Electric pole lifter and extension device

Abstract

To provide an electric pole lifter and an extension device that are inexpensively manufactured and can be used safely even in situations where a first scaffolding bolt installed at the lowest point of an electric pole cannot be used.SOLUTION: An extension device 2 is detachably attached to a branch pole of an electric pole lifter and includes: a rectangular cylindrical body 3 formed with a square cross section; a mounting bracket 55c screwed to a lower end 3a of the rectangular cylindrical body; a pair of second steps 6, 6 respectively connected to both sides of the mounting bracket; a fastening belt 59 secured to the rectangular cylindrical body 3 by a belt fastener 58; and an anti-slip plate 60 attached to a back surface 3c of the rectangular cylindrical body 3 below the fastening belt 59 so that the back side can abut against the electric pole with a circular arc shape in side view and so that both ends protrude on either side of the rectangular cylindrical body 3. A block-shaped connector 4 is attached to an upper end 3b of the rectangular cylindrical body 3, and base ends 5b, 5b of a pair of hooks 5, 5 with their tips 5a bent like hooks are fixed to its upper surface 4a.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a pole lifter used when performing distribution line work while ascending a utility pole, and particularly to a pole lifter that can be used even in a situation where the first scaffold bolt installed at the lowest position of the pole cannot be utilized, and an extension device constituting the same.

Background Art

[0002] The scaffold bolts used as scaffolds when workers ascending utility poles for distribution line work or the like are installed at a height of 1.8 m or more from the ground so as not to obstruct pedestrians. Therefore, conventionally, workers have moved to the location of the lowest scaffold bolt (hereinafter referred to as the first scaffold bolt) using a step ladder or a ladder. In addition, as a substitute for a step ladder or a ladder, for example, a pole lifter as shown in FIG. 5 is known. Here, the structure of the conventional pole lifter will be described with reference to FIG. 5. FIGS. 5(a) and 5(b) are respectively a front view (viewed from the front side) and a left side view of a pole lifter 50 according to the prior art, and FIG. 5(b) shows a state where the pole lifter 50 is attached to a utility pole P.

[0003] As shown in FIGS. 5(a) and 5(b), the utility pole hoist 50 includes a main pole 51 formed of three long aluminum sub - poles 52 to 54 with a square cross - section, which are pivotally connected via hinges 62 so as to be foldable; fixtures 55a, 55b, and 55c fixed to the lower ends of the sub - poles 52, 53, and 54 respectively using screws; a pair of first steps 56a, 56a respectively connected to both sides of the fixture 55a; a first step 56b connected to one side of the fixture 55b; a first step 56c connected to one side of the fixture 55c; an aluminum hanging bracket 57 fixed to the upper end of the sub - pole 52; a tightening belt 59 fixed to the sub - poles 53, 54 below the fixtures 55a, 55b using belt fixtures 58; and a non - slip plate 60 fixed to the back surface (the back surfaces 52a - 54a of the sub - poles 52 - 54) of the main pole 51, which is formed of a long body with an arc - shaped side view, such that the back surface 60a can contact the utility pole P, and both ends protrude outward from the side surfaces (the side surfaces 52b - 54b of the sub - poles 52 - 54) of the main pole 51. The non - slip plate 60 has a function of preventing the main pole 51 from tilting in the left - right direction around the hanging bracket 57 locked to the scaffolding bolt 63 when the weight of the operator is alternately applied to the first steps 56a - 56c.

[0004] As shown by the dashed - line arrows in FIG. 5(a), the first steps 56a - 56c can tilt within a range of approximately 90 degrees with respect to the sub - poles 52 - 54. The hanging bracket 57 has a bolt insertion hole 61 formed in a daruma - hole shape by a first insertion portion 61a through which only the shaft portion 63a of the scaffolding bolt 63 can be inserted and a second insertion portion 61b through which the head portion 63b of the scaffolding bolt 63 can be inserted. Further, the fixtures 55a - 55c, which are composed of a back plate 64 arranged on the back surface 52a - 54a side of the sub - poles 52 - 54 and a pair of side plates 65, 65 extending perpendicularly in the same direction from both ends of this back plate 64, are in a "C" - shaped side view. The pair of side plates 65, 65 are arranged so as to sandwich the sub - poles 52 - 54, and are fixed to the sub - poles 52 - 54 by screws (not shown) screwed into screw holes provided at corresponding positions when viewed laterally with respect to the pair of side surfaces of the sub - poles 52 - 54.

[0005] That is, as shown in Fig. 5(b), the pole hoist 50 has a structure in which the main column 51 is fixed to the pole P by locking the suspension fitting 57 to the scaffold bolt 63 and winding the tightening belt 59 around the pole P. Therefore, by using the pole hoist 50, it is possible to safely raise and lower the pole P. However, depending on the installation location of the pole P, it may not be possible to use the first scaffold bolt installed at the lowest position among the scaffold bolts 63, and the suspension fitting 57 of the pole hoist 50 may have to be locked to a scaffold bolt installed above the first scaffold bolt. In this case, since the position of the first step 56c at the lowermost stage of the pole hoist 50 is too high for the operator to step on, it is necessary to separately prepare a stepladder or a footstool.

[0006] To address such problems, for example, Patent Document 1 discloses an invention related to a pole hoist and an overhanging portion that can bring the height of the lowermost step sufficiently close to the ground under the name of "pole hoist and overhanging portion". Explaining using the reference numerals shown in the drawings of Patent Document 1, the invention disclosed in Patent Document 1 is such that in a main column 56 composed of a plurality of elongated bodies foldably connected via joints, an overhanging body 4 extends from the lowermost elongated body 53 arranged at the lowermost position, and overhanging steps 5 and 5 are provided at the lower end 4a of this overhanging body 4. According to such a structure, since the first scaffold bolt cannot be used and as a result, a locking body is locked to a scaffold bolt arranged above it, even when the operator's foot cannot reach the step of the lowermost elongated body 53 arranged at the lowermost position, when the overhanging body 4 is pulled downward from the lowermost elongated body 53, the operator can step on the overhanging steps 5 and 5 provided at the lower end 4a of the overhanging body 4, so there is no need to separately prepare a stepladder or a footstool.

[0007] Also, Patent Document 2 discloses an invention related to an auxiliary tool for pole installation equipment that can be attached to the outer peripheral surface of a pole regardless of the position of the scaffold bolt under the name of "auxiliary tool for pole installation equipment". Explaining with the reference numerals described in the drawings of Patent Document 2, the auxiliary tool 10 for a utility pole hoist disclosed in Patent Document 2 has a structure in which a hook portion 17 formed in a ring shape through which the scaffold bolt B of the utility pole D can be inserted and a metal ring 25 are respectively provided at both ends, and a wire 12 with a holder 11 suspended in the middle part. According to such a structure, when the suspension fitting 103 cannot be hung on the lowest scaffold bolt B, if the hook portions 17 provided at both ends of the wire 12 are respectively hung on the scaffold bolt B and the scaffold bolt arranged above it, the suspension fitting 103 provided at the upper end of the main column 101 will be suspended on the holder 11 provided in the middle part of the wire 12. Therefore, the main column 101 of the utility pole hoist 100 is arranged lower than when the suspension fitting 103 is hung on the scaffold bolt B. Therefore, there is no risk that the worker's foot will reach the scaffold 104 of the branch column 101c arranged at the lowest part of the main column 101.

[0008] Furthermore, Patent Document 3 discloses an invention related to an auxiliary latching tool that is used in combination with a simple ladder when ascending a utility pole under the name of "auxiliary latching tool for a simple ladder". Explaining with the reference numerals described in the drawings of Patent Document 3, the latching tool 1 disclosed in Patent Document 3 is composed of a wire in which latching portions 3 formed in a ring shape are provided at both ends and a pin 2 is attached at about 1 / 3 of the total length. According to such a structure, after latching the shorter one of the latching tools 1 on the lowest first step and latching the longer one of the latching tools 1 on the second step located higher than the first step, and then hanging and fixing the hook of the simple ladder on the pin 2, the simple ladder is arranged lower than when the hook of the simple ladder is hung on the first step. Therefore, the worker's foot will not be caught on the step provided at the lowest position of the simple ladder.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

[0010] In the invention disclosed in Patent Document 1, even when the first scaffold bolt cannot be used, by pulling out the protruding body 4 downward from the lowermost elongated body 53, the feet of the operator can be hooked on the protruding steps 5 provided at the lower end 4a of the protruding body 4. However, it is necessary to form two pairs of first pin holes 7a and 7b in both end faces 53a and 53a of the lowermost elongated body 53 or to install the adapter 13. That is, in the invention disclosed in Patent Document 1, the existing pole hoist cannot be used as it is, and it is necessary to process the lowermost elongated body 53 or separately manufacture the adapter 13, so there is a problem that the manufacturing cost is high. Further, in the invention disclosed in Patent Document 1, since the protruding portion 2 includes the protruding body 4 having the same length as the lowermost elongated body 53, there is a problem that it is heavier than the conventional pole hoist. Furthermore, since the protruding portion 2 is bulky even when taken out from the pole hoist main body, it may be obstructive during transportation and storage.

[0011] In the invention disclosed in Patent Document 2, even when the hanging tool 103 cannot be hung on the lowermost scaffold bolt B, the feet of the operator can reach the scaffold 104 of the branch column 101c arranged at the lowermost part of the main column 101. However, since the distance from the hanging tool 103 to the scaffold bolt B becomes long, there is a high possibility that the hand of the operator cannot reach the scaffold bolt B. In the device disclosed in Patent Document 3, even when the hook 6 cannot be hung on the lowermost first step, there is an advantage that the feet of the operator can always be hooked on the step provided at the lowest position of the simple ladder. However, since the distance from the hook 6 to the first step becomes long, there is a possibility that the hand of the operator cannot reach the first step.

[0012] The present invention has been made to address such conventional circumstances, and an object thereof is to provide a pole lifter and an extension device that can be used safely even in a situation where the manufacturing cost is low and the first scaffold bolt installed at the lowest position of the pole cannot be used.

Means for Solving the Problems

[0013] To achieve the above object, a first invention is a pole lifter used when working on a pole, comprising a long main column having a square cross section, a suspension fitting fixedly provided at the upper end of the main column so as to be suspendable from a scaffold bolt of the pole, a fixture installed on the main column, a first step installed on the side surface of the main column via this fixture, a slip prevention plate made of a long body having an arcuate shape in side view and fixed to the back surface of the main column so that both ends protrude from the side surface respectively, and an extension device detachably attached to the main column. The extension device comprises a rod-shaped body having a square cross section, second steps respectively installed on both side surfaces at the lower end of this rod-shaped body, a pair of latching tools having hooked tips that can be latched to the slip prevention plate, and a connecting tool installed at the upper end of the rod-shaped body and having the base ends of the latching tools fixedly provided therein. The pair of latching tools are each shaped so as to be latched to the slip prevention plate while sandwiching the main column therebetween in a state where the rod-shaped body is disposed below the main column such that the center lines of the pair of latching tools coincide with each other. In the first invention, the cross section of the main column refers to a plane perpendicular to the longitudinal direction of the main column, and the cross section of the rod-shaped body of the extension device refers to a plane perpendicular to the longitudinal direction of the rod-shaped body.

[0014] In the first invention, when the extension device is attached to the main column by hanging the hooking tool on the anti-slip plate, the second step has a rod-shaped body provided on both side surfaces at the lower end and is arranged below the main column. Therefore, even when a suspension fitting is hung on a scaffold bolt located above the first scaffold bolt, the second step is arranged at a position lower than the first step provided near the lower end of the main column. In addition, in the first invention, since the extension device is attached to the main column by hanging the hooking tool on the anti-slip plate, the attachment work of the extension device to the main column is easy. Also, in this case, there is no need to newly provide a mechanism for attaching the extension device to the main column. Furthermore, in the first invention, unlike the overhanging portion in the invention disclosed in Patent Document 1, it is not necessary to make the rod-shaped body of the extension device long. Therefore, the extension device is not heavier than the overhanging portion, and there is no risk of protruding even when the extension device is removed from the main column.

[0015] The second invention is the first invention, wherein the fixture is fixed to the main column using screws. The main column is composed of a square tube body provided at positions corresponding when viewed laterally with respect to a pair of side surfaces near the lower end where screw holes for screwing in the screws are provided. Instead of including a connecting tool and a hooking tool, the extension device is provided with an insertion portion that can be arranged inside the main column at the upper end of the rod-shaped body, and includes a lock pin that can be inserted into both the insertion hole provided on the side surface of the insertion portion and the screw hole. The insertion hole is provided at a position corresponding to the screw hole when the insertion portion is arranged inside the main column. Note that the insertion portion of the rod-shaped body in the second invention may have either a solid structure or a hollow structure. For example, when the insertion portion is composed of the same square tube body as the main column, the insertion holes provided at positions corresponding when viewed laterally with respect to a pair of parallel side surfaces become the insertion holes through which the above-mentioned lock pin is inserted.

[0016] In the second invention, in addition to the operation of the first invention, the screw screwed into the screw hole provided on the side surface of the lower end of the main column is removed, and the fixture fixed to the main column by this screw is removed from the main column. In this state, after inserting the insertion part provided on the rod-shaped body into the main column from the lower end side, when a lock pin is communicated with the screw hole of the main column and the insertion hole of the insertion part, the extension device has the effect of being connected to the main column via the lock pin.

[0017] The third invention is characterized in that, in the second invention, a male screw portion is formed on at least one side of the end portion of the lock pin, and the extension device is provided with a nut that screws into the male screw portion. In the third invention, in addition to the operation of the second invention, when the male screw portion formed at the end of the lock pin is screwed into the nut in a state where the rod-shaped body of the extension device is connected to the main column via the lock pin, the lock pin has the effect of being difficult to fall out from the rod-shaped body and the screw hole of the main column.

[0018] The extension device according to the fourth invention is a component of the utility pole lifter according to any one of the first to third inventions. In the fourth invention, the operation of the utility pole lifter according to any one of the first to third inventions is exhibited.

Effect of the Invention

[0019] According to the first invention, even when the first scaffold bolt cannot be used, by attaching the extension device to the main column, the second step is arranged at a position lower than the first step provided near the lower end of the main column, so that the operator can easily step on the second step. As a result, there is no need to prepare a stool or a ladder, and the work efficiency of work such as distribution line construction is improved. In addition, according to the first invention, since there is no need to perform processing for attaching the extension device to the main column and the existing utility pole lifter can be used as it is, the manufacturing cost can be reduced. Furthermore, in the first invention, since the upper part of the rod-shaped body is not inserted into the main column when attaching the extension device to the main column, the extension device can be attached to a solid-structured main column as well. And in the first invention, the extension device is not heavy compared to the overhanging part in the invention disclosed in Patent Document 1, and moreover, it does not take up much space when the extension device is removed from the main column, so it is easy to transport and store.

[0020] According to the second invention, since the extension device is surely connected to the main column, there is an effect that the safety during use is higher than that in the case of the first invention. Also, since there is no need to additionally attach a mechanism for attaching the extension device to the main column, and the existing pole lifter can be used as it is, according to the second invention, the manufacturing cost can be reduced.

[0021] According to the third invention, in addition to the effects of the second invention, when the rod-shaped body of the extension device is connected to the main column via a lock pin, the lock pin is difficult to fall out from the screw holes of the rod-shaped body and the main column, so there is an effect that the safety during use is further enhanced. Also, in the third invention, since the lock pin can be made thinner than the screw removed from the screw hole of the main column and another screw that can be inserted into the screw hole can be used as the lock pin, the manufacturing cost of the lock pin can be reduced.

[0022] According to the fourth invention, the effects of the pole lifter according to any one of the first to third inventions are exhibited.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0024] The utility pole elevator according to the embodiment of the present invention will be described with reference to Figs. 1 to 4. Note that the number of branch poles and tightening belts constituting the main pole of the present invention, or the number of the first steps and anti-slip plates, is not limited to the cases shown below and can be appropriately changed. Also, the first step provided at the lower end of the main pole may be provided not only on one side surface of the main pole but also on both side surfaces.

Example

[0025] Figs. 1(a) and 1(b) are respectively the front view and the left side view of the extension device 2 that constitutes the utility pole elevator 1a according to Example 1. Also, Figs. 2(a) and 2(b) are respectively diagrams showing the state in which the extension device 2 is attached to the main pole 51. Since the utility pole elevator 1a of Example 1 has a structure in which the extension device 2 is attached to the branch pole 54 of the main pole 51 of the utility pole elevator 50 already described with reference to Figs. 5(a) and 5(b), the same reference numerals are given to the components shown in Figs. 5(a) and 5(b), and the description thereof will be omitted as appropriate.

[0026] As shown in FIGS. 1(a) and 1(b), the extension device 2 is detachably installed on the branch column 54 of the pole hoist 1a. It includes an aluminum square tube body 3 with a square cross-section, a fixture 55c fixed to the lower end 3a of the square tube body 3 using screws, a pair of second steps 6, 6 having the same structure as the first step 56c and connected to both sides of the fixture 55c respectively, a tightening belt 59 fixed to the square tube body 3 using a belt fixture 58, and an anti-slip plate 60 fixed to the back surface 3c of the square tube body 3 below the tightening belt 59 so that it has an arc shape in side view and the back side can contact the pole P, and both ends protrude to both sides centered on the square tube body 3.

[0027] At the upper end 3b of the square tube body 3, a block-shaped connector 4 is installed, and at its upper surface 4a, the base ends 5b, 5b of a pair of hooks 5, 5 with the tips 5a bent in a hook shape are fixedly installed. As shown by the dashed arrow in FIG. 1(a), the pair of second steps 6, 6 can tilt within a range of approximately 90 degrees with respect to the square tube body 3. Also, the width (distance between the sides) and thickness (distance between the front and back) of the square tube body 3 are substantially the same as those of the main column 51. The pair of hooks 5, 5 are arranged such that when the square tube body 3 is below the branch column 54 and their center lines (overhead straight lines parallel to the longitudinal direction and passing through the intersection of the diagonals of the rectangle) coincide, they can be hooked with the anti-slip plate 60 installed to protrude to both sides of the branch column 54 with the branch column 54 sandwiched therebetween.

[0028] In the pole lifter 1a with such a structure, since the first scaffold bolt (the scaffold bolt 63 provided at the lowest position of the pole P as shown in Fig. 5(b)) cannot be used, when it is necessary to lock the suspension fitting 57 to the scaffold bolt 63 installed above the first scaffold bolt, as shown in Figs. 2(a) and 2(b), after tilting the first step 56c upward in the pole lifter 1a, the extension tool 2 is attached to the branch pole 54 by hanging the hooking tool 5 on the anti-slip plate 60. Since the pair of second steps 6, 6 and the square tube body 3 provided on both side surfaces of the lower end 3a are arranged below the main pole 51, the pair of second steps 6 are arranged at a position lower than the first step 56c provided near the lower end of the branch pole 54. As a result, the operator can easily hook his feet on the second steps 6, 6, eliminating the need to prepare a stepladder or a ladder, and thus improving the work efficiency of work such as distribution line work.

[0029] Also, unlike the case where the first step 56c is provided only on one side surface 54b of the branch pole 54 as in the conventional pole lifter 50, in the pole lifter 1a, since the second steps 6 are respectively provided on both side surfaces of the square tube body 3, the operator can hook the foot on the side that is easier to work on either the left or right foot with respect to the second step 6. Moreover, the extension tool 2 is attached to the main pole 51 by hanging the hooking tool 5 on the anti-slip plate 60, and the hooking tool 5 is removed from the main pole 51 by releasing the hooked state, so the attachment work and removal work of the extension tool 2 to the main pole are easy. Therefore, the pole lifter 1a is excellent in workability. In addition, in the pole lifter 1a, it is not necessary to perform processing for attaching the extension tool 2 to the main pole 51, and the existing pole lifter 50 can be used as it is, so the manufacturing cost can be reduced. Also, in the pole lifter 1a, unlike the overhanging portion in the invention disclosed in Patent Document 1, it is not necessary to make the square tube body 3 of the extension tool 2 have a long structure, so the extension tool 2 is not heavy, and there is no risk of taking up space even when the extension tool 2 is removed from the main pole 51, so it is easy to transport and store.

[0030] Incidentally, the extension device 2 may have a structure in which a connecting tool 4, a mounting tool 55c, a second step 6, a belt fixing tool 58, a tightening belt 59, and an anti-slip plate 60 are installed in the same manner as in the case of the square tube body 3, instead of the square tube body 3. Further, the main column 51 of the utility pole hoist 1a is not limited to a square tube body and may be a square column body. Furthermore, the extension device 2 may have a structure in which the base end 5b of the hooking tool 5 is fixed to the side surface 4b instead of the upper surface 4a of the connecting tool 4.

Embodiment

[0031] FIG. 3(a) and FIG. 3(b) are respectively a front view and a left side view of an extension device 7 constituting the utility pole hoist 1b according to Embodiment 2, FIG. 3(c) is an enlarged view of a portion surrounded by a broken line in FIG. 3(a), and FIG. 3(d) is an enlarged view of a lower end portion of the branch column 54 in the utility pole hoist 1b. Further, FIG. 4(a) and FIG. 4(b) are respectively diagrams showing a state in which the extension device 7 is attached to the main column 51. Further, since the utility pole hoist 1b of Embodiment 2 has a structure in which the extension device 7 is attached to the branch column 54 in a state where the mounting tool 55c and the first step 56c are removed in the utility pole hoist 50 already described with reference to FIGS. 5(a) and 5(b), the same reference numerals are given to the components shown in FIGS. 5(a) and 5(b), and the description thereof will be omitted as appropriate. Furthermore, the same reference numerals are given to the components shown in FIGS. 1 and 2, and the description thereof will be omitted as appropriate.

[0032] As shown in FIGS. 3(a) to 3(d), in the extension device 7 of the utility pole hoist 1a, instead of including the coupler 4 and the hanger 5, an insertion portion 8 made of a rectangular tube body that can be disposed inside the branch pole 54 is provided at the upper end 3b of the rectangular tube body 3. A screw 10 that can be inserted into both the insertion holes 9 provided at corresponding positions when viewed laterally with respect to a pair of side surfaces 8a, 8a of the insertion portion 8 that are parallel to each other and the screw holes 54c of the branch pole 54, and a nut 11 that is screwed onto the screw 10 are provided. The pair of insertion holes 9, 9 are provided at positions corresponding to the screw holes 54c when the insertion portion 8 is disposed inside the branch pole 54. Further, the screw 10 functions as a lock pin to prevent the insertion portion 8 from coming out of the branch pole 54.

[0033] In the utility pole hoist 1b having such a structure, since the first scaffold bolt (the scaffold bolt 63 provided at the lowest position of the utility pole P as shown in FIG. 5(b)) cannot be used, when the suspension fitting 57 has to be locked to the scaffold bolt 63 installed above the first scaffold bolt, as shown in FIGS. 4(a) and 4(b), with the insertion portion 8 provided on the rectangular tube body 3 in the utility pole hoist 1b inserted into the inside of the branch pole 54 from the lower end side, after inserting the screw 10 into the screw hole 54c of the branch pole 54 and the insertion hole 9 of the insertion portion 8, and attaching the nut 11 to the screw 10, since the rectangular tube body 3 provided with the pair of second steps 6, 6 on both side surfaces of the lower end 3a is disposed below the main pole 51, the pair of second steps 6 are disposed at a position lower than the first step 56c provided near the lower end of the branch pole 54. Thereby, similar to the case of the utility pole hoist 1a, the operator can easily step on the second steps 6, 6, and there is no need to prepare a stepladder or a ladder, so the work efficiency of work such as distribution line work is improved.

[0034] Also, in the utility pole hoist 1b, since the second steps 6 are provided on both side surfaces of the square tube body 3, the operator can place the foot on the easier side for working on either the left or right side of the second step 6. Then, the insertion part 8 of the square tube body 3 is inserted into the sub-column 54, and the extension device 7 is connected to the sub-column 54 by attaching a nut 11 to a screw 10 that communicates the screw hole 54c and the insertion hole 9. Also, by removing the nut 11 and pulling out the screw 10 from the screw hole 54c and the insertion hole 9, the connection state between the extension device 7 and the sub-column 54 is released. Therefore, the attachment and detachment operations of the extension device 7 to and from the main column 51 are easy. Thus, the utility pole hoist 1b also has good workability like the utility pole hoist 1a.

[0035] Furthermore, in the utility pole hoist 1b, there is no need to perform processing for attaching the extension device 7 to the main column 51. The extension device 7 can be attached to the main column 51 simply by removing the fixture 55c from the sub-column 54. That is, since the existing utility pole hoist 50 can be used as it is in the utility pole hoist 1b, it is possible to reduce the manufacturing cost. Also, similar to the case of the utility pole hoist 1a, the utility pole hoist 1b does not require the square tube body 3 of the extension device 7 to have a long structure unlike the overhanging part in the invention disclosed in Patent Document 1. Therefore, the extension device 7 is not heavy, and there is no risk of it being bulky even when the extension device 7 is removed from the main column 51, so it is easy to transport and store. In addition, since the main column 51 and the extension device 7 are securely connected via the screw 10, the safety during use is higher than that of the utility pole hoist 1a.

[0036] In addition, in the utility pole lifter 1b, instead of the screw 10, an elongated cylindrical body having a male screw portion formed at least at one end can also be used as a lock pin. Even in a lock pin having such a structure, when a nut is screwed onto the male screw portion formed at the end of the lock pin in a state where the square tube body 3 of the extension device 7 is connected to the branch pole 54 via the lock pin, the lock pin is less likely to fall out from the insertion hole 9 of the insertion portion 8 and the screw hole 54c of the branch pole 54, and the same effect as when the screw 10 is used as the lock pin is exhibited. And, since the lock pin having the above structure is thinner than the screw removed from the screw hole 54c of the branch pole 54 and any member that can be inserted into the screw hole 54c may be used, it is possible to reduce the manufacturing cost of the lock pin by using a member that is cheaper than the screw 10.

[0037] Also, in the extension device 7, instead of the square tube body 3, a rod-shaped body in which the insertion portion 8, the fixture 55c, the second step 6, the belt fixture 58, the tightening belt 59, and the anti-slip plate 60 are installed in the same manner as in the case of the square tube body 3 can be used. Also, the insertion portion 8 is not limited to a square tube body, and may have a solid structure such as a square prism.

Industrial Applicability

[0038] The present invention can be used when performing distribution line work while ascending a utility pole.

Explanation of Reference Numerals

[0039] 1a, 1b... Utility pole lifters 2... Extension devices 3... Square tube bodies 3a... Lower ends 3b... Upper ends 3c... Rear surfaces 4... Connectors 4a... Upper surfaces 4b... Side surfaces 5... Hanging tools 5a... Tips 5b... Base ends 6... Second steps 7... Extension devices 8... Insertion portions 8a... Side surfaces 9... Insertion holes 10... Screws 11... Nuts 50... Utility pole lifters 51... Main poles 52 to 54... Branch poles 52a to 54a... Rear surfaces 52b to 54b... Side surfaces 54c... Screw holes 55a to 55c... Fixtures 56a to 56c... First steps 57... Suspension fittings 58... Belt fixtures 59... Tightening belts 60... Anti-slip plates 60a... Rear surfaces 61... Bolt insertion holes 61a... First insertion portions 61b... Second insertion portions 62... Hinges 63... Scaffold bolts 63a... Shaft portions 63b... Heads 64... Back plates 65... Side plates P... Utility poles

Claims

1. A pole lifter used when working while ascending a utility pole, comprising: a long main pole having a square cross-section; a suspension fitting fixedly provided at the upper end of the main pole so as to be suspendable from a scaffold bolt of the utility pole; a fixture installed on the main pole; a first step installed on a side surface of the main pole via this fixture; an anti-slip plate formed of a long body having an arc shape in side view and fixed to the back surface of the main pole so that both ends project from the side surface; an extension device detachably attached to the main pole, wherein the extension device is a rod-shaped body having a square cross-section; second steps respectively installed on both side surfaces at the lower end of this rod-shaped body; a pair of latching tools having hooked tips bent so as to be latchable to the anti-slip plate; a connecting tool installed at the upper end of the rod-shaped body and having the base ends of the latching tools fixedly provided thereon, wherein the pair of latching tools are shaped such that, in a state where the rod-shaped body is disposed below the main pole with their center lines aligned, they can be respectively latched to the anti-slip plate so as to sandwich the main pole therebetween. The pole lifter is characterized by this.

2. The fixture is fixed to the main pole using screws, the main pole is composed of a square tube body provided with screw holes into which the screws are screwed at positions corresponding to each other when viewed laterally on a pair of the side surfaces near the lower end, instead of including the connecting tool and the latching tools, the extension device is provided with an insertion portion that can be disposed inside the main pole at the upper end of the rod-shaped body, and a lock pin that can be inserted through both an insertion hole provided on the side surface of the insertion portion and the screw hole, wherein the insertion hole is provided at a position corresponding to the screw hole when the insertion portion is disposed inside the main pole. The pole lifter according to Claim 1 is characterized by this.

3. A male screw portion is formed on at least one side of the end of the lock pin, wherein the extension device includes a nut that screws onto the male screw portion. The pole lifter according to Claim 2 is characterized by this.

4. An extension device characterized by being a component of the pole lifter according to any one of Claims 1 to 3.

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