JPH0532393A - Backstop device of tower crane - Google Patents

Abstract

(57) [Summary] [Objective] To provide a backstop device for smoothly stopping a jib boom in a tower crane at a set angle. [Structure] The tower head 3 of the tower boom 3 is attached to the lower end of the back stay 13 attached to the lower back of the jib boom.
The rolling roller 15 that contacts a is attached via the shaft 14.
When the raising angle of the jib boom increases, the rolling roller 15 of the back stay 13 contacts the tower head 3a, and then the rolling roller 15 rolls on the tower head 3a, and stops when the jib boom reaches the set angle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention connects a tower head at the top of a tower boom so that the jib boom can be swung up and down, and the lower back portion of the jib boom hits the tower head to raise the jib boom. The present invention relates to a backstop device for a tower crane equipped with a backstay for limiting the load.

[0002]

2. Description of the Related Art Next, a tower crane equipped with a conventional backstop device will be described with reference to FIGS.

A revolving structure 2 is rotatably mounted on an upper part of the traveling structure 1, and a tower boom 3 is attached to a front part of the revolving structure 2. The jib boom 4 is connected to the front part of the tower head 3a at the top of the tower boom 3 by a pin so that the jib boom 4 can be vertically swung, and the swing lever 5 having a triangular side surface is swung at the rear part. Installed as you can. The tower boom 3 is held almost vertically during the cargo handling work. The rope 7 provided from the undulating drum 6 installed on the revolving structure 2 is stretched over a plurality of sheaves of a jib hanger 8 and a jib bridle 9. The other end of the pendant rope 10 whose one end is connected to the jib bridle 9 is connected to a link 11A attached to the upper rear side of the swing lever 5, and the other end of the pendant rope 12 whose one end is connected to the tip of the jib boom 4 is the swing lever. 5 is connected to a link 11B attached to the front upper part.

A back stay 13 having a shock-absorbing spring is attached to the lower rear portion of the jib boom 4 by a pin, and the jib boom 4 is attached to the lower end portion of the back stay 13.
Is raised at a predetermined angle, the contact portion 13a that abuts the tower head 3a is welded. The contact portion 13a is made of a steel plate and has a circular arc-shaped cross section as shown in FIG.

When the rope 7 is wound around the undulating drum 6, the jib boom 4 is raised via the pendant rope 10, the swing lever 5 and the pendant rope 12. When the jib boom 4 is raised up to the set angle, the contact portion 13a of the backstay 13 hits the tower head 3a, and the jib boom 4 is stopped.

[0006]

In such a backstop device, the contact portion 13a of the backstay 13 has a circular arc-shaped cross section and is in sliding contact with the contact portion 1.
The movement after 3a contacts the tower head 3a is poor,
An excessive load is applied to the jib boom 4 due to the cushion springs coming into close contact with each other or suddenly slipping out, and vibrations are transmitted to the operator room on the tower boom 3 and the revolving structure 2 to impair workability.
It is an object of the present invention to provide a backstop device that can eliminate this difficulty very easily.

[0007]

A backstop device according to the present invention is characterized in that a rolling roller for contacting a tower head is attached to a lower end portion of a backstay via a shaft.

[0008]

[Operation] When the raising angle of the jib boom becomes large, the rolling roller of the back stay contacts the tower head, and when the swing lever is further swung, the rolling roller smoothly rolls on the tower head, and the jib boom reaches the set angle. It will stop.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.
Will be explained.

A bifurcated bracket 13b is integrally attached to the lower end of the backstay 13, and a rolling roller 15 is rotatably supported by the bracket 13b via a shaft 14.

When the raising angle of the jib boom 4 increases, the rolling roller 15 comes into contact with the tower head 3a, and when the swing lever 5 is further swung to the raising side, the rolling roller 1
5 smoothly rolls on the tower head 3a, and the jib boom 4
Will stop when becomes the set angle.

[0012]

According to the present invention described above, since the rolling roller of the back stay is in rolling contact with the tower head, the back stay does not suddenly move after being caught by the tower head. Move smoothly over. Therefore, an excessive force does not act on the jib boom, vibration is prevented from occurring, and workability can be improved.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of the present invention,

FIG. 2 is a rear view seen from the line AA of FIG.

FIG. 3 is a side view showing an example of a tower crane equipped with a conventional backstop device,

FIG. 4 is an enlarged side view showing a state in which the lower end portion of the back stay in FIG. 3 contacts the tower head.

[Explanation of symbols]

 3 Tower Boom 3a Tower Head 4 Jib Boom 5 Swing Lever 13 Back Stay 14 Shaft 15 Rolling Roller

Claims (1)

Claims: 1. A tower head at the top of the tower boom is connected to the jib boom so that the jib boom can be swung up and down, and the lower back part of the jib boom hits the tower head so that the jib boom is raised. In the backstop device of the tower crane equipped with the limiting backstay,
A backstop device comprising a rolling roller attached to a tower head attached to the lower end of the backstay via a shaft.