Here, FIGS. 1 to 3
Assuming that the state where the fourth counterweight 5d and the weight 13 described above are removed from the upper revolving unit 2 and the lower traveling unit 1 is a standard specification, and the state where the counterweights are added is a lifting capacity increasing specification, in the latter case, Second stability moment M
The values of a and Mb are larger than the former, and the lifting load can be increased.

The above-mentioned overturning moment Mt is set by a boom elevation angle β detected by a boom angle meter (not shown), a suspension load Wt detected by a load meter, and a boom length setting device attached to the overload prevention device. Calculated based on the boom length l. The stability moments Ma and Mb are calculated in advance based on the weights of the upper revolving unit 2 and the lower traveling unit 1 and the positions of the centers of gravity thereof, and determine the relationship between the allowable working radius and the suspension load based on the stable moments Ma and Mb. It is determined in advance as a rated load curve for each boom length. The rated load curve for each boom length is stored in a storage device such as a ROM as a table, and during operation, a rated load curve corresponding to the boom length is selected from the table and read into the overload prevention device for use. . Then, a working radius is determined from the boom elevation angle and the boom length detected by the goniometer, and the maximum lifting load is determined from the rated load curve using the working radius. Further, the detected actual lifting load is compared with the obtained maximum lifting load, and a danger is avoided by, for example, stopping a warning or stopping the operation of the work machine when a danger state set in advance is reached.

[0011]

In such a conventional example, the state of the counterweight device must be checked at a glance to confirm the current lifting capacity, which is troublesome. By the way, the above rated load curve table is
The crane standard specification and the capacity increase specification are naturally different. In general, two storage devices (for example, cassettes) are prepared for each specification, and the operator selectively uses them according to the specification. Therefore, the replacement work must be performed for each specification change, which is complicated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a crane safety device capable of detecting a state of a counterweight device and notifying an operator of information on a lifting capacity.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to FIGS. 1 to 7 showing an embodiment. The present invention relates to a lower traveling body 1 and an upper revolving body 2 provided on the lower traveling body 1. FIG.
A boom 4 provided on one end side of the upper swing body 2 so as to be able to move upward and downward, and first counterweights (5a, 5b, 5) mounted on the other end side of the upper swing body 2 on the opposite side of the boom 4
c) A counterweight device 5 for setting two types of counterweight by attaching and detaching a second counterweight (5d) to and from the suspension load by the boom 4 and the working radius based on the boom elevation angle and the boom length. The present invention is applied to a crane safety device including an overload prevention device that monitors an overload state of the crane from a falling moment and a rated load curve table stored in advance by a cassette.
According to the first aspect of the present invention, there is provided a detecting means 14a for detecting attachment / detachment of the second counterweight (5d), and mounting of the counterweight device 5 based on a signal detected by the detecting means 14a regardless of the cassette loaded state. The above-described object is achieved by providing the notifying means 18 for notifying the state. The invention according to claim 2 is shown in FIGS.
As shown in FIG. 10, a lower traveling structure 1, an upper revolving structure 2 provided on the lower traveling structure 1, a boom 4 provided on one end side of the upper revolving structure 2 so as to be able to move up and down, and the opposite of the boom 4 Side, is mounted on the other end side of the upper swing body 2, at least in the first mode (5a, 5b, 5c) and the second mode (5a, 5).
b, 5c, 5d), a counterweight device 5 for setting two different types of counterweight weights, a overturning moment consisting of a suspension load by the boom 4, a working radius based on the boom elevation angle and the boom length, and The present invention is applied to a crane safety device including an overload prevention device that monitors a crane overload state from a stored rated load curve table. A detecting device (14, 21) for detecting the first and second aspects, respectively, and a display device 22 for displaying the maximum lifting load regardless of the cassette loaded state based on the detection result by the detecting device (14, 21). The above-mentioned object is also achieved by providing the following.

[0014]

According to the first aspect of the present invention, the detecting means 14a provided on the upper swing body 2 detects the attachment / detachment of the second counterweight (5d) of the counterweight device 5, and notifies based on the detected signal. Means 18 informs the mounting state of counterweight device 5. According to the second aspect of the present invention, the first aspect (5a, 5b, 5c) and the second aspect (5a, 5b, 5c) of the counterweight device 5 in which the detection device (14, 21) is mounted on the upper swing body 2 are provided. 5c, 5d) are detected. Then, the maximum lifting load in that state is displayed on the display device 22 in accordance with each mode detected by the detection device (14, 21).

In the means and means for solving the above problems which explain the constitution of the present invention, in order to make the present invention easy to understand, the drawings of the embodiments are used. However, the present invention is not limited to this.

[0016]

【Example】

-First Embodiment- A first embodiment will be described with reference to FIGS. FIG.
Fig. 6 is a detailed view of the part a in Fig. 3, Fig. 6 is a view showing a state in which the fourth counterweight 5d in Fig. 5 is removed,
FIG. 7 is a circuit diagram of the alarm device.

As shown in FIG. 5, the rear legs 6 of the A-frame
a includes a block 5b of the second counterweight 5b.
A limit switch 14a is mounted via a pedestal 16 at a position corresponding to a fourth counterweight 5d additionally mounted on the first and the fifth b5. The rod-shaped detecting portion 14a1 of the limit switch 14a extends toward the fourth counterweight 5d, and the detecting portion 14a1 contacts and bends with the fourth counterweight 5d as shown in FIG. The switch turns on. FIG.
As shown in the figure, when the fourth counterweight 5d is not mounted, the detection unit 14a1 is in a horizontal state, and the switch unit is turned off. Reference numeral 17 denotes a stay suspended between the left and right rear legs 6a of the A frame 6.

FIG. 7 shows a circuit of the alarm device including the limit switch 14a. This circuit includes the detection unit 14a described above.
1 has a movable contact CP which has an ON terminal NO and an OFF terminal N.
A limit switch 14a that opens and closes with C, a warning light 18 provided in the cab 3, a power supply 19, and a fuse 20 are connected in series.

The operation of the embodiment constructed as described above will be described. Fourth counterweight 5d as shown in FIG.
Is not attached, limit switch 1
The detector 14a1 of 4a is in a horizontal state, and the movable contact piece CP at this time is at the off terminal position NC. In this case, FIG.
Since the power supply 19 and the warning light 18 in the circuit of the above are cut off by the limit switch 14a, the warning light 18 in the cab 3 is not turned on. When the fourth counterweight 5d is attached as shown in FIG. 5, the movable contact piece CP of the limit switch 14a switches to the ON terminal position NO as described above. Thereby, the power supply 19 and the warning light 18 are connected, and the warning light 18 is turned on.

Since this embodiment is configured as described above,
The operator can be notified that the fourth counterweight 5d is additionally mounted. Therefore, when there are two types of storage devices for the rated load curve table including the cassettes to be loaded in the overload prevention device, it is possible to easily determine which cassette is to be loaded by turning on / off the warning light 18.

-Second Embodiment- A second embodiment will be described with reference to FIGS. In this embodiment, the state in which the first counterweight 5a, the second counterweight 5b, and the third counterweight 5c are mounted is a standard specification, and the maximum lifting load is 150t. Further, a state in which the fourth counterweight 5d is further mounted on the standard specification state is referred to as a lifting capacity increasing specification.
80t. Furthermore, the blocks 5b1 and 5b of the second counterweight 5b correspond to the state of the standard specification.
5 is hereinafter referred to as a lifting capacity reduced specification, and its maximum lifting load is set to 120 t.

As shown in FIG. 9 which is a detailed view of a part b in FIG. 8, the rear legs 6a of the A frame are provided with the fourth counterweight 5d and the respective positions of the blocks 5b1 and 5b2 of the second counterweight 5b. Limit switch 14
a, 14b, and 14c are attached. These limit switches 14a, 14b and 14c are incorporated in a circuit as shown in FIG. 10 to be described later, and the operator is notified of the maximum lifting load allowed from the weight of the mounted counterweight.

The circuit shown in FIG. 10 includes a power supply 19, a switch group 14 including limit switches 14a, 14b, and 14c, and a display device 22 provided in the cab 3.
And a judging device 21 for judging the maximum lifting load based on a signal from the switch group 14. The display device 22 includes a first lamp 22a that displays a maximum lifting load of 180 t and a second lamp 22 that displays 150 t.
b, and a third lamp 22c for displaying 120t, which is turned on based on a combination of the on / off state of each of the limit switches 14a, 14b, and 14c of the switch group 14.

The judgment device 21 has a maximum lifting load 180
t (suspending capacity increase specification) to determine the first lamp 22
a first AND gate 21a for supplying a lighting signal to a.
A second AND gate 21b that determines a 150t (standard specification) and supplies a lighting signal to the second lamp 22b;
0t (hanging capacity down specification)
Third AND Gate 21c for Supplying Lighting Signal to 2c
And two inverters 21d and 21e. Then, by performing a logical operation on a combination of signals detected by the limit switches 14a, 14b, and 14c, the weight of the mounted counterweight, that is, the maximum lifting load is determined, and the display device 22 is operated.
Is output to one of the corresponding lamps 22a, 22b, and 22c. Limit switch 1 below
Judgment device 2 based on signals of 4a, 14b and 14c
The operation 1 will be described separately for three states: a lifting capacity specification, a standard specification, and a lifting capacity reduction specification.

(1) Lifting capacity increasing specification A fourth counterweight 5d is provided on the blocks 5b1 and 5b5 of the second counterweight 5b used for the standard specification.
Is mounted, the switches 14a, 14b, and 14c are all turned on, and it can be determined that the suspension capacity is increased. That is, the switch 14a is turned on,
When the switch 14b is on and the switch 14c is on,
Since all three inputs of the first AND gate 21a of the judging device 21 are at a high level, the AND gate 21a outputs a lighting signal to the first lamp 22a to light the first lamp 22a. Since the inverted signal of the switch 14a or 14b is input to the second and third AND gates 21b and 21c via the inverters 21d and 21e, the AND gates 21b and 21c are turned off, and the switch 14a or 14b is turned off. When turned on, the AND gates 21b and 21c do not output a lighting signal.

(2) Standard Specifications In the standard specifications, the blocks 5b1 and 5b5 of the second counterweight 5b are mounted, respectively, and the fourth counterweight 5d is not mounted. Therefore, the switch 14a is off, and the switches 14b and 14c are on. When the switch 14a is off, the switch 14b is on, and the switch 14c is on, all three inputs of the second AND gate 21b of the judging device 21 are at a high level. And the second lamp 22b is turned on. At this time, the outputs of the first and third AND gates 21a and 21c are at a low level.

(3) Lifting capacity down specification In the lifting capacity down specification in which the blocks 5b1 and 5b5 of the fourth counterweight 5d and the second counterweight 5b are not mounted, the switches 14a and 14b are turned off and the switch 14c is turned off. Turns on. The third AND gate 21c of the judgment device 21 is a switch 1
When the switch 4a is off, the switch 14b is off, and the switch 14c is on, all three inputs are at a high level. Therefore, the AND gate 21c outputs a lighting signal to the third lamp 22c, and outputs the lighting signal to the third lamp 22c. 22c is turned on. At this time, the first and second AND gates 21a, 21a,
The output of 21b is at low level.

In this embodiment constructed as described above, the mounted state of the counterweight is detected by the switches 14a, 14b and 14c, and the maximum lifting load in the mounted state is determined by the first, second, and third lamps. 22
Since the worker is notified by a, 22b, and 22c, the worker can grasp the maximum lifting load without looking at the state of the counterweight device. Further, even when there are three types of cassette devices storing a rated load curve table used for the overload prevention device, it is possible to easily determine which cassette should be loaded based on the light-on / off state of the lamp.

The combination of the on / off states of the switches 14a, 14b and 14c other than those described in the above (1) to (3), for example, the switch 14a is on, the switch 1
4b is off, switch 14c is on, switch 1
In a state where it is substantially impossible such as a state where only 4c is off, the display device is not turned on as an error state due to a failure of a device such as a switch. Display device 2
A second lamp for error may be provided in 2 and turned on when an error is determined.

Third Embodiment A third embodiment will be described with reference to FIGS. In this embodiment, the weight of the counterweight is determined from the signal of the switch group 14 shown in FIGS. 8 and 9 by the control device 30 described later, and the maximum lifting load according to the weight is displayed. The rated load curve table used in the overload prevention device is automatically selected according to the state of the counterweight device 5.

The control device 30 includes a CPU, ROM, R
Various processes are executed by the program shown in FIG. 12 using an AM or the like as a main component, and the following components are functionally provided.
That is, the weight of the counterweight is determined based on the on / off signals of the switches 14a, 14b and 14c attached in the same manner as in the second embodiment (FIGS. 8 and 9), and the maximum lifting load is calculated based on the weight. The maximum lifting load calculation unit 23, the storage unit 24 that stores a plurality of rated load curves according to the counterweight weight and the boom length as a table, the calculation result of the maximum lifting load calculation unit 23, and the boom length setting unit 31a. A selection unit 25 for selecting one rated load curve from the storage unit 24 based on the boom length l. Further, the boom length 1 set by the boom length setting device 31a, the suspension load Wt detected by the load meter 31b, the boom elevation angle β detected by the angle meter 31c, and the rated load selected from the storage unit 24 by the selection unit 25. Overload prevention device 2 that monitors the fall of the crane using a curve
6 is provided. The control device 30 displays a message prompting confirmation of the presence or absence of the weight 13 to be attached to the undercarriage 1 and the maximum lifting load based on the weight of the mounted counterweight based on the calculation result of the maximum lifting load calculation unit 23. The display device 27 and a confirmation switch 29 for canceling a confirmation message displayed on the display device 27
And a warning device 28 that alerts the operator about the fall of the crane monitored by the overload prevention device 26.

The operation of the control device 30 constructed as described above is controlled by the switches 14a, 14a in the same manner as in the second embodiment.
b, and 14c are in the ON state with the increased lifting capacity (maximum lifting load of 180 tons), switches 14b and 14c
Are divided into three states of a standard specification (maximum lifting load of 150 tons) in an ON state, and a specification of reduced lifting capacity (maximum lifting load of 120 tons) in which only a switch 14c is in an ON state, which will be described with reference to portions c and d in FIG. .

In FIG. 12c, first, in step S1, it is determined whether all of the signals X1, X2, X3 output from the switches 14a, 14b, and 14c are on. If the signals are on, the process proceeds to step S2. If not, the process proceeds to step S6. In step S2, a confirmation message of the state of attachment of the weight 13 of the lower traveling structure 1 is displayed on the display device 27, and the process proceeds to step S3. In step S3, it is determined whether or not the confirmation switch 29 is on. If it is on, the process proceeds to step S4. If it is not on, the process returns to step S2, and the confirmation message is continuously displayed on the display device 27. When the process proceeds to step S4, the maximum lifting load of 180 tons is displayed on the display device 27, and the process proceeds to step S5 to set the flag 180.

In step S6, the switches 14b, 14
It is determined whether or not only the signals X2 and X3 output from c are on. If the determination is affirmative, the process proceeds to step S7. If the determination is negative, the process proceeds to step S9. In step S7, the maximum lifting load of 150 tons is displayed on the display device 27, and the process proceeds to step S8 to set the flag 150.

In step S9, it is determined whether or not only the signal X3 output from the switch 14c is on. If the result is affirmative, the process proceeds to step S10. If the result is negative, the process proceeds to step S12 to display an error on the display device 27. Step S1
At 0, the maximum lifting load of 120 tons is displayed on the display device 27, and the process proceeds to step S11, where the flag 12 is set.
Set 0. The above is the operation of the maximum lifting load calculation unit 23 of the control device 30.

Next, the selector 25 and the overload prevention device 2
The operation of No. 6 will be described with reference to a part d in FIG. Load cell 31
b, the boom elevation angle β detected by the goniometer 31c, the boom length setting device 31
The boom length l preset by a is determined in step S1.
Read in 3. Further, in step S13, a work radius R is calculated by multiplying the cosine value of the boom elevation angle β by the boom length l. Next, proceeding to step S14, the flag set in steps S5, S8, and S11 of the maximum lifting load calculating unit 23 (part c) is determined. If the flag is 180, the process proceeds to step S15 and 150. For example, if it is 120, the process proceeds to step S17.

When the process proceeds to step S15, the storage unit 2
4, a rated load curve corresponding to the boom length is selected from the first rated load curve table for the maximum lifting load of 180 tons stored in advance, and the working radius R calculated in step S13 from the rated load curve. Rated load Ws at
Is calculated. Then, the process proceeds to step S18, in which the value obtained by multiplying the rated load Ws calculated in step S15 by the first safety factor α1 and the actual suspension load W read in step S13.
Compare with t

## EQU00002 ## It is determined whether or not the relationship of Wt> Ws.times..alpha.1 (2) is satisfied. Equation (2) above
If the condition is satisfied, the process proceeds to step S19, where the operator is alerted by an alarm 28 such as an alarm, and the process proceeds to step S19.
Proceeding to step 20, if formula (2) is denied, the process returns to step S13 and repeats the above control.

Steps S14 to S16
Alternatively, when the process proceeds to step S17, using the second rated load curve table for the maximum lifting load of 150 tons and the third rated load curve table for 120 tons, which are stored in the storage unit 24 in advance, as described above. In the same manner as in step S18, the determination of the equation (2) is performed.

Further, in step S20,

## EQU00003 ## The determination of Wt> Ws.times..alpha.2 (3) is performed, and if this determination is satisfied, the process proceeds to step S2.
The program proceeds to 1 and the boom lowering and hoisting are stopped by the signal Y. If the expression (3) is negative in step S20, the process returns to step S13, and the above control is repeated again. The above is the operation of the selection unit 25 and the overload prevention device unit 26.

Here, α1 and α2 described in the equations (2) and (3) are safety factors in consideration of the crane's falling load, and have a relationship of α1 <α2.

In the third embodiment configured as described above, the following effects can be obtained. (1) Since the state of the counterweight device is detected and the maximum lifting load is displayed based on the state, the operator can easily grasp the maximum lifting load. (2) When the fourth counterweight 5d is mounted, the operator is urged to confirm whether or not the weight 13 to be attached to the lower traveling body 1 exists.
Weight 13 when the counter weight 5d is mounted
You can eliminate forgetting to install. (3) The optimal rated load curve table used in the overload prevention device can be automatically selected based on the maximum lifting load according to the weight of the mounted counterweight, so that complicated cassette replacement work is eliminated.

In the above-described second and third embodiments, the limit switch is attached to the blocks 5b1 and 5b2 of the fourth counterweight 5d and the second counterweight 5b. It can be attached to all the counterweights mounted on the vehicle, and the presence or absence of attachment of the weight 13 attached to the side frame 8 of the lower traveling body 1 is also detected by a detection means such as a limit switch. May be.

In the first to third embodiments, the state of the counterweight device is detected by the contact type limit switch. However, a non-contact type proximity switch may be used. In that case, the switch may be mounted so that the distance between the switch and the counterweight is reduced.

In the above embodiment, the limit switch 14a serves as the detecting means, the limit switch group 14 and the judging device 21 serve as the detecting device, the warning light 18 serves as the notifying means, the first counterweight 5a and the second counterweight. 5b and the third counterweight 5c are the first counterweight, the fourth counterweight 5d is the second counterweight, the first counterweight 5a, the second counterweight 5b and the third counterweight. 5c is the first
The first counterweight 5a, the second counterweight 5b, the third counterweight 5c, and the fourth counterweight 5d correspond to the second mode, the first ramp 22a and the second ramp 22b. And the third lamp 22c
Constitute the display device.

[0045]

According to the present invention configured as described above, the following effects can be obtained. (1) The detection means detects the attachment / detachment of the second counterweight of the counterweight device, and informs the user of the mounting state of the counterweight device based on the detected signal. The detached state of the weight and the maximum lifting load in each state can be easily confirmed. As a result, when there are a plurality of cassettes storing the rated load curve, it is possible to easily determine which cassette is to be loaded. (2) Since the detecting device detects either the first mode or the second mode of the counterweight device and displays the maximum lifting load on the display device based on the detected mode, the counterweight device is used. The increase and decrease of the maximum lifting load according to the aspect can be easily grasped. As a result, when there are a plurality of cassettes storing the rated load curve, it is possible to easily determine which cassette is to be loaded.

[Brief description of the drawings]

FIG. 1 is an overall side view showing a structure of a crane in a crane safety device of the present invention.

FIGS. 2A and 2B show details of a side frame of the lower traveling body in FIG. 1, wherein FIG. 2A is a front view and FIG.

FIG. 3 is a view in the direction of arrow A in FIG. 1 showing the first embodiment of the safety device for the crane according to the present invention.

FIG. 4 is a view in the direction of arrow B in FIG. 3;

FIG. 5 is a detailed view of a part a in FIG. 3;

6 is a state diagram showing a state where a fourth counterweight in FIG. 5 is removed.

FIG. 7 is a circuit diagram showing a first embodiment of a crane safety device according to the present invention.

FIG. 8 is a configuration diagram showing a second embodiment of a crane safety device according to the present invention.

FIG. 9 is a detailed view of a part b in FIG.

FIG. 10 is a circuit diagram showing a crane safety device according to a second embodiment of the present invention.

FIG. 11 is a circuit diagram showing a third embodiment of the crane safety device according to the present invention.

FIG. 12 is a control flow of the control device in FIG. 11;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 Lower traveling structure 2 Upper revolving structure 4 Boom 5 Counterweight device 5b Second counterweight 5d Fourth counterweight 14a to 14c Limit switch 18 Warning light 21 Judgment device 22 Display device 23 Maximum lifting load calculation unit 24 Storage unit 25 Selection unit 26 Overload prevention unit 30 Control unit

Claims (2)

(57) [Claims] A lower traveling structure; an upper revolving structure provided on the lower traveling structure; a boom provided on one end side of the upper revolving structure so as to be able to move up and down; Mounted on the other end,
A counterweight device for setting two types of counterweights by attaching and detaching a second counterweight to and from the first counterweight; a hanging load by the boom; and a working radius based on a boom elevation angle and a boom length. In a crane safety device provided with an overload prevention device for monitoring a crane overload state from a tipping moment and a rated load curve table stored in advance by a cassette, a detection for detecting attachment / detachment of the second counterweight. A safety device for a crane, comprising: means for notifying a mounting state of the counterweight device based on a signal detected by the detecting means regardless of a loaded state of the cassette. 2. A lower traveling structure; an upper revolving structure provided on the lower traveling structure; a boom provided on one end side of the upper revolving structure so as to be capable of raising and lowering; Mounted on the other end,
A counterweight device for setting at least two different types of counterweight weights according to at least the first aspect and the second aspect; and a falling moment comprising a hanging load by the boom, and a working radius based on the boom elevation angle and the boom length; In a crane safety device including an overload prevention device that monitors an overload state of the crane from a rated load curve table stored in advance by a cassette, a detection device that detects the first and second aspects, A display device for displaying a maximum lifting load based on a detection result by the detection device, regardless of a loaded state of the cassette.