JP2820912B2 - Crane boom hoist - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crane boom raising and lowering device, and more particularly to a crane boom raising and lowering device for reducing fatigue of a boom raising and lowering rope.

[0002]

2. Description of the Related Art FIG.
A boom 3 is attached to the front part of the boom so as to be rotatable back and forth, and a hook 4 is hung at the tip of the boom 3. The winch unit 5 provided on the body 2 lifts and lowers the hook rope 6 to move the hook 4 up and down, and also raises and lowers the boom raising and lowering rope 7 to raise and lower the boom 3.

The lower portion of the rear surface of the boom 3 is supported by a back stop 8 so that the boom 3 does not exceed the maximum angle.

[0004]

The conventional crane 1 has the following features.
As described above, the operation of raising and lowering the boom 3 and the operation of raising and lowering the hook 4 are performed by the winch unit 5.

Generally, the frequency of raising and lowering the boom 3 is higher than the operation of raising and lowering the hook 4, and the boom raising and lowering rope 7 is easily worn out due to fatigue, causing deformation of the rope and breaking of the wire. The life of the boom hoisting rope 7 was reduced earlier than the rope 6. The reduction in the life of the boom hoisting rope 7 causes the rope to be cut, and causes the boom 3 to fall down.

Accordingly, there arises a technical problem to be solved in order to reduce the frequency of use of the boom hoisting rope, prolong the life of the boom hoisting rope, and prevent occurrence of accidents. The purpose is to solve.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been proposed to achieve the above object, and has a boom mounted on a front part of a body so as to be able to rotate back and forth, and a boom is provided by a winch unit provided on the body. In a crane in which a hoisting rope is hoisted and lowered to raise and lower the boom, a jib protruding both forward and rearward of the tip of the boom and swinging back and forth with the tip of the boom as a pivot point. Provided, a hook is suspended by a hook rope at the front end of the jib, and this hook rope is connected to a winch unit, while one end of a pendant rope is locked at the rear end of the jib,
A bridle is connected to the other end of the pendant rope, a bail is pivotally connected to the end of a high mast erected at the rear of the fuselage, and a boom hoisting rope is wound between the bridle and the bail to connect to a winch unit. Further, the present invention provides a crane boom raising / lowering device in which one end of a boom raising / lowering cylinder is connected to a rear surface of the boom, and the other end of the boom raising / lowering cylinder is connected to a rear portion of the fuselage.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. For convenience of explanation, the same reference numerals are given to the same components as those in the related art, and the description is omitted.

FIG. 1 shows a crane 1 in which a jib 10 is provided at the tip of a boom 3. The jib 10 is projected forward and backward of both the tip of the boom 3, is and formed swingably back and forth the end of the boom 3 as a rotation fulcrum O _1. A hook 4 is attached to the front end of the jib 10 with a hook rope 6.
And hook rope 6 to winch unit 5
Connect to

Here, a high mast 11 is provided at the rear of the body 2.
Is provided. The high mast 11 includes a gate-shaped strut 12 pivotally connected to the front and rear, and a strut 12.
And a pair of left and right stays 13 that support the tip of the stay from behind, and the stays 13 can be expanded and contracted by hydraulic pressure.

Then, one end of a pendant rope 14 is locked at the rear end of the jib 10 and the pendant rope 14
A bridle 15 is connected to the other end of the high mast 11 and a bail 16 is pivotally connected to the tip of the high mast 11.
The boom hoisting rope 7 is wound between the bail 16 and the winch unit 5.

Further, one end of a boom hoist cylinder 17 is connected to the rear surface of the boom 3, and the other end of the boom hoist cylinder 17 is connected to the body 2 together with the lower end of the strut 12.

When the boom 3 is raised from the horizontal state, as shown in FIG. 2, the stay 13 is stopped from expanding and contracting, and the high mast 11 is fixed so that the strut 12 is inclined backward. 5 is driven to wind up the boom hoisting rope 7.

[0014] Thus, the jib 10 is pulling backward to shorten the distance between the bridle 15 and bail 16, as shown in two-dot chain line in the figure, the boom jib 10 about the said pivot point O ₁ The boom 3 is raised while rotating forward with respect to the boom 3.

At this time, the ports (not shown) on both the top side and the bottom side of the boom hoist cylinder 17 communicate with the tank, and the boom hoist cylinder 17 expands and contracts in a free state with respect to the rotation of the boom 3.

Then, as shown in FIG. 3, after the boom 3 has reached the working posture angle, the winding of the boom hoisting rope 7 is stopped, and the boom hoisting cylinder 17 is expanded and contracted to extend the boom 3.
Change the angle of.

Therefore, the rear end of the jib 10 and the high mast 11
Distance tip is contoured while the boom 3 is maintained at a constant, as shown by a two-dot chain line in the figure, around the said pivot point O ₁ at the end of the boom 3, the jib 10 in the front and rear The angle of the boom 3 changes while swinging.

As described above, the boom hoisting rope 7 is wound up and down to change the angle of the boom 3 until the boom 3 is raised to the working posture or when the boom 3 is turned down from the working posture to a horizontal state. When raising and lowering within the working range, the angle of the boom 3 is changed by extending and retracting the boom raising and lowering cylinders 17, so that the frequency of use of the boom raising and lowering ropes 7 is reduced, so that fatigue of the ropes is reduced and the life of the boom raising and lowering ropes 7 Becomes longer.

FIG. 4 shows the acting force when the load W ₁ is hung on the hook 4. If the distance from the pivot point O ₁ of the jib 10 up to the line of action of the load W ₁ and L _1, the rotation moment of the W ₁ × L ₁ occurs in the drawing around the the pivoting fulcrum O ₁ counterclockwise . In order to balance this rotational moment, the pendant rope 14 at a distance L ₂ from the pivot O _1.
, A tension T ₁ of W ₁ × L ₁ / L ₂ is generated, and only a simple compressive load P _B acts on the boom 3.

If the weight of the boom 3 is represented by W ₂ and the distance from the base end O ₂ of the boom 3 to the line of action of the weight W ₂ is represented by L ₃ , the center of the base end O ₂ of the boom 3 in FIG. A rotational moment of W ₂ × L ₃ is generated in the counterclockwise direction. Therefore, the boom derricking cylinder 17 of the distance L ₄ from the base end O ₂ W ₂ ×
Load P _C of L ₃ / L ₄ is applied. That is, regardless of the magnitude of the load W _1, since only the constant load P _C acts against the own weight W ₂ of the boom 3 is the boom derricking cylinder 17,
The pressure of the boom hoist cylinder 17 can be easily set, and the durability can be improved.

The present invention can be variously modified without departing from the spirit of the present invention, and it goes without saying that the present invention extends to the modified ones.

[0022]

As described above, according to the present invention, when the boom is raised in the working posture or when the boom is turned down from the working posture to the horizontal state, the boom hoisting rope is wound up and down to change the angle of the boom. When the boom is raised and lowered within the working range, the boom raising and lowering cylinder is extended and contracted to change the angle of the boom, so that the frequency of use of the boom raising and lowering rope is reduced and fatigue of the rope is reduced.

In this manner, the life of the boom hoist rope is prolonged, the durability is improved, and safety can be ensured.

[Brief description of the drawings]

FIG. 1 is a side view of a crane in a working posture state, showing an embodiment of the present invention.

FIG. 2 is a side view of the crane when raising the boom from a horizontal state.

FIG. 3 is a side view of the crane showing a process of raising the boom.

FIG. 4 is an explanatory diagram showing an acting force when a load is suspended.

FIG. 5 is a side view of a conventional crane.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crane 2 Body 3 Boom 4 Hook 5 Winch unit 6 Hook rope 7 Boom hoisting rope 10 Jib 11 High mast 14 Pendant rope 15 Bridle 16 Bail 17 Boom hoisting cylinder

Claims (1)

(57) [Claims] 1. A crane in which a boom is rotatably mounted on a front portion of a fuselage so that the boom can be raised and lowered by a winch unit provided on the fuselage to raise and lower the boom. A jib protruding both forward and rearward of the tip of the boom and swinging back and forth with the tip of the boom as a fulcrum is provided, and a hook is hung at a front end of the jib with a hook rope. Connect to the winch unit, meanwhile, lock one end of the pendant rope to the rear end of the jib, connect the bridle to the other end of the pendant rope, and attach the bail to the end of the high mast erected at the rear of the fuselage. Pivotally connected to a winch unit by wrapping a boom hoisting rope between the bridle and the bail, and further comprising one end of a boom hoisting cylinder on the rear surface of the boom. And a crane boom raising / lowering device, wherein the other end of the boom raising / lowering cylinder is connected to a rear portion of the fuselage.