JPH032555Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a backstop for supporting the boom or mast from the rear side of a lattice boom type mobile crane.

[Conventional technology]

In general, for lattice boom type mobile cranes, for example, Japanese Utility Model Publication No. 59-5039,
As seen in the '12593 publication, a backstop is provided to prevent the boom or mast from exceeding a limited elevation angle.

Regarding the construction of this backstop, a conventional technique for a counterbalance type crane will be explained with reference to FIG.

1 is a crawler type lower traveling body 1a and an upper revolving body 1
A boom 2 and a mast 3 supporting the boom 2 are each tiltably mounted on an upper revolving body 1b of the crane main body 1. Reference numeral 4 denotes a counterweight truck (hereinafter abbreviated as weight truck) placed behind the crane main body 1, and this weight truck 4 and the mast 3
The upper part of the mast 3 is connected via a mast guy line 5, and the weight of the weight truck counteracts the moment acting on the mast 3 in the forward tilting direction.

The mast backstop 6 that supports the mast 3 from the rear includes a lower pipe 61, an upper pipe 62 slidably fitted into the lower pipe 61, and a compression coil spring 63 provided between the upper ends of these pipes 61, 62. It consists of This back stop 6 has the upper end of the upper pipe 62 at the lower part of the mast 3, and the lower end of the upper pipe 61 at the rear of the upper revolving structure 1b (usually at the lower part of the rear member G1 of the gantry G attached to the upper revolving structure _1b ). The mast 3 is supported by a spring 63.

[Problem to be solved by the invention] In this counterbalance type crane, if, for example, the wheel 41 of the weight truck 4 is punctured or the ground supporting the weight truck 4 sinks, the entire weight of the weight truck 4 is transferred to the mast guy line. 5 is applied to the mast 3 as a load in the backward tilting direction. If this happens, the spring 63 of the backstop 6 will come into close contact and will not be able to support the load, causing the backstop 6 to buckle, or the backstop installation at the rear of the mast 3 and upper rotating body (gantry rear member G ₁ , the same applies hereinafter) to Parts will be destroyed.

As a countermeasure to this point, it is conceivable to increase the overall length of the spring 63 by an amount corresponding to the downward stroke of the weight truck 4 as described above, but since the spring 63 becomes extremely large and heavy, This is disadvantageous in terms of cost, attachment/detachment of the backstop 6, and other handling issues.

Therefore, the present invention provides a backstop for a lattice boom type mobile crane that can automatically reduce its length and escape from the load when an overload condition occurs in which the springs are stuck together as described above. .

[Means to solve the problem]

The present invention consists of a lower pipe whose lower end is attached to the rear of the crane body, an intermediate pipe which is slidably fitted into the lower pipe, and whose upper end is slidably fitted into the middle pipe and whose upper end is attached to the bottom of the boom or mast. A backstop main body is constituted by the attached upper pipe, and a compression coil spring that supports the boom or mast is provided between the intermediate pipe and the upper pipe, and the intermediate pipe and the lower pipe are connected to the compression coil spring. A shear pin that ruptures under a load that exceeds the load that causes the backstop body to come into close contact with each other, and that is smaller than the load that causes the backstop body to break at the attachment part of the backstop body on the mast or boom, the attachment part of the backstop body on the crane body, and the backstop body, respectively. They are connected.

[Effect]

With this configuration, in the event of an overload condition in which the springs are stuck tightly together due to a puncture of the weight truck in a counterbalance type crane, the shear pin will break and automatically reduce its length, allowing it to escape from the load. .

〔Example〕

1 to 3 show an embodiment to which the present invention is applied to a backstop for supporting a mast of a counterbalance crane. In addition, in each figure, the same parts as in FIG. 4 are shown with the same reference numerals, and redundant explanation thereof will be omitted.

The backstop 7 has a lower pipe 71 connected to an intermediate pipe 72 and an upper pipe 73 connected to this intermediate pipe 72.
a backstop main body (hereinafter simply referred to as the main body) 7a, each of which is slidably inserted into the backstop main body 7a;
Both middle and upper pipes 72, 7 of this main body 7a
Compression coil spring 7b provided between the upper ends of 3
The shear pin 7c fixes the main body 7a at a predetermined length, and the stopper pin 7d acts as a stopper when the shear pin 7c is broken. The lower end of the main body 7a (lower pipe 7
Similar to the lower pipe of the conventional backstop, the lower end of the gantry rear member _G1 serving as the rear part of the upper revolving body 1b is connected to
) are attached to the bottom of the mast 3.

The shear pin 7c is connected to both the lower and middle pipes 7.
The shear pin 7c is inserted across the shear pin holes 74 and 75 provided in the pipes 1 and 72, and both the lower and intermediate pipes 71 and 72 are connected by this shear pin 7c. Further, a stopper pin hole 76 is provided in the lower pipe 71 at a position a predetermined distance below the shear pin hole 74 in a direction perpendicular to the shear pin hole 74, and a stopper pin 7d is inserted into the stopper pin hole 76.

The main body 7a has both lower and middle pipes 71, 7.
Due to the sliding action between 2, the mast 3 used
The length is changed in multiple stages according to the change in length. In order to fix the main body 7a in a plurality of lengths with the shear pin 7c in this way, the lower pipe 7
1 shear pin hole 74 and stopper pin hole 76
are provided in multiple levels above and below. Note that only one shear pin hole 75 of the intermediate pipe 72 is provided at the lower end.

Here, the shear pin 7c is subjected to a load greater than the backstop load at which the spring 7b is brought into close contact, and the main body 7a buckles, and the main body attachment portions of the mast 3 and the rear part of the upper rotating body (gantry rear member G ₁ ) are destroyed (bending deformation). The strength is set so that it will break at a load smaller than the load that causes it. Therefore, as described above, when a large load is applied to the mast 3 in the backward tilting direction due to a puncture of the wheel of the weight truck, etc., and the spring 7b of the backstop 7 comes into close contact, after this spring 7b comes into close contact, the above-mentioned The shear pin 7c will be broken before each part is broken. When the shear pin 7c breaks, the intermediate pipe 72 slides downward as shown in FIG. 3, and the length of the main body 7a is automatically reduced, so that the main body 7a, the mast 3, and the rear part of the upper swing body are protected from the above-mentioned load. Escape and these destructions will be prevented.

The large load due to the weight of the weight truck acting on the backstop 7 disappears when the weight truck descends a certain stroke and becomes stable. Therefore, by setting the distance between the shear pin 7c and the stopper pin 7d based on the realistically expected downward stroke of the weight truck, the intermediate pipe 72 can be adjusted after the shear pin breaks and when the heavy load is removed. When the lower end hits the stopper pin 7d, the length reduction action of the main body 7a can be stopped. At the time when this large load is removed, only the weight of the mast acts on the backstop 7, so that the impact when the stopper pin 7d acts as a stopper is small.

Furthermore, if the boom 2 shown in Fig. 4 is in a sufficiently forward-inclined state, the backstop 7 will be closed unless the boom 2 is significantly reversed due to the reaction of the sudden drop of the suspended load.
Even if the boom 2 does not fall forward, the forward falling moment of the boom 2 prevents the mast 3 from falling backward. Therefore,
If a large load is applied to the backstop 7 as described above and the shear pin 7c breaks, there is no problem in reality even if the function of the backstop 7 is temporarily lost until the situation is repaired. . Therefore, as mentioned above, there is no need for the stopper pin 7d to always exert the stopping action when the shear pin breaks, that is, it is not necessary to provide the stopper pin 7d, and the intermediate pipe 72 can be freely lowered until the mast 3 stops naturally. It is also possible to have a configuration in which the However, it goes without saying that it is desirable to provide the stopper pin 7d from the viewpoint of safety.

[Effect of idea]

As mentioned above, when using the backstop of the present invention, if an overload condition occurs in which the spring supporting the boom or mast is in close contact with each other, the shear pin will break and automatically reduce its length, allowing it to escape from the load. Therefore, it is possible to prevent the backstop main body, the mounting portion of the backstop main body on the mast or boom, and the mounting portion of the backstop main body at the rear of the crane main body from being destroyed due to overload. In addition, the simple structure of just connecting the lower and middle pipes constituting the backstop main body with shear pins is advantageous in terms of cost and handling.

[Brief explanation of drawings]

Fig. 1 is a side view of a backstop and its mounting portion according to an embodiment of the present invention, Fig. 2 is an enlarged side view of a section of the same, and Fig. 3 is a view equivalent to Fig. 2 showing the backstop in a state when the shear pin is broken. 4 is a schematic side view for explaining the configuration of a counterbalance type crane and a conventional backstop. 1... Crane body, 1b... Upper revolving body to which the back stop is attached, G ₁ ... Gantry rear member as the back stop attachment part,
2...Boom, 3...Mast, 4...Weight truck, 5...Mast guy line, 7...Back stop, 7a...Back stop body, 71...Lower pipe, 72...Middle pipe, 73...Upper pipe , 7b... Spring, 7c... Shear pin.

Claims (1)

[Scope of utility model registration request] A lower pipe whose lower end is attached to the rear of the crane body, an intermediate pipe which is slidably fitted into this lower pipe, and an upper pipe which is slidably fitted into this intermediate pipe and whose upper end is attached to the lower part of a boom or mast. A backstop main body is constructed by: a compression coil spring supporting a boom or mast is provided between the intermediate pipe and the upper pipe; and the compression coil spring is in close contact with the intermediate pipe and the lower pipe. be connected by a shear pin that breaks under a load greater than or equal to the load at which the backstop body is attached to the mast or boom, the attachment portion of the backstop body to the crane body, and the backstop body, respectively. A backstop for a lattice boom type mobile crane featuring: