Simple crane

Abstract

To provide a simple crane which has fewer parts and can be installed in a small space.SOLUTION: There is provided a simple crane X equipped with a pillar-shaped boom Y which includes a first boom 1 and a second boom 2. The first boom 1 has a mounting plate 12 provided at one end of the first boom and having a through-hole 121 extending in a direction intersecting the axial direction of the first boom. The mounting plate 12 further has a protruding portion 122 extending in a direction intersecting the axial direction. A mounting hole H is formed on the protruding portion 122.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a simple crane that is easy to install and handle when working at height. [Background technology]

[0002] Temporary cranes are required to lift heavy loads in structures where electrical and communication equipment is installed at high altitudes, such as communication towers and high-rise buildings. When working at such high altitudes, scaffolding is often provided for workers, and temporary cranes are fixed to the scaffolding for use. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Publication No. 01-070784 Summary of the Invention [Problem to be solved by the invention]

[0004] The lightweight, simple crane described in Patent Document 1 can be installed in high places such as on steel towers, and is configured with a support column that can rotate horizontally and an arm that can lift heavy loads. This lightweight, simple crane has a large number of parts and occupies a large area of ​​floor space because it connects a rotation shaft, arm, two pillars, and two guy wires to a bottom metal fitting (foundation), so there is still room for improvement in terms of easy and safe installation and disassembly in limited spaces.

[0005] In view of the above problems, an object of the present invention is to provide a simple crane that has fewer parts and can be installed in a small space. [Means for solving the problem]

[0006] The present invention, which solves the above problem, is a simple crane equipped with a pillar-shaped boom, which includes a first boom and a second boom, and the first boom has an attachment plate at one end which has a through hole in a direction intersecting its axial direction, and the attachment plate further has a protruding portion which protrudes in a direction intersecting the axial direction, and the protruding portion has an attachment hole provided in the protruding portion. This configuration allows for fewer parts and allows for installation in small spaces.

[0007] In a preferred embodiment of the present invention, the first boom and the second boom are each provided with a fitting portion that can be fitted in series in the axial direction. This configuration allows the boom to be assembled and disassembled easily and safely.

[0008] In a preferred embodiment of the present invention, the first boom and the second boom are further provided with flanges that enlarge the end faces of the ends where the fitting portions are provided. This configuration allows the boom to be assembled and disassembled more stably and safely.

[0009] In a preferred embodiment of the present invention, the boom further includes a pillar-shaped intermediate boom that can be inserted between the first boom and the second boom. This configuration allows the length of the simple crane to be easily extended.

[0010] In a preferred embodiment of the present invention, the boom further includes a base to which the boom can be attached, the base having an attachment portion including two rotation axes that are positioned to intersect or twist with each other. This configuration allows the boom to be pointed in various directions to move an object. [Effects of the Invention]

[0011] The present invention, which solves the above-mentioned problems, provides a simple crane that has fewer parts and can be installed in a small space. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is an explanatory diagram showing a configuration of a simple crane according to an embodiment of the present invention. FIG. [Figure 2] 1 is an explanatory diagram showing the configuration of a boom included in a simple crane according to an embodiment of the present invention. FIG. [Figure 3] 1 is an explanatory diagram showing the detailed configuration of each part of a boom included in a simple crane according to an embodiment of the present invention. FIG. [Figure 4] 1 is an explanatory diagram showing the detailed configuration of each part of a boom included in a simple crane according to an embodiment of the present invention. FIG. [Figure 5] 1 is an explanatory diagram showing the detailed configuration of each part of a boom included in a simple crane according to an embodiment of the present invention. FIG. [Figure 6] 1 is an explanatory diagram showing the configuration of a boom and a base part included in a simple crane according to an embodiment of the present invention. FIG. [Figure 7] FIG. 10 is an explanatory diagram showing a modified example of a boom included in a simple crane according to an embodiment of the present invention. [Figure 8] FIG. 10 is an explanatory diagram showing a modified example of the configuration of the simple crane according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, a simple crane X according to an embodiment of the present invention will be described with reference to the drawings. The description will be made in detail in the order of the configuration of the embodiment, the method of implementation, and other examples. The following embodiment is an example of the present invention, and the present invention is not limited to the following embodiment.

[0014] <Embodiment> As shown in FIG. 1 , the simple crane X according to this embodiment includes a first boom 1, a second boom 2, a base 4, a wire W, a pulley P, and a hoist R. An intermediate boom 3 is also provided as needed, and the simple crane X is fixed to a scaffolding S and a beam B supporting the scaffolding S. Also, as shown in FIGS. 2( a) and 2(b), in the following description, the first boom 1, the second boom 2, and the intermediate boom 3 are collectively referred to as boom Y. The first boom 1, the second boom 2, and the intermediate boom 3 each have a mating portion C to which their respective ends can be connected. In the following description, the mating portion C includes all of the portions that allow the first boom 1, the second boom 2, and the intermediate boom 3 to be mated in series in the axial direction (the length direction of each boom).

[0015] As shown in Figures 2(a), 2(b), 3(a), and 3(b), the first boom 1 is provided on the boom Y closest to the base of the simple crane X, and has a columnar boom main body 11, a mounting plate 12 connectable to the base 4, a fitting portion 13 serving as a fitting portion C, and a flange 14. In the following description, the center line indicating the length direction of the first boom 1 is referred to as the axis A, the direction parallel to the axis A is referred to as the axial direction, and the direction of a plane perpendicular to the axial direction is referred to as the cross-sectional direction (the same applies to the second boom 2 and the intermediate boom 3).

[0016] The boom body 11 is a columnar or cylindrical member that has a substantially constant cross section and extends in the axial direction, and constitutes the main part of the first boom 1. The cross section of the boom body 11 is preferably rounded, and a circular shape is particularly preferable. With this configuration, when the crane is used to suspend a heavy load, the load is appropriately distributed, allowing for safe and long-term use.

[0017] Mounting plate 12 is a flat member provided at one end of boom main body 11, and has through-holes 121 to enable connection to base 4. Mounting plate 12 is configured to be split approximately along the axis so that its surface faces one diameter direction of the end face of boom main body 11 and the axial direction, with a portion overlapping boom main body 11 in the axial direction and the remainder being provided on an extension of boom main body 11 in the axial direction.

[0018] The through-hole 121 is a hole that passes through the mounting plate 12 in the thickness direction on the extension of the boom body 11. In other words, the mounting plate 12 has the through-hole 121 in a direction intersecting with the axial direction. With this configuration, the first boom 1 can be attached to the base portion 4 with a small number of parts.

[0019] As shown in Figures 3(a) and 3(c), the mounting plate 12 has a protruding portion 122 that protrudes away from the axis A at a portion that overlaps with the boom body 11 in the axial direction. The protruding portion 122 is a flat plate-shaped member that protrudes in a direction intersecting the axial direction, and is preferably configured to be integrally formed flush with the mounting plate 12 in the surface direction. The protruding portion 122 also has a mounting hole H that penetrates it in the thickness direction. This configuration allows other components required for the simple crane X to be easily attached.

[0020] The fitting-receiving portion 13 is a cylindrical member provided at the other end of the boom main body 11 (the end opposite the end where the mounting plate 12 is provided), and forms part of the fitting portion C that can be connected to the second boom 2 or the intermediate boom 3. In the example shown in FIGS. 3(a) and 3(b), the outer diameter of the fitting-receiving portion 13 is larger than the outer diameter of the boom main body 11, the inner diameter of the fitting-receiving portion 13 is substantially equal to the outer diameter of the boom main body 11, and the fitting-receiving portion 13 and the boom main body 11 have a stepped configuration with the axis A as their concentric axes. This configuration makes it easy to visually check the depth (axial length) of the fitting portion C, and also makes it easier to stabilize the entire boom Y because the members on the base side of the boom Y hold the members on the tip side so as to cover them from the outside.

[0021] The flange 14 is a flat member that enlarges the opening at the tip of the fit-receiving portion 13, i.e., the end face of the end of the first boom 1 where the fitting portion C is provided, and protrudes in the cross-sectional direction from the side face of the fit-receiving portion 13 in a direction away from the axis A. Also, as shown in FIG. 2(b), the flange 14 is provided with fixing holes that enable it to be fixed to the second boom 2 or the intermediate boom 3 by fastening bolts. With this configuration, the boom Y can be stably fixed and assembled in two different connection methods: by fastening bolts in the axial direction and by the fitting portion C in the cross-sectional direction.

[0022] As shown in FIGS. 2(b) and 3(b), the first boom 1 has a plurality of stays 15 attached to the side of the boom body 11. The stays 15 are box-shaped or columnar protrusions for attaching scaffolding bolts that a user (worker) climbs on after the boom Y is installed, and have holes parallel to the protrusion direction through which the bolts can be inserted. Preferably, a plurality of stays 15 are provided at equal intervals in the axial direction. In this embodiment, two stays 15 are provided at equal intervals on opposite sides of the axis A, and are positioned midway between the stays 15 on the opposite sides. With this configuration, scaffolding bolts can be attached to the first boom 1, allowing it to be used for purposes other than a crane (such as a substitute for a ladder).

[0023] As shown in Figures 2(a), 2(b), 4(a), and 4(b), the second boom 2 is provided at the tip end of the boom Y on the simple crane X, and has a columnar boom body 21, a suspension plate 22 to which a wire W can be attached, a swivel plate 23, a fitting portion 24 as a fitting portion C, and a flange 25. As with the first boom 1, the following description will use the axis A, axial direction, and cross-sectional direction.

[0024] Like the boom body 11 of the first boom 1, the boom body 21 is a columnar or tubular member that has a substantially constant cross section and extends in the axial direction, and forms the main part of the second boom 2. The cross section of the boom body 21 is substantially the same as that of the boom body 11 of the first boom 1, and preferably has no corners, with a circular shape being particularly preferable. With this configuration, the boom Y always has a substantially constant cross-sectional shape, which allows the load to be appropriately distributed when a heavy object is hung, ensuring safe use.

[0025] As shown in Figures 4(a) and 4(b), the lifting plate 22 is provided at one end of the second boom 2, particularly at the end that will be the tip of the simple crane X, and as shown in Figure 4(c), it is a flat member that is split along one diameter of the cross section of the boom main body 21 and protrudes outward from the boom main body 21 so as to extend across that diameter on both sides. Furthermore, the lifting plate 22 has mounting holes H formed in both areas that protrude outward from the boom main body 21. With this configuration, the wire W or pulley P can be easily attached to the tip of the simple crane X, and the boom Y can be operated with little force.

[0026] As shown in FIG. 4(c), the rotation plates 23 are flat plate-like members that protrude from the side surfaces of the boom main body 21 in a direction away from the axis A, and at least one pair of rotation plates 23, preferably symmetrically arranged, is provided with the suspension plate 22 in between. Each rotation plate 23 is provided with a mounting hole H that penetrates through in the thickness direction. Furthermore, the rotation plates 23 are preferably configured to be provided at the same position in the axial direction as the suspension plate 22, i.e., at the end of the boom main body 21. With this configuration, a wire W is added to the tip of the boom Y, and by pulling the wire W, the boom Y can be easily rotated in the horizontal direction.

[0027] The fitting portion 24 is a cylindrical member provided at the other end of the boom main body 21 (the end opposite to the end where the hanging plate 22 and the swivel plate 23 are provided), and forms part of the fitting portion C that can be connected to the first boom 1 or the intermediate boom 3. In the example shown in Figures 4(a) and 4(b), the fitting portion 24 is configured to extend with substantially the same cross section as the boom main body 21, and a flange 25 is provided at a position where the depth (axial length) of the fitting portion C is ensured.

[0028] Flange 25 is a flat member that expands the end face (or cross section) of boom main body 21, particularly at the end that forms the boundary with fitting portion 24, and protrudes in the cross-sectional direction from the side surface of fitting portion 24 in a direction away from axis A. Also, as shown in FIG. 2(b), flange 25 is provided with fixing holes that enable it to be fixed to first boom 1 or intermediate boom 3 by bolting.

[0029] As shown in FIGS. 2(b) and 4(b), the second boom 2 has a plurality of stays 26 attached to the side of the boom body 21. The stays 26 are box-shaped or column-shaped protrusions for attaching scaffolding bolts that a user (worker) climbs onto after the boom Y is installed. The stays 26 have holes parallel to the protrusion direction through which the bolts can be inserted. Preferably, the stays 26 are arranged at equal intervals in the axial direction. In this embodiment, two stays 26 are arranged at equal intervals on opposite sides of the axis A, midway between the two opposite stays 26. Preferably, the axial spacing of the stays 26 is the same as that of the stays 15 of the first boom 1. With this configuration, the scaffolding bolts are arranged at equal intervals when a user moves up and down the boom Y, making movement safer and easier.

[0030] As shown in Figures 2(a), 2(b), 5(a) and 5(b), the intermediate boom 3 is an expansion part that can be inserted between the first boom 1 and the second boom 2 of the boom Y, and has a boom main body 31, a fitting portion 32 and a fitting portion 33 as fitting portions C, and a flange 34. As with the first boom 1 and the second boom 2, the following description will use the axis A, axial direction and cross-sectional direction.

[0031] Like the boom body 11 of the first boom 1 and the boom body 21 of the second boom 2, the boom body 31 is a columnar or tubular member that has a substantially constant cross section and extends in the axial direction, and forms the main part of the intermediate boom 3. Furthermore, the cross section of the boom body 31 preferably has no corners, and a circular shape is particularly preferable.

[0032] The fitting portion 32 is a cylindrical member provided at one end of the boom main body 31, and forms part of the fitting portion C that can be connected to the second boom 2 or another intermediate boom 3. In the example shown in Figures 5(a) and 5(b), the outer diameter of the fitting portion 32 is larger than the outer diameter of the boom main body 31, the inner diameter of the fitting portion 32 is approximately equal to the outer diameter of the boom main body 31, and the fitting portion 32 and the boom main body 31 have a stepped configuration with the axis A as a concentric axis.

[0033] The fitting portion 33 is a cylindrical member provided at the other end of the boom main body 31 (the end opposite to the end where the fitting-receiving portion 32 is provided), and forms part of the fitting portion C that can be connected to the first boom 1 or another intermediate boom 3. In the example shown in Figures 5(a) and 5(b), the fitting portion 33 is configured to extend with substantially the same cross section as the boom main body 31, and a flange 34 is provided at a position where the depth (axial length) of the fitting portion C is ensured.

[0034] The flange 34 is a flat plate-like member that is provided at the opening at the tip of the fit-receive portion 32 (the end portion where the fitting portion C is provided in the intermediate boom 3) and at the end portion that forms the boundary between the boom main body 31 and the fit-in portion 33, and that extends from the side surfaces of the fit-in portion 32 and the fit-in portion 33 in a direction away from the axis A. Also, as shown in FIG. 2(b), the flange 34 is provided with fixing holes that enable it to be fixed to the first boom 1, the second boom 2, or another intermediate boom 3 by bolting.

[0035] As shown in Figures 2(a), 2(b), and 7(a), the boom Y is constructed by connecting the first boom 1 and second boom 2 having the above-described configuration, with an intermediate boom 3 added between them as needed. In this case, as shown in Figure 7(a), when the first boom 1 and second boom 2 are directly connected, the fitting portion 24 of the second boom 2 fits into the fitting portion 13 of the first boom 1, and the flanges 14 and 25 abut against each other to form the fitting portion C. As shown in Figures 2(a) and 2(b), when the intermediate boom 3 is included, the fitting portion 24 of the second boom 2 fits into the fitting portion 32 of the intermediate boom 3, and the fitting portion 33 of the intermediate boom 3 fits into the fitting portion 13 of the first boom 1, and the flanges 25 and 34, and the flanges 14 and 34 abut against each other to form the fitting portion C. Furthermore, when connecting intermediate booms 3 to each other, the fitting portion 33 of one intermediate boom 3 fits into the fitting portion 32 of the other intermediate boom 3, and the flange 34 of one intermediate boom 3 abuts against the flange 34 of the other intermediate boom 3, forming a fitting portion C.

[0036] This configuration makes it easier to connect the booms together at the fitting portion C. If the flanges were simply abutted together and fixed with bolts, it would be necessary to maintain the booms aligned at all times while the bolts were being tightened, and even after connection, the bolts would bear the entire shear load associated with the fitting portion C, which posed a strength problem. However, positioning is possible using the fitting portions 24, 33 and the fitting-receiving portions 13, 32, which not only reduces the workload when connecting the booms Y, but also improves strength against shear loads.

[0037] As shown in Figures 1, 6(a) and 6(b), the base portion 4 is a structure that can fix the simple crane X to a predetermined location, and has a fixing plate 41 and an attachment portion 42 to which the first boom 1 can be attached.

[0038] The fixing plate 41 is a flat member that forms the bottom of the base 4, and is used to place the base 4 in a fixed location and fix it with a fixing device. In the example of this embodiment, the fixing device may be a bolt or an anchor bolt, and as shown in Fig. 6(b), the fixing plate 41 has holes or grooves that allow the fixing device to pass through.

[0039] The mounting portion 42 is a structure erected above the fixed plate 41, and enables the mounting plate 12 of the first boom 1 to be attached thereto. The mounting portion 42 has a pair of flat plate-like members facing each other with a gap slightly wider than the thickness of the mounting plate 12, and holes aligned with the through-holes 121 are formed in the mounting portion 42 in a straight line. As shown in FIG. 6( b), the mounting plate 12 and the mounting portion 42 are connected by passing mounting bolts 5 (a typical fastener consisting of a combination of a bolt and a nut) through the aligned through-holes 121, thereby enabling the first boom 1 to be rotatable relative to the mounting portion 42. The central axis of the hole and the mounting bolt 5 in this case is a first rotation shaft 421, and the boom Y is rotatable in the elevation and depression directions around this first rotation shaft 421.

[0040] 6(b), the mounting portion 42 is provided with a second rotation shaft 422 that intersects with or is twisted from the first rotation shaft 421. The second rotation shaft 422 is a rotation shaft that rotatably connects the mounting portion 42 to the fixed plate 41 on the underside of a flat-plate-like member that can be connected to the mounting plate 12. In the example of this embodiment, the mounting portion 42 is rotatable approximately parallel to the surface direction of the fixed plate 41, and the first rotation shaft 421 and the second rotation shaft 422 are approximately perpendicular to each other. With this configuration, the boom Y can rotate, i.e., swing, approximately parallel to the surface direction of the fixed plate 41.

[0041] The boom Y and base 4 having the above configuration are fixed to a scaffolding S and / or a beam B as shown in Figure 1, and a wire W, a pulley P, and a hoist R are further attached to form a simple crane X. In the following description, the wire W includes a support wire W1, a swivel wire W2, and a suspension wire W3.

[0042] The wire W is a wire rod (or braided cord) having sufficient strength to withstand the tension caused by the weight of a heavy object, and is attached to each part of the simple crane X.

[0043] The support wire W1 is inserted through one of the mounting holes H of the suspension plate 22 and attached by tying, and the other end is fixed to a structure in the vicinity of the simple crane X, making it possible to hold the boom Y at a predetermined angle. It is preferable that the length of the support wire W1 from one end attached to the suspension plate 22 to the other end attached to the surrounding structure be adjustable by the hoist R or the like. With this arrangement, the boom Y is rotatable about the first rotation shaft 421, making it possible to change the elevation angle and depression angle in the axial direction.

[0044] The swivel wire W2 is inserted into the mounting hole H of the swivel plate 23 and attached by tying, and the other end is attached in a manner that allows its length to be changed to a structure in the vicinity of the simple crane X. In addition, at least one swivel wire W2 is attached to one swivel plate 23, and with this configuration, by appropriately pulling the multiple swivel wires W2, the boom Y rotates about the second rotation shaft 422, and the boom Y can rotate in the horizontal direction.

[0045] The hoisting wire W3 is a wire W that, together with the boom Y, forms a main part of the simple crane X, with one end attached to a heavy load for suspending it and the other end connected to the hoisting machine R so that it can be lifted. The hoisting wire W3 passes through a mounting hole H on the other side of the hoisting plate 22 (the side to which the support wire W1 is not attached) midway and is attached so as to run along the boom Y. Furthermore, the hoisting wire W3 has its direction changed by a pulley P near the hoisting plate 22 and the overhanging portion 122. This configuration not only enables the heavy load to be lifted and lowered safely, but also makes it easier to select a location for installing the hoisting machine R.

[0046] The pulley P is a typical pulley having a rotating body on which the wire W can be hooked and a hook that can be attached to the attachment hole H. In this embodiment, as shown in FIG. 1, the pulley P is attached to the attachment hole H of the suspension plate 22 and the extension portion 122 to change the direction of the suspension wire W3.

[0047] The hoist R is a general hoist that includes a power unit and a rotating part that can wind or unwind the wire W, and can be attached to one end of each wire W. The hoist R may be configured in any manner as long as it can safely suspend a heavy load, including a configuration in which it is installed at any position on the scaffolding S as shown in FIG. 1, or a configuration in which a portable, manual winch is directly attached to the extension 122 as shown in FIG. 8.

[0048] With the above configuration, the simple crane X can be constructed with a small number of parts while ensuring sufficient strength and safety, so there is less effort required to lift the parts to high places (such as the scaffolding S), and it can be operated safely and at low cost.

[0049] The present invention may have the following configurations. However, the following configurations are merely examples, and the presence or absence of the configurations can be determined arbitrarily unless otherwise specified.

[0050] <Example of change> It is preferable that the peripheral portions of mounting plate 12, extension 122, hanging plate 22, and swivel plate 23, when viewed from the surface direction near through-hole 121 or mounting hole H, are configured to be rounded in an arc shape. With this configuration, even if mounting plate 12, extension 122, hanging plate 22, or swivel plate 23 come into contact with a nearby object when moving boom Y, damage to the object can be reduced. Furthermore, when mounting plate 12 is attached to mounting portion 42 and rotates, interference with the components of mounting portion 42 can be avoided.

[0051] As shown in FIG. 4(c), it is preferable that the extension direction of the rotation plate 23 is not perpendicular to the suspension plate 22, but rather is closer to one end of the suspension plate 22. With this configuration, when the boom Y is used tilted (or laid down) as shown in FIG. 1, the tip of the rotation plate 23 faces slightly upward, making it easier to pull and operate the rotation wire W2 from approximately the same height as the support wire W1 (or from the opposite side of the tip of the boom Y when viewed from the base 4 in the horizontal direction). Furthermore, shear loads are less likely to be applied to the rotation plate 23, reducing the possibility of breakage during use. In this case, when assembling the first boom 1 and the second boom 2, it is preferable that the extension portion 122 of the suspension plate 22 closest to the rotation plate 23 be oriented in the same direction. With this configuration, the extension portion 122 faces vertically upward as shown in FIG. 1 and does not interfere with the base 4, etc.

[0052] The flange 14 of the first boom 1 and the flange 25 of the second boom 2 may each be configured to have only one notch or mold. Preferably, this notch or mold is provided in the direction in which the overhanging portion 122 overhangs on the flange 14 of the first boom 1, and in the direction in which the hanging plate 22 on the side on which the swivel plate 23 is biased, as described above, on the flange 25 of the second boom 2. This configuration facilitates the task of aligning the orientation of the boom Y when connecting the first boom 1 and the second boom 2 at the fitting portion C, i.e., the task of assembling the boom Y such that the overhanging direction of the overhanging portion 122 and the direction of the hanging plate 22 on the side on which the swivel plate 23 is biased, as described above, are in the same direction with respect to the axis A. In this case, the user can use the notch or mold provided in the flanges 14, 25 as a guide, eliminating the need to check both ends of the boom Y, thereby reducing errors during operation. Similarly, it is preferable that the intermediate boom 3 also has one notch or mold in each of the flanges 34 at both ends in the same direction.

[0053] As shown in FIG. 7(b), the intermediate boom 3 may be configured to be shorter in the axial direction than the first boom 1 and the second boom 2. Such a configuration improves the degree of freedom in changing the length of the boom Y. For example, if the axial lengths of the first boom 1 and the second boom 2 are both 2 m and the axial length of the intermediate boom 3 is 1 m, the axial length of the boom Y can be adjusted in 1 meter increments as long as it is 4 m or more. However, the values ​​shown here are merely examples, and the axial length of each boom may be set freely.

[0054] Hereinafter, a method for carrying out the present invention will be described in detail with reference to the drawings. The ...

[0055] <<Implementation Method>> When assembling the simple crane X, the user first installs the base 4. The base 4 is placed at the installation location and fixed with fixing devices (such as bolts or anchor bolts).

[0056] Next, the user attaches the first boom 1 to the mounting portion 42. At this time, as shown in FIG. 6(b), the user aligns the through holes 121 of the mounting plate 12 with the holes in the mounting portion 42, passes the mounting bolts 5 through each hole, and tightens the nuts to rotatably connect the first boom 1 to the mounting portion 42. Thereafter, the user lays the first boom 1 down, and prepares the second boom 2 or intermediate boom 3 to be connected at the receiving portion 13.

[0057] Next, the user inserts the fitting portion 24 of the second boom 2 into the fitting receiving portion 13, and once the flange 14 of the first boom 1 and the flange 25 of the second boom 2 are abutted, they align the bolt fixing holes on both and fasten the two overlapping flanges with bolts. This work is the same when connecting the first boom 1 and the intermediate boom 3, when connecting the intermediate booms 3 to each other, and when connecting the intermediate boom 3 to the second boom 2. This reduces the effort required for aligning the booms when connecting them, allowing the work to be done safely and in a short amount of time.

[0058] Next, the user attaches wires W to the mounting holes H of the extension 122, the suspension plate 22, and the swivel plate 23. At this time, if necessary, particularly for the suspension wire W3, the user attaches pulleys P to the mounting holes H of the extension 122 and the suspension plate 22 and hooks the suspension wire W3. Thereafter, the user uses the support wire W1 to raise the boom Y and operate it as the simple crane X.

[0059] When dismantling the simple crane X, the user performs the work in the reverse order of the above. By performing the above work, the simple crane X can be set up and removed safely in a small area at high places including the scaffolding S. [Explanation of symbols]

[0060] X Simple crane Y Boom 1. First Boom 11 Boom body 12 Mounting plate 121 Through hole 122 Overhang 13 Receptacle 14 flange 15 Stay 2. Second Boom 21 Boom body 22 Hanging board 23 Swivel plate 24 Inset part 25 flange 26 Stay 3 Intermediate boom 31 Boom body 32 Receptacle 33 Inset part 34 flange 35 Stay 4 Foundation 41 Fixed plate 42 Mounting part 421 First rotation axis 422 Second rotation axis 5 Mounting bolts A axis B beam C Fitting part H Mounting hole P pulley R hoisting machine S Scaffolding W Wire W1 Supporting wire W2 Swivel wire W3 Suspension Wire

Claims

1. A simple crane equipped with a pillar-shaped boom, the boom includes a first boom and a second boom, The first boom has a mounting plate at one end, the mounting plate having a through hole in a direction intersecting with the axial direction of the first boom, The mounting plate further includes a protruding portion that protrudes in one direction intersecting the axial direction, The simple crane has a mounting hole provided in the protruding portion.

2. The first boom and the second boom are each provided with a fitting portion that can be fitted in series in the axial direction.

2. The simple crane of claim 1.

3. The first boom and the second boom are further provided with flanges that enlarge end faces of the ends where the fitting portion is provided.

3. The simple crane of claim 2.

4. The boom further includes a pillar-shaped intermediate boom that can be inserted between the first boom and the second boom.

2. The simple crane of claim 1.

5. Further provided is a base portion to which the boom can be attached, The base portion has a mounting portion including two pivot axes that are in a mutually intersecting or twisted position.

2. The simple crane of claim 1.

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