JP2016098092A - Boom breakage prevention device of crane vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a tube of a boom extension cylinder from swinging in a vertical direction due to vibration during traveling when driving a crane vehicle.SOLUTION: A projection piece receiving section 22 provided inside a tip section of a tip side boom component 5 is made to approach a projection piece 21 provided at an end section on a counter piston rod projection side of a tube 9 in a boom extension cylinder 6 in a downsizing stroke of a boom 1. Entering of the projection piece 21 into the projection piece receiving section 22 is guided using tapered surfaces of a guide section 34 provided in the projection piece 21 and a guide section 36 provided in the projection piece receiving section 22. A state that the end section on the counter piston rod projection side of the tube 9 is slightly lifted up against gravity by a slide contact action between the tapered surfaces is held. A state that the tube 9 of the boom extension cylinder 6 and the peripheral parts are separated together from a bottom face and a top face of the tip side boom component 5 is maintained.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an improvement in a boom breakage prevention device for a crane vehicle including a boom formed by sequentially inserting three or more stages of boom components in a nested manner.

A crane in which three or more stages of boom components are inserted in a nested manner in order to form a boom, and the boom is expanded and contracted using a boom telescopic cylinder, a plurality of sheaves, a boom extending wire and a boom reducing wire. A car is already known as Patent Document 1, Patent Document 2, and the like.
In this type of boom, with the small-diameter side piston rod of the components of the boom telescopic cylinder composed of a tube and a piston rod facing the base side of the boom, the piston rod is attached to the base of the base side boom component. A boom telescoping cylinder pivotally attaches to the base of the boom component adjacent to the base side boom component, that is, the second boom component counted from the base side, and the end on the piston rod protruding side of the tube. By expanding and contracting, the boom component adjacent to the base side boom component is moved relative to the base side boom component in the direction of expansion and contraction of the boom telescopic cylinder. In addition, each boom from the second-stage boom component adjacent to the base-side boom component to the distal-end boom component, that is, the boom component at the most advanced stage of the boom, is necessary to achieve weight reduction of the boom tip. The expansion and contraction of the components is different in the boom configuration via a sheave pivotally attached to each of the end of the tube in the boom telescopic cylinder on the side opposite to the piston rod protruding side and the end in the longitudinal direction of each boom component. It implement | achieves using the interaction of the wire for boom extension | expansion which connects an element, the wire for boom reduction | decrease, and the above-mentioned relative movement.
Then, when moving the crane truck, the boom telescopic cylinder and the boom are in a fully contracted state and the boom components from the base side boom component to the tip side boom component are overlapped inside and outside horizontally. When the crane is operated by storing, the base of the boom component adjacent to the base-side boom component remarkably approaches the base of the base-side boom component as the boom is reduced. Since the distance between the pivoting position of the end of the piston rod projecting side of the tube of the telescopic cylinder and the pivoting position of the piston rod tip of the boom telescopic cylinder becomes extremely short, the boom telescopic cylinder is substantially It will be held in a cantilever shape with the two pivoting positions as fixed ends. The end on the anti-piston rod protruding side of the probe may swing up and down due to vibration during travel, hitting the bottom and top surfaces of the end-side boom components located on the innermost side, and damaging the boom telescopic cylinder and boom is there.

JP 2000-177991 A (paragraphs 0003 to 0005, paragraph 0041, paragraph 0043, paragraph 0046, FIG. 3, FIG. 7) JP 2006-199407 A (paragraphs 0025 to 0026, paragraph 0030, FIG. 4)

In order to improve such an inconvenience, in the invention described in Patent Document 1, the bottom surface of the anti-piston rod projecting end of the tube of the boom telescopic cylinder and the inner bottom surface of each boom component when the boom expands and contracts. In order to prevent rubbing, the roller (21) provided on the lower surface of the end of the tube on the side opposite to the piston rod is pressed toward the bottom surface of the boom component on the tip side with the tension of the boom reduction wire (107). Thus, the upper and lower rollers (21) provided at the end of the boom telescopic cylinder on the anti-piston rod projecting side and the upper surface provided on the upper side of the end of the boom telescopic cylinder are suppressed. The guide plate (51) is prevented from being struck against the bottom surface or top surface of the boom component on the distal end side. By bringing a guide roller (48) biased by a spring (50) outwardly from both the left and right sides of the end portion on the side opposite to the piston rod projecting against the left and right wall portions inside the tip side boom component In addition, the end of the anti-piston rod protruding side of the tube of the boom telescopic cylinder is prevented from swinging to the left and right and hitting the left and right wall portions of the tip side boom component.
However, in the invention described in the cited document 1, the roller (21) is not pressed against the bottom surface of the tip side boom component by directly using the tension acting along the axis of the boom reduction wire (107). The roller (21) is merely pressed against the bottom surface of the boom component on the distal end side by utilizing the repulsive force of the string against the force to loosen the boom reducing wire (107) in the direction orthogonal to the axis. Therefore, particularly when the crane vehicle travels on a rough road, it becomes difficult to maintain the state in which the roller (21) is pressed against the bottom surface of the boom component on the distal end side. Possibility that the end of the anti-piston rod projecting side swings up and down and the roller (21) or the upper surface guide plate (51) hits the bottom surface or top surface of the tip side boom component. It can not be denied.

On the other hand, in the invention described in Patent Document 2, a pair of upper and lower guide ribs (71a, 71b) are provided to project over the entire length in the longitudinal direction inside the left and right walls of the tip side boom component, and the tube of the boom telescopic cylinder is provided. The boom telescopic cylinder is supported from above, below, left, and right so that the rollers (65, 65) or sliders provided on both the left and right sides of the end of the anti-piston rod projecting side are held by the upper and lower guide ribs (71a, 71b) I am doing so.
However, since the rollers (65, 65) need to roll between the pair of upper and lower guide ribs (71a, 71b) when the boom telescopic cylinder and the boom extend and contract, the rollers (65, 65) and the guide ribs (71a, 71b) A certain clearance is required between them, and similarly, a certain clearance is also required between the outer end surface of the rollers (65, 65) and the left and right wall portions of the distal boom component.
In the invention described in Patent Document 2, the pair of upper and lower guide ribs (71a, 71b) restrains the position of the rollers (65, 65) from above and below. Although it is considered that the peripheral parts do not hit the bottom surface or top surface of the tip side boom component, there is a clearance between the rollers (65, 65) and the upper and lower guide ribs (71a, 71b). , The roller (65, 65) with the weight of the boom telescopic cylinder is struck against the guide ribs (71a, 71b).
These guide ribs (71a, 71b) are formed integrally with the wall portion of the distal boom component over the entire length in the longitudinal direction inside the left and right walls of the distal boom component, even though they are guide ribs. Therefore, as with the case where the bottom surface or top surface of the tip side boom component is struck, there is concern about damage to the left and right side surfaces of the cylindrical tip side boom component itself forming the stress skin structure, and the boom extension and contraction The impact force acting on the boom telescopic cylinder when the rollers (65, 65) provided at the end of the cylinder tube opposite to the piston rod projecting side is struck against the guide ribs (71a, 71b) causes the boom telescopic cylinder and its surroundings. There are also concerns about the negative effects on parts.

  Therefore, an object of the present invention is to store the boom horizontally with the boom telescopic cylinder and the boom in the fully contracted state, with the boom components from the base side boom component to the tip side boom component superposed inside and outside. When operating a crane truck, the end of the boom telescopic cylinder tube on the anti-piston rod protruding side is prevented from swinging up and down due to vibration during travel and hitting the bottom or top surface of the tip boom component. Another object of the present invention is to provide a boom breakage prevention device for a crane truck capable of preventing an excessive impact force from acting on a front end side boom constituent element, a boom telescopic cylinder and its peripheral parts forming a stress skin structure.

The present invention provides a boom telescopic cylinder at the base of the base-side boom component in a boom formed by sequentially fitting three or more stages of boom components from the base-side boom component to the tip-side boom component. The end of the boom rod telescopic cylinder on the piston rod protruding side is pivotally mounted to the base of the boom component adjacent to the base side boom component, and the boom telescopic cylinder The boom component adjacent to the base-side boom component is moved relative to the base-side boom component in the expansion / contraction direction of the boom telescopic cylinder by extending and contracting, and the end of the tube on the anti-piston rod protruding side and Different from each other via a sheave pivotally attached to each of the longitudinal ends of each boom component. Each boom component from the boom component adjacent to the base-side boom component to the distal-end boom component by the interaction between the boom extension wire and the boom contraction wire connecting the boom component and the relative movement. A boom breakage prevention device for a crane truck provided with a boom that is relatively moved in the telescopic direction, and in order to achieve the object,
Providing a protruding piece having a shape that can be supported at least in the vertical direction on either the end of the tube on the anti-piston rod protruding side or the inner end of the distal end boom component,
On the other hand, a projecting piece receiving portion that supports the projecting piece in close contact with at least the upper and lower surfaces of the projecting piece in the most contracted state of the boom telescopic cylinder and the boom is provided in the axial direction of the tube and its peripheral parts. Provided in a position to support the lower end and the upper end of the maximum outer shape of the cross-section separated from the bottom surface and the top surface of the tip side boom component,
At least one of the projecting piece and the projecting piece receiving part guides the intrusion of the projecting piece into the projecting piece receiving part in the process of contracting the boom telescopic cylinder and the boom and A guide portion having a tapered surface for lifting the piston rod protruding side end against gravity is provided.

In the above configuration, when moving the crane truck, first, the boom telescopic cylinder in the extended state is reduced, and each boom component from the boom component adjacent to the base-side boom component to the distal boom component To the base boom component side.
At this time, all the boom components from the boom component adjacent to the boom telescopic cylinder tube and the base boom component to the distal boom component start to shrink simultaneously toward the base of the base boom component. However, the boom of the crane truck extends from the boom component adjacent to the base boom component to the distal boom component when the expansion of the piston rod of the boom telescopic cylinder in the extended state is completed. Designed so that all boom components are fully retracted and fit inside the base boom component, so the base boom configuration is compared to the speed of the boom telescoping cylinder tube relative to the base boom component The speed of movement of the distal boom component relative to the element is necessarily faster.
Accordingly, the distal end portion of the distal boom component gradually approaches the end of the boom telescopic cylinder on the anti-piston rod projecting side, following the tube of the boom telescopic cylinder.
In the boom telescopic cylinder and the boom shrinking process, the bottom end of the maximum outer shape of the axial cross section of the tube of the boom telescopic cylinder and its peripheral parts, more specifically, the anti-piston rod protruding side of the tube when the boom expands and contracts The rollers, sliders, etc. provided to prevent friction between the bottom surface of each end of the boom and the bottom surface of each boom component roll or slide against the bottom surface of the boom component, Support a part of.
Next, when the boom telescopic cylinder and the boom retracting operation reach the start stage of the most contracting process, the tip of the projecting piece (or projecting piece receiving part) provided at the end of the boom telescopic cylinder tube on the side opposite to the piston rod projecting side is provided. The projecting piece receiving portion (or projecting piece) provided inside the tip of the side boom constituent element approaches, via the taper surface of the guide portion provided on at least one of the projecting piece and the projecting piece receiving portion. The protruding piece and the protruding piece receiving portion are in sliding contact.
Then, the boom telescopic cylinder and the boom shrinking process proceed, and the distal end of the distal boom component is placed on the projecting piece (or projecting piece receiving part) provided at the end of the boom telescopic cylinder on the side opposite to the piston rod projecting side of the tube. When the protruding piece receiving portion (or protruding piece) provided inside the portion further approaches, the intrusion of the protruding piece into the protruding piece receiving portion is guided by the tapered surface of the guide portion, and the sliding action with this tapered surface The end of the tube on the protruding side of the anti-piston rod is lifted up slightly against gravity, and finally the boom telescopic cylinder and the projecting piece installed up and down when the minimum reduction process of the boom is completed. The receiving portion is in close contact with the upper and lower surfaces of the protruding piece and supports the protruding piece.
In this state, the lower end and the upper end of the maximum outer shape of the axial cross section of the tube and its peripheral parts are both separated from the bottom surface and the top surface of the tip side boom component, and in the boom telescopic cylinder The end of the tube on the protruding side opposite to the piston rod is fixed to the inside of the distal end of the distal boom component via a protruding piece and a protruding piece receiving portion that supports the protruding piece in close contact with the upper and lower surfaces of the protruding piece. Therefore, even when the crane is operated with the boom telescopic cylinder and the boom in the most contracted state, the boom in which the boom components from the base side boom component to the tip side boom component are overlapped inside and outside is horizontally stored. The lower end and upper end of the maximum outer shape of the axial section of the tube of the boom telescopic cylinder and its peripheral parts are moved up and down by vibration during travel. Fear is no such strike the bottom surface and the top surface of the distal boom components are.
Also, since there is almost no vertical clearance between the protruding piece receiving portion and the protruding piece, the protruding piece receiving portion and the protruding piece do not come into contact with each other. There is no problem that the impact force exerts an adverse effect on the boom telescopic cylinder and its peripheral parts.

More specifically, while the projecting piece is constituted by a plate-like member that is horizontally fixed to the end of the tube on the side opposite to the piston rod projecting side,
The projecting piece receiving portion is configured by a pair of upper and lower support members fixed to the left and right wall portions inside the distal end portion of the distal end side boom component with an interval equivalent to the thickness of the projecting piece in the vertical direction,
A configuration in which the lateral width of the protruding piece is formed slightly shorter than the distance between the left and right wall portions inside the distal end portion of the distal end boom component can be applied.

When such a configuration is applied, the lateral swing range of the end of the tube on the side opposite to the piston rod protruding from the boom telescopic cylinder is such that the left and right sides of the plate-like member constituting the protruding piece and the tip side boom configuration The clearance is limited to a clearance formed between the left and right walls inside the tip of the element.
Therefore, it is possible to alleviate the problem that the end of the boom telescopic cylinder on the anti-piston rod protruding side swings to the left and right and strikes the left and right wall portions of the tip side boom component.
The projecting piece provided at the end of the boom telescopic cylinder on the side opposite to the piston rod projecting side is relatively moved over the entire length in the longitudinal direction inside the left and right walls of the tip side boom component when the boom is expanded and contracted. Therefore, a clearance between the left and right sides of the plate-like member constituting the projecting piece and the left and right wall portions inside the tip portion of the tip side boom component is necessary, and by setting this clearance to zero It is impossible to completely eliminate the left and right runout on the anti-piston rod protruding side in the tube of the boom telescopic cylinder.
There is no danger of the boom telescopic cylinder tube swinging up and down and hitting the bottom or top surface of the boom component on the tip side, and there is almost no substantial vertical clearance between the protruding piece receiving part and the protruding piece. In the same manner as described above, the problem that the impact force caused by the contact between the protruding piece receiving portion and the protruding piece adversely affects the boom telescopic cylinder and its peripheral parts is eliminated.

Further, the projecting piece is constituted by a rod member projecting along the expansion / contraction direction of the boom telescopic cylinder at the center of the tip of the end of the tube opposite to the piston rod projecting side,
The protruding piece receiving portion may be configured by an annular member having an inner diameter comparable to the outer diameter of the rod member and installed inside the distal end portion of the distal boom component through a stay.

When such a configuration is applied, the rod member constituting the protruding piece does not interfere with or slidably contact with the left and right wall portions inside the distal end portion of the tip side boom constituent element, and the protruding piece becomes an object to be slidably contacted. Since only the inner peripheral surface of the protruding piece receiving portion formed of an annular member installed inside the distal end portion of the distal end side boom component through the stay, there is no particular limitation on the lateral width with respect to the protruding piece.
Accordingly, the inner diameter of the annular member constituting the protruding piece receiving portion is set to a size comparable to the outer diameter of the rod member serving as the protruding piece, and the fitting between the protruding piece and the protruding piece receiving portion is performed in all directions, up and down and left and right. A tight fitting state can be achieved, and the lateral vibration of the end of the boom telescopic cylinder on the anti-piston rod protruding side can be surely eliminated as well as the vertical vibration.

The boom breakage prevention device for a crane truck according to the present invention includes a boom telescopic cylinder and a projecting piece (or projecting piece receiving part) provided at an end of the boom telescopic cylinder on the side opposite to the piston rod projecting in the boom contraction process. The projecting piece receiving part (or projecting piece) provided inside the tip part of the tip side boom component is brought close to each other, and the taper surface of the guide part provided on at least one of the projecting piece and the projecting piece receiving part is used. Then, it guides the intrusion of the protruding piece into the protruding piece receiving portion, and further lifts the end of the tube on the protruding side opposite to the piston rod slightly against the gravity by the sliding action of the tapered surface, and the boom telescopic cylinder When the boom is fully retracted, the upper and lower protruding piece receiving portions are in close contact with the upper and lower surfaces of the protruding piece to support the protruding piece, and the boom telescopic cylinder Since the bottom end and the top end of the maximum outer shape of the axial cross section in the shaft and its peripheral parts are kept apart from the bottom surface and the top surface of the distal boom component, the boom telescopic cylinder Even when the boom is stored in a horizontal position with the boom components in which the boom components from the base side boom components to the tip side boom components are overlapped in the most contracted state and the crane is operated, the tube of the boom telescopic cylinder And the inconvenience that the lower end portion and the upper end portion of the maximum outer shape of the axial cross section in the peripheral parts thereof swing up and down due to vibration during traveling strikes the bottom surface and the top surface of the tip side boom component.
In addition, since there is almost no vertical clearance between the protruding piece receiving portion and the protruding piece, the protruding piece receiving portion and the protruding piece do not collide with each other, and the boom telescopic cylinder rattles. The problem that the impact force that exerts an adverse effect on the boom telescopic cylinder and its peripheral parts is also eliminated.

  In addition, the projecting piece is constituted by a plate-like member horizontally fixed to the end of the tube on the anti-piston rod projecting side of the tube in the boom telescopic cylinder, while the interval equal to the thickness of the projecting piece is placed in the vertical direction. A pair of upper and lower support members fixed to the left and right walls inside the distal end of the side boom component constitutes a protruding piece receiving portion, and the lateral width of the protruding piece is determined by the left and right walls inside the distal end of the distal boom component. In the case of applying a configuration that is formed slightly shorter than the separation distance, the lateral deflection range of the end of the tube on the anti-piston rod protruding side of the boom telescopic cylinder forms a protruding piece. Since it is limited within the clearance range between the left and right sides of the member and the left and right walls inside the tip of the tip side boom component, the anti-piston rod in the tube of the boom telescopic cylinder It is possible to reduce the problem of striking the walls of the left and right tip side boom component swings to the right and left end portions of de protruding side is large.

  In addition, a projecting piece is constituted by a rod member projecting along the telescopic direction of the boom telescopic cylinder at the center of the tip of the end of the tube on the side opposite to the piston rod projecting side of the boom telescopic cylinder. If the projecting piece receiving part is configured by an annular member having an inner diameter comparable to the diameter and installed inside the distal end part of the tip side boom component through the stay, the rod member constituting the projecting piece is the tip The projecting piece does not interfere with or slide against the left and right walls inside the tip part of the side boom component, but is placed inside the tip part of the tip boom component via the stay. Since only the inner peripheral surface of the projecting piece receiving portion made of an annular member is provided, the projecting piece has an inner diameter of the annular member constituting the projecting piece receiving portion equal to the outer diameter of the rod member serving as the projecting piece. The fitting with the protruding piece receiving part is a tight fitting state in all directions, up and down and left and right. It can be reliably eliminated as well.

It is the conceptual diagram which simplified and showed the structure and the principle of operation about an example of a four-stage type boom among the booms mounted in a crane vehicle. It is side sectional drawing which showed the boom which mounted the boom damage prevention apparatus of one Embodiment to which this invention is applied. FIG. 3A is a front view showing the boom breakage prevention device from the front end side of the boom, and FIG. 3B is a view showing the configuration of the boom breakage prevention device of the embodiment. It is the side view which showed the periphery of the edge part by the side of the anti-piston rod protrusion of the tube in a boom expansion-contraction cylinder including. It is the perspective view which showed entirely the structure of the boom breakage prevention apparatus of the embodiment by removing a part of front end side boom component. It is the perspective view which divided and showed the component of the boom breakage prevention apparatus of the embodiment, among these, Fig.5 (a) was arrange | positioned at the edge part by the side of the anti-piston rod protrusion of a tube among boom breakage prevention apparatuses. FIG. 5B is a perspective view showing only a portion of the boom breakage prevention device that is disposed on the distal boom component, with a part of the distal boom component removed, and FIG. is there. It is the sectional side view shown in the state which mounted the boom breakage prevention apparatus of other one Embodiment to which this invention was applied to the boom. 7A and 7B are diagrams showing the configuration of the boom breakage prevention apparatus according to the embodiment. FIG. 7A is a front view showing the boom breakage prevention apparatus from the front end side of the boom, and FIG. It is the side view which showed the periphery of the edge part by the side of the anti-piston rod protrusion of the tube in a boom expansion-contraction cylinder including.

  Next, some embodiments to which a boom breakage prevention device (hereinafter simply referred to as a boom breakage prevention device) for a crane truck according to the present invention is applied will be specifically described with reference to the drawings.

FIG. 1 is a conceptual diagram showing the configuration and operating principle of an example of a four-stage boom 1 among various booms mounted on a crane vehicle. However, the mounting structure of the boom 1 with respect to the crane vehicle, the mounting structure of the boom hoisting cylinder for raising and lowering the boom 1, the bracket structure provided at the distal end of the distal end boom component 5 and the like are well known, and the description is omitted. Yes.
This boom 1 is a boom of a crane truck formed by inserting four stages of boom constituent elements 2, 3, 4, and 5 from the base side boom constituent element 2 to the distal end boom constituent element 5 in order in a nested manner. Yes, the tip of the piston rod 7 of the boom telescopic cylinder 6 is pivotally attached to the base of the base side boom constituent element 2 by a pin 8, while the boom telescopic cylinder 6 is attached to the base of the boom constituent element 3 adjacent to the base side boom constituent element 2. By pivoting the end of the tube 9 on the piston rod projecting side with the pin 10, the boom component 3 adjacent to the base side boom component 2 can be moved relative to the base side boom component 2 by the expansion and contraction of the boom telescopic cylinder 6. Thus, the boom telescopic cylinder 6 can be moved relative to the telescopic direction.
In addition, the boom 1 is pivotally attached to the inner side of the distal end portion of the base side boom component 2 and the sheave 11 rotatably attached to the end of the tube 9 in the boom telescopic cylinder 6 on the side opposite to the piston rod protruding side. Of the sheave 12, the sheave 13 pivotally attached to the base of the boom component 3, the sheave 14 pivotally pivotally attached to the tip of the boom component 4, and the tip boom component 5 A sheave 15 pivotally attached to the base is provided, and one end of the sheave 15 is fixed to the base 2r of the base-side boom component 2, and a sheave 11 at the end of the tube 9 on the side opposite to the piston rod is provided. A boom extension wire 16 that connects the base side boom component 2 and the boom component 4 to each other by fastening the other end to the base 4r of the boom component 4 via the boom, and a boom at one end thereof. Of component 3 The other end is fixed to the base 5r of the distal boom component 5 via the sheave 12 at the distal end of the base boom component 2 and the sheave 13 at the base of the boom component 3. Thus, the boom contracting wire 17 for connecting the boom component 3 and the distal boom component 5 to each other, and one end of the wire 17 are fixed to the distal end 2t of the base boom component 2 to connect the distal end of the boom component 4 The base side boom component 2 and the boom component 4 are mutually connected by the other end being fixed to the tip 4t of the boom component 4 via the sheave 14 of the base and the base sheave 15 of the tip side boom component 5. Boom telescopic wire 18 connected to The boom telescopic wire 18 functions as both a boom extending wire and a boom reducing wire.

As is clear from FIG. 1, when the boom telescopic cylinder 6 is extended, the boom component 3 adjacent to the base side boom component 2 is moved relative to the base side boom component 2 by the extension operation itself of the boom telescopic cylinder 6. The boom telescopic cylinder 6 moves relative to the extending direction.
Further, as the boom telescopic cylinder 6 extends, the sheave 11 at the end of the tube 9 on the protruding side of the anti-piston rod moves in the extending direction of the boom telescopic cylinder 6 so that one end of the sheave 11 becomes the base side boom component. The other end portion of the boom extension wire 16 that is fixed to the base portion 2r of the No. 2 and is wound around the sheave 11 pulls the base portion 4r of the boom component 4 in the extension direction of the boom telescopic cylinder 6 so that the boom component 4 also moves relative to the base side boom component 2 and the boom component 3 in the extending direction of the boom telescopic cylinder 6.
At the same time, the sheave 14 at the tip of the boom component 4 is moved in the extending direction of the boom telescopic cylinder 6 by the relative movement of the boom component 4, so that one end thereof is fixed to the tip 2 t of the base boom component 2. A boom telescopic wire 18 is wound around the sheave 14 at the tip of the boom component 4 and the sheave 15 at the base of the boom component 5 and the other end is fixed to the tip 4t of the boom component 4. By pulling the base portion of the distal boom component 5 in the extending direction of the boom telescopic cylinder 6 at the contact position between the boom telescopic wire 18 and the sheave 15 of the distal boom component 5, the distal boom component 6 is pulled. 5 also moves relative to the base side boom component 2, the boom component 3, and the boom component 4 in the extending direction of the boom telescopic cylinder 6.
The above operations are all performed in the process of the boom telescopic cylinder 6 from the fully contracted state to the fully extended state. Therefore, the absolute movement speed of the boom component 5 in the distal end side compared with the absolute moving speed of the tube 9 in the boom telescopic cylinder 6. The moving speed is much faster.

On the other hand, when the boom telescopic cylinder 6 is contracted, the boom constituent element 3 adjacent to the base-side boom constituent element 2 moves from the base-side boom constituent element 2 to the boom by the contracting operation of the boom telescopic cylinder 6 itself. The telescopic cylinder 6 moves relative to the reduction direction.
Further, the sheave 13 at the base of the boom component 3 moves in the contraction direction of the boom telescopic cylinder 6 with the relative movement of the boom component 3 in the contraction direction, so that one end of the sheave 13 becomes the base of the boom component 3. Boom fixed to 3r and fixed to the base 5r of the distal boom component 5 via the sheave 12 at the distal end of the base boom component 2 and the sheave 13 at the base of the boom component 3 The other end of the reduction wire 17 pulls the base 5r of the distal boom component 5 in the reduction direction of the boom telescopic cylinder 6 so that the distal boom component 5 is relatively moved in the reduction direction of the boom telescopic cylinder 6. .
At the same time, the base sheave 15 of the distal boom component 5 is moved in the shrinking direction of the boom telescopic cylinder 6 by the relative movement of the distal boom component 5, so that one end thereof is moved to the distal end of the base boom component 2. Boom telescoping that is fastened to 2t and hung around the sheave 14 at the tip of the boom component 4 and the sheave 15 at the base of the boom component 5 at the other end and fastened to the tip 4t of the boom component 4 The boom wire 18 pulls the tip of the boom component 4 in the shrinking direction of the boom telescopic cylinder 6 at the contact position between the boom telescopic wire 18 and the sheave 14 at the tip of the boom component 4. 4 moves relative to the direction in which the boom telescopic cylinder 6 is reduced.
As described above, these operations are all performed in the process of the boom telescopic cylinder 6 from the fully extended state to the fully contracted state. The absolute movement speed of 5 is faster.

  Sheaves 11, 12, 13 pivotally attached to the end of the tube 9 in the boom telescopic cylinder 6 on the side opposite to the piston rod protruding side and the end of each boom component 2, 3, 4, 5 in the longitudinal direction. , 14, 15 and the interaction between the wires 16, 17, 18 and the relative movement that occurs between the boom component 3 adjacent to the base boom component 2 and the base boom component 2. The boom components from the boom component 3 to the distal boom component 5 are extended and retracted by using the boom 1 in order to avoid the use of a plurality of heavy cylinders, and to extend the distal end of the boom 1 in the extended state. The main purpose is to reduce the weight.

  Here, as an example, the configuration and principle of operation of one example of a four-stage boom 1 have been briefly described, but a boom formed by sequentially fitting three or more stages of boom components in a nested manner, in particular, In the retracted state of the boom in which each boom component from the base side boom component located closest to the crane body to the distal end boom component is overlapped inside and outside, the inside is roughly equivalent to the entire length of the boom. A boom having a structure with a built-in boom telescopic cylinder of a certain length, that is, between the pivot position of the end of the piston rod protruding side of the tube of the boom telescopic cylinder and the pivot position of the end of the piston rod of the boom telescopic cylinder The distance between the two is extremely short when the boom is retracted, so that the long boom telescopic cylinder is substantially cantilevered with these two pivot positions as fixed ends. Can be applied to the boom breakage preventing device of the present invention for all of the boom having a structure be forced to hold the beam-shaped.

[First embodiment]

FIG. 2 is a side sectional view showing the boom breakage prevention device 19 according to an embodiment to which the present invention is applied in a state where the boom breakage prevention device 19 is mounted on the boom 1. In order to avoid complication of the drawings, the sheaves 12, 13, 14, 15 and The description regarding the wires 16, 17, and 18 is omitted. FIG. 2 shows the boom 1 and the boom breakage prevention device in the most contracted retracted state in which the boom components 2, 3, 4 and 5 from the base side boom component 2 to the distal end boom component 5 are overlapped inside and outside. 19, the position of the pin 8 that pivots the end of the tube 9 of the boom telescopic cylinder 6 on the piston rod protruding side to the base of the boom component 3 and the tip of the piston rod 7 of the boom telescopic cylinder 6 are the base. The distance from the position of the pin 10 pivotally attached to the base part of the side boom component 2 is extremely short, and the long boom telescopic cylinder 6 is substantially made with the pivoted position of these two pins 8 and 10 as fixed ends. It can be seen that it has to be held in a cantilever shape.
FIG. 3 is a diagram showing the configuration of the boom breakage prevention device 19, in which FIG. 3 (a) is a front view showing the boom breakage prevention device 19 from the tip side of the boom 1, and FIG. 3 (b) is a boom view. It is the side view which showed the periphery of the edge part by the side of the anti-piston rod protrusion of the tube 9 in the boom expansion-contraction cylinder 6 including the damage prevention apparatus 19. FIG.
FIG. 4 is a perspective view generally showing the configuration of the boom breakage prevention device 19 by removing a part of the tip side boom component 5.
FIG. 5 is a perspective view showing the components of the boom breakage prevention device 19 in a divided state. FIG. 5A is a perspective view of the boom breakage prevention device 19 mounted on the end of the tube 9 on the side opposite to the piston rod. FIG. 5B is a perspective view showing only a portion mounted on the tip-end boom component 5 in the boom breakage prevention device 19.

  The boom breakage prevention device 19 of this embodiment is horizontally fixed to the tip of the end of the tube 9 on the anti-piston rod projecting side of the boom telescopic cylinder 6 as shown in FIGS. 2 and 3A, 3B. The projecting piece 21 having the plate-shaped member 20 as a main part, and the left and right wall parts inside the distal end part of the distal end boom component 5 with an interval equivalent to the thickness of the projecting piece 21 in the vertical direction. The upper support member 29 and the lower support member 30 are formed by a pair of upper and lower protruding piece receiving portions 22.

In order to prevent rubbing between the end of the tube 9 of the boom telescopic cylinder 6 on the anti-piston rod projecting side and the inner bottom surface of each boom component 3, 4, 5 during expansion and contraction of the boom 1, via the stay 23. The configuration and function of the roller 24 provided on the lower surface of the end of the tube 9 on the side opposite to the piston rod protruding, the end of the tube 9 on the side opposite to the piston rod protruding when the boom 1 extends and contracts, and the boom components 3 and 4 The structure and function of the upper surface guide plate 26 provided on the upper surface of the end of the tube 9 on the anti-piston rod protruding side through the stay 25 in order to prevent rubbing against the inside of the top surface of the is there.
An arc-shaped cover 27 covering a part of the outer peripheral portion of the sheave 11 is for preventing the boom extending wire 16 (see FIG. 1) hung around the sheave 11 from being detached, and a fixing means 28 such as a rivet is provided. The base of the tube 9 is fixed to the end of the tube 9 on the side opposite to the piston rod.

The sheave 11, the stay 23, the roller 24, the stay 25, the upper surface guide plate 26, the cover 27, and the like are all types of peripheral parts of the tube 9 in the boom telescopic cylinder 6.
Therefore, in this embodiment, the lower end portion of the maximum outer shape of the axial cross section in the tube 9 and its peripheral parts is the lower end portion of the outer peripheral surface of the roller 24, and the axial direction in the tube 9 and its peripheral parts. The upper end portion of the maximum outer shape of the cross section is the upper surface of the upper surface guide plate 26.
Further, the left and right ends of the maximum outer shape of the axial cross section of the tube 9 and its peripheral parts are the outer end surfaces of the sheaves 11 on the left and right sides and the outer end portions of the cover 27.

More specifically, the protruding piece 21 fixed to the end of the tube 9 on the protruding side opposite to the piston rod is, as shown in FIG.
It consists of left and right inclined portions 20b and 20b obtained by obliquely cutting the periphery of the left and right ends of the front edge portion 20a of the metal plate cut out in a rectangular shape, and the left and right edges of the remaining portion that is avoided from cutting. Side portions 20c, 20c, a rear edge portion 20d parallel to the front edge portion 20a, a plate-like member 20 formed with the front edge portion 20a as an outer contour,
A strip-like metal having the same width as the plate-like member 20 and having one side thereof aligned with the rear edge portion 20d of the plate-like member 20 and being integrally fixed to the upper and lower surfaces of the plate-like member 20 by welding or the like. Reinforcing members 31, 31 made of plates;
A metal band fixed integrally to the inclined portion 20b and the side portion 20c by welding or the like so as to cover the inclined portion 20b and the portion of the side portion 20c communicating with the inclined portion 20b of the outer contour of the plate-like member 20 from the outer periphery. Side sliding members 32, 32 comprising:
The upper and lower reinforcement members 31, 31 sandwiching the plate-like member 20, the rear edge portions thereof, and the left and right end portions of the rear edge portion 20 d of the plate-like member 20 are surrounded by the front of the upper and lower reinforcement members 31, 31. The ends of the taper surfaces 33a, 33a formed by bending the surplus portion protruding forward from the edge toward the plate member 20 at an obtuse angle are integrally fixed to the front and back of the plate member 20 by welding or the like. The other parts are integrally formed by upper and lower sliding contact members 33, 33 made of metal bands that are integrally fixed to the upper and lower surfaces of the reinforcing members 31, 31 and the rear edge portion 20d of the plate-like member 20 by welding or the like. Composed.

The purpose of such a complicated structure is to reduce the weight of the protruding piece 21 that protrudes forward with a large distance from the pin 8 pivotally attached to the tip of the piston rod 7 when the boom telescopic cylinder 6 is extended. In addition, the main purpose is to effectively use the output of the boom lifting cylinder that holds the boom 1 in the raised state and to reduce the material cost in the manufacturing process of the boom breakage prevention device 19.
Therefore, in a situation where there is no problem of weight, material cost, etc., for example, an iron plate having a thickness equivalent to the maximum thickness portion of the entire protruding piece 21 including the reinforcing members 31, 31 and the upper and lower sliding contact members 33 is used as a mother plate. The left and right side portions of the base material are left as portions corresponding to the upper and lower surface sliding contact members 33 and 33, and the other portion corresponding to the plate member 20 is cut to a thickness equivalent to the vertical height of the side surface sliding contact member 32. It is also possible to take out a completely integrated part and use the machined part as the protruding piece 21.

  The total thickness of the projecting piece 21 including the plate member 20 and the upper and lower reinforcing members 31, 31 and the thickness of the upper and lower surface sliding contact members 33 that overlap with each other at the upper and lower intervals is the vertical height of the side sliding contact members 32, 32. Therefore, in this embodiment, the thickness of the protruding piece 21 is the sum of the thicknesses of the plate-like member 20, the upper and lower reinforcing members 31, 31 and the upper and lower surface sliding contact members 33 overlapping the upper and lower surfaces. .

  Further, the lower surface side taper surfaces 33a, 33a formed by the surplus portions of the upper and lower surface sliding contact members 33, 33 protruding forward from the front edge of the lower surface side reinforcing member 31 are formed on the projecting piece 21 side guide portion 34, 34 functions.

On the other hand, the protruding piece receiving portions 22 fixed to the left and right wall portions inside the distal end portion of the distal end side boom component 5 are more specifically, as shown in FIG. The rectangular reinforcing plate 35 that is integrally fixed to the left and right wall portions by welding or the like, and the interval that matches the thickness of the protruding piece 21 is vertically fixed to the reinforcing plate 35 by welding or the like. The upper support member 29 and the lower support member 30 are formed.
The upper support member 29 is formed by bending a strip-shaped metal plate upward at one end portion in the longitudinal direction, and the main body portion 29a is parallel to the bottom surface and the top surface of the distal end side boom component 5. The bent portion 29b at the end is bent in a direction approaching the top surface of the distal boom component 5. At the other end and the bent portion of the upper support member 29, right-angled triangular metal ribs are erected, and the upper support member 29 is firmly fixed on the reinforcing plate 35 via these ribs. .
The lower support member 30 is formed by bending a strip-shaped metal plate downward at one end portion in the longitudinal direction, and the main body portion 30a is parallel to the bottom surface and the top surface of the distal end side boom component 5. The bent portion 30 b at the end is bent in a direction approaching the bottom surface of the distal end boom component 5. Similarly to the upper support member 29, metal ribs having a right triangle shape are formed on the other end and the bent portion of the lower support member 30, respectively, and the lower support member 30 is mounted on the reinforcing plate 35 via these ribs. It is firmly fixed to.

  That is, the main body portion 29 a of the upper support member 29 and the main body portion 30 a of the lower support member 30 are parallel to each other, and the vertical interval between the upper support member 29 and the lower support member 30 is the main body of the upper support member 29. The distance between the lower surface of the portion 29 a and the upper surface of the main body portion 30 a of the lower support member 30 is determined as a reference.

  Tapered surfaces formed by the bent portions 30b and 30b of the lower support members 30 and 30 function as guide portions 36 and 36 on the protruding piece receiving portion 22 side.

And the horizontal width of the protrusion piece 21 mentioned above, ie, the total width of the protrusion piece 21 which combined the thickness of the side-sliding contact members 32 and 32 which overlap with the horizontal width of the plate-shaped member 20 or the reinforcing members 31 and 31, is the tip. The plate-like member 20 and the reinforcing member 31, so as to be equal to the separation distance between the surfaces of the rectangular reinforcing plates 35 and 35 integrally fixed to the left and right wall portions of the side boom component 5 by welding or the like. The width of 31 and the thickness of the side-sliding contact members 32, 32 are determined.
That is, the lateral width of the entire protruding piece 21 is equal to the distance between the surfaces of the rectangular reinforcing plates 35 and 35 fixed to the left and right wall portions of the distal boom component 5, and the distal boom configuration. Compared to the separation distance between the left and right wall portions inside the tip portion of the element 5, the distance is slightly shorter, for example, by an amount corresponding to the thickness of the two reinforcing plates 35. This dimensional difference functions as a clearance for allowing the protruding piece 21 to relatively move in the longitudinal direction along the inner wall of the distal boom component 5.

  In this embodiment, as shown in FIGS. 3A, 3B, and 4, the boom telescopic cylinder 6 and the boom 1 are in the most contracted state during storage, and the end of the tube 9 on the piston rod projecting side is set. When the projecting piece 21 located in the part enters between the upper support member 29 and the lower support member 30 constituting the projecting piece receiving part 22, the upper and lower surface sliding contact members 33 located on the lower surface side of the projecting piece 21 are The upper and lower surface sliding contact members 33 which are supported from the lower side by the upper surface of the main body portion 30a of the lower support member 30 in close contact with the lower surface and located on the upper surface side of the protruding piece 21 are in close contact with the upper surface. The lower end portion of the outer peripheral surface of the roller 24 that is supported from above by the lower surface of the main body portion 29a of the support member 29 and that is the lower end portion of the maximum outer shape of the axial cross section of the tube 9 and its peripheral parts is the tip side boom configuration. The upper surface of the upper surface guide plate 26 which is spaced apart from the bottom surface of the element 5 and has a certain clearance between them and which is the upper end portion of the maximum outer shape of the axial cross section of the tube 9 and its peripheral parts is the tip side boom configuration. The mounting positions of the protruding piece receiving portions 22 and 22 on the left and right wall portions of the tip-side boom component 5 are determined so as to ensure a certain clearance between the elements 5 away from the top surface.

  Next, the overall operation and function of the boom breakage prevention device 19 in this embodiment will be specifically described.

  When moving the crane vehicle mounted with the boom 1, first, the boom telescopic cylinder 6 in the extended state is gradually reduced, and the boom component 3 adjacent to the base side boom component 2 is changed to the distal boom component 5. The boom components 3, 4, and 5 that reach the base are pulled toward the base-side boom component 2 side. The specific reduction operation of the boom 1 has already been described in paragraph 0021.

At this time, all of the boom components 3, 4 and 5 from the tube 9 of the boom telescopic cylinder 6 and the boom component 3 to the distal boom component 5 start to shrink simultaneously, and the base of the base boom component 2 However, as already described, the absolute movement speed of the boom component 5 on the distal end side is faster than the absolute movement speed of the tube 9 of the boom telescopic cylinder 6.
Accordingly, the tip end portion of the tip end boom component 5 gradually approaches the end portion of the tube 9 on the side opposite to the piston rod protruding so as to follow the tube 9 of the boom telescopic cylinder 6.

In the contraction process of the boom telescopic cylinder 6 and the boom components 3, 4, and 5, the tube 9 of the boom telescopic cylinder 6 and the lower end portion of the maximum outer shape of the axial cross section in the peripheral parts of the tube 9, more specifically, the tube 9 The lower end portion of the outer peripheral surface of the roller 24 provided on the lower surface of the end portion on the anti-piston rod projecting side is in turn contacted with the bottom surface of the boom components 3, 4 and 5 to Support the department.
Further, when vibration in the vertical direction occurs for some reason, the upper surface guide plate 26 provided on the upper surface of the end of the tube 9 on the side opposite to the piston rod protruding from the vibration is provided with the boom component 3, It abuts against the top surfaces of 4 and 5 to prevent damage to other peripheral parts such as the sheave 11 and the cover 27.
Further, when the vibration is accompanied by a lateral component, the side sliding members 32, 32 provided on the left and right sides of the protruding piece 21 provided at the tip of the tube 9 on the protruding side opposite to the piston rod. However, it contacts the left and right side walls of the boom components 3, 4 and 5 to prevent damage to other peripheral parts such as the sheave 11 and the cover 27.
In this contraction process, as the boom components 3, 4 and 5 are drawn, the object to which the side sliding contact members 32 and 32 abut changes from the outer boom component 3 to the boom component 4 and the boom component 5. In each case, the distance between the left and right side walls decreases, resulting in a step, but the side sliding members 32, 32 are inclined along the inclined portions 20b, 20b of the plate-like member 20, that is, as they go to the tip side. Since the slopes approaching each other are formed, even if the side sliding members 32, 32 are in contact with the left and right side walls of the boom components 3, 4, 5, the side sliding members 32, 32 and the boom Inadvertent catching does not occur between the components 3, 4 and 5. A similar target inclined surface is also formed at the tip of the upper surface guide plate 26.
As is clear from FIG. 3B, FIG. 5A, etc., the side sliding members 32, 32 protrude rearward slightly beyond the rear edge portion 20d of the plate-like member 20, and this protruding portion is A slope that is slightly bent inward is formed, but when the boom components 3, 4 and 5 are extended, the distance between the left and right side walls increases, and the side sliding members 32 and 32 and the boom configuration There is no need to take a long span of the slope because there is no catching with the base side end of the elements 3, 4, 5. A similar inclined surface is also formed at the rear end portion of the upper surface guide plate 26.

When the boom retracting operation of the boom telescopic cylinder 6 and the boom 1 reaches the start stage of the most contracting process, the distal end of the distal boom component 5 is placed on the projecting piece 21 provided at the end of the tube 9 on the projecting side opposite to the piston rod. A taper surface formed by a bent portion 30b that functions as a guide portion 36 of the lower support member 30 that constitutes a part of the projecting piece receiving portion 22, and a projecting piece; The protruding piece 21 and the protruding piece receiving portion 22 are in sliding contact with each other via a taper surface 33a formed by an excess portion of the upper and lower surface sliding contact member 33 that functions as the guide portion 34 on the 21 side.
Next, the boom telescopic cylinder 6 and the boom 1 are further reduced, and the protruding piece receiving portion 22 of the distal boom component 5 is further provided on the protruding piece 21 provided at the end of the tube 9 on the protruding side of the anti-piston rod. When approaching, the intrusion of the protruding piece 21 between the upper supporting member 29 and the lower supporting member 30 constituting the protruding piece receiving portion 22 is a bent portion 30b of the lower supporting member 30 that functions as the guide portion 36 of the lower supporting member 30. And the taper surface of the upper and lower surface sliding contact member 33 functioning as the guide portion 34 on the protruding piece 21 side, and the sliding contact action between the guide portion 36 and the guide portion 34, that is, positive If an article placed on a slope with a slope is pushed horizontally from the rear, or if the article is moved horizontally while the horizontal movement of the article is suppressed, the article moves along the slope. According working principle such raised Chi lifted slightly above by the end of the opposite piston rod protruding side of the tube 9 against the force of gravity.

Finally, when the most contracting process of the boom telescopic cylinder 6 and the boom 1 is completed, the upper and lower surfaces located on the lower surface side of the protruding piece 21 as shown in FIGS. The sliding contact member 33 is supported from the lower side by the upper surface of the main body portion 30a of the lower support member 30 in close contact with the lower surface thereof, and the upper and lower surface sliding contact members 33 positioned on the upper surface side of the protruding piece 21 are The lower end portion of the outer peripheral surface of the roller 24 which is supported from the upper side by the lower surface of the main body portion 29a of the upper support member 29 which is in close contact with the upper surface and which is the lower end portion of the tube 9 and its peripheral parts with the maximum outer shape in the axial section Is separated from the bottom surface of the distal end side boom component 5 so that a certain clearance is formed between them, and the upper surface guide which is the upper end portion of the maximum outer shape of the axial cross section of the tube 9 and its peripheral parts. The upper surface of the de plate 26 in a state where a predetermined clearance is guaranteed between them apart from the top surface of the distal boom component 5.
Further, in this embodiment, the entire lateral width of the protruding piece 21 is spaced between the surfaces of the rectangular reinforcing plates 35 and 35 that are integrally fixed to the left and right wall portions of the distal boom component 5 by welding or the like. Since the length is equal to the distance, the projecting piece 21 is constrained in close contact with the left and right directions at the time when the boom retracting cylinder 6 and the boom 1 are fully contracted. Become.
When the protruding piece 21 enters the protruding piece receiving portion 22, the left and right side portions of the protruding piece 21 must get over the convex portions formed on the inner wall of the distal boom component 5 by the reinforcing plates 35, 35. The left and right tip portions of the projecting piece 21 are formed with inclined portions 20b, 20b that reduce the lateral width of the projecting piece 21 toward the front edge of the projecting piece 21, so that the projecting piece 21 is a reinforcing plate 35, It is easy to get over the 35 convex portions, and side sliding members 32, 32 having a certain vertical height are provided on the inclined portions 20b, 20b and the side portions 20c, 20c communicating therewith. Therefore, problems such as inadvertent galling or shaving on the surfaces of the reinforcing plates 35 and 35 and the left and right wall portions of the distal boom component 5 do not occur.

When moving the crane vehicle, the boom 1 that has been reduced to the minimum is horizontally stored and the crane vehicle is operated. At this stage, the tube 9 and its peripheral parts such as the roller 24 and the sheave are already operated. 11 and the like are separated from the bottom surface of the front end boom component 5, and the clearance between the upper surface of the upper surface guide plate 26 and the top surface of the front end boom component 5 is also guaranteed. ing.
The end of the tube 9 in the boom telescopic cylinder 6 on the side opposite to the piston rod projecting side is located on the distal end side via the projecting piece 21 and the projecting piece receiving part 22 that supports the projecting piece 21 in close contact with the upper and lower surfaces of the projecting piece 21. Since it is being fixed inside the front-end | tip part of the boom component 5, the tube 9 of the boom expansion-contraction cylinder 6 and its lower end part and upper end part do not shake up and down by the vibration at the time of driving | running | working, These members Therefore, there is no fear that the bottom surface or the top surface of the tip side boom component 5 can be hit.
Moreover, since there is almost no vertical clearance between the protruding piece receiving portion 22 and the protruding piece 21, the protruding piece receiving portion 22 and the protruding piece 21 do not collide with each other, and the boom telescopic cylinder The problem that the impact force generated by the rattling of 6 adversely affects the boom telescopic cylinder 6 and its peripheral parts is also solved.
In particular, in this embodiment, the entire lateral width of the protruding piece 21 is equal to the distance between the surfaces of the reinforcing plates 35 and 35 fixed to the left and right wall portions of the distal end boom component 5. Since the end of the tube 9 on the side opposite to the piston rod protruding side is also fixed in the left-right direction, the tube 9 of the boom telescopic cylinder 6 and its peripheral parts may swing in the left-right direction due to vibration during travel. The left and right ends of the tube 9 of the boom telescopic cylinder 6 and its peripheral parts, for example, the outer end surface of the left and right sheaves 11 and the outer end of the cover 27 are left and right of the distal boom component 5 due to vibration during travel. The problem of hitting the side wall is also eliminated.
Note that, in the situation where the reinforcing plates 35 are not installed, the range of lateral deflection of the end of the tube 9 in the boom telescopic cylinder 6 on the side opposite to the piston rod projecting side is such that the projecting piece 21 is the tip side boom component 5. Although it is only limited to the range of clearance required to allow relative movement in the longitudinal direction along the inner wall of the tube 9, even in that case, the anti-piston rod protruding side of the tube 9 It is possible to alleviate the disadvantage that the end portion swings to the left and right and strikes the left and right wall portions of the distal boom component 5.

Here, as one embodiment, a horizontal protruding piece made of a plate-like member is provided at the tip of the end of the tube 9 on the anti-piston rod protruding side of the boom telescopic cylinder 6 so that the left and right inside the tip of the tip side boom component 5 are left and right. Although the example which provided the protrusion piece receiving part which consists of a pair of upper and lower support members in the wall part of the tube was described, the protrusion piece receiving part which consists of a pair of upper and lower support members on the left and right of the end part on the anti-piston rod protrusion side of the tube 9 was described. The effect equivalent to the above can also be achieved by providing and horizontally providing a protruding piece made of a plate-like member through an appropriate stay inside the distal end portion of the distal boom component 5.
Moreover, it is good also as a structure which provided the guide part only in any one of the protrusion piece or the protrusion piece receiving part.

  [Second Embodiment]

FIG. 6 is a side cross-sectional view showing a boom breakage prevention device 37 according to another embodiment to which the present invention is applied mounted on the boom 1. In order to avoid complication of the drawings, description of the sheaves 12, 13, 14, 15 and the wires 16, 17, 18 is omitted.
FIG. 7 is a diagram showing the configuration of the boom breakage prevention device 37. FIG. 7A is a front view showing the boom breakage prevention device 37 from the tip side of the boom 1, and FIG. It is the side view which showed the periphery of the edge part by the side of the anti-piston rod protrusion of the tube 9 in the boom expansion-contraction cylinder 6 including the damage prevention apparatus 37. FIG.

  As shown in FIGS. 6 and 7A and 7B, the boom breakage prevention device 37 of this embodiment has a boom at the center of the tip of the end of the tube 9 on the anti-piston rod protruding side of the boom telescopic cylinder 6. A projecting piece made up of a rod member 38 projecting along the direction of expansion / contraction of the telescopic cylinder 6, an inner diameter comparable to the outer diameter of the rod member 38, and the tip side boom component 5 via the stays 39, 39. It is comprised by the protrusion piece receiving part which consists of the annular member 40 installed in the front-end | tip part inner side.

  The configurations and functions of the stay 23, the roller 24, the stay 25, the upper surface guide plate 26, and the like are the same as those of the boom breakage prevention device 19 in the first embodiment described above.

  As shown in FIG. 7B, the rod member 38 constituting the protruding piece is a columnar member having a conical tapered surface 38a at the tip. The lower half of the conical tapered surface 38a of the rod member 38 constituting the protruding piece functions as a guide portion on the rod member 38 side, that is, the protruding piece side.

  Further, as shown in FIG. 7A, the annular member 40 constituting the protruding piece receiving portion is a circular annular member having an inner diameter comparable to the outer diameter of the cylindrical portion in the protruding piece made of the rod member 38. The inner diameter is slightly larger than the outer diameter of the cylindrical portion of the rod member 38 serving as a protruding piece. This difference in diameter corresponds to a so-called intermediate fit or a kind of loose fit, and the rod member 38 can easily enter and leave the annular member 40 and is fitted to the annular member 40. This is the level that does not cause rattling.

  As shown in FIGS. 6 and 7B, the stays 39, 39 are positioned below the left and right wall portions inside the distal end portion of the distal boom component 5 with an interval in the telescopic direction of the boom telescopic cylinder 6. The bottom is integrally fixed by welding or the like. Then, as shown in FIG. 7 (a), the annular member 40 fitted into the semicircular cutout formed at the upper end of the stays 39, 39, that is, the protruding piece receiving portion, 39 is integrally fixed.

In this embodiment, as shown in FIG. 6 and FIG. 7B, the rod member that is located at the end of the tube 9 on the piston rod protruding side with the boom telescopic cylinder 6 and the boom 1 in the most contracted state during storage. When the cylindrical portion of the projecting piece made of 38 enters the hole of the annular member 40 that functions as the projecting piece receiving portion, the lower surface of the cylindrical portion of the rod member 38 is located on the lower side by the lower inner peripheral surface of the hole of the annular member 40. And the upper surface of the cylindrical portion of the rod member 38 is closely supported from above by the upper inner peripheral surface of the hole of the annular member 40, and the tube 9 of the boom telescopic cylinder 6 and its surroundings The lower end portion of the outer peripheral surface of the roller 24, which is the lower end portion of the maximum outer shape of the axial cross section of the part, is separated from the bottom surface of the tip side boom component 5, and a certain clearance is formed between them. In addition, the upper surface of the upper surface guide plate 26 which is the upper end portion of the maximum outer shape of the axial cross section in the tube 9 and its peripheral parts is separated from the top surface of the distal end boom component 5 so that a certain clearance is guaranteed between them. Thus, the attachment position of the up-down direction of the annular member 40 with respect to the front end side boom component 5 is determined.
Further, when the cylindrical portion of the rod member 38 enters the hole of the annular member 40, the left side surface of the cylindrical portion of the rod member 38 is closely supported from the left side by the left inner peripheral surface of the hole of the annular member 40, and The right side surface of the cylindrical part of the rod member 38 is supported in close contact with the right inner peripheral surface of the hole of the annular member 40 from the right side, and the maximum outer shape of the axial section of the tube 9 of the boom telescopic cylinder 6 and its peripheral parts The front end boom component 5 is formed such that the outer end surfaces of the left and right sheaves 11 that are the left and right end portions of the front end are separated from the left and right side walls of the front end boom component 5 and a certain clearance is formed therebetween. The mounting position in the left-right direction of the annular member 40 is determined.

In this embodiment, when the vibration in the left and right direction is generated for some reason in the expansion and contraction process of the boom telescopic cylinder 6 and the boom components 3, 4, and 5, the axial cross section in the tube 9 and the peripheral parts of the tube 9 is provided. The sheaves 11 positioned on the left and right ends of the maximum outer shape, more specifically on the left and right sides of the end of the tube 9 on the side opposite to the piston rod, are opposed to the left and right side walls of the boom components 3, 4, 5. For the purpose of preventing contact and damage, support members 41 are provided to project from the left and right sides of the end portion of the tube 9 on the piston rod protruding side.
As shown in FIGS. 7A and 7B, the support member 41 is a metal plate 42 having substantially the same shape as the plate-like member 20 described above, that is, the lateral width of the metal plate 42 decreases toward the front edge. The metal plate 42 having the inclined portions on both the left and right sides and the side portions parallel to the left and right sides, and the inclined portions and the side portions formed on the left and right sides of the metal plate 42 are continuously covered from the outside. In order to avoid interference with the rod member 38 that functions as the protruding piece and the annular member 40 that functions as the protruding piece receiving portion, the mounting position of the rod member 38 is constituted by the side-sliding contact member 43 made of the fixed metal band. The tube 9 is offset horizontally upward and is fixed horizontally to the tip of the end of the tube 9 on the protruding side of the piston rod.
As shown in FIG. 7A, the lateral width of the support member 41 is slightly shorter than the distance between the left and right wall portions of the distal end boom component 5. This is because a clearance is required when the support member 41 relatively moves in the longitudinal direction along the inner wall of the distal boom component 5.

  Next, the overall operation and function of the boom breakage prevention device 37 in this embodiment will be briefly described.

  The boom telescopic cylinder 6 in the extended state is gradually reduced, and each boom component 3, 4, 5 from the boom component 3 adjacent to the base boom component 2 to the distal boom component 5 is configured as a base boom configuration. As it is drawn toward the element 2 side, the distal end portion of the distal boom component 5 gradually follows the tube 9 of the boom telescopic cylinder 6 and gradually approaches the end of the tube 9 on the non-piston rod protruding side. .

And, in the contraction process of the boom telescopic cylinder 6 and the boom components 3, 4 and 5, the lower end portion of the maximum outer shape of the axial cross section in the tube 9 and the peripheral parts of the tube 9 of the boom telescopic cylinder 6, more specifically, The lower end portion of the outer peripheral surface of the roller 24 provided on the lower surface of the end of the tube 9 on the side opposite to the piston rod projecting is in contact with the bottom surfaces of the boom components 3, 4, 5 in order. Support a part of.
Further, when vibration in the vertical direction occurs for some reason, the upper surface guide plate 26 provided on the upper surface of the end of the tube 9 on the side opposite to the piston rod protruding from the vibration is provided with the boom component 3, It abuts on the top surfaces of 4 and 5 to prevent damage to other peripheral parts such as the sheave 11.
Further, when the vibration is accompanied by a lateral component, the side sliding members 43, 43 provided on the left and right sides of the support member 41 provided at the tip of the end of the tube 9 on the side opposite to the piston rod projecting side are provided. However, it contacts the left and right side walls of the boom components 3, 4, 5 and prevents other peripheral parts such as the sheave 11 from being damaged.

When the boom telescopic cylinder 6 and the boom 1 are contracted to reach the start stage of the most contracted process, the tip side boom structure is formed on the projecting piece formed of the rod member 38 provided at the end of the tube 9 on the anti-piston rod projecting side. An annular member 40 that is a protruding piece receiving portion provided inside the tip of the element 5 approaches, and the lower half of the conical tapered surface 38a that functions as a guide portion on the rod member 38 side, that is, the protruding piece side, and the protruding piece receiving portion. The rod member 38 and the annular member 40 are in sliding contact with each other through the lower inner peripheral surface of the hole of the annular member 40 constituting a part of the portion.
Then, the boom retracting cylinder 6 and the boom 1 are further reduced, and the annular member 40 on the distal boom element 5 side further approaches the rod member 38 provided at the end of the tube 9 on the non-piston rod protruding side. Then, the penetration of the rod member 38 into the hole of the annular member 40 that functions as the protruding piece receiving portion is guided by the lower half of the conical tapered surface 38a that functions as the guiding portion on the protruding piece side, and the tapered surface 38a. The end of the tube 9 on the protruding side of the anti-piston rod is lifted slightly against gravity by the sliding action of the lower half of the tube and the lower inner peripheral surface of the hole of the annular member 40.
Further, at this time, if the position of the rod member 38 that is the protruding piece is shifted to either the left or right within the clearance range between the support member 41 and the inner wall of the distal end side boom component 5, The rod member 38 penetrates into the hole of the annular member 40 functioning as a protruding piece receiving portion, and is guided by the left and right side surfaces of the conical tapered surface 38a of the rod member 38 functioning as the protruding piece. The left and right side surfaces of the part are guided to a position where the left and right inner peripheral surfaces of the annular member 40 are in sliding contact, that is, a position where the central axis of the rod member 38 coincides with the central axis of the hole of the annular member 40.

  And finally, when the boom telescopic cylinder 6 and the boom 1 are fully contracted, as shown in FIGS. 7A and 7B, the lower surface of the cylindrical portion of the rod member 38 functioning as a protruding piece is formed. The cylindrical member of the rod member 38 is supported in close contact with the lower inner peripheral surface of the hole of the annular member 40 functioning as a projecting piece receiving portion, and the upper inner peripheral surface of the hole of the annular member 40 The lower end portion of the outer peripheral surface of the roller 24, which is the lower end portion of the maximum outer shape of the axial section of the tube 9 of the boom telescopic cylinder 6 and its peripheral parts, is supported in close contact from above. The upper surface of the upper surface guide plate 26, which is the upper end portion of the maximum outer shape of the axial cross section of the tube 9 and its peripheral parts, is formed at a distance from the bottom surface so that a certain clearance is formed between them. The left side surface of the cylindrical portion of the rod member 38 functioning as a protruding piece is separated from the top surface of the side boom component 5 by the left inner peripheral surface of the hole of the annular member 40. The cylinder 9 of the rod member 38 is supported in close contact from the left side, and the right side surface of the cylindrical portion of the rod member 38 is supported in close contact from the right side by the right inner peripheral surface of the hole of the annular member 40. The outer end surfaces of the left and right sheaves 11 that are the left and right ends of the maximum outer shape of the axial cross section of the peripheral part are separated from the left and right side walls of the distal boom component 5, and a certain clearance is formed between them. It becomes a state.

When moving the crane vehicle, the boom 1 that has been reduced to the minimum is horizontally stored and the crane vehicle is operated. At this stage, the tube 9 and its peripheral parts such as the roller 24 and the sheave are already operated. 11 and the like are separated from the bottom surface of the tip boom component 5, the clearance between the upper surface of the upper guide plate 26 and the top surface of the tip boom component 5, and the boom telescopic cylinder 6. The clearance between the outer end surfaces of the left and right sheaves 11 which are the left and right ends of the maximum outer shape of the axial section of the tube 9 and its peripheral parts and the left and right side walls of the tip boom component 5 is also guaranteed. It is in a state.
The end of the tube 9 in the boom telescopic cylinder 6 on the protruding side of the anti-piston rod is in close contact with the cylindrical portion of the rod member 38 that functions as a protruding piece and supports the rod member 38 in the vertical and horizontal directions. Is fixed to the inside of the tip of the tip boom component 5 via the annular member 40, so that the tube 9 of the boom telescopic cylinder 6 and the lower and upper ends of its peripheral parts move up and down due to vibration during travel. There is no possibility that the bottom surface, the top surface, or the left and right side walls of the front-end boom component 5 will be struck by these members.
Moreover, since there is almost no substantial vertical and horizontal clearance between the cylindrical portion of the rod member 38 that functions as a protruding piece and the inner peripheral surface of the annular member 40 that functions as a protruding piece receiving portion, the protruding piece receiver Therefore, the problem that the impact force generated by the rattling of the boom telescopic cylinder 6 adversely affects the boom telescopic cylinder 6 and its peripheral parts is solved.

Here, as an embodiment, a protruding piece made of a rod member is provided at the tip of the end of the tube 9 in the boom telescopic cylinder 6 on the side opposite to the piston rod, and an annular member is formed inside the tip of the tip side boom component 5. Although the example which provided the protrusion piece receiving part was described, the protrusion piece receiving part which consists of a cyclic | annular member was provided in the front-end | tip of the anti-piston rod protrusion side of the tube 9, and it was suitable for the inner side of the front-end | tip part of the front end side boom component 5 An effect equivalent to that described above can also be achieved by providing a projecting piece made of a rod member via a simple stay.
Moreover, it is good also as a structure which provided the guide part in only the protrusion piece receiving part which consists of an annular member, or both the protrusion piece which consists of a rod member, and the protrusion piece reception part which consists of an annular member. When providing a guide part in the protrusion piece receiving part which consists of an annular member, the shape is made into the taper hole which the side which faces a protrusion piece expands gradually.

[Other configuration examples]

A part or all of the embodiment disclosed above can be appropriately expressed by the description shown in [Appendix] to be described later, but the form for carrying out the invention and the technical idea of the invention are limited to these. It is not a thing.
For example, the stay 23, the roller 24, the stay 25, and the upper surface guide plate 26 in the first and second embodiments are omitted, and a pair of rollers that support the load of the boom telescopic cylinder 6 is used instead of the roller 24 in the boom telescopic cylinder 6. These rollers are provided so as to protrude on both the left and right sides of the end portion of the tube 9 on the side opposite to the piston rod (may be coaxial with the sheave 11), and these rollers extend over the entire length of the left and right side walls of the tip-side boom component 5. The guide groove having a width slightly larger than the diameter of the boom is formed, and the left and right rollers are loosely fitted in the guide groove so as not to prevent the rolling of the guide groove. The position of the end of the anti-piston rod protruding side at the time is restricted, and the guide groove is formed near the tip of the tip boom component 5 at the tip boom assembly. It is also possible to adopt a configuration in which the width of the guide groove is made to coincide with the diameters of the left and right rollers only at the distal end portion of the distal boom component 5 after being slightly bent or refracted toward the top surface side of the element 5. Is possible.
When such a configuration is applied, the rollers provided to project to the left and right of the end on the anti-piston rod projecting side function as “a projecting piece having a shape that can be supported at least in the vertical direction”, and The portion of the guide groove located at the distal end portion of the distal boom component 5 functions as a “projection piece receiving portion that supports the projection piece in close contact with at least the upper and lower surfaces”. The portion of the guide groove slightly bent or refracted toward the top surface side of the tip boom component 5 in the vicinity of the tip is “the boom telescopic cylinder 6 and the boom 1 are projected to the protruding piece receiving portion in the most contraction process”. It functions as a “guide section provided with a tapered surface that guides the intrusion of the protruding piece and lifts the end of the tube 9 on the protruding side of the anti-piston rod against gravity.

[Appendix 1]
Boom (1) in which three or more stages of boom constituent elements (2, 3, 4, 5) from the base side boom constituent element (2) to the distal end boom constituent element (5) are inserted in a nested manner in order. The boom component (3) adjacent to the base-side boom component (2) while pivoting the tip of the piston rod (7) of the boom telescopic cylinder (6) to the base of the base-side boom component (2) The end of the tube (9) on the side of the piston rod protruding from the boom telescopic cylinder (6) is pivotally attached to the base of the boom, and the boom configuration adjacent to the base boom component (2) by the expansion and contraction of the boom telescopic cylinder (6). The element (3) is moved relative to the base boom component (2) in the telescopic direction of the boom telescopic cylinder (7). Different boom components (2,3) via sheaves (11,12,13,14,15) pivotably mounted on each of the longitudinal ends of (2,3,4,5). , 4, 5) and the boom component adjacent to the base-side boom component (2) due to the interaction of the boom extension wires (16, 18) and the boom contraction wires (17, 18) with the relative movement. Prevention of breakage of a boom of a crane vehicle having a boom (1) in which each boom component (3, 4, 5]) from (3) to the distal boom component (5) is relatively moved in the telescopic direction. In the device
A protruding piece (21) having a shape that can be supported at least in the vertical direction on either the end of the tube (9) on the side opposite to the piston rod protruding side or the inner side of the distal end of the tip boom component (5). And providing
On the other hand, a projecting piece receiver that supports the projecting piece (21) in close contact with at least the upper and lower surfaces (33, 33) of the projecting piece (21) when the boom telescopic cylinder (6) and the boom (1) are in the most contracted state. The bottom end portion (22) of the tube (9) and its peripheral parts (23, 24, 25, 26, 27) are the bottom end portion (24) and the top end portion (26) of the maximum outer shape in the axial direction. Provided at a position to support the element (5) separately from the bottom and top surfaces,
At least one of the projecting piece (21) and the projecting piece receiving part (22) includes a projecting piece (22) that projects into the projecting piece receiving part (22) in the most contraction process of the boom telescopic cylinder (6) and the boom (1). 21) A crane vehicle provided with a guide portion (34, 36) having a tapered surface that guides the intrusion of 21) and lifts the end of the tube (9) on the protruding side opposite to the piston rod against gravity. Boom breakage prevention device (19).

[Appendix 2]
The protruding piece (21) is constituted by a plate-like member (20) horizontally fixed to the end of the tube (9) on the side opposite to the piston rod protruding side,
The protruding piece receiving part (22) is a pair of upper and lower parts fixed to the left and right wall parts inside the distal end part of the distal boom component (5) with an interval comparable to the thickness of the protruding piece (21) in the vertical direction. Constituted by support members (29, 30),
The crane vehicle according to appendix 1, characterized in that the lateral width of the projecting piece (21) is formed slightly shorter than the distance between the left and right wall portions inside the distal end portion of the distal boom component (5). Boom breakage prevention device (19).

[Appendix 3]
The pair of upper and lower support members (29, 30) is provided on the inner side of the distal end portion of the distal boom component (5) through a rectangular reinforcing plate (35) to which the support members (29, 30) are fixed vertically. Fixed to the left and right walls,
The lateral width of the projecting piece (21) is formed to be equal to the distance between the reinforcing plates (35, 35) fixed to the left and right wall portions inside the distal end portion of the distal end boom component (5). The boom breakage prevention device (19) for a crane truck according to appendix 2, characterized in that:
Thereby, the effect described in the fourth stage in the paragraph 0044, that is, the tube (9) of the boom telescopic cylinder (6) and its peripheral parts are prevented from shaking in the left-right direction due to vibration during traveling, and the tube (9) and There is an effect that the problem that the left and right end portions of the peripheral parts hit the left and right side walls of the tip-end boom component (5) due to vibration during traveling is eliminated.

[Appendix 4]
The left and right sides of the protruding piece (21) are formed with inclined portions (20b, 20b) that reduce the lateral width of the protruding piece (21) toward the front edge of the protruding piece (21). The boom breakage prevention device (19) for a crane truck according to Supplementary Note 2 or Supplementary Note 3.
As a result, the effect described in the fourth step in paragraph 0041, that is, the side surface sliding contact members (32, 32) are inclined along the inclined portions (20b, 20b) of the plate-like member (20), that is, on the tip side. As the slopes that are closer to each other are formed, the side-sliding contact is made even when the side-sliding contact members (32, 32) are in contact with the left and right side walls of the boom components (3,4, 5). The effect that inadvertent catching does not occur between the members (32, 32) and the boom components (3, 4, 5) and the effect described in the third stage in the paragraph 0043, that is, the protruding piece (21) There is an effect that it becomes easy to get over the convex portion of the reinforcing plate (35).

[Appendix 5]
The projecting piece is constituted by a rod member (38) projecting along the expansion / contraction direction at the center of the end of the tube (9) on the side opposite to the piston rod projecting side,
The protruding piece receiving portion has an inner diameter comparable to the outer diameter of the rod member (38), and is an annular member installed inside the distal end portion of the distal boom component (5) via the stay (39, 39). (40) A boom breakage prevention device (37) for a crane truck as set forth in appendix 1, wherein
As a result, the effects described in the second and third stages in paragraph 0060, that is, the end of the tube (9) on the side opposite to the piston rod protruding from the boom telescopic cylinder (6) is a rod member (38) that functions as a protruding piece. ) Is fixed to the inside of the distal end portion of the distal boom component (5) via an annular member (40) which is a protruding piece receiving portion that supports the rod member (38) in the vertical and lateral directions in close contact with the cylindrical portion of Therefore, the lower end and the upper end of the tube (9) of the boom telescopic cylinder (6) and its peripheral parts do not swing up and down or left and right due to vibration during traveling, and these members make the tip side boom component (5) The effect that the bottom surface, the top surface, or the left and right side walls are not struck, and the protruding piece receiving portion and the protruding piece do not contact each other. It produces the effects that the impact force generated by the backlash of the boom telescopic cylinder (6) is also solved problem adversely affecting the boom telescopic cylinder (6) and its peripheral parts.

[Appendix 6]
In addition to the protruding piece, the tube (9) is formed with a slightly shorter lateral width than the protruding piece at the end of the end opposite to the piston rod. The support member (41) is provided side by side, and the support member (41) is provided with inclined portions on both the left and right sides that reduce the lateral width toward the front edge. Boom breakage prevention device (37) for cranes in Japan.
Thereby, even when the effect described in the third stage in the paragraph 0057, that is, when vibration with a lateral component occurs in the contraction process of the boom telescopic cylinder (6) and the boom components (3, 4, 5), Side sliding members (43, 43) provided on the left and right sides of the support member (41) provided at the tip of the end of the tube (9) on the side opposite to the piston rod project are boom components (3, 4, 5). ) Is brought into contact with the left and right side walls, and other peripheral parts can be prevented from being damaged.

  The present invention is a boom formed by inserting three or more stages of boom components in a nested manner in order, in particular, each component from the base side boom component to the tip side boom component at the position closest to the main body of the crane vehicle. The present invention can be applied to all booms in which the boom telescopic cylinder is substantially held in a cantilever shape in the retracted state of the boom in which the boom components are superposed inside and outside.

DESCRIPTION OF SYMBOLS 1 Boom 2 Base side boom component 2r Base 2t Tip 3 Boom component (the second-stage boom component counted from the base side)
3r Base 4 Boom component (third-stage boom component counted from the base side)
4r Base 4t Tip 5 Tip-side boom component (boom component at the most advanced stage)
5r Base 6 Boom telescopic cylinder 7 Piston rod 8 Pin 9 Tube 10 Pin 11 Sheave (tube peripheral parts)
12 to 15 Sheave 16 Boom extension wire 17 Boom reduction wire 18 Boom expansion / contraction wire 19 Boom breakage prevention device 20 Plate-like member 20a Front edge portion 20b Inclined portion 20c Side portion 20d Rear edge portion 21 Protruding piece 22 Protruding piece receiving portion 23 stay (peripheral parts of the tube)
24 Roller (peripheral parts of the tube)
25 stay (peripheral parts of the tube)
26 Top guide plate (peripheral parts of the tube)
27 Cover (tube peripheral parts)
28 Fixing means 29 Upper support member 29a Main body portion 29b Bending portion 30 Lower support member 30a Main body portion 30b Bending portion 31 Reinforcing member 32 Side surface sliding contact member 33 Upper and lower surface sliding contact member 33a Tapered surface 34 Guide portion 35 Reinforcing plate 36 Guide portion 37 Boom breakage prevention device 38 Rod member (protruding piece)
38a Conical tapered surface 39 Stay 40 Annular member (projection piece receiving portion)
41 Support member 42 Metal plate 43 Side sliding member

Claims (3)

Three or more stages of boom components from the base-side boom component to the tip-side boom component are sequentially nested and fitted in the base of the base-side boom component in the boom, and the piston rod of the boom telescopic cylinder The end of the boom telescopic cylinder on the piston rod protruding side is pivotally attached to the base of the boom constituent element adjacent to the base side boom constituent element while the tip is pivoted, and the boom telescopic cylinder extends and contracts to The boom component adjacent to the base-side boom component is moved relative to the base-side boom component in the expansion / contraction direction of the boom telescopic cylinder, and the end of the tube on the anti-piston rod protruding side and each boom configuration Different boom configurations via sheaves pivotally mounted at each of the longitudinal ends of the element Expansion and contraction of each boom component from the boom component adjacent to the base side boom component to the distal boom component by the interaction of the boom extension wire and boom reduction wire connecting the elements with the relative movement In a boom breakage prevention device for a crane truck having a boom that is relatively moved in a direction,
Providing a protruding piece having a shape that can be supported at least in the vertical direction on either the end of the tube on the anti-piston rod protruding side or the inner end of the distal end boom component,
On the other hand, a projecting piece receiving portion that supports the projecting piece in close contact with at least the upper and lower surfaces of the projecting piece in the most contracted state of the boom telescopic cylinder and the boom is provided in the axial direction of the tube and its peripheral parts. Provided in a position to support the lower end and the upper end of the maximum outer shape of the cross-section separated from the bottom surface and the top surface of the tip side boom component,
At least one of the projecting piece and the projecting piece receiving part guides the intrusion of the projecting piece into the projecting piece receiving part in the process of contracting the boom telescopic cylinder and the boom and A boom breakage prevention device for a crane truck, comprising a guide portion having a tapered surface that lifts an end portion on a piston rod protruding side against gravity. While the protruding piece is constituted by a plate-like member horizontally fixed to the end of the tube on the side opposite to the piston rod protruding side,
The protruding piece receiving portion is constituted by a pair of upper and lower support members fixed to the left and right wall portions inside the distal end portion of the distal end side boom component with an interval equivalent to the thickness of the protruding piece in the vertical direction,
The boom breakage of a crane truck according to claim 1, wherein the lateral width of the projecting piece is formed slightly shorter than the distance between the left and right wall portions inside the distal end portion of the distal end boom component. Prevention device. While the protruding piece is constituted by a rod member protruding along the expansion / contraction direction at the center of the end of the tube on the side opposite to the piston rod protruding side,
The protruding piece receiving portion has an inner diameter comparable to the outer diameter of the rod member, and is configured by an annular member installed inside a distal end portion of the distal boom component through a stay. The boom breakage prevention device for a crane truck according to claim 1.

Images