CROSS REFERENCE TO PRIOR APPLICATION

This application is a National Stage Patent Application of PCT International Patent Application No. PCT/JP2019/009295 (filed on Mar. 8, 2019) under 35 U.S.C. § 371, which claims priority to Japanese Patent Application No. 2018-043257 (filed on Mar. 9, 2018), which are all hereby incorporated by reference in their entirety.

TECHNICAL FIELD

The present invention relates to cranes. More specifically, the present invention relates to a crane which achieves improvement in manipulability and safety.

BACKGROUND ART

Conventionally, a crane, which is a typical work vehicle, has been known (see Patent Literature (hereinafter referred to as “PTL”) 1). The crane is mainly composed of a traveling body and a swiveling body. The traveling body is provided with a plurality of wheels and is configured to travel freely. The swiveling body is provided with a boom, a wire rope, a winch, and a hook, and is configured to carry a load freely.

Meanwhile, such a crane travels in a posture in which the boom is luffed down, or performs carriage work in a posture in which the boom is luffed up (see PTL 2). Here, the posture in which the boom is luffed down is defined as “traveling posture” and the posture in which the boom is luffed up is defined as “working posture.” In transition from the traveling posture to the working posture, it is necessary to luff up the boom while appropriately unwinding the wire rope to prevent the hook from swinging because of being hoisted from a predetermined place such as a hook base. On the other hand, in transition from the working posture to the traveling posture, it is necessary to luff down the boom while appropriately winding the wire rope, with the hook being placed in advance in the predetermined place such as the hook base, to prevent the wire rope from slackening. However, there has been a problem that the manipulation of luffing up the boom while unwinding the wire rope and the manipulation of luffing down the boom while winding the wire rope are complicated and difficult. Moreover, there has also been another problem that the swinging hook collides with the traveling body or the like and the slack wire rope comes off a sheave or the like. Hence, a crane which achieves improvement in manipulability and safety has been required.

CITATION LIST

Patent Literature

PTL 1

Japanese Patent Application Laid-Open No. 2017-122003

PTL 2

Japanese Patent Application Laid-Open No. 2017-30634

SUMMARY OF INVENTION

Technical Problem

A crane which achieves improvement in manipulability and safety is provided.

Solution to Problem

The crane of the present invention is a crane provided with a boom, a wire rope, a winch, and a hook, the boom being capable of being luffed up and down, extended, and retracted, the wire rope being configured to hang from the boom, the winch being configured to wind or unwind the wire rope, the hook being configured to be raised or lowered by the wire rope wound or unwound, the crane including:

a winding manipulation tool that allows giving an instruction on an operating state of the winch; and

a switch that allows giving an instruction for switchover of a control mode for manipulation of the winding manipulation tool, in which

it is preferable that, when the switch is set to an “ON” state and the winding manipulation tool is manipulated to one side in a traveling posture in which the hook is placed in a predetermined place and the boom is luffed down, the boom is luffed up to adopt a working posture while the wire rope is unwound to prevent the hook from being hoisted.

In the crane of the present invention,

a luffing-up speed of the boom is changed in accordance with a manipulation amount of the winding manipulation tool manipulated by an operator.

In the crane of the present invention,

a luffing-up speed of the boom is maintained constant regardless of a manipulation amount of the winding manipulation tool manipulated by an operator.

In the crane of the present invention,

when the boom is luffed up to a predetermined angle, unwinding operation of the winch for unwinding the wire rope stops at the same time as luffing-up operation of the boom stops.

The crane of the present invention is a crane provided with a boom, a wire rope, a winch, and a hook, the boom being capable of being luffed up and down, extended, and retracted, the wire rope being configured to hang from the boom, the winch being configured to wind or unwind the wire rope, the hook being configured to be raised or lowered by the wire rope wound or unwound, the crane including:

a winding manipulation tool that allows giving an instruction on an operating state of the winch; and

a switch that allows giving an instruction for switchover of a control mode for manipulation of the winding manipulation tool, in which

it is preferable that, when the switch is set to an “ON” state and the winding manipulation tool is manipulated to an other side in a working posture in which the hook is placed in a predetermined place and the boom is luffed up, the boom is luffed down to adopt a traveling posture while the wire rope is wound to prevent the wire rope from slackening.

In the crane of the present invention,

a luffing-down speed of the boom is changed in accordance with a manipulation amount of the winding manipulation tool manipulated by an operator.

In the crane of the present invention,

a luffing-down speed of the boom is maintained constant regardless of a manipulation amount of the winding manipulation tool manipulated by an operator.

In the crane of the present invention,

when the boom is luffed down to a predetermined angle, winding operation of the winch for winding the wire rope stops at the same time as lulling-down operation of the boom stops.

Advantageous Effects of Invention

According to the crane of the present invention, the crane includes the winding manipulation tool that allows giving an instruction on the operating state of the winch, and the switch that allows giving an instruction for switchover of the control mode for the manipulation of the winding manipulation tool. When the switch is set to the “ON” state and the winding manipulation tool is manipulated to one side in the traveling posture in which the hook is placed in a predetermined place and the boom is luffed down, the boom is luffed up to adopt the working posture while the wire rope is unwound to prevent the hook from being hoisted. According to such a crane, manipulation of luffing up the boom while unwinding the wire rope is not required. Further, since no manipulative error can occur in connection with the transition from the traveling posture to the working posture, it is possible to prevent the hook from swinging and colliding with the traveling body or the like. Accordingly, it is possible to achieve improvement in manipulability and safety.

According to the crane of the present invention, the luffing-up speed of the boom is changed in accordance with the manipulation amount of the winding manipulation tool manipulated by the operator. According to such a crane, the luffing-up speed can be freely changed depending on the presence or absence of risk of interference or the like of the boom, so that it is possible to achieve further improvement in safety.

According to the crane of the present invention, the luffing-up speed of the boom is maintained constant regardless of the manipulation amount of the winding manipulation tool manipulated by the operator. According to such a crane, it is possible for the operator to concentrate on the transition from the traveling posture to the working posture without worrying about the luffing-up speed of the boom, so that it is possible to achieve further improvement in safety.

According to the crane of the present invention, when the boom is luffed up to a predetermined angle, the unwinding operation of the winch for unwinding the wire rope stops at the same time as the luffing-up operation of the boom stops. According to such a crane, each operation for transition from the traveling posture to the working posture is automatically stopped, so that it is possible to achieve further improvement in manipulability and safety.

According to the crane of the present invention, the crane includes the winding manipulation tool that allows giving an instruction on the operating state of the winch, and the switch that allows giving an instruction for switchover of the control mode for the manipulation of the winding manipulation tool. When the switch is set to the “ON” state and the winding manipulation tool is manipulated to the other side in the working posture in which the hook is placed in a predetermined place and the boom is luffed up, the boom is luffed down to adopt the traveling posture while the wire rope is wound to prevent the wire rope from slackening. According to such a crane, manipulation of luffing down the boom while winding the wire rope is not required. Further, since no manipulative error can occur in connection with the transition from the working posture to the traveling posture, it is possible to prevent the wire rope from slackening and coming off the sheave or the like. Accordingly, it is possible to achieve improvement in manipulability and safety.

According to the crane of the present invention, the luffing-down speed of the boom is changed in accordance with the manipulation amount of the winding manipulation tool manipulated by the operator. According to such a crane, the luffing-down speed can be freely changed depending on the presence or absence of risk of interference or the like of the boom, so that it is possible to achieve further improvement in safety.

According to the crane of the present invention, the luffing-down speed of the boom is maintained constant regardless of the manipulation amount of the winding manipulation tool manipulated by the operator. According to such a crane, it is possible for the operator to concentrate on the transition from the working posture to the traveling posture without worrying about the luffing-down speed of the boom, so that it is possible to achieve further improvement in safety.

According to the crane of the present invention, when the boom is luffed down to a predetermined angle, the winding operation of the winch for winding the wire rope stops at the same time as the luffing-down operation of the boom stops. According to such a crane, each operation for transition from the working posture to the traveling posture is automatically stopped, so that it is possible to achieve further improvement in manipulability and safety.

