JPH03186598A - Bending moment reduction device for telescopic boom in crane - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention provides a device for reducing the bending moment of a telescopic boom in a crane, and in particular, a device for reducing the bending moment of a telescopic boom in a crane. This invention relates to a bending moment reduction device for a telescopic boom in a crane.

(Prior Art) A conventional bending moment reduction device for a telescopic boom in a crane that prevents an excessive load from being applied to the hoisting cylinder of the telescopic boom during cargo handling operations using a crane is shown in Fig. 7, for example. There is something like this (Unexamined Japanese Patent Publication No. 5
7-184092).

In this crane, the base of a telescoping boom 5 that is operated by a hoisting cylinder 8 is attached to a shaft 6 on an upper revolving body 4 provided on a body frame 2 of a crane 1, and a main hoisting body provided on the upper revolving body 4 is attached to a shaft 6. The hook 13 is suspended from the load hanging part 11a of the main hoisting rope 1 which is let out from the winch 12 and hangs down from the boom head 7 of the telescopic boom 5, and the folded end 11bb of the load hanging part 11aa is attached to the boom head 7. With something.

Winding of the main hoisting rope 11 by the main hoisting winch 12.

By rewinding, the suspended load is suspended from the load hanging portion 11aa via the hook 13, and a desired cargo handling operation is performed.

In addition, in FIG. 7, 3 is an outrigger provided at the lower part of the vehicle body frame 2, 9.10 is a connecting shaft between the luffing cylinder 8 and the lower side of the upper part of the base cylinder of the upper rotating body 4 and the telescopic boom 5, and 14 is an upper rotating shaft. It is an overhang rod that protrudes further rearward from the rear end (right end in FIG. 7) of the body 4, and the top of the overhang rod 14 is connected to the upper side of the base cylinder of the telescopic boom 5 by a rope 15.
7, and a counterweight 19 is suspended from the top of this extending rod 14 via a rope 18 to reduce the bending moment generated in the telescopic boom 5 due to the suspended load and to act on the undulating cylinder 8 of the telescopic boom 5. This is a measure of load reduction.

The upright angle of the overhanging rod 14 with respect to the horizontal plane is adjusted according to the up-and-down angle of the telescopic boom 5, and a counterweight 19 suspended from the top of the overhanging rod 14 via a rope 18 allows the upper revolving structure to be 4 in the clockwise direction (FIG. 7), which offsets the overturning moment generated in the telescopic boom 5 due to the suspended load, thereby reducing the bending moment generated in the telescopic boom.

Although not shown in the figure, Japanese Patent Publication No. 56-43995 discloses that the top of a gantry, the base of which is pinned to the back side of the central part of the telescoping boom of a truck crane, and the back side of the base of the telescoping boom can be removably connected with a pin. In addition, by winding a hoisting rope multiple times between the sheave between the boom head and the top of the gantry, and tensioning the chain hoisting rope by a hoisting winch on the upper rotating body, the telescopic boom can be used for cargo handling using the hoisting rope. This is designed to reduce the bending moment that occurs on the front side of the

(Problem to be Solved by the Invention) However, in the bending moment reduction device for the telescopic boom of the crane shown in FIG. The inclination angle of the hanging overhang rod 14 with respect to the horizontal plane is
By adjusting according to the raising and lowering angle of the telescopic boom 5, the rotational moment in the counterclockwise direction (Fig. 7) generated around the support shaft 6 at the base of the telescopic boom 5, and therefore the lodging moment of the crater, is reduced. Although the clockwise rotational moment of the telescopic boom 5 caused by the luffing cylinder 8 is reduced, and the bending moment generated around the connecting shaft 10 of the telescopic boom 5 is reduced by a corresponding amount, the overhang rod 14 is In addition to requiring a large turning space to project rearward beyond the rear end of the rotating body 4, an auxiliary device is required to change the inclination angle of the extending rod 14 in accordance with changes in the elevation angle of the telescopic boom 5. I need it.

Furthermore, there is a problem in that a counterweight 9 and a means for suspending the same are required, which increases the cost.Also, regardless of the weight of the suspended load, the weight of the counterweight 19 and the angle of inclination of the rod 14 are When the magnitude of the moment was determined and the weight of the suspended load was small, there was a risk that the backward stability of the crane would decrease. The hoisting rope wound around the sheave between the boom head and the top of the gantry, the base of which is pinned to the back of the center of the telescopic boom and the top pinned to the back of the base of the telescopic boom, is hoisted onto the upper rotating structure. With the winch,
Since the telescopic boom was pulled along the telescopic boom, the bending moment to the front of the telescopic boom due to the load applied to the boom head via the hoisting rope due to the suspended load was reduced, and the undulation that raised and lowered the telescopic boom was reduced. Since it is not possible to reduce the load on the cylinder, and compressive force due to the suspended load acts on the gantry, it is necessary to increase the strength and rigidity of this telescoping boom, which increases its weight. Therefore, there is a problem in that it is necessary to increase the size of the hoisting cylinder of the telescopic boom, which increases in weight, or to increase its operating pressure.

This invention was made by paying attention to such problems in the conventional example, and includes a telescoping boom that is hoisted by a hoisting cylinder and a rope suspended from the boom head of the telescoping boom on the upper revolving body of a crane. A winch is provided, and the folded end of the load hanging part of the rope hanging from the boom head is extended beyond the boom head to the rear side of the upper revolving structure, and the extended part is connected to the rear of the upper revolving structure. An object of the present invention is to provide a bending moment reduction device for a crane that can solve the above-mentioned problems by folding back to the front side of an upper rotating body via a side sheave and attaching the folded end to the boom head directly or indirectly. That is.

(Means for Solving the Problems) In order to solve the problems of the conventional examples as described above, the present invention provides a telescopic boom that is operated to be raised and lowered by a raising and lowering cylinder and a boom head of the telescopic boom on the upper revolving body of a crane. a winch for a rope suspended through the rope, and a folded end of a load hanging part of the rope hanging from the boom head is extended beyond the boom head to the rear side of the superstructure; The folded end portion is folded back to the front side of the upper revolving structure via a sheave on the rear side of the upper revolving structure, and the folded end portion is attached directly or indirectly to the boom head.

(Function) Since the present invention has the above-mentioned configuration, a load is suspended from a load hanging portion of a rope hanging from a boom head of a telescopic boom provided on an upper revolving structure of a crane, and the telescopic boom is moved by a luffing cylinder. The extension part of the rope that extends beyond the boom head to the rear side of the superstructure is further folded back to the front side of the upper revolving structure via a sheave on the rear side of the upper revolving structure, and this folded end is attached directly or indirectly to the boom head. is transmitted to the rear side of the superstructure, and the boom head of the telescopic boom is actively pulled toward the rear side of the superstructure, thereby reducing the bending moment generated in the telescopic boom by a corresponding amount.

(Example) Hereinafter, an example of the bending moment reducing device for a telescopic boom in a crane according to the present invention will be described with reference to FIGS. 1 to 6. Note that the same names and symbols are used for parts common to the conventional example shown in FIG.

(First Embodiment) FIG. 1 is a schematic perspective view showing essential parts of a first embodiment of the present invention, and FIG. 2 is an explanatory diagram of its operation.

In Fig. 1.2, numeral 1 is a crane, 4 is an upper revolving body installed on the body frame of crane I (see reference numeral 2 in Fig. 7), and 5 is a telescoping boom. The base of the base cylinder is mounted on a shaft 6 at the center of the upper revolving body 4 so as to be able to rise and fall.

7 is a boom head of the telescopic boom 5; 8 is a luffing cylinder; the upper and lower parts of the luffing cylinder 8 are connected to the front part of the upper revolving body 4 and the upper lower side of the base cylinder of the telescopic boom 5 through a connecting shaft 9.10; They are each rotatably connected. 11 is a main winding rope as a cargo handling rope; 12 is a main winding winch as a winch for the cargo handling rope provided slightly behind the center of rotation of the upper revolving structure 4; and 13 is a hook; It is provided on a sheave block 14 suspended from a load hanging part 11a hanging from a boom head 7 of a winding rope.

Note that these structures are substantially the same as the conventional similar crane 1 shown in FIG. 7 above.

11c extends from the folded end of the load hanging part 11a of the main hoisting rope 11, beyond the boom head 7, to the rear side of the upper revolving structure 4 (the first
The extension part 11c extends to the front side (left side in the figure) of a rising part 21 rising from the rear of the upper revolving structure 4 via a bracket 22 rotatably attached to a shaft 22a. After that, it is further folded onto the sheave 23 which is supported on the shaft, and then further folded back toward the front side of the upper revolving structure 4, and the folded end portion 11b is attached to the boom head 7.

Next, the operation of this embodiment will be explained.

First, the crane is moved to the intended cargo handling work area, and the car body frame (reference numeral 2 in the same figure) is supported on the ground by the outriggers (refer to numeral 3 in Figure 7), and then the telescopic boom 5 is moved to the hoisting cylinder 8. It is raised and lowered to a desired angle, and expanded and contracted to a desired length by a telescopic cylinder (not shown) in the telescopic boom 5, and in conjunction with these operations, the main hoisting rope 1 is wound in or rewound by a required amount by the main hoisting winch 12. Accordingly, the hook 13 is moved up and down and left and right via the sheave block 14 of the load hanging part 11a to perform the desired cargo handling operation.

At this time, the hanging blade Q of the load (including the hook 13, hook block 14, sheaves 14a to 14c, etc.) hanging from the boom head 7 of the upper rope 11 to the load hanging part 11a
As a result, the tension Q2 generated in the load hanging part 11a of the main winding rope 1 is increased by the sheaves 14a, 14b of the sheave block 14,
14c, and sheaves 15a, 15b, 15c, 15d of the boom head 7 corresponding to these sheaves (however, 15
Since a and 15d are wound three times around the guide sheave), the number of turns is 1/6, which is divided into twice the number of turns n = 3, but these actions are approximately the same as those of conventional cranes of the same type. The same is true.

However, in this first embodiment, the folded end 11b of the load hanging part 11a of the main hoisting rope 11 is different from that of the conventional example which does not take any measures to reduce the bending moment of the telescopic boom 5 (for simplicity of explanation, the folded end 11b is of a simple structure). 11aa of a crane (taken as a comparative example) (in Fig. 2, this conventional example and the
In order to distinguish between the two examples, the corresponding parts of the conventional example are indicated by chain dots in FIG. Folded end (
11b b), the extension 11cL is extended beyond the boom head 7 to the rear side of the upper revolving structure 4 without being directly attached to the boom head 7, and the extension part 11c is attached to the upper revolving structure 4.
The rear rising portion 21 was further folded back to the front side of the upper revolving body 4 via a sheave 23 pivoted to a bracket 22 provided on the front side of the upper part, and the folded end portion 2b was attached to the boom head 7.

For this reason, in this first embodiment, the load hanging portion 11a of one roll is
The tension Q2 of the main winding rope 11, which is reduced to an IQ of 20 minutes, is also transmitted to the extension part 11c, and
1c and the extension part 11c wound around the sheave 23 by m (m=1 in this example), this tension Q2 is multiplied by 2m=2 and transmitted to the rising part 21 on the rear side of the upper revolving structure 4, and the extension part 11c is Since the orthogonal distance between the portion 11C and the support shaft 6 is B, the telescopic boom 7 is raised by receiving a clockwise rotational moment 2 m Q , B '' m Q B / n around the support shaft 6. become.

Then, the horizontal orthogonal distance between the support shaft 6 of the telescopic boom 5 and the hook 13 during loading is determined between the R5 support shaft 6 and the main winch 1.
The perpendicular distance to the main hoisting rope 11 that is let out from 2 and stretched over the boom head 7 is A, and the tension is set between the support shaft 6, the boom head 7, and the sheave 23 of the rising part 21 on the rear side of the upper revolving structure 4. B is the perpendicular distance between the main hoisting rope 11 and the extension 11c, and C1 is the perpendicular distance between the support shaft 6 and the connecting shaft 9 of the luffing cylinder 8 to the upper revolving structure 4 in the same direction. 5 and the undulating cylinder 8 is θ, the main winding rope 1
Assuming that the number of turns of the load hanging part 11a of the crane 1 is n, and the number of turns of the extension part lie thereof is m (see FIG. 2), the following relationship is established between each part of the crane 1.

However, here, in order to simplify the explanation, we will explain the telescopic boom 5.
, the weight of the undulating cylinder 8, the main winding rope 11, etc. is ignored.

First, the telescopic boom 5 has a rotational moment that rotates the telescopic boom 5 counterclockwise due to the hanging load Q suspended from the hook 13 of the load hanging part 11a of the main hoisting rope 11 hanging from the top of the boom 5. -R occurs.

Then, the telescopic boom 5 is
The clockwise rotational moment F2・C around the support shaft 6 applied to the main hoisting winch 12 and the tension generated in the portion of the upper hoisting rope 11 fed out from the main hoisting winch 12 that reaches the load hanging part 11a hanging from the sheave of the boom head 7. In addition to the rotation moment Q2 exerted on the rear side of the telescopic boom 5 in the direction Q2・A=Q-A/2n=Q-Al1, the upper revolving structure 4 moves beyond the boom head 7 of the main hoisting rope 1, which will be described later. An extension IC extending to the rear side is wound around the sheave 23 on the rear side of the upper revolving body 4, and its folded end 1
1b is attached to the boom head 7, a clockwise rotational moment about the support shaft 6 acts at the same time.

However, the main rope 11 of the first embodiment has a load hanging portion 11.
Since it is wound n (=3) times at a, Q2 = Q/ 2 n = Q/ 2 X 3 = Q/ 6
becomes.

The above-mentioned rotational moments are substantially the same as the rotational moments generated around the support shaft 6 of the conventional telescopic boom 5 shown in FIG.

In the crane of the first embodiment, the extension portion 11c of the main hoisting rope 11 extending beyond the boom head 7 to the rear side of the upper revolving structure 4 is connected to the rear rising portion 21 of the upper revolving structure 4.
Since the folded end portion 11b is attached to the boom head 7, this extension portion 11c
Due to the tension Q2 of the main rope 11 at , the 2m=
A tension of 2X1 times is transmitted to the rear rising part 21 of the upper revolving structure 4, and the telescopic boom 5 receives a clockwise rotational moment around its support shaft 6 2 rn Q z B = 2 m Q B / 2
n== Q B m / n act simultaneously.

Therefore, the rotational moment around the support shaft 6 is balanced, and Q R = F z C + Q A / 2 n + Q
B m / n is established, and the lifting blade F2 of the telescopic boom 5 by the hoisting cylinder 8 in this state is F 2 = (Q RA Q / 2 n - B Q m
/n)/C.

(Comparison between the conventional example without a counterweight and the first embodiment) On the other hand, in the conventional example (here, in order to simplify the explanation, the conventional example without a counterweight will be compared), the main winding rope 11 The folded end 11bb of the load hanging part 1 is attached to the boom head 7, and there is no extension part 11c of the present invention, but the rest of the structure and operation are substantially the same as in the first embodiment. , Q R=F , C+ A Q / 2 rxF-=
(QR-AQ/2n)/C.

Then, the tension Q□ generated in the hoisting rope 11 of the conventional example
If Q2 of the first embodiment is equal to
It becomes R/2n, Q R=F z C0A Q/2
n+2BQm/2n=F1C+AQ/2n.

Further, the lifting force F2 applied to the telescopic boom 5 by the luffing cylinder 8 of the first embodiment is F2'' (QR-
AQ/2n-BQm/n)/C, and in this formula (QR-AQ/2n)/C=F□, the above F2 becomes F,=F,-BQm/Cn.

Therefore, the push-up blade F2 of the undulating cylinder 8 of the first embodiment is
rBQm/C from the push-up blade F0 of the conventional undulating cylinder 8
The bending moment generated around 0 on the axis of connection between the hoisting boom 5 and the hoisting cylinder 8 is reduced by an amount equivalent to rBQm/CnJ.

In addition, as a result of being able to reduce the pushing-up blade F2 of the undulating cylinder 8 compared to the pushing-up blade F1 of the conventional example, the undulating cylinder 8 of the first embodiment has a smaller outer diameter than the conventional example, or The operating pressure can be lowered, and the undulation cylinder 8
The connecting shaft 9.10 between the telescopic boom 5 and the upper revolving body 4 can be made smaller in diameter, and the structure around the connecting shaft 9.10 can be made smaller and lighter.

In addition, in the first embodiment and the conventional example without a counterweight as described above, the number of windings n and m of the load hanging parts 11a and 1laa are rl=3 and m=1, so the above Q2. R, Ql・R and F2, Fl etc. are QR=F2C+AQ/2n+BQm/n=F2C+AQ
/6+BQ/3 F2= (QR-AQ/6-BQ/3)/C=F1-B
Q/3G, and the push-up blade F2 due to the cylinder rond of the undulating cylinder 8 of the first embodiment is BQ/3C smaller than the pushing-up force F of the cylinder rond of the undulating cylinder 8 of the conventional example.

Therefore, the bending moment factor generated around the connecting shaft 10 of the telescopic boom 5 in this first embodiment is larger than that in the conventional example.

BQ/3C equivalent amount becomes smaller.

In addition, if the number of turns n of the load hanging part 11a of the upper rope 11 and the number m of turns of the extension part are made equal (n=m), the above F z =(Q RA Q / 2 n-BQm/n)
/C F2= (QR-AQ/ 2 rt E Q) /
C = (R - A / 2 n - B) Q / C, and by making B large, in other words, the rear side of the upper revolving structure 4 is extended rearward, and the two rising parts rising from the rear side are made higher. By providing the sheave 23 at the top, this F2 can be made considerably smaller.

(Second Example) Next! The second embodiment of the invention will be described with reference to FIG.
The same names and symbols are used for parts common to the first embodiment shown in the figures.

In Fig. 3, 7 is the boom head of the telescopic boom 5;
1 is a main hoisting rope, lla is a load hanging part of the main hoisting rope 11 hanging from the boom head 7, and llb is an end of the main hoisting rope 11, and the end 11b is attached to the boom/head 7.

Reference numeral 12 indicates a main winding winch provided on the upper revolving body 4, 21 a rising portion standing up on the rear side of the upper revolving structure 4, and 32.36 the left and right portions (left side in FIG. 3) of the upper front side of the rising portion 21 (the left side in FIG. 3). (upper and lower) first and third brackets provided on both sides, 33.37
is the first bracket provided on the first and third brackets 32 and 36. Third
The sheave 34 is a third bracket provided on the rear side of the boom head 7 (on the right side in the figure), and the numeral 37 is a third sheave.

Further, llc is an extension of the main hoisting rope 11 that extends beyond the boom head 7 to the rear side (right side in FIG. 3) of the upper revolving structure 4, and the extension 11c is the first extension of the first bracket 32.
sheave 33, second sheave 35 of second bracket 34; The third bracket 36 is folded into the front side of the upper revolving structure 4 via the third sheave 37, and its folded end 11b is attached to the rear side of the boom head 7.

Next, the operation of the second embodiment will be explained.

First, an extension part lie of the main hoisting rope 11 that extends beyond the boom head 7 to the rear side of the upper revolving structure 4 is attached to the front side of the rising part 21 on the rear side of the upper revolving structure 12 and to the rear side of the boom head 7. Since it is wound 2 (=m) times around the first to third sheaves 33, 35, 37 of the first to third brackets 32, 34, 36, the tension Q3 generated in the extension part 11c of the main winding rope 11 is , 2m = 4 times and transmitted from the sheave 23 to the rising part 21 on the rear side of the upper revolving structure 4, and the boom head 7 is pulled toward the rear side of the upper revolving structure 4 by this 4Q.
The telescopic boom 5 receives a clockwise rotational moment about its support shaft 6.

Note that in this second embodiment, the first. 3rd sheave 33.3
7 are disposed on the left and right sides (upper and lower in FIG. 3) of the rising portion 21, and a second sheave 35 is disposed at the center of the boom head 7 (as shown in the figure). 11c and its end 11b engage with both left and right sides of the boom head 7, the extension 1 of the main hoisting rope 11
The rear of the boom head 7 due to the tension Q generated at 1C (
The tensile force to the right side in FIG. 2 is once transmitted more uniformly to the entire area of the boom head 7 in the left-right direction.

In addition, in FIG. 3, there is a
Although the example in which the number of sheaves 33.37 is provided is shown, if the number of meters of these sheaves 33.37 is increased, the first and third sheaves 33 The tensile force transmitted to the rising portion on the rear side of the upper revolving structure 4 through the .

(Third Embodiment) Next, a third embodiment of this invention will be described with reference to FIG. 4, which shows a schematic plan view of the main parts thereof.

Note that the same names and symbols are used for parts common to the first embodiment shown in FIG. 1.2.

In FIG. 4, 7 is the boom head, 11 is the main hoisting rope, lla is the load hanging part thereof, and llc is the folded end of the load hanging part 11a, extending beyond the boom head 7 to the upper revolving body (the reference numeral in FIG. 1). 4) The extension part extending to the rear side, the lid is the extension part 11
In the winding part c, the winding part lid is connected to the first and third brackets 42 and 46 provided on the left side of the upper part of the rising part 21 on the rear side of the upper revolving superstructure 4, with an interval above and below. , 3rd sheave 4
3.47 and the second bracket 4 installed on the boom rad 7
The second sheave 45 of No. 4 is wound and stretched. Reference numeral 11b denotes a folded end portion of the extension portion 11c that is folded back toward the front side of the upper revolving body 4, and the folded end portion 11b is attached to the boom l bed 7.

In this third embodiment, an extension portion 11c of the main hoisting rope 11 extending beyond the boom head 7 to the rear side of the upper revolving structure is vertically spaced on the left side of the upper part of the rising portion 21 on the rear side of the upper revolving structure 4. This can be understood from the fact that the structure is the same as that of the second embodiment except that the second sheave 45 is wound twice around the first and third sheaves 43 and 47 provided at the boom head 7. As shown in FIG. 2, the tension Q4 generated in the extension part 11c of the main winding rope 11 is multiplied by 2 m by the winding part lid, and the other functions and effects are almost the same as in the second embodiment. be.

(Fourth Embodiment) Next, a fourth embodiment of this invention will be described with reference to FIGS. 5 and 6, which show the main parts thereof in a schematic side view and a plan view. Note that the same names and symbols are used for parts common to the first embodiment shown in FIG. 1.2.

In Fig. 5.6, 4 is an upper revolving structure, 5 is a telescopic boom whose base cylinder is attached to the center of the upper revolving structure 4 by a shaft 6 so that it can be raised and lowered, 7 is a boom head, 8 is a luffing cylinder, 9 is a construction machine. 0 is a connecting ring between the upper and lower parts of the luffing cylinder 8, the lower part of the upper part of the base cylinder of the telescopic boom 5, and the upper revolving body 4; 12 is a main winch; 1
4 is a sheave block, 16 is an auxiliary hoisting winch, 21 is a rising part on the rear side of the upper rotating structure 4, 42 is an auxiliary hoisting rope, and 42a is hanging from the boom head 7 of the auxiliary hoisting rope 42, and is an auxiliary hoisting hook (not shown) The second load hanging part 42c that supports the second
an extension portion 50 in which the folded end portion of the load hanging portion 42a is extended beyond the boom head 7 toward the rear side of the upper revolving structure 4;
A mounting shaft 51 is attached to the top of the rear rising portion 21 of the upper revolving body 4.
Bracket 52 is rotatably attached to bracket 5.
The sheave 53 is supported on the pendant 55, and the main winding rope 1 is attached to both the sheaves 52 and 53.
The winding portion 11e of the first extension portion lie is stretched.

56 is a pendant rope for suspending the pendant 55 from the boom head 7, and llf is the main winding rope 11 extension part 11c.
The folded end 11f of the winding portion 11e of the winding portion 11e is the end of the extension portion 42c extending from the boom head 7 of the auxiliary winding rope 42 toward the rear side of the upper revolving structure 4. The section 42f is connected to the section 42f.

Note that lip indicates the position of the main rope 11 adjacent to the drum of the main winch 12, and 42p indicates the position of the auxiliary rope 42 adjacent to the drum of the auxiliary winch 16.

Next, the operation of this fourth embodiment will be explained.

The upper revolving structure 4 goes beyond the boom head 7 of the upper rope rope 1.
The winding portion 11e of the extension portion 11c extending rearward is connected to a sheave 52 provided at the top of the rear rising portion 21 of the upper rotating body 4 and a pendant rope 56 from the boom head 7 of the telescopic boom 5.
The folded end 11f of the auxiliary winding rope 42 is wound around the sheave 53 of the pendant 55 suspended by the sheave 53, and the end 42f of the extension 42C extends beyond the boom head 7 of the auxiliary winding rope 42 to the rear side of the upper revolving structure 4. , the telescopic boom 5 is extended by a telescopic cylinder (not shown).

When the boom head 7 is raised, the pendant 55 and the sheave 53 pivotally attached to the pendant 55 are simultaneously raised by the pendant rope 56.

As the sheave 53 rises, the main hoisting rope 11 extension 1
The winding portion 11a of 1c is stretched, but its folded end 11f and the end 42f of the extension portion 42C of the auxiliary winding rope 42 are stretched.
As a result, the tension Q generated in the upper rope 11 is increased by 2m of the number of turns m of the winding part lie through the sheave 52 on the bracket 50 of the winding part lie of the extension part 11c. Doubled, upper revolving body 4 rear rising part 21
2mQ is transmitted (tensioned) to the side, and the boom head 7 of the telescopic boom 5 is pulled toward the rear side of the upper revolving structure 4 by this 2mQs, and the telescopic boom 5 receives a clockwise rotational moment around its support shaft 6. As a result, the counterclockwise rotational moment QR of the telescopic boom 5 due to the suspended load Q is reduced accordingly.

In addition, as the height of the rising section 2 increases, its installation location can be moved to the front side of the upper rotating structure 4, and if the rear side of the upper rotating structure 4 can be extended sufficiently rearward, the rising section The bracket 50 can be directly pivoted (51) to the rear upper part of the revolving upper structure 4 without lowering or installing the part 21.

(Effects of the Invention) Since the present invention has the configuration and functions as described above,
The following effects can be obtained.

(1) Extend the folded end of the load hanging part of the crane's (main hoist or auxiliary hoist) rope beyond the boom head to the rear of the upper revolving structure, and pass the extension through the sheave on the rear side of the upper revolving structure. Since the folded end is attached directly or indirectly to the boom head, part of the tension generated in the rope (main or auxiliary) due to the hanging load, etc. is The rotational moment that acts as a rotational moment to raise the boom, the lodging moment of the telescopic boom, and the bending moment that acts on the mounting portion of the hoisting cylinder are reduced compared to conventional cranes of the same type.

(2) Since the lodging moment of the telescopic boom is reduced, the lifting blade of the telescopic boom by the hoisting cylinder can be set smaller than in the conventional example, and it is possible to reduce the outer diameter of the hoisting cylinder or reduce its operating pressure.

(3) The extended part of the crane's telescopic boom (main or auxiliary hoisting) that extends beyond the boom head to the rear of the superstructure is wound around a sheave installed at the rising part of the rear superstructure; By simply changing the structure by simply attaching the end to the boom head, it can be implemented as a device for reducing the bending moment and lodging moment of the telescopic boom of an existing crane.

(4) Since there is no risk of generating an excessive bending moment on the crane's hoistable telescopic boom, the strength and rigidity of the hoisting cylinder of the telescopic boom and its mounting pins, etc.
This can be reduced compared to conventional examples of the same type, and the overall weight can be reduced.

(5) Either one of the extensions of the telescopic boom of the main hoisting rope and the auxiliary hoisting rope beyond the boom l head is folded back to the boom head side via the sheave on the rear side of the upper revolving structure, and the ends and The bending moment of the telescopic boom of an existing crane can be reduced by simply changing the configuration by simply connecting the extension part to the other end.

(6) If a sheave for folding or winding the extension of the main hoisting rope or auxiliary hoisting rope beyond the boom head is provided at the rising part on the rear side of the upper revolving structure, the amount of rearward extension of the upper revolving structure can be increased. can be made relatively short to ensure the required amount of bending moment reduction.

(7) The extension of the main hoisting rope beyond the boom head,
The first. If a secondary winding is applied to the third sheave and the second sheave provided on the boom head, and the folded end of the winding part of the extension is attached to the boom head, the winding will occur in the extension of the main hoist rope. Not only is the tension caused by the load reduced, but the flexibility in designing the telescoping boom of large lanes without torsion is increased.

[Brief explanation of drawings]

1 to 6 show an embodiment of a bending moment reduction device for a telescopic boom in a crane according to the present invention, and FIG. 1 is a schematic explanatory diagram showing essential parts of the first embodiment in perspective; FIG. 2 is an explanatory diagram of its operation, FIGS. 3 and 4 are schematic plan explanatory diagrams of the main parts of the second and third embodiments, and FIG.
The figure is a schematic side view showing the main parts of the fourth embodiment.
The figure is an enlarged plan explanatory view of the main part thereof, and FIG. 7 is a schematic explanatory view of a conventional example. 1... Crane, 4... Upper revolving structure, 5... Telescopic boom, 7...
...Boom head, 8...Luffing cylinder,
Work 1: Main winding rope. 11b...Folded end of main winding rope (attachment part)
, 11c... extension, lid, lie...
- Winding part, 11f... Connection part, 12.
...Main hoisting winch, 16...Auxiliary hoisting winch, 2nd work...Rising section, 22...Bracket, 23.52.53...・Sheave, 33.43...
...Second Sheave, 5.45...Second Sheave. 7.47... Third sheave, 2... Auxiliary winding rope, 2c... Auxiliary winding rope extension, 2f... Auxiliary winding rope connection part, 5・・・・・・
Pendant, 6...Pendant rope.

Claims (4)

[Claims] (1) The upper revolving structure of the crane is provided with a telescoping boom that is operated by a luffing cylinder and a rope winch that is suspended via the boom head of the telescoping boom;
A folded end of the load hanging part of the rope hanging from the boom head is extended beyond the boom head to the rear side of the upper revolving structure, and the extended part is passed through a sheave on the rear side of the upper revolving structure. 1. A bending moment reduction device for a telescopic boom in a crane, characterized in that it is folded back to the front side of an upper revolving structure, and the folded end portion is attached directly or indirectly to the boom head. (2) The telescopic boom in the crane according to claim (1) or (2), wherein the sheave on the rear side of the upper revolving body is provided at the top of a rising part rising from the rear of the upper revolving body. Bending moment reduction device. (3) An extension part of the rope extending beyond the boom head to the rear side of the upper revolving body is provided on the first and third sheaves provided at the top of the rear rising part of the upper revolving body, and on the boom head. Claim 1, characterized in that the second sheave is wound sequentially around the second sheave, and the folded end portion thereof is attached to the boom head.
A bending moment reduction device for a telescopic boom in the crane described in 1) or (2). (4) An extension part of the load hanging part of the main hoisting rope that extends beyond the boom head to the rear side of the upper revolving structure is connected to a sheave on the rear rising part of the upper revolving structure and a pendant suspended from the boom head. At the same time, the winding rope is wound around the provided sheave, and is let out from the folded end of this winding portion of the main hoisting rope extension portion toward the front side of the revolving structure, and from the auxiliary hoisting winch provided on the upper revolving structure, and from the boom head. The second hanging auxiliary rope
A bending moment reduction device for a telescopic boom in a crane, characterized in that a load lifting part is connected to an extension part extending beyond the boom head to the rear side of the upper revolving structure.