JPS6145888A - Jib shifting defective-operation preventive device for car type crane - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a device for preventing erroneous jib transfer of a vehicle type crane.

[Technical background of the invention]

Generally, vehicle type cranes are equipped with a jib to compensate for the length of the boom.

This jib is extended to the front of the boom by having its base end supported by the tip of the boom and rotating around the base end.When not in use, the jib's base end is directed toward the boom tip, and the jib is extended toward the front of the boom. It is stored along the boom with the side facing toward the base end of the boom.

Vehicle-type cranes equipped with this jib include those that store the jib along the bottom surface of the boom, and those that store the jib along the side of the boom. Vehicle-type cranes that are stored together can extend the jib by rotating the jib vertically under the boom, so while it is possible to extend the jib even in narrow spaces, it is difficult to extend the jib when the jib is stored. During crane work, there is a problem that the view from the crane operator's cab is obstructed by the jib under the boom.Also, with self-propelled cranes where traveling and crane operation are performed in the same operator's cab,
When traveling with the boom retracted and laid down, the view from the driver's cab is obstructed by the jib under the boom.
In order to widen the field of view from the operator's cab, the boom must be mounted high and the jib stored along the bottom of the boom must be placed high.
The problem was that the position was high and stability deteriorated.

On the other hand, those that store the jib along the side of the boom,
Since there is no jib under the boom, the boom can be mounted in a high position to provide a wide view from the operator's cab. This is more advantageous than the jib that is stored along the bottom of the boom, but in the past, the jib that was stored along the side of the boom was rotated laterally and extended to the front of the boom. However, there was a problem in that the jib could not be extended in locations where there was no space on the sides of the boom that was at least the length of the jib.

Therefore, recently, the jib is stored along the side of the boom, and when the jib is used, the jib that is stored along the side of the boom is moved to the underside of the -H boom. Therefore, a vehicle-type crane has been considered in which the jib is placed under the boom and rotated in the vertical direction to extend the jib.

This vehicle-type crane stores the jib along the side of the boom, and when using the jib, first extend the boom and retract the sheave block at the tip of the boom forward from the base end of the jib. Rotate around the boom axis to move from the side of the boom to the bottom side of the boom, contract the boom, and engage the jib support shaft provided on the side of the sheave block with the fork part at one end of the jib base 5. If you want to extend the jib to the front of the boom by rotating the jib around the jib spindle after the The jib is retracted forward from the base end of the boom, then the jib is rotated around the boom axis and moved from the bottom of the boom to the side of the boom for storage. Since the boom is stored along the road, it is possible to have a wide field of view from the operator's cab without having to install the boom at a high height, and the jib can be rotated vertically to extend it. This allows you to extend the jib even in tight spaces.

To transfer the jib from the side of the boom to the bottom of the boom when extending the jib in this vehicle-type crane, the boom is generally raised by connecting the tip of the jib connecting rod, whose base end is pivoted to the swivel base of the crane, to the jib. By rotating the jib around the boom axis by its own weight while supporting the jib with the jib connecting rod, or by connecting the auxiliary hoisting rope of the crane to the jib and retracting the boom or letting out the rope, the jib can be rotated by its own weight. This is done by rotating the jib around the boom axis, and when storing the jib, transferring the jib from the bottom of the boom to the side of the boom is done by connecting the tip of the jib connecting rod to the jib, in the opposite way to the above operation. This can be done either by pushing the jib up with the jib connecting rod by lowering the boom down, or by connecting the auxiliary hoisting rope of the crane to the jib and pulling up the jib by extending the boom or hoisting the rope and rotating the jib around the boom axis. It is being said.

[Problems with background technology]

By the way, with this vehicle type crane, when the jib is moved from the side of the boom to the bottom side of the boom when extending the jib, and when the jib that has been tucked under the bottom of the boom is moved to the side side of the boom when storing the jib, In this case, the boom must be extended until the sheave block at the tip of the boom is retracted forward from the base end of the jib before the jib transfer can be started, but in reality, the jib transfer operation is performed by the crane operator. Because the crane operator is working alone, the crane operator may become depressed and start the jib transfer without fully extending the boom, or may start the jib transfer operation before the boom is fully extended. If the jib transfer is started before the sheave block is retracted from the base end of the jib, the base end of the jib rotated around the boom axis may become attached to the sheave at the boom tip. The problem is that if you continue to transfer the jib because it hits the block and is prevented from rotating, unreasonable force will be applied to the jib and sheave block, damaging them.

[Purpose of the invention]

This invention was made in view of the above-mentioned circumstances, and its purpose is to prevent the crane operator from relocating the jib before retracting the sheave book at the tip of the boom from the base end of the jib. If an attempt is made to start, make sure that the boom hoisting cylinder, boom extension/retraction mechanism, or auxiliary rope hoisting machine is not activated, or issue an alarm to prevent damage to the jib or sheave block at the tip of the boom due to incorrect jib transfer operation. Activate the boom hoisting cylinder, boom telescoping mechanism, or auxiliary rope hoist regardless of the boom extension length, except when transferring the jib, or operate the crane without issuing an alarm. An object of the present invention is to provide a device for preventing erroneous operation of jib transfer for a vehicle-type crane.

[Summary of the Invention] That is, the present invention compares the detected value of the boom length detector with a set value to determine whether the boom has been extended until the sheave block at the tip of the boom is retracted forward of the base end of the jib. A boom extension detection circuit is provided at the jib connecting rod pivot portion of the swivel base or the jib connecting rod connecting portion of the jib, and is activated by the pulling of the jib connecting rod or the pivoting of the jib connecting rod to the jib. A limit switch that detects the connection of the jib connecting rod to the jib or is provided at the auxiliary rope connection part of the jib and is actuated by the connection of the auxiliary rope to the jib to detect the connection of the auxiliary rope to the jib. If the limit switch is detecting the connection of the jib connecting rod or auxiliary rope, and the boom extension detection circuit has not detected the extension of the boom, the boom hoisting cylinder, boom extension/retraction mechanism, or auxiliary rope If the limit switch does not detect the connection of the jib connecting rod or auxiliary hoisting rope, the boom hoisting cylinder or It is designed to allow the boom extension/contraction mechanism or the auxiliary rope hoist to operate, or to stop the alarm.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a jib transfer error prevention device, and FIG. 2 shows a vehicle-type crane equipped with a jib.

First, to explain a vehicle type crane equipped with a jib, in Fig. 2, 1 is a car body, 2 is a swivel base, and 3 is an extendable boom that is raised and lowered by a boom hoisting cylinder 4. A sheave block 5 with a sheave 6.7 is provided at the tip. Note that 8 is a driver's cab that serves both as a traveling operation and a crane operating room, and 9 is an outrigger.

10 is a jib that supplements the length of the boom 3, and this jib 10
The boom 3 is supported at its proximal end and distal end by the jib holder 20 and jib support bracket 30 provided on the boom 3, with the proximal end facing the boom distal end and the distal end facing the boom proximal end. It is stored along one side of the boom, and when in use, it is moved from the side of the boom to the bottom of the boom.
Thereafter, the base end is supported by the boom tip and rotated around the base end, so that it is extended to the front of the boom 3.

Although detailed description of the jib holder 20 will be omitted,
As shown in FIG. 6, the boom 3 is pivotally supported to be movable up and down on a bracket 21 provided on the side surface of the boom 3, and the base end side of the jib 10 is attached to a bracket 12 for mounting a holder provided on the jib 10.
is detachably supported by the jib holder 20 by being fixed to the jib holder 20 by a pin 22.

Furthermore, a bracket mounting plate 13 is provided on the distal end side of the jib 10 and is removably attached to a jib support bracket 30 provided on the proximal end side of the boom 3. In this bracket mounting, the plate 13 is L-shaped as shown in FIG. It is supported so that it can be rotated about the proximal end from the state shown by the solid line in FIG. 2 to the state shown by the chain line. Incidentally, the reference numeral 32 designates a stopper for receiving the base end of the plate 13, which is attached to the bracket rotated to the state shown by the chain line.

In addition, a lock bin insertion hole is provided at the tip of the plate 13 for bracket installation, and the plate 13 can be installed in the state shown by the solid line, that is, in the state in which the jib 10 is stored along the side of the boom 3. It is designed to be locked to the jib support bracket 30 by a lock pin 33.

In addition, in FIGS. 2 and 3, 40 is an extendable jib connecting rod used when transferring the jib 10 between the side surface of the boom and the bottom surface of the boom. , is provided on the swivel base 2 of the crane.

4 and 5 show a jib connecting rod 40, which consists of a hollow rod 41 and a slide rod 42 inserted into the hollow rod 41. The base end of 41 is pivotally connected to the swivel base 2 by a universal joint 43 so as to be movable up and down. Further, the distal end of the slide rod 42 is a jib coupling portion 42a that is detachably coupled to a rod coupling bracket 14 provided on the distal end side of the jib 10 by means of a pin 44. Note that this jib connecting rod 40 is laid down on the upper surface of the swivel base 2 when not in use.

Next, jib 1 is stored along the side of boom 3.
0 to the front of the boom. In this case, first, as shown by the chain line in Fig. 2, the boom 3 is slightly extended, and when transferring the jib 10 to the bottom of the boom, the base end of the jib 10 is extended. The sheave block 5 is retracted forward from the base end of the jib 10 so that it does not hit the sheave block 5, and the jib connecting rod 40 which is laid down on the swivel base 2.
as shown by the chain line in FIG.
is connected by a bottle 44. In this case, since the jib connecting rod 40 is extendable and retractable, the jib connecting rod 4
By expanding and contracting the jib connecting portion 42a, the jib connecting portion 42a can be easily aligned with the rod connecting bracket 14 on the jib 10 side.

After this, to attach the bracket on the jib 10 side, remove the lock bin 33 that locks the plate 13 to the jib support bracket 30 on the boom 3 side, and then remove the lock bin 33 from the boom hoisting cylinder 4.
The boom 3 can be raised by extending the boom 3. When the boom 3 is raised, the jib 10, whose base end is supported by a rotatable jib holder 20 and whose distal end is pivotally supported by a jib support bracket 30, is exposed. is supported by the jib connecting rod 40 due to its own weight and rotates around the boom axis, so that it is held on the underside of the boom 3 as shown in FIG. Note that the jib 10 that has been moved to the lower surface side of the boom 3 has its base end positioned directly below the boom 3, and its tip side protrudes to the side of the boom 3 (see FIG. 8).

After the jib 10 is transferred to the bottom side of the boom 3 in this way, the jib connecting rod 40 is first removed from the jib 10 and laid down on the swivel base 2, and then it is extended when the jib 10 is transferred to the bottom side of the boom. The boom 3 is retracted as shown in FIGS. 7 and 8, and the jib support shafts 15, 15 protruding from both sides of the sheave block 5 are attached to the base end of the jib 10. After inserting and engaging the fork part 16.16 and inserting the pin 17 into the tip of the fork part 16.16 to prevent the fork part 16.16 from coming off the jib support shaft 15.15, the jib 10 is extended. start.

Figure 9 shows the jib 10 in the middle of being extended.
The jib 10 transferred to the lower surface of the boom 3 is extended as follows.

First, the rooster sheave 18 is attached to the sheave block 5 at the tip of the boom, and the auxiliary hoist row 150 of the crane is wrapped around the rooster sheave 18, the guide sheave 11 at the tip of the jib 10, and the guide sheave 19 at the base end of the boom. After connecting the tip of the rope 50 to the tip of the jib 10, attach the holder of the jib 10 to the jib boulder 20 with the auxiliary rope 50 under tension. To attach the jib 10 to the bracket 30, the jib 10 is removed from the jib holder 20 and the jib support bracket 30 by removing the pin 31 that pivotally supports the plate 13.

After this, the auxiliary rope 50 is let out while raising the boom 3, and the jib 10 is rotated by its own weight around the jib support shaft 15.15 as a fulcrum, as shown in FIG. Then, remove the auxiliary rope 50 from the guide sheave 19 at the base end of the boom and remove the auxiliary rope 50 from the guide sheave 19 at the base end of the boom.
By hoisting up the jib 10, the jib 10 is extended to the front of the boom.

After the jib 10 is extended in front of the boom in this way, the boom 3 is lowered close to the ground and the tip of the jib 10 and the sheave block 5 at the tip of the boom are connected as shown in FIG.
are connected with the tension rod 51, and then the jib 10 is connected with the tension rod 51.
What is necessary is to remove the auxiliary winding rope 50 from the auxiliary winding rope 50, attach the hook 52 to this auxiliary winding rope 50, and perform crane work. In addition,
The tension rod 51 is supported by the jib 10 by having its proximal end pivoted to the distal end of the jib 10 and removably locked to the jib 10. It is set by attaching it to a tension rod set bin 53 provided in the.

In addition, when storing the jib 10, connect the tip of the auxiliary loaf 50, which is hung on the guide sheave 11 at the tip of the jib, to the tip of the jib 10, remove the tension rod 51 from the sheave block 5, and attach it to the jib 10. After supporting, the auxiliary hoisting rope 50 is let out to make the jib 10 hang from the tip of the boom by its own weight, and then the auxiliary hoisting rope 50 is hung on the guide sheave 19 at the base end of the boom. By hoisting the jib 10, the jib 10 is rotated and placed under the boom 3. After that, the jib 10 holder is fixed to the jib holder 20 with the pin 22. For installation, the plate 13 is pivotally attached to the jib support bracket 30 by means of pins 31.

After this, the boom 3 is slightly extended and the sheave block 5 at the tip of the boom is retracted forward from the base end of the jib 10 (
At this time, the jib support shaft 15.15 of the sheave block 5 also separates from the fork portion 16.16 of the jib 10), and the jib connecting rod 40 is connected to the jib 10, and then the boom 3 is laid down. The jib 10 is pushed up and rotated by the jib connecting rod 40 to be stored on the side of the boom 3, and then the jib 10 is attached to the bracket by locking the plate 13 to the jib support bracket 30 using the lock bin 33.

By the way, when extending and storing the jib 10,
When moving the jib 10 stored along the side of the boom 3 to the bottom side of the boom 3, or when moving the jib 10 tucked into the bottom side of the boom 3 to the side side of the boom 3, the boom There will be no problem if the sheave block 5 at the tip of the boom is retracted forward from the base end of the jib 10 by extending the sheave block 3 and then starting the transfer of the jib 10. However, in reality, as mentioned above, crane operation It is possible for a person to become sick and start transferring the jib 10 without extending the boom 3, or to start transferring the jib 10 before the boom 3 is fully extended. If you mistakenly start transferring the jib 10 before retracting the sheave block 5 from the base end of the jib 10 in this way, the jib 10 that is being transferred and rotated between the side and bottom sides of the boom will be damaged. If you continue to transfer the jib 10 because the base end hits the sheave block 5 at the tip of the boom and is prevented from rotating,
If excessive force is applied to the jib 1 (it sheave block 5), it may damage them.

Therefore, this vehicle-type crane is equipped with a jib transfer error prevention device that prevents the boom hoisting cylinder 4 from operating until the boom is extended and the sheave block 5 at the tip of the boom is retracted from the base end of the jib 10. hand,
This is to prevent erroneous operations when changing the jib.

The configuration of this device for preventing erroneous jib transfer operation will be explained with reference to FIG. 1. In FIG. By switching, it is expanded and contracted by pressure oil sent from the hydraulic pump 62.

Note that 63 is a counterbalancing valve.

Further, in FIG. 1, 65 is a cylinder operation prevention circuit that prevents the operation of the boom hoisting cylinder 4, and this cylinder operation prevention circuit 65 includes a relay switch 66 that is opened and closed by the output of a boom extension detection circuit 75, which will be described later. and,
A rod connection detection limit switch 67 that is closed when the jib connecting rod 40 is connected to the jib 10 when transferring the jib 10, and a lever interlocking switch 68 that is opened and closed in conjunction with the operation of the boom hoisting operation lever 60. are interposed in series.

This cylinder operation blocking circuit 65 is closed when the three switches 66, 67, and 68 are all turned on, and supplies operating power to the solenoid valve 69.
9 is opened by the supply of operation power from the cylinder operation prevention circuit 65, and opens the relief valve 70 connected to the discharge side of the hydraulic pump 62. Therefore, the three switches 66, 67, and 68 are all turned on.
In this state, all the oil discharged from the hydraulic pump 62 is returned to the tank 71 by opening the relief valve 70.
Pressure oil is not supplied to the boom hoisting cylinder 4.

Here, the detection of rod connection to the jib 10 by the rod connection detection limit switch 67 will be explained.
As shown in FIG. 11, the rod connection detection limit switch 67 is provided on the swivel base 2 of the crane near the pivot point of the jib connection rod 40. Further, in FIG. 11, 45 is a rotary cam rotatably supported on a support shaft 46 provided in front of the limit switch 67 for rod connection detection, and the actuator 67a of the limit switch 67 for rod connection detection is The rotation of the rotary cam 45 causes the limit switch 67 to be turned on. Further, 47 is an arm protruding from the rotating cam 45, and this arm 47 is constantly connected to the jib connecting rod by the spring force of the spring 48 that rotates the rotating cam 45 in the direction away from the actuator 67a of the limit switch 67. It is brought into contact with the upper surface of the proximal end of 40. Therefore, when the jib connecting rod 40 is laid down on the swivel base 2, the arm 47 is also laid down, so the rotating cam 45 is in a state away from the actuator 67a of the limit switch 67. Although the limit switch 67 is in the OFF state,
When the jib connecting rod 40 is pulled up and connected to the jib 10, the arm 47 is raised as shown by the chain line in FIG. Since the actuator 67a of the limit switch 67 is pressed, the limit switch 67 is turned OFF.
N is given.

On the other hand, in FIG. 1, reference numeral 73 is a boom length detector provided in an overload prevention device 72 provided in the vehicle type crane. The extended length of 3 is detected and the detected value signal is output. In addition to the boom length detector 73, the overload prevention device 72 is equipped with a boom angle detector, a load detector, etc. (not shown), and the crane is controlled based on the detected values of these detectors. The system calculates the load on the crane and automatically stops the crane when it becomes overloaded.

74 also connects the sheave block 5 at the tip of the boom to the jib 10.
A boom extension length setting device 75 is a boom extension detection circuit that presets the boom extension length necessary for retracting the boom forward from the base end of the boom extension detection circuit 75.
consists of a comparison circuit that compares the detected value of the boom length detector 73 and the set value of the setter 74, and when the detected value of the boom length detector 73 is smaller than the set value of the setter 73, that is, When the boom 3 is in the retracted state, an excitation current is output to the excitation coil 66a that closes the relay switch 66, and the detected value of the boom length detector 73 changes to the setting device 74. When the value exceeds the set value, that is, sheave block 5 at the tip of the boom shifts to jib 1.
When the boom 3 is extended until it is retracted forward from the base end of the boom 3, the excitation current is cut off and the relay switch 66 is opened.

To explain the operation of this jib transfer misoperation prevention device,
When boom 3 is in the retracted state, or when boom 3
When the boom extension detection circuit 75 is not extended to the set length, the excitation current is output from the boom extension detection circuit 75, so the relay switch 66 is in the ON state at this time. Furthermore, when the jib connecting rod 40 is connected to the jib 10, the rod connection detection limit switch 67 is turned on. At this time, the boom hoisting operation lever 60
When the lever interlock switch 68 is operated, the lever interlock switch 68 is turned on, but at this time, since the relay switch 66 and the limit switch 67 are in the ON state, the solenoid valve 69 is turned on at the same time as the lever interlock switch 68 is turned on. This opens the relief valve 70, and at this time, pressure oil is not supplied to the hydraulic circuit 76 that sends pressure oil to the boom hoisting cylinder 4 and other hydraulic equipment, so the crane operator cannot operate the boom hoisting operation. Since the boom hoisting cylinder 4 does not operate even if the lever 60 is operated, it is possible to prevent the erroneous operation of starting the transfer of the jib 10 without extending the boom 3, and prevent the jib 10 or Damage to the sheave block 5 can be prevented.

If the boom hoisting cylinder 4 does not operate, the crane operator must first return the boom hoisting operation lever 60 to the neutral position, and then move the boom 3 to the set length, that is, move the sheave block 5 at the tip of the boom to the base of the jib 10. It is sufficient to extend the cylinder to the extension length to be retracted from the end, and then operate the cylinder hoisting operation lever 60 again.
When 0 is returned to the neutral position, the lever interlock switch 68 is set to 0F.
At FL, the solenoid valve 69 closes, the relief valve 70 closes, and the oil discharged from the hydraulic pump 62 is sent to the hydraulic circuit 76 again.When the boom 3 is extended to the set length, the boom extension detection circuit is activated. Since the excitation current from 53 is cut off and the relay switch 66 is turned off, the solenoid valve 69 will not open even if the cylinder hoisting operation switch 68 is turned on by operating the cylinder hoisting operation lever 60. Therefore, the solenoid valve 69 will not open. 4 can be operated to transfer the jib 10.

In addition, in this jib transfer erroneous operation prevention device, a relay switch 66, a rod connection detection limit switch 67, and a lever movement switch 68 are interposed in series in the cylinder operation prevention circuit 65, so that all three switches are turned on.
Only when this occurs, the cylinder operation blocking circuit 65 closes to cut off the supply of pressure oil to the hydraulic circuit 76, and when any one of the three switches is OFF, the cylinder operation blocking circuit 65 closes to cut off the supply of pressure oil to the hydraulic circuit 76. 65 is opened and the hydraulic circuit 76
Since the supply of pressurized oil to the jib 10 is not cut off, unless the jib 10 is being transferred, that is, when the jib connecting rod 40 is not connected to the jib 10, the boom will not rise or fall regardless of the extension length of the boom 3. The boom 3 can be raised and lowered by operating the cylinder 4, and even when the boom 3 is in the contracted state and the jib connecting rod 40 is connected to the jib 10, the hydraulic pressure is Since pressure oil can be continuously supplied to the circuit 76, the boom 3 can be retracted and the jib connecting rod 4
Other hydraulic equipment such as the outrigger 9 can be operated even when the 0 is connected to the jib 10.

In addition, in the above embodiment, the circuit that sends pressure oil to the boom hoisting cylinder 4 and the circuit that sends pressure oil to other hydraulic equipment are shared, but the circuit that sends pressure oil to other hydraulic equipment can also be used as a separate system. In that case, the lever interlocking switch 68 may be removed from the cylinder operation blocking circuit 65 and this portion may be short-circuited. Further, in the above embodiment, a limit switch 67 for detecting jib connection is provided on the swivel base 2, and the limit switch 67 is actuated by pulling up the jib connection rod 40 to detect connection of the jib connection rod 40 to the jib 10. However, this jib connection detection limit switch 6
7 may be provided on the jib 10 as shown by the broken line in FIG. 4, and the limit switch 67 may be actuated by a pin 44 or the like that fixes the jib connecting rod 40 to the jib 10.

Furthermore, in the embodiment described above, erroneous operation of relocating the jib 10 is prevented by blocking the operation of the boom hoisting cylinder 4, but erroneous operation of relocating the jib 10 can also be prevented by issuing a warning to the crane operator. Therefore, when the jib connection detection limit switch 67 is detecting the connection of the jib connection rod 40 and the boom extension detection circuit 75 has not detected the extension of the boom 3, an alarm is issued and the limit switch 67 is activated. When the switch 67 is not detecting the connection of the jib connecting rod 40, the alarm may be stopped regardless of the output of the boom extension detection circuit 75.

Furthermore, in the above embodiment, the jib connecting rod 40 is
0 and the jib 10 is transferred by raising and lowering the boom 3. However, the present invention describes how to prevent jib transfer errors when the jib 10 is transferred using the auxiliary hoisting rope 50. It can also be used to prevent incorrect operation.

That is, when transferring the jib using the auxiliary rope 50, as shown in FIGS. 12 and 13, the auxiliary rope 50
0 to the guide sheave (not shown) at the tip of the jib and the guide sheave 19 at the base end of the boom, and turn this auxiliary loaf 5.
Rope locking bracket 8 with the tip of 0 attached to the jib 10
When connecting the jib 10 to the boom 3 from the side of the boom 3 to the bottom using the rope attachment pin 81, the boom 3, which has been extended in advance, is contracted and the auxiliary rope 50 is connected to the boom 3.
or by letting out the auxiliary hoisting rope 50 from the hoisting machine, the jib 10 is rotated around the boom axis by its own weight,
When transferring the jib 10 from the bottom surface of the boom to the side of the boom, either extend the boom 3 and pull the auxiliary hoisting rope 50, or hoist the auxiliary hoisting row 150 with a hoisting machine, and move the jib 10 to the auxiliary hoisting rope 50. This is done by pulling it up and rotating it. Note that in FIGS. 12 and 13, the same reference numerals are given to the parts explained in the above embodiment, and the explanation thereof will be omitted.

Therefore, in order to utilize the present invention to prevent erroneous jib transfer operations when transferring a jib using the auxiliary hoisting rope 50, the auxiliary hoisting rope connecting portion of the jib 10 must be As shown, a limit switch 82 for detecting rope connection is provided which is activated by being pushed by the rope fixing bottle 81 when the rope fixing bottle 81 is inserted.
is detecting the connection of the auxiliary hoisting rope 50 to the jib 10, and when the extension of the boom 3 is not detected by the boom extension detection circuit explained in the previous embodiment, the boom extension/contraction mechanism or When the operation of the auxiliary hoisting rope hoist is blocked or an alarm is issued and the limit switch 82 is not detecting the connection of the auxiliary hoisting row 150, the boom is suspended regardless of the output of the boom extension detection circuit. The operation of the telescopic mechanism or the auxiliary rope hoist may be allowed, or the alarm may be stopped.

〔Effect of the invention〕

According to this invention, when the crane operator attempts to transfer the jib before retracting the sheave block at the tip of the boom from the base end of the jib, the boom hoisting cylinder, the boom telescoping mechanism, or the auxiliary rope Prevent damage to the jib or sheave block at the tip of the boom by disabling the hoisting machine or issuing an alarm to prevent damage to the jib or sheave block at the tip of the boom due to incorrect jib transfer operations, except when transferring the jib.
Regardless of the extension length of the boom, normal crane operations can be performed by operating the boom hoisting cylinder, the boom telescoping mechanism, or the auxiliary rope hoisting machine, or by not issuing an alarm.

[Brief explanation of the drawing]

Figures 1 to 11 show an embodiment of the present invention, with Figure 1 being a circuit diagram of a jib transfer error prevention device;
The figure is a side view of a vehicle-type crane equipped with a jib with the jib stored, FIG. 3 is an enlarged sectional view taken along line 8-A in FIG. 2, and FIG.
Figures 5 and 5 are side views and longitudinal front views of the jib connecting rond, Figure 6 is a side view with the jib moved to the underside of the boom, and Figures 7 and 8 are views with the jib moved to the underside of the boom. A side view and a plan view of the jib support shaft of the sheave block engaged with the fork part of the jib, Figure 9 is a side view of the jib in the middle of being extended, Figure 10 is a side view of the jib being extended, and Figure 10 is a side view of the jib being extended. FIG. 11 is a diagram showing a jib connection detection structure using a limit switch. FIGS. 12 and 13 are longitudinal front views showing an example of installation of a limit switch for detecting rope connection when the present invention is used to prevent incorrect jib transfer operations when transferring the jib using the auxiliary hoisting row 150. FIG. 3 is an enlarged side view of the limit switch installation section. 3...Boom, 4...Boom hoisting cylinder, 5...
・Sheave block, 10... Jib, 20... Jib holder, 3o... Jib support bracket, 15... Jib support shaft, 16... Fork part, 50... Auxiliary winding rope, 40... ... Jib connecting rod, 67... Limit switch for rod connection detection, 73... Boom length detector,
74... Boom extension length setting device, 75... Boom extension detection circuit, 82... Limit switch for detecting rope connection. Applicant's agent Patent attorney Takehiko Suzue Figure 11 Figure 12 8□8゜

Claims (1)

[Claims] The jib is stored along the boom with the base end facing the boom tip and the tip facing the boom base, and the jib is stored along the side of the boom, and the base end is pivoted to the swivel base. The jib can be rotated around the boom axis by raising the boom with the jib connecting rod connected to the jib, or the jib can be retracted or the rope can be retracted by connecting the crane's auxiliary hoisting rope to the jib. The jib is rotated around the boom axis by its own weight, and the jib is moved from the side of the boom to the bottom of the boom. After this, the base end of the jib is supported by the sheave block at the tip of the boom, and the jib is moved around the jib spindle. For vehicle-type cranes that extend the jib forward of the boom by rotating it around the center, this device prevents erroneous operations such as starting the jib transfer before retracting the sheave block at the tip of the boom forward from the base end of the jib. a boom extension detection circuit that compares a detected value of a boom length detector with a set value and detects that the boom has been extended until a sheave block at the tip of the boom is retracted forward from the base end of the jib; , provided at the jib connecting rod pivot portion of the swivel table or the jib connecting rod connecting portion of the jib, and operated by raising the jib connecting rod or pivoting the jib connecting rod to the jib to connect the jib connecting rod to the jib. A limit switch is provided at the auxiliary rope connection part of the jib and is actuated by the connection of the auxiliary rope to the jib to detect the connection of the auxiliary rope to the jib. Or, if the connection of the auxiliary rope is being detected and the extension of the boom is not detected by the boom extension detection circuit, the operation of the boom hoisting cylinder, boom extension/contraction mechanism, or auxiliary rope hoisting machine is blocked. or an alarm is issued and the limit switch does not detect the connection of the jib connecting rod or auxiliary rope, the boom hoisting cylinder, boom extension/retraction mechanism, or auxiliary rope is activated regardless of the output of the boom extension detection circuit. A jib transfer error prevention device for a vehicle type crane, characterized by comprising a circuit that allows the operation of a hoist or stops an alarm.