Telescopic leg device for high-altitude work equipment

Abstract

To provide a telescopic leg device in a high place work device.SOLUTION: In a leg body formed in a ladder shape by installing a tread of a plurality of vertical stages at main legs oppositely arranged left and right, a main leg (22) constitutes a telescopic leg device in which a lock mechanism (25) is provided which detachably locks and fixes a slidably inserted telescopic leg (24) in an arbitrary telescopic posture containing a storage posture (P1) and a maximum extended posture (P2). The telescopic leg (24) is constituted in such a manner that, when it is in the maximum extended posture (P2), a tail end part is positioned below a tread (23a) of the lowest stage inside the main leg. The lock mechanism (25) is disposed below the tread of the lowest stage. The tread (23a) of the lowest stage is supported by an arm part (29) of a bracket metal fitting (28) fastened to the main leg. The bracket metal fitting (28) integrally forms an upper side extension part (28a) extending further upward than the arm part along the main leg.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to an extendable leg device for legs formed in a ladder shape in high-altitude work equipment such as stepladders, workbenches, and ladders. [Background technology]

[0002] A conventional high-altitude work device, for example a stepladder, has a pair of legs 1, 1 as shown in FIG. 1, and the upper ends of the legs 1, 1 are pivotally connected to each other by a pivot means (not shown) so that the device can be opened and closed. A detachable opening prevention device 2 is provided which is connected in the open state.

[0003] The leg body 1 has a top plate 4 between a pair of main legs 3, 3 arranged opposite each other on the left and right, and is formed in a ladder shape by erecting multiple upper and lower steps 5 including a lowest step 5a.

[0004] The main landing gear 3 constitutes a telescopic landing gear device, and is provided with a telescopic leg 6 slidably inserted into the main landing gear 3, and a locking mechanism 7 which detachably locks and fixes the telescopic leg 6 in any telescopic position, including a stored position P1 in which the telescopic leg 6 is inserted into the main landing gear 3 over almost its entire length, and a maximum extended position P2 in which the telescopic leg 6 protrudes the furthest from the main landing gear 3.

[0005] The telescopic leg device has the advantage that by extending the telescopic legs 6, the overall length of the leg bodies 1, 1 can be increased, making it possible to work at higher altitudes. In addition, by adjusting the length of the extended position of the telescopic legs 6 of the multiple main legs 3, it is possible to install the device on uneven ground.

[0006] The main leg 3, the telescopic leg 6, and the treads 5, 5a are each formed from an aluminum extrusion. The main leg 3 is made of a grooved member with a groove-shaped cross section that opens toward the inside facing the tread 5, and has a guide cylinder 8 fixed to its lower end. The telescopic leg 6 is inserted through the guide cylinder 8 and slidably inserted inside the main leg 3.

[0007] The telescopic leg 6 is provided with a band-shaped rack 9 having a number of rack teeth 9a arranged in a row in the sliding direction, and by detachably engaging the lock teeth 15a of the locking mechanism 7 with the rack teeth 9a, the telescopic leg 6 is fixed so as to be unable to telescope in any telescopic position including the storage position P1 and the maximum extension position P2.

[0008] The telescopic legs 6 are configured to assume the maximum extended position P2 when protruding from the main landing gear 3 over nearly their entire length, so that the tail end of the telescopic legs 6 is positioned below the lowest step 5a inside the main landing gear 3 when in the maximum extended position P2, as shown in Fig. 3(B). The locking mechanism 7 is arranged below the lowest step 5a, as shown in Fig. 2, so that the rack teeth 9a can be locked and fixed in a position near the tail end of the telescopic legs 6 in the maximum extended position P2.

[0009] The multiple treads 5 are each attached to and supported by an arm portion 11 of a bracket 10 fixed to the main landing gear 3, and in the drawings, the bracket supporting the lowest tread 5a is indicated by the reference symbol 10a.

[0010] 2, the locking mechanism 7 is composed of a locking member 12 arranged facing the underside of the lowest tread 5a, and the locking member 12 is provided with an operating arm 15 extending from a pivot support 14 rotatably supported on a pivot 13 consisting of a horizontal shaft toward the rack teeth 9a, and an operating lever 16 extending in the opposite direction, and the pivot support 14 is urged to rotate in the forward direction by a spring 17, thereby engaging and fixing the locking tooth 15a provided at the tip of the operating arm 15 to the rack teeth 9a. Therefore, when an operator pulls up the operating lever 16 with his / her finger against the spring 17, the locking tooth 15a comes off the rack teeth 9a, and the telescopic leg 6 can be slid relative to the main leg 3 to telescope. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Patent No. 4789907 [Patent Document 2] Patent No. 6368220 [Patent Document 3] Patent No. 6656036 [Patent Document 4] JP 2018-12922 A Summary of the Invention [Problem to be solved by the invention]

[0012] The telescopic leg device has a double-wall structure with the telescopic leg 6 inserted into the main leg 3, and is therefore stronger than a normal column leg having a single-wall structure. The main leg 3 is formed from an aluminum profile having a grooved cross section with a bottom wall 3a and both side walls 3b, 3b, and the telescopic leg 6 is formed from an aluminum profile having a cylindrical cross section.

[0013] The telescopic leg device can be moved from a stored posture P1 in which almost the entire length of the telescopic leg 6 is inserted inside the main leg 3 as shown in FIG. 3(A) to a maximum extended posture P2 in which the telescopic leg 6 protrudes to its maximum extent from the main leg 3 as shown in FIG. 3(B), and can be used in any telescopic length state.

[0014] For this reason, a double-wall structure is formed in the area where the telescopic legs 6 overlap the main landing gear 3, but the upper area of ​​the main landing gear 3, bordered by the tail end of the telescopic legs 6, is a single-wall structure, resulting in a strength difference between the two.

[0015] Therefore, in order to confirm whether the telescopic leg device has sufficient strength, the applicant carried out a strength test in which a load of 900N was applied to the tip of the telescopic leg 6 in the maximum extended position P2 as shown in Fig. 3(B) and damage, deformation, etc. were measured. At this time, the main landing gear 3 was fixed and supported by a jig near the lowest bracket metal fitting 10a, and an inward bending strength test was carried out in which a load F1 was applied in the inward bending direction to the telescopic leg 6, and an outward bending strength test was carried out in which a load F2 was applied in the outward bending direction to the telescopic leg 6.

[0016] In the case of the prior art, as shown in Figure 3(B), a protruding deformation portion 18 was found on the bottom wall 3a of the main landing gear 3, located slightly above the lowest bracket fitting 10a. Also, as shown in Figure 3(C), inward deformation portions 19, 19 were found on both side walls 3b, 3b of the main landing gear 3, located slightly above the lowest bracket fitting 10a.

[0017] An object of the present invention is to provide a telescoping leg device that can show good test results in strength tests carried out by the applicant. [Means for solving the problem]

[0018] The first aspect of the present invention is a ladder-shaped work platform having a ladder-shaped leg body formed by installing multiple steps on the main legs, each of which has a groove-shaped cross section, and is arranged opposite to the left and right. In The main landing gear comprises a telescopic landing gear device that is slidably inserted into the main landing gear and a locking mechanism that detachably locks and fixes the telescopic landing gear in any telescopic position including a stored position in which the telescopic landing gear is inserted into the main landing gear over substantially the entire length and a maximum extended position in which the telescopic landing gear is protruded the furthest from the main landing gear, and the telescopic landing gear device comprises: When the landing gear is in the stowed position, the tail end of the landing gear is positioned above the lowest step inside the main landing gear, Maximum extension posture and when the locking mechanism is engaged, the tail end of the telescopic leg is positioned below the lowest tread inside the main landing gear, the locking mechanism is disposed below the lowest tread, the lowest tread is supported by an arm portion of a bracket metal fitting fixed to the main landing gear, and the bracket metal fitting has an integral upper extension portion which extends upward beyond the arm portion along the main landing gear.

[0019] The second aspect of the present invention is a high-altitude work device having a ladder-like leg body formed by installing multiple steps on the main legs, each of which has a groove-shaped cross section and is arranged opposite to the left and right. In The main landing gear comprises a telescopic landing gear device that is slidably inserted into the main landing gear and a locking mechanism that detachably locks and fixes the telescopic landing gear in any telescopic position including a stored position in which the telescopic landing gear is inserted into the main landing gear over substantially its entire length and a maximum extended position in which the telescopic landing gear is protruded the furthest from the main landing gear, and the telescopic landing gear device comprises: When the landing gear is in the stowed position, the tail end of the landing gear is positioned above the lowest step inside the main landing gear, Maximum extension posture and the locking mechanism is disposed below the lowest tread, and the lowest tread is supported by an arm portion of a bracket metal fitting fixed to the main leg, the bracket metal fitting is integrally formed with an upper extension portion that extends upward beyond the arm portion along the main leg, and a lower extension portion that extends downward beyond the arm portion along the main leg, the locking mechanism is attached via the lower extension portion, and a length dimension L1 from the vertical center position of the arm portion to the lower end of the lower extension portion, and a length dimension L2 to the upper end of the upper extension portion are formed so that L1≦L2.

[0020] In a preferred embodiment, the bracket fitting has a fixed portion fixed to the side wall of the main leg and a rib portion facing the groove opening of the main leg integrally formed therewith, and at least the upper extension portion is formed by extending the fixed portion and the rib portion along the main leg. In this case, it is preferable that the rib portion is formed along the inside of a bone portion integrally formed from the fixed portion along the edge of the groove opening of the main leg, and it is preferable that the lower extension portion and the upper extension portion are formed by extending the fixed portion, bone portion and rib portion along the main leg.

[0021] The locking mechanism is composed of a locking member having locking teeth that can be freely engaged and disengaged with rack teeth arranged in a row in the sliding direction of the telescopic leg, and a safety member. The locking member has an operating arm extended from the lower side of a support part that is rotatably supported around a horizontal axis, and an operating lever extended from the upper side. The support part is urged to rotate in the forward direction by a spring to engage the locking teeth with the rack teeth, and the locking teeth are disengaged from the rack teeth by pushing in the operating lever and rotating the support part in the reverse direction. The safety member faces the operating lever of the locking member from above, and is provided so as to be freely movable in the vertical direction between the locked position and the unlocked position, and is configured to prevent the operating lever from being pushed in when moved to the locked position, and to allow the operating lever to be pushed in when moved to the unlocked position, and is provided with a retaining piece that holds the safety member in the locked position so as not to move downward under its own weight. Effect of the Invention

[0022] According to the present invention, by configuring the bracket fitting 28 that attaches and supports the lowest tread 23a in the manner described above, it is possible to ensure sufficient strength of the main leg 22 against loads in the inward bending direction and outward bending direction, even when the telescopic leg 24 is in the maximum extended position P2. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 shows a stepladder as an example of a high-altitude working device, and is a perspective view showing a stepladder equipped with a telescopic leg device according to a conventional technology. [Diagram 2] FIG. 11 is a cross-sectional view showing an extension lock mechanism in a conventional extension leg device. [Diagram 3] Regarding the function of the telescopic leg device of the prior art, (A) is a cross-sectional view showing the stored position, (B) is a cross-sectional view showing how to conduct a strength test in the maximum extended position, and (C) is a perspective view showing the inward deformation part confirmed by the strength test. [Figure 4] 1 is a perspective view showing a stepladder equipped with an extendable leg device according to an embodiment of the present invention; [Diagram 5] FIG. 2 is a perspective view showing an embodiment of the present invention, illustrating a telescopic leg device with a telescopic leg inserted into a main leg, the lowest step, and the lowest bracket metal fitting in an exploded state. [Figure 6] FIG. 2 is a perspective view showing an embodiment of a telescopic leg device with a telescopic leg inserted into a main leg, the lowest step bar, and the lowest bracket metal fitting in an assembled state. [Figure 7] Regarding the embodiment, (A) is a cross-sectional view of the telescopic leg device, (B) is an oblique view showing the portion where the lowest bracket fitting is attached to the telescopic leg device, and (C) is a cross-sectional view showing the portion where the lowest bracket fitting and the lowest tread are attached to the telescopic leg device. [Figure 8] FIG. 2 is a perspective view showing the telescopic leg device in the telescopic position with the lowest bracket fitting and the lowest tread attached; [Figure 9] Regarding the operation of the telescopic leg device, (A) is a cross-sectional view showing the state in which it is in a stored position, and (B) is a cross-sectional view showing a method of conducting a strength test in the state in which it is in a maximum extended position. [Figure 10] FIG. 2 is a perspective view showing a locking mechanism according to an embodiment of the present invention, illustrating a telescopic leg device with a telescopic leg inserted into a main leg, the lowest step, the lowest bracket fitting, and the locking mechanism in a disassembled state. [Figure 11] 1 is a perspective view showing a telescopic leg device with a telescopic leg inserted into a main leg, the lowest step, the lowest bracket metal fitting, and the locking mechanism in an assembled state, with respect to the locking mechanism; FIG. [Figure 12] FIG. 4 is a perspective view showing the lock mechanism in an exploded state. [Figure 13] FIG. 4 is an enlarged perspective view showing components of the locking mechanism. [Figure 14] 1 shows a safety member in a locking mechanism, where (A) is a perspective view showing its function, (B) is a perspective view from the front, (C) is a cross-sectional view of (B), (D) is a perspective view from the rear, and (E) is a cross-sectional view of (D). [Figure 15] 11 is a cross-sectional view showing a locked state in which the lock teeth are engaged with the rack teeth, with respect to the operation of the lock mechanism. FIG. [Figure 16]13 is a cross-sectional view showing an unlocked state in which the lock teeth are released from engagement with the rack teeth in relation to the operation of the lock mechanism. FIG. [Figure 17] 11 is a cross-sectional view showing the operation of the locking mechanism, illustrating a state in which the locking member is locked by the safety member in a locked state in which the locking teeth are engaged with the rack teeth. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Representative embodiments of the present invention will be described in detail below with reference to the drawings.

[0025] (Telescopic leg device)

[0026] FIG. 4 shows a stepladder as an example of aerial work equipment, in which the upper ends of a pair of legs 21, 21 are pivotally connected to each other by a pivot means so that the stepladder can be opened and closed, and is provided with a detachable opening prevention device that is connected in the open state.

[0027] The leg body 21 is formed in a ladder shape by installing multiple upper and lower steps 23, including the lowest step 23a, on a pair of main legs 22, 22 having a groove-shaped cross section arranged opposite to each other on the left and right.

[0028] The main landing gear 21 constitutes a telescopic landing gear device, and is provided with a telescopic leg 24 slidably inserted into the main landing gear 21, and a locking mechanism 25 which detachably locks and fixes the telescopic leg 24 in any telescopic position, including a stored position P1 in which the telescopic leg 24 is inserted into the main landing gear 21 over almost its entire length, and a maximum extended position P2 in which the telescopic leg 24 protrudes the furthest from the main landing gear 21.

[0029] The main leg 22, the telescopic leg 24, and the tread 23, 23a are each formed of an aluminum extrusion. The main leg 22 is formed of a groove-shaped member having a groove-shaped cross section that opens toward the inside of the tread 23, and has a bottom wall 22a that becomes the groove bottom of the groove and both side walls 22b, 22b as shown in FIG. 7(A). A first protrusion 26a and a second protrusion 26b are provided on the outer surfaces of both side walls 22b, 22b in the longitudinal direction. The first protrusion 26a is disposed near the bottom wall 22a, and the second protrusion 26b is disposed near the groove opening, and a flat side wall 22b is formed between the two protrusions 26a, 26b. A guide cylinder 27 is fixed to the lower end of the main leg 22, and the telescopic leg 24 is inserted through the guide cylinder 27 and slidably inserted into the inside of the main leg 22.

[0030] Of the upper and lower multiple steps of treads 23, the lowest step 23a is attached and supported by an arm portion 29 of a bracket metal fitting 28 fixed to the main landing gear 22. Although not shown, the upper and middle steps 23 may be configured so that the ends inserted into the grooves of the main landing gear 22 are fixed inside the grooves by connecting metal fittings, or may be fixed by bracket metal fittings provided on the outside of the grooves.

[0031] The telescopic leg 24 is formed from an aluminum profile having a cylindrical cross section, is inserted into the main leg 22, and is provided with a number of rack teeth 30a located on the side where the groove of the main leg 22 opens in the sliding direction of the telescopic leg 24. Specifically, a strip-shaped rack 30 provided with rack teeth 30a is inserted into the groove-shaped passage of the telescopic leg 24 and fixed thereto.

[0032] The telescopic legs 24 are As shown in FIG. 9(A), in the storage position P1, the retaining member 31 provided at the tail end of the telescopic leg 24 is located above the lowest step 23a inside the main landing gear 22, 9(B), in the maximum extended position P2, the anti-pull-out member 31 provided at the tail end of the telescopic leg 24 is configured to be located below the lowest step 23a inside the main landing gear 22. This allows the telescopic leg 24 to protrude from the main landing gear 22 over nearly its entire length, and this position is called the maximum extended position P2.

[0033] The locking mechanism 25 is disposed below the lowest tread 23a so as to be able to lock and fix the rack teeth 30a in the vicinity of the tail end of the telescopic leg 24 in the maximum extended position P2. The details of the locking mechanism 25 will be described later.

[0034] (Bracket fittings) The bracket metal fitting 28 will now be described in detail with reference to FIGS.

[0035] When attaching and supporting the lowest step 23a (hereinafter sometimes simply referred to as "step 23a"), a pair of bracket fittings 28, 28 are fixed to both side walls 22b, 22b of the main landing gear 22. As a result, the end of the step 23a is inserted between the opposing arm portions 29, 29, and is fixed and supported by fixing means 32 such as rivets.

[0036] The pair of bracket fittings 28, 28 are formed so as to be symmetrical to each other and include a fixing portion 33 that is attached in surface contact with the flat side wall 22b of the main leg 22, and a bone portion 34 that protrudes beyond the second protrusion 26b of the main leg 22 and extends along the groove opening edge of the main leg 22, and the arm portion 29 is extended from the bone portion 34.

[0037] Furthermore, a band-shaped rib portion 35 extending along the inside of the bone portion 34 is formed integrally with the bone portion 34 and faces the groove opening of the main leg 22. A grooved portion 36 is positioned between the fixing portion 33 and the rib portion 35 and is fitted onto the second protrusion 26b of the main leg 22.

[0038] In this case, as shown in the figure, the bracket metal fitting 28 is formed in an elongated shape extending along the main leg 22, and is integrally formed with an upper extension portion 28a extending upward beyond the arm portion 29, and a lower extension portion 28b extending downward beyond the arm portion 29. As will be described later, a locking mechanism 25 is attached to the lower extension portion 28b.

[0039] The upper extension 28a and the lower extension 28b are formed by extending the fixing portion 33, the bone portion 34, the rib portion 35 and the groove portion 36 in the axial direction of the main leg 22, and preferably, the length dimension L1 from the center position of the arm portion 29 (the position of the hole where the fixing means 32 is provided) to the lower end of the lower extension 28b and the length dimension L2 to the upper end of the upper extension 28a are formed so that L1≦L2. In this case, it is preferable that the rib portion 35 is extended vertically along the main leg 22 to constitute both the upper extension 28a and the lower extension 28b together with the fixing portion 33, but the rib portion 35 may be provided only on the upper extension 28.

[0040] The lower extension portion 28b for mounting the locking mechanism 25 is located below the arm portion 29, and by integrally forming the bone portion 34 into a wide plate shape, an upper support portion 37a and a lower support portion 37b are provided which are spaced apart from each other above and below.

[0041] In the illustrated embodiment, the bracket member 28 having the above-mentioned structure is provided by cutting an aluminum extrusion material.

[0042] Therefore, the bracket fitting 28 is attached to the main leg 22 with the grooved portion 36 fitted onto the second protrusion 26b and the fixing portion 33 attached to the side wall 22b in a surface contact state, and the fixing portion 33 is fixed to the side wall 22b by fixing means 38 such as rivets at multiple locations spaced apart in the longitudinal direction of the main leg 22. In the illustrated example, at least two fixing means 38 are provided on the fixing portion 33 of the upper extension portion 28a, and at least two fixing means 38 are provided on the fixing portion 33 of the lower extension portion 28b.

[0043] With the bracket fittings 28, 28 attached and fixed to the main landing gear 22, the end of the tread 23a is inserted between the arm portions 29, 29 and connected and fixed by the fixing means 32. At this time, the end of the tread 23a can be abutted against the rib portion 35 of the bracket fitting 28, making positioning easy.

[0044] (Bracket metal fittings function) As in the above-mentioned conventional technology, the telescopic landing gear system has a double-wall structure with the telescopic legs 24 inserted into the main landing gear 22, and therefore has greater strength than a normal column leg having a single-wall structure. However, when the telescopic legs 24 are extended, the overlapping area between the telescopic legs 24 and the main landing gear 22 forms a double-wall structure, but the upper area of ​​the main landing gear 22, bordered by the tail end of the telescopic legs 24, is a single-wall structure, resulting in a difference in strength between the two.

[0045] In relation to this point, the applicant has conducted strength tests in which a load of 900N was applied to the tip of the telescopic leg in the maximum extended position P2, and damage, deformation, etc. were measured. As described above, in the strength tests of the prior art, deformation of the main landing gear was observed in a position near the top of the lowest bracket metal fitting.

[0046] Therefore, for the telescopic leg device of the illustrated embodiment, a strength test was also conducted by applying a load of 900 N to the tip side of the telescopic leg 24 with the telescopic leg 24 in the maximum extended position P2 as shown in FIG. 9(B) and the main leg 22 fixedly supported by a jig near the arm portion 29 of the bracket fitting 28.

[0047] An inward bending strength test was conducted by applying a load F1 in the inward bending direction with a load of 900N, and an outward bending strength test was conducted by applying a load F2 in the outward bending direction, and the results were observed, and no deformation was visible in either the main landing gear 22 or the bracket metal fitting 28. This confirmed that the strength of the main landing gear 22 is sufficiently ensured by providing the bracket metal fitting 28 configured as described above, even if the bracket metal fitting 28 is made of aluminum.

[0048] (locking mechanism) 10 to 14 show the configuration of the lock mechanism 25, and FIGS. 15 to 17 show its operation.

[0049] The lock mechanism 25 constitutes a unit that is assembled by mounting a lock member 40, a spring 41, an operation cover 42, and a safety member 43 on a base metal fitting 39, and then covering the entire assembly with a housing cover 44 from above.

[0050] The base metal fitting 39 is formed by cutting an aluminum extrusion material, and has retaining grooves 46, 46 provided on both side edges of a base portion 45. As a result, the base metal fitting 39 is positioned between the lower extensions 28b, 28b of the bracket metal fittings 28, 28 by fitting the rib portions 35 of the bracket metal fittings 28, 28 into and retaining the retaining grooves 46, 46.

[0051] Upper and lower pivotal support portions 47a and 47b are formed integrally from both side edges of the base portion 45 and are disposed in an overlapping state on the upper and lower support portions 37a and 37b of the lower extension portion 28b, respectively. A pivot 48 (see FIG. 15) that supports the safety member 43 is inserted into the upper and upper support portions 47a and 37a in an overlapping state. A pivot 49 (see FIG. 15) of the lock member 40 is inserted into the lower support portion 47b and 37b in an overlapping state.

[0052] A guide rail 50 that protrudes like a ridge and extends vertically is integrally formed in the widthwise center of the base portion 45, and the guide rail 50 is cut out in the vertical center and lower end of the base portion 45 to create an upper window portion 51 and a lower window portion 52 that penetrate the base portion 45.

[0053] The locking member 40 has a support portion 53 which is rotatably supported on the pivot 40, an operating arm 54 which extends in a direction facing the lower window portion 52 of the base metal fitting 39, and an operating lever 55 which extends upward. The operating lever 55 has a protrusion 55a which faces the upper window portion 51 of the base metal fitting 39, and the support portion 53 is configured to be rotated in the forward direction by the spring 41.

[0054] The operation cover 42 is configured to cover the pivot support portion 53 of the lock member 40 and the operation lever 55, including the spring 41, and displays a locking indication 56 consisting of the letters "LOCK" or the like on the surface of the upper end portion of the finger receiving portion 42a that covers the operation lever 55.

[0055] As shown in Figs. 15 to 17, the locking member 40 is supported by the pivot 40 and is biased to rotate in the normal direction by the spring 41 while covered by the operation cover 42. The operating arm 54 is inserted through the lower window 52 and elastically contacts the rack 30 of the telescopic leg 24, and the locking tooth 54a at the tip of the operating arm 54 is engaged and fixed to the rack tooth 30a (this state is called the engaged state Q1). From the engaged state Q1, the operator presses the operating lever 55 through the operation cover 42 with his / her fingertip, and rotates the locking member 40 in the reverse direction against the spring 41 until the protrusion 55a enters the upper window 51. The operating arm 54 separates from the rack tooth 30a and releases the engagement of the locking tooth 54a (this state is called the released state Q2). In the released state Q2, the telescopic leg 24 is allowed to slide.

[0056] The safety member 43 is positioned to face the operating lever 55 of the locking member 40 from above, and when moved upward, it engages and locks the locking member 40, which is in the locked state Q1, so that it cannot rotate (this upward movement position is called the locked position R1), thereby preventing the locking member 40 from entering the released state Q2.

[0057] As shown in FIG. 14, the safety member 43 is integrally formed by sequentially arranging a support portion 57, an operating portion 58, and a locking portion 59 from top to bottom, and is supported so as to be freely movable up and down by inserting the spindle 48 into a long hole 60 provided in the support portion 57. The upward movement position (FIG. 17) is the locked position R1, and the downward movement position (FIGS. 15 and 16) releases the lock (this position is called the unlocked position R2).

[0058] At this time, a holding piece 61 is provided inside the support part 57 to elastically hold the side surface of the support shaft 48 so as not to move the safety member 43 loosely when it is moved to the locked position R1 and the unlocked position R2. The safety member 43 can be moved up and down against the holding force of the holding piece 61 by pushing the operating part 58 with the fingertip of an operator, and is preferably configured so that a clicking sensation is given to the fingertip when the holding force is applied and when the holding force is released.

[0059] The holding piece 61 is formed integrally with the safety member 43 from, for example, flexible plastic, and holds the safety member 43 so that it does not descend under its own weight when the safety member 43 is moved upward to the locked position R1. In other words, if there is no holding by the holding piece 61, the safety member 43 will descend to the unlocked position R2 under its own weight and stop at that position. Therefore, no special means is required to hold the safety member 43 at the unlocked position R2.

[0060] When the safety member 43 is moved upward to the locked position R1, the locking portion 59 is positioned between the protrusion 55a of the operating lever 55 of the lock member 40 and the upper window portion 51 of the base metal fitting 39. This prevents the operating lever 55 from rotating toward the released state Q2.

[0061] When the safety member 43 is moved downward to the unlocked position R2, the unlocking window 62 formed adjacent to the locking portion 59 is positioned between the protrusion 55a of the operating lever 55 in the lock member 40 and the upper window portion 51 of the base metal fitting 39. This allows the operating lever 55 to rotate toward the released state Q2.

[0062] In order to guide the vertical movement of the safety member 43, with the support shaft 48 inserted and held in the long hole 60, the guide grooves 63a, 63b formed on the back surfaces of the support portion 57 and the locking portion 59 are fitted freely into the guide rail 50 of the base metal fitting 39 so as to be able to slide freely.

[0063] The operation unit 58 of the safety member 43 is provided with a concealing portion 64. When the safety member 43 is moved upward to set it to the locked state R1, the concealing portion 64 is configured to retreat from above the lock indication 56 of the operation cover 42 to make the lock indication 56 (the characters LOCK) visible, and conversely, when the safety member 43 is moved downward to set it to the unlocked state 2, the concealing portion 64 is configured to be positioned above the lock indication 56 to conceal the lock indication 56 (the characters LOCK) so that it cannot be seen.

[0064] The locking member 40 covered with an operating cover 42 is supported on the base metal fitting 39 together with the spring 41 by a pivot 49, and the safety member 43 is supported on a support shaft 48. In this state, the housing cover 44 is placed on top and fixed in place, thereby assembling the locking mechanism 25 unit.

[0065] The housing cover 44 has a window opening 65 for exposing the finger receiving portion 42a of the operation cover 42 which covers the operation lever 55 of the lock member 40, and the operation portion 58 of the safety member 43. The support portion 57 located directly above the operation portion 58 of the safety member 43 is exposed to the inside of the housing cover 44, and when the safety member 43 is lowered to the unlocked state R2, an unlocked indication 66 consisting of the letters "FREE" or the like is displayed on the surface of the portion that appears in the window opening 65.

[0066] Therefore, when the safety member 43 is moved downward to the unlocked position R2, the locked indicator 56 is hidden by the concealing portion 64 so as not to be visible, whereas the unlocked indicator 66 appears so as to be visible in the window opening 65. Therefore, by seeing this, the user can know that the operating lever 55 of the locking member 40 is in a state where it can be pushed in, that is, by changing the locking state Q1 to the released state Q2, the telescopic leg 24 can be extended or retracted.

[0067] From this state, when the safety member 43 is moved upward to the locked position R1, the unlocked indicator 66 retreats from the window opening 65 and is hidden inside the housing cover 44, whereas the concealing portion 64 moves upward to expose and become visible the locked indicator 56. Therefore, by seeing this, the user can know that the operating lever 55 of the locking member 40 cannot be pushed in, that is, it cannot be changed from the engaged state Q1 to the released state Q2, and the telescopic leg 24 cannot be extended or retracted.

[0068] (action) 15 shows a state in which the lock member 40 is in the engaged state Q1 and the safety member 43 is moved downward to the unlocked position R2. At this time, the lock indication 56 (the characters LOCK) is hidden from view by the concealing portion 64, and the unlock indication 66 (the characters FREE) appears in the window opening 65. The safety member 43 has moved the unlock window 62 to a position communicating with the upper window portion 51 of the base metal fitting 39.

[0069] Therefore, as shown in FIG. 16, when the user pushes in finger receiving portion 42a with his / her fingertip to push operating lever 55 and rotates locking member 40 in the reverse direction against spring 41, operating arm 54 retracts and moves locking tooth 54a away from rack tooth 30a, allowing telescopic leg 24 to move in the telescopic direction.

[0070] 17 shows a state in which the safety member 43 has been moved upward to the locked position R1 with the lock member 40 in the engaged state Q1. At this time, the unlocked indicator 66 (the characters FREE) is hidden inside the housing cover 44, and the concealing portion 64 is moved upward to make the locked indicator 56 (the characters LOCK) visible. The safety member 43 moves the locking portion 59 onto the upper window portion 51 of the base metal fitting 39 to face the protrusion 55a of the operating lever 55 of the lock member 40, thereby preventing the lock member 40 from rotating reversely against the spring 41 to the released state Q2.

[0071] However, with repeated up and down movements of the safety member 43 over a long period of use, the holding piece 61 may gradually become fatigued and may no longer be able to properly hold the safety member 43. In this case, as described above, the safety member 43 will descend and stop under its own weight, and this stopping position is the unlocked position R2, so the user can push the operating lever 55 and there will be no hindrance to the extension and retraction operation of the telescopic leg 24. [Explanation of symbols]

[0072] 21 Legs 22 Main landing gear 22a Bottom wall 22b side wall 23, 23a stepping sill 24 Telescopic legs 25 Locking mechanism 26a 1st protrusion 26b 2nd protrusion 27 Guide cylinder 28 Bracket fittings 28a Upper extension 28b Lower extension 29 Arm section 30 racks 30a rack teeth 31 Anti-pullout member 32 Fixing means 33 Fixed part 34 Bones 35 Rib section 36 Groove 37a Upper support part 37b Lower support part 38 Fixing means 39 Base bracket 40 Locking member 41 Spring 42 Operation cover 42a Finger rest 43 Safety Components 44 Housing cover 45 Base 46 Retaining groove 47a Upper shaft support 47b Lower support 48 Spindle 49 Axis 50 Guide rail 51 Upper window section 52 Lower window part 53 axis branch 54 Actuating Arm 54a locking teeth 55 Operating lever 55a protrusion 56 Locked sign 57 Support part 58 Control section 59 Locking section 60 long hole 61 Holding piece 62 Unlocking window 63a, 63b Guide groove 64 Concealment 65 Window Opening 66 Unlocked indicator

Claims

1. In an aerial work device, a ladder-like leg body is formed by installing multiple steps on the upper and lower main legs that are arranged opposite to each other and have a groove-shaped cross section, The main landing gear (22) constitutes a telescopic landing gear device including a telescopic landing gear (24) slidably inserted into the main landing gear and a locking mechanism (25) for detachably locking and fixing the telescopic landing gear in any telescopic position including a stored position (P1) in which the telescopic landing gear is inserted into the main landing gear over substantially its entire length and a maximum extended position (P2) in which the telescopic landing gear is protruded the furthest from the main landing gear, The telescopic legs (24) are configured such that, when in the stowed position (P1), the tail end of the telescopic legs is positioned above the lowest step (23a) inside the main landing gear, and, when in the maximum extended position (P2), the tail end of the telescopic legs is positioned below the lowest step (23a) inside the main landing gear, and the locking mechanism (25) is disposed below the lowest step, The lowest step (23a) is supported by an arm portion (29) of a bracket (28) fixed to the main landing gear, The bracket fitting (28) is integrally formed with an upper extension portion (28a) that extends upward beyond the arm portion along the main leg.

2. In an aerial work device, a ladder-like leg body is formed by installing multiple steps on the upper and lower main legs that are arranged opposite to each other and have a groove-shaped cross section, The main landing gear (22) constitutes a telescopic landing gear device including a telescopic landing gear (24) slidably inserted into the main landing gear and a locking mechanism (25) for detachably locking and fixing the telescopic landing gear in any telescopic position including a stored position (P1) in which the telescopic landing gear is inserted into the main landing gear over substantially its entire length and a maximum extended position (P2) in which the telescopic landing gear is protruded the furthest from the main landing gear, The telescopic legs (24) are configured such that, when in the stowed position (P1), the tail end of the telescopic legs is positioned above the lowest step (23a) inside the main landing gear, and, when in the maximum extended position (P2), the tail end of the telescopic legs is positioned below the lowest step (23a) inside the main landing gear, and the locking mechanism (25) is disposed below the lowest step, The lowest step (23a) is supported by an arm portion (29) of a bracket (28) fixed to the main landing gear, the bracket metal fitting (28) is integrally formed with an upper extension portion (28a) extending upward beyond the arm portion along the main leg and a lower extension portion (28b) extending downward beyond the arm portion along the main leg, and the locking mechanism (25) is attached via the lower extension portion; A telescopic leg device for aerial work equipment, characterized in that a length dimension L1 from the vertical center position of the arm portion (29) to the lower end of the lower extension portion (28b) and a length dimension L2 to the upper end of the upper extension portion (28a) are formed so that L1≦L2.

3. The bracket metal fitting (28) is integrally formed with a fixing portion (33) which is fixed to the side wall (22b) of the main landing gear and a rib portion (35) which faces the groove opening of the main landing gear, 3. The telescopic leg device for aerial work equipment according to claim 1, wherein the upper extension portion (28a) is formed by extending the fixing portion (33) and the rib portion (35) along the main leg.

4. The bracket metal fitting (28) is integrally formed with a fixing portion (33) which is fixed to the side wall (22b) of the main landing gear and a bone portion (34) which is disposed along the groove opening edge of the main landing gear, and the arm portion (29) is integrally extended from the bone portion (34), 3. The telescopic leg device for aerial work equipment according to claim 2, wherein the lower extension portion (28b) and the upper extension portion (28a) are formed by extending the fixing portion (33) and the bone portion (34) along the main leg.

5. The bracket metal fitting (28) is integrally formed with a fixing portion (33) fixed to the side wall (22b) of the main landing gear, a bone portion (34) extending along the groove opening edge of the main landing gear, and a rib portion (35) extending along the inside of the bone portion, and the arm portion (29) is integrally extended from the bone portion, 3. The telescopic leg device for a high-altitude work device according to claim 2, wherein the lower extension portion (28b) and the upper extension portion (28a) are formed by extending the fixing portion (33), the bone portion (34) and the rib portion (35) along the main leg.

6. The lock mechanism (25) is composed of a lock member (40) having lock teeth (54a) that can be disengaged from and engaged with rack teeth (30a) arranged in a row in the sliding direction of the telescopic leg (24), and a safety member (43). The lock member (40) is configured such that an operating arm (54) having lock teeth is extended from a pivotal support part (53) rotatably supported about a horizontal axis, and an operating lever (55) is extended from the upper side thereof, and the lock teeth (54a) are engaged with the rack teeth (30a) by urging the pivotal support part (53) to rotate in the forward direction by a spring (41), and the lock teeth (54a) are disengaged from the rack teeth (30a) by pushing in the operating lever (55) and rotating the pivotal support part (53) in the reverse direction. The telescopic leg device for aerial work equipment according to claim 1, 2, 3, 4 or 5, characterized in that the safety member (43) faces the operating lever (55) of the locking member from above, is provided so as to be freely movable in the vertical direction between a locked position (R1) and an unlocked position (R2), and is configured to prevent the operating lever (55) from being pushed in when moved up to the locked position, and to allow the operating lever (55) to be pushed in when moved down to the retracted position, and further comprises a retaining piece (61) that retains the safety member (43) at the locked position (R1) so as not to move downward under its own weight.

Images