JPH0725588A - Safety device of mobile crane - Google Patents

Abstract

PURPOSE:To prevent damage of a sub hook or a head end part of a jib by way of actuating an overwinding preventive device even at the time of forgetting to return a release means to the original position by releasing an overwind preventive mechanism only at a boom hoisting angle of a telescopic boom of less than a specified value. CONSTITUTION:At the time of practicing crane work while forgetting to return a release switch 18 to the original position after overhanging work of a jib 6, if a boom hoisting angle of a telescopic boom 2 is more than specified value, a discriminator 21 of a release range limitting device 20 receives a signal from a boom hoisting angle detector 19 and outputs a signal to actuate a relay R2. By actuation of the relay R2, a normally-closed contact point R2b becomes open. Additionally, a winding sub-hook 9 of a sub-winch lifts a plumb bob 12, and when a swirling switch 10 is switched on, by actuation of a relay R1, a constantly open contact point P1b is made open. Consequently, to a regulation means 15, even if the release switch 18 is switched on, no electric current from an electric power source 14 is supplied, and movement of awalking crane is made impossible. Consequently, it is possible to prevent collision of the sub hook 9 and the head end part of a jib.

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 mobile crane.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3, a mobile crane of this type has a main winch 3 in which a telescopic boom 2 which can be raised and lowered is arranged on a vehicle 1 and which is provided on the base end side of the telescopic boom 2.
The extended main wire rope 4 is passed along the telescopic boom 2 up to the tip of the telescopic boom 2, and the main wire 5 is used to suspend the main hook 5 from the tip of the telescopic boom 2. The suspended load is hung so that the suspended load can be moved to a desired position.

Further, in order to position the suspended load to a higher position, the mobile crane is provided with a jib 6 which is releasably attached to the tip of the telescopic boom 2. When performing a crane operation using the jib 6, the sub wire rope 8 fed from the sub winch 7 provided on the base end side of the telescopic boom 2 is passed along the telescopic boom 2 to the tip of the jib 6, The sub wire rope 8 suspends a sub hook 9 from the tip of the jib 6, and the suspended load is suspended on the sub hook 9 so that the suspended load can be moved to a desired position.

In order to prevent the sub winch 7 from being overwound and the sub hook 9 to abut against the tip of the jib 6 to damage the sub hook 9 or the tip of the jib 6 when the crane is operated on the jib 6. 4, an overwinding prevention device A is provided. The overwinding prevention device A includes an overwinding switch 10 attached to the tip of the jib 6, a weight 12 and a weight 12 which are located between the tip of the jib 6 and the subhook 9 and pass a subwire rope 8 therein. The ropes 11 and 13 for suspending the jib at the tip of the jib 6 are provided. Rope 11
The rope 13 is directly attached to the tip of the jib 6 via the overwind switch 10 and is directly fixed to the tip of the jib 6 to suspend the weight 12.

The overwinding prevention device A is adapted to turn on the overwinding switch 10 when the subwinch 7 is rolled up and the subhook 9 lifts the weight 12. As shown in FIG. 7, the overwind switch 10 is connected to the power supply 14 via the relay R1, and the normally closed contact R1b is opened by the operation of the relay R1 so that the power supply to the regulating means 15 is cut off. I am doing it. The regulation means 15 constantly supplies power, and disables the operation of the mobile crane when the power supply is cut off.

The regulating means 15 regulates only the operation on the overwinding side and does not regulate the operation on the non-overwinding side. That is, the hoisting movement of the sub winch 7, the extension movement of the telescopic boom 2, and the fall movement of the telescopic boom 2 are restricted so that the sub winch 7 is unwound, the telescopic boom 2 is contracted, and the telescopic boom 2 is raised and lowered. I try not to regulate it.

When not in use, the jib 6 is stored along the side surface of the telescopic boom 2 on the base end side, and when in use, the jib 6 is removed from the side surface of the telescopic boom 2 on the base end side. After moving it to the bottom by appropriate means, the jib 6
The base end of the sub-wire rope 8 pulled out from the end of the jib 6 is locked to the locking part 16 arranged at the proper position of the base of the extension boom 2. . Then, by pulling out the sub wire rope 8 from the sub winch 7, as shown in FIG. 5, the position a is passed from the bottom position of the telescopic boom 2 to the position a (the jib 6 is in the vertical posture).

Next, the sub wire rope 8 from the engaging portion 16
And the sub hook 9 is connected to the tip of the sub wire rope 8. Then, as shown in FIG. 6, the sub winch 7 is hoisted and driven, the sub hook 9 is brought into contact with a locking member 17 provided at the tip end portion of the jib 6, and the sub winch 7 is further hoisted to drive the jib 6 From the c position to the d position, which is the extension position of the telescopic boom 2. Then, a jib 6 is added to the tip of the telescopic boom 2 by connecting a tension rod between the tip of the telescopic boom 2 and an appropriate place of the jib 6. The above is the case where the jib 6 is overhanged for use, but the reverse operation is carried out when the jib 6 is stored.

When the jib 6 is extended and stored, the weight 1
Since 2 is not in a suspended state, the overwinding prevention device A acts and the sub winch 7 cannot be driven to wind. That is, when the jib 6 is extended, the movement from the position c to the position d in FIG.
In order to cope with the problem that the movement from the position (a) to the position (a) cannot be performed, a release switch 18 (corresponding to the release means described in the claims) is provided as shown in FIG. That is, the overwinding switch 10 operates and the relay R1
Even if the normally closed contact R1b opens due to the
The operation of 8 supplies power to the regulating means 15 so that the operation of the mobile crane is not disabled. When storing the jib 6 in this way,
The release switch 18 was always operated.

[0010]

However, although it is sufficient to return the release switch 15 to its original position after the jib 6 is extended, it is often forgotten to return the release switch 15 to its original position. . Then, when the crane operation is performed after the jib is extended, the release switch 18 operates even if the overwinding state actually occurs.
There was a case where the sub hook 9 was brought into contact with the tip portion of the jib 6 by winding too much and the sub hook 9 or the tip portion of the jib 6 was damaged. It is an object of the present invention to provide a safety device for a mobile crane that solves the above problems as much as possible.

[0011]

To achieve the above object, a safety device for a mobile crane according to the present invention engages and disengages a telescopic boom that can be raised and lowered on a vehicle and a jib that is added to the tip of the telescopic boom. A mobile type in which a wire rope that is freely arranged and is fed from a winch provided on the base end side of the telescopic boom is passed along the telescopic boom to the tip of the jib, and the hook is suspended from the tip of the jib by the wire rope. A safety device for a crane, comprising: an overwinding prevention device for preventing a hook from coming into contact with the tip of a jib, and having a regulation means for disabling the operation of the mobile crane when the overwinding prevention device operates. Together with a safety device for a mobile crane, which is manually operated and is provided with a releasing means for releasing the function of the overwinding preventing device, a hoisting angle detector for detecting the hoisting angle of the telescopic boom, Relief angle of at least telescopic boom receives a signal from the standing dip detector is characterized in that it comprises a release range limiting device enabling release by said release means only below a predetermined value.

[0012]

The safety device for a mobile crane according to the present invention constructed as described above is equipped with a release range limiting device which enables the release means to release the extension boom only when the hoisting angle of the telescopic boom is less than a predetermined value. Even if the crane work is forgotten to return the releasing means to the original position after the overhanging work, the hoisting angle of the telescopic boom is within a predetermined range (the jib is disengaged (extended storage)).
The overwinding prevention device can be operated in a boom state where the work is not performed. Therefore, even when forgetting to return the releasing means to the original position, the overwinding prevention device is operated to prevent the sub-hook from contacting the tip of the jib and damaging the tip of the jib or the jib as much as possible. You can

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a safety device for a mobile crane according to the present invention will be described below with reference to FIG. It should be noted that the reference numerals 1 to 18 and the reference numeral A described in the prior art are used as the same in the following description, and detailed description thereof will be omitted.

In FIG. 1, 19 is a hoisting angle detector for detecting the hoisting angle of the telescopic boom 2. A release range limiting device 20 is composed of a discriminator 21 and a relay R2. The discriminator 21 receives the signal from the undulation angle detector 19, and the undulation angle of the telescopic boom 2 reaches a predetermined value (for example, 30).
The signal is output only when the temperature exceeds the above, and the relay R2 is operated. The normally closed contact R2b of the relay R2 is connected in series with the release switch 18 and is interposed between the power source 14 and the regulating means 15. The predetermined value sets a minimum hoisting angle required when the jib 6 is engaged with and disengaged from (extends in) the tip of the telescopic boom 2.

The mobile crane safety device of the present invention thus constructed operates as follows. When the jib 6 is extended, the overwind switch 10 is used as described in the related art.
Is activated and the normally closed contact R1b is opened by the relay R1, but by operating the release switch 18, power is supplied from the power source 14 to the regulating means 15 so that the operation of the mobile crane is not disabled. . That is, when the jib 6 is disengaged (extended and retracted), since the hoisting angle of the telescopic boom 2 is less than or equal to a predetermined value, the determination means 21 does not output a signal,
Do not activate relay R2. Therefore, the normally-closed contact R2b remains closed, and power can be supplied from the power source 14 to the regulating means 15 by operating the release switch 18, and the erection angle of the telescopic boom 2 can be increased by the release range limiting device 20. When is less than a predetermined value, it can be released by the release switch 18.

Next, a case will be described in which the crane operation is performed after forgetting to return the release switch 18 to the original position after the jib 6 is extended. It is assumed that the hoisting angle of the telescopic boom 2 at the time of crane work is above a predetermined value. Then, the discriminator 21 of the release range limiting device 20 receives the signal from the undulation angle detector 19 and outputs a signal to operate the relay R2. By the operation of relay R2,
The normally closed contact R2b is opened. Further, when the hoisting angle of the telescopic boom 2 is equal to or greater than a predetermined value, when the sub winch 7 is hoisted up, the sub hook 9 lifts the weight 12, and the overwinding switch 10 is turned on, the normally closed contact R1b is activated by the operation of the relay R1.
To open.

Therefore, in the regulating means 15, the release switch 18 is operated but the normally closed contact R2b is opened, and when the overwinding switch 10 is turned on, the relay R1 is operated to normally close. Since the contact R1b is opened, the power from the power source 14 is not supplied and the operation of the mobile crane is disabled. Therefore, even if the release switch 18 is forgotten to be returned to its original position, the overwinding prevention device A can be operated to bring the sub-hook 9 into contact with the tip of the jib 6 and damage the sub-hook 9 or the tip of the jib 6. It can be prevented as much as possible.

In the first embodiment described above, when the jib 6 is disengaged (extended and retracted), the hoisting angle of the telescopic boom 2 is below a predetermined value, and the hoisting angle of the telescopic boom 2 is predetermined. Above the value, the overwinding prevention device A is operated even if the release switch 18 is operated. However, as a second embodiment, not only the hoisting angle of the telescopic boom 2 but also the boom length of the telescopic boom 2 can be set. Now, the load acting on the telescopic boom 2 is detected, and the detection value detected from these is the disengagement (extension storage) of the jib 6.
If the value does not reach the value specified above, the release switch 1
Even if 8 is operated, the overwinding prevention device A may be operated.

The mobile crane of this type is provided with an overload preventing device B, and the hoisting angle detector 22 and boom length detector 2 of the telescopic boom 2 are provided in this overload preventing device B.
3. A load detector 24 for detecting the load acting on the telescopic boom 2 is provided. In addition, the overload prevention device B receives signals from the hoisting angle detector 22 and the boom length detector 23,
The allowable load on the telescopic boom 2 in the operating state of the telescopic boom 2 is obtained, the obtained load is compared with the load detected by the load detector 24, and when the detected load is larger than the obtained load, the relay R3 It is provided with a calculator 25 that outputs a signal for activating. Normally closed contact R3b for relay R3
Is interposed in the circuit between the power source 14 and the regulating means 15, and when the relay R3 is activated, the power supply to the regulating means 15 is cut off and the operation of the mobile crane is disabled.

The case where the second embodiment is carried out on the mobile crane in which the overload preventing device B is arranged will be described below. That is, the overload prevention device B is connected to the release range limiting device 2
The case where the function of 6 is also given will be described. Calculator 2
Reference numeral 5 denotes a first discriminating means for discriminating whether or not the hoisting angle of the telescopic boom 2 is a predetermined value (for example, 30 °) or more in response to a signal from the hoisting angle detector 22, and a boom length detector 23. And a load detector 24, which receives a signal from the second telescopic boom 2 to determine whether or not the boom length of the telescopic boom 2 is equal to or greater than a predetermined value (for example, a state where the boom is not in a fully contracted state).
The third determination for determining whether or not the load acting on the telescopic boom 2 in response to a signal from the load is equal to or more than a predetermined value (for example, the load acting when the jib 6 is disengaged (extended and stored)). Equipped with means.

In the calculator 25, the boom length of the telescopic boom 2 is set such that the hoisting angle of the telescopic boom 2 is a predetermined value (for example, 30 °) or more in response to the signals from the first discriminating means, the second discriminating means and the third discriminating means. Is greater than or equal to a predetermined value (for example, not fully contracted), and the load acting on the telescopic boom 2 is greater than or equal to a predetermined value (for example, the load acting when the jib 6 is engaged and disengaged (expanded)). If one of the conditions is satisfied, a signal is output to the relay R4. The normally closed contact R4b of the relay R4 is the normally closed contact R2b of the first embodiment.
Since it is located at the same circuit position as the above, even when the release switch 18 is operated during the operation of the relay R4, the release switch 18 acts so that it cannot be released.

In the releasing range limiting device 26 of the second embodiment thus constructed, the above three conditions are conditions for engaging and disengaging (extending and storing) the jib 6, and the above three conditions. If any one of the conditions is satisfied, it is determined that the work is not the work of engaging and disengaging (extending and storing) the jib at this time, and the release switch 18 disables the release. Conversely, when the above three conditions are met, the release switch 18 enables the release. In the case of the second embodiment, the range in which it is determined that the work is the work for engaging and disengaging (extending and retracting) the jib is more limited as compared with the first embodiment, so that the release switch 18 enables the release. It is possible to limit the range and widen the operating range of the overwinding prevention device A when the crane work is performed without forgetting to return the release switch 18 to the original position.

Although the second embodiment is constructed under the three conditions, it goes without saying that it may be constructed only under the two conditions depending on the boom length and the undulation angle. In addition, in the second embodiment, the hoisting angle detector 22, the boom length detector 23, and the load detector 24 of the overload prevention device B are used, and the release range limiting device 26 is arranged in the overload prevention device B. However, it goes without saying that these may be arranged as a dedicated device separately from the overload prevention device B.

[0024]

The safety device for a mobile crane of the present invention configured and operated as described above is in a boom state in which the work for engaging and disengaging the jib (extension and storage) is not performed even if the operator releases the release means. In the above, the overwinding prevention device can be operated, and it is possible to prevent the subhook from coming into contact with the tip portion of the jib and damaging the tip portion of the subhook or the jib as much as possible.

[Brief description of drawings]

FIG. 1 is an explanatory diagram illustrating a first embodiment of a safety device for a mobile crane according to the present invention.

FIG. 2 is an explanatory view illustrating a second embodiment of the safety device for a mobile crane according to the present invention.

FIG. 3 is an explanatory diagram illustrating a mobile crane.

FIG. 4 is an explanatory diagram illustrating an overwinding prevention device.

FIG. 5 is an explanatory view for explaining a work for engaging and disengaging the jib (extended storage).

FIG. 6 is an explanatory diagram illustrating a work of engaging and disengaging the jib (extended storage).

FIG. 7 is an explanatory diagram illustrating a conventional safety device for a mobile crane.

[Explanation of symbols]

 1 Vehicle 2 Telescopic Boom 6 Jib 7 Winch (Sub Winch) 8 Wire Rope (Sub Wire Rope) 9 Hook (Sub Hook) 15 Restricting Means 19,22 Lifting Angle Detector 20,26 Release Range Limiting Device A Overwinding Prevention Device

Claims (1)

[Claims] 1. A telescopic boom that can be undulated on a vehicle and a jib that is replenished at the tip of the telescopic boom are disengageably disposed, and a wire rope that is extended from a winch provided at the base end side of the telescopic boom is used as the telescopic boom. A safety device for a mobile crane in which the hook is suspended from the tip of the jib by the wire rope along the end of the jib so that the hook does not come into contact with the tip of the jib. With a prevention device, and having a regulation means for disabling the operation of the mobile crane when the overwinding prevention device operates,
In a safety device for a mobile crane, which is manually operated and is provided with a releasing means for releasing the function of the overwinding prevention device, a hoisting angle detector for detecting the hoisting angle of a telescopic boom and a signal from the hoisting angle detector are provided. A safety device for a mobile crane, comprising: a release range limiting device that enables release by the release means only when the hoisting angle of at least the telescopic boom is less than or equal to a predetermined value.