Telescopic leg device for high-altitude work equipment

Abstract

To provide a telescopic leg device for use in a high lift work device.SOLUTION: A lock mechanism (15) for engageably-disengageably locking and fixing a telescopic leg (14) slidably inserted in a main leg (12) is provided in the vicinity of a lower step tread (13c), an operation mechanism (18) for engaging / disengaging the lock mechanism is provided in the vicinity of an upper step tread (13b), an interlocking mechanism (19) for connecting both mechanisms in an interlocking manner is made of a bendable transmission cable (35) in which an inner cable (37) is slidably inserted into an outer cable (36), an intermediate section (35c) extending between an operation side end section (35a) connected to the operation mechanism and an operation side end section (35b) connected to the lock mechanism is arranged in a linear state along an outer surface of the main leg (12) located on a rear side (R) of the leg with respect to a length of the transmission cable, and the outer cable in the intermediate section is held in a non-bendable state by an elongated holding tool (40) fixed to the outer surface of the main leg (12).SELECTED DRAWING: Figure 9

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, is configured to be openable and closable by arranging a pair of legs opposite each other and pivoting the upper ends of both legs to each other with a pivoting means, and is used for high-altitude work by engaging a detachable opening prevention means in the open state.

[0003] The legs are formed in a ladder shape by attaching multiple upper and lower step rails to a pair of main legs arranged side by side on the left and right.

[0004] The main landing gear is provided as a telescopic landing gear device. The telescopic landing gear device is provided with a telescopic leg slidably inserted into the main landing gear, a locking mechanism provided with a locking means that can be freely engaged and disengaged to engage and fix the telescopic leg, and an operating mechanism provided with an operating means for operating the locking means.

[0005] The telescopic leg device has the advantage that by extending the telescopic legs, the overall length of the leg body can be increased, making it possible to work at higher altitudes, and by adjusting the length of the extended position of the telescopic legs of multiple main legs, it can be installed to accommodate uneven ground.

[0006] Generally, the locking means is provided near the lower end of the main leg and is composed of a locking body that is rotatably supported on a shaft so that it engages with rack teeth arranged in a row on the telescopic leg by rotating in a forward direction and releases the engagement by rotating in a reverse direction, and the locking body is normally held in the engaged state by being resiliently biased in the forward direction by a spring. Therefore, to release the engagement, the user needs to operate the lever piece of the locking body with his fingertip and rotate it in the reverse direction against the spring.

[0007] However, the configuration in which the locking body is rotated against the spring by operating the lever requires the user to perform cumbersome tasks such as lifting the stepladder or lowering himself / herself each time. Moreover, such cumbersome tasks must be performed for all of the main landing gear (usually four).

[0008] Therefore, it is desirable to provide a remote control mechanism for the locking mechanism of the telescopic leg device in the high-altitude work device, which allows the locking mechanism to be operated from an upper position, and this has already been proposed. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent No. 6895798 [Patent Document 2] Patent No. 6860987 [Patent Document 3] Patent No. 6761689 [Patent Document 4] JP 2005-61033 A Summary of the Invention [Problem to be solved by the invention]

[0010] The present applicant has proposed a locking mechanism for a telescopic leg device in an aerial work device equipped with a remote control mechanism (Patent Documents 1 to 3).

[0011] However, when providing a high-altitude work device equipped with such a remote control mechanism, it is necessary to minimize the number of parts as much as possible, to keep the cost of newly required parts low, and to ensure high safety. Considering these points, it is preferable that the interlocking mechanism provided between the locking mechanism at the lower position and the operating mechanism at the upper position utilizes a transmission cable that is arranged for transmitting power in vehicles such as bicycles and mechanical devices, rather than using the relatively large-scale structures proposed in Patent Documents 1 to 3.

[0012] This type of power transmission cable is composed of a flexible, bendable cable with an inner cable made of a wire slidably inserted into an outer cable made of a flexible tube. Therefore, there are no restrictions on the installation position, and it is possible to freely form a wiring path. In addition, the installation work is simple, and the parts cost is low.

[0013] In this regard, Patent Document 4 proposes utilizing a transmission cable in a remote control mechanism for the locking mechanism of a telescopic leg device.

[0014] Patent Document 4 describes a basic configuration of a conventional telescopic leg device in which a telescopic leg is slidably inserted into the main leg, a locking body is journalled at the lower end of the main leg, and a lever piece of the locking body faces above the lower step. However, in contrast to this basic configuration, an operating lever is provided near the top plate, the operating lever and the lever piece of the locking body are connected by a transmission cable, and the locking body is rotated by pulling the operating lever, thereby releasing the engagement of the telescopic leg.

[0015] However, in Patent Document 4, in order to provide a wiring path for the power transmission cable inside the legs, a mold material with an auxiliary frame with a C-shaped cross section is molded on the inside surface of the main landing gear (the side facing the tread) and the power transmission cable is wired inside the auxiliary frame. As a result, the main landing gear is formed about twice as thick as usual, which not only increases manufacturing costs but also shortens the tread, reducing the tread surface for the user to place their feet on, creating safety problems.

[0016] As has been pointed out in the past, the operability of the inner cable in a power transmission cable is determined by the amount of compression of the outer cable in the longitudinal direction. This characteristic is affected by the routing path of the power transmission cable. However, in Patent Document 4, the power transmission cable is routed in the wide internal space of the auxiliary frame in a state where it can be freely bent, and this does not take into account the characteristics of the power transmission cable.

[0017] Figure 10 shows the problems caused by the wiring route in a configuration where a transmission cable 1 is routed between an operation unit A and an operating unit B that are vertically separated by a distance L, and the operating unit B is operated via the transmission cable 1 by operating the operation unit A.

[0018] In the figure, the transmission cable 1 is inserted into the outer cable 2 with the upper end 2a of the outer cable 2 fixed near the operation unit A and the lower end 2b fixed near the operating unit B. Of the insertion ends of the inner cable 3 inserted into the outer cable 2, the upper end 3a is fixed to the operation unit A and the lower end 3b is fixed to the operating unit B.

[0019] As is well known, the inner cable 3 is inserted into the outer cable 2 with play and is slidable. When the upper end 3a of the inner cable 3 is pulled by the operation unit A, in order to preferably pull and drive the operating unit B by the lower end 3b at the same time, it is necessary to maintain a predetermined tension in the inner cable 3. At this time, the tension of the inner cable 3 increases when the outer cable 2 is compressed in the length direction and decreases when the compression is relaxed. That is, the balance between the tension and play of the inner cable 3 is determined by the length of the outer cable 2.

[0020] Figure 10 shows a case where the wiring route changes under the same conditions where the total length of the outer cable 2 (total length including both fixed ends) and the effective length of the inner cable 3 (total length including both ends fixed to the operation unit A and the operating unit B) are the same. The outer cable 2 of the transmission cable 1A shown by the solid line holds the total length L1 in a state compressed by a predetermined amount in the length direction. On the other hand, the transmission cable 1B shown by the chain line holds the total length L2 in a state where the outer cable 2 is relaxed by bending the middle part. Therefore, there is a difference of L1 < L2.

[0021] The power transmission cable 1A shown by the solid line has the outer cable 2 compressed by a predetermined amount and the inner cable 3 left with an appropriate amount of play, so that when the upper end 3a is pulled, the lower end 3b can be pulled in conjunction with it at the same time, and there are no problems with operability.

[0022] In contrast, in the power transmission cable 1B shown by the chain line, the compression of the outer cable 2 is loosened, which increases the play of the inner cable 3, so that when the upper end 3a is pulled, the lower end 3b does not move in tandem at the same time, causing problems in operability. Moreover, because the middle portion of the outer cable 2 is curved or bent, the sliding resistance of the inner cable 3 increases, requiring a large operating force and reducing the durability of the cable.

[0023] In the case of Patent Document 4, the power transmission cable is routed within the internal space of the auxiliary frame that is integrally molded with the main leg, so the routing path of the outer cable will not change due to external forces, etc.; however, when workers at an assembly plant where stepladders are manufactured load the power transmission cable into the internal space of the auxiliary frame, the routing path of the outer cable may sometimes be straight and sometimes bent into an arc, and so on, and different routes may be supplied as the finished product.

[0024] The above problem has been solved in the case of power transmission cables arranged for power transmission in vehicles such as bicycles and mechanical devices by providing an adjustment means such as a screw on the fixing metal fitting at the end of the outer cable.

[0025] However, since the purpose of the telescopic leg device in this case is to prevent the user from being forced to perform complicated tasks, as described above, it is not appropriate to require the user to adjust the end fixing bracket of the outer cable using the adjustment means.

[0026] An object of the present invention is to provide a telescoping leg device for an aerial work device that solves the above-mentioned problems. [Means for solving the problem]

[0027] The present invention provides a means for working at height, which is comprised of a pair of legs arranged opposite each other and pivoted so as to be freely opened and closed, with multiple steps of treads installed on main legs arranged side by side and having a grooved cross section, and the pair of legs arranged opposite each other being the back side and the opposite side being the front side for a user to ascend and descend, and the main legs are provided with telescopic legs slidably inserted into the main legs, a locking mechanism having locking means for detachably engaging and fixing the telescopic legs, an operating mechanism having operating means for operating the locking means, and an interlocking mechanism for interlocking and connecting the operating means and the locking means, and the locking mechanism is provided near both ends of the lower step tread, and the operating mechanism is provided near both ends of the upper step tread, and the interlocking mechanism is made of a flexible tube. the operating side end fixes the lower end of the outer cable to a fixed part of the locking mechanism and fastens the lower end of the inner cable to the locking means, the operating side end fixes the upper end of the outer cable to a fixed part of the operating mechanism and fastens the upper end of the inner cable to the operating means, the intermediate part extending between the operating side end and the operating side end of the transmission cable is arranged in a straight state along the outer surface of the main leg located on the back of the leg body, and the outer cable in the intermediate part is held unbendably by a long retainer fixed to the outer surface of the main leg.

[0028] In a preferred embodiment of the present invention, the retainer comprises a strip-shaped plate portion which is secured by a fastener in a state of being overlapped on the outer surface of the main landing gear located on the underside of the leg body, and a retaining groove which is bent from the strip-shaped plate portion along an edge of the outer surface of the main landing gear facing the tread bar, and has an approximately U-shaped cross section, and an outer cable at the middle portion of the power transmission cable is fitted into the retaining groove.

[0029] The locking mechanism includes a housing provided at the end of the lower step bar, a locking body that is rotatably supported inside the housing and engages with the telescopic leg when rotated forward and disengages when rotated backward, and a lock spring that biases the locking body in the forward direction. The relay member is interlocked with the locking body via a horizontal shaft portion so as to drive the locking body in the reverse direction when it receives a pulling force, and the lower end of an outer cable at the working side end of the transmission cable is fixed to the housing and the lower end of an inner cable is fixed to the relay member. The relay member has an unlocking button that protrudes from a portion near the horizontal shaft portion, passing through the housing and protruding to the outside, and when the relay member is pushed from outside the housing via the unlocking button, the locking body is rotated in the reverse direction.

[0030] The upper tread on which the operating mechanism is provided constitutes a tread body consisting of a hollow profile formed by a back wall facing the back side of the leg body, a front wall facing the front side, and an upper wall and a lower wall, and the operating mechanism is composed of an operating lever that is inserted into the longitudinal direction of the tread body and extended from an operating body that is pivotally supported so as to be freely rotatable in the vertical direction, connected to the lower wall and protruding from the back wall, a fixed body attached to the back wall, and a movable body that faces the fixed body and is attached to the operating lever, and the upper end of the outer cable at the operating side end of the transmission cable is fixed to the fixed body, and the upper end of the inner cable is fixed to the movable body in a state where it is bent downward via a guide means of the fixed body. Effect of the Invention

[0031] According to the present invention, a telescopic leg device 20 is provided which is composed of a telescopic leg 14 slidably inserted into the main leg 12, a detachable locking mechanism 15 which engages and fixes the telescopic leg 14, an operating mechanism 18 which activates the locking mechanism, and an interlocking mechanism 19 which interlocks and connects the operating mechanism and the locking mechanism.The locking mechanism 15 is provided near both ends of the lower step and the operating mechanism 18 is provided near both ends of the upper step, and remote operation is possible via the interlocking mechanism 19, so that a user-friendly telescopic leg device 20 can be provided.

[0032] In this case, the interlocking mechanism 19 is composed of a flexible transmission cable 35 in which an inner cable 37 made of a wire is inserted so as to be able to slide freely through an outer cable 36 made of a flexible tube, and thus has the advantages of being easy to assemble and low cost.

[0033] Furthermore, the transmission cable 36 is arranged in a straight line with its intermediate portion 35c extending along the outer surface of the main leg 12 located on the back side R of the leg body 11 between the operating side end portion 35a near the upper end which is connected to the operating mechanism 18, and the actuating side end portion 35b near the lower end which is connected to the locking mechanism 15, and the outer cable 36 of the intermediate portion 35c is held unbendingly by a long retainer 40 fixed to the outer surface of the main leg 12, thereby providing an interlocking mechanism 19 with excellent interlocking operability and smooth sliding properties.

[0034] In particular, since the middle section 35c of the power transmission cable 35 is kept straight over its entire length, the compression of the outer cable 36 will not loosen due to repeated operation over a long period of time, and the interlocking operability and smooth sliding properties described above will not be impaired. Moreover, since the middle section 35c of the power transmission cable 35 is disposed on the rear side R of the main leg 12, it will not get in the way of the user ascending or descending the leg 11, and furthermore, it will not be hit by foreign objects, so there will be no change in posture from a straight position to a bent position due to external forces, and in this respect too, the interlocking operability and smooth sliding properties described above will not be impaired. [Brief description of the drawings]

[0035] [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. 1 is a perspective view showing the back side of one of a pair of legs that constitute a stepladder according to one embodiment of the present invention. [Diagram 3] FIG. 2 is an exploded perspective view of a locking mechanism in the telescopic leg device according to the embodiment. [Figure 4] FIG. 11 is a cross-sectional view showing a locked state with respect to the operation of the locking mechanism. [Diagram 5] FIG. 11 is a cross-sectional view showing an unlocked state with respect to the operation of the locking mechanism. [Figure 6] Regarding the embodiment, (A) is an oblique view showing one of the main legs of the leg body from the back side, (B) is a cross-sectional view showing an operating body provided on the upper step bar, and (C) is a cross-sectional view showing the state when the operating lever of the operating body is operated. [Figure 7] FIG. 2 is a perspective view showing a fixed body and a movable body of an operating mechanism provided on an upper step bar before installation. [Figure 8] Regarding the operation of the operation mechanism, (A) is a perspective view showing a state in which the operation lever is not operated, and (B) is a perspective view showing a state in which the operation lever is operated. [Figure 9] 1A is a perspective view showing one of the main legs of the leg body from the rear side, and FIG. 1B is a cross-sectional view showing the portion where the holder is attached to the main leg, with respect to the holder that holds the middle part of the transmission cable. [Figure 10] 1 is an explanatory diagram showing characteristics and problems of a power transmission cable. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] Representative embodiments of the present invention will be described in detail below with reference to the drawings.

[0037] (High altitude work equipment)

[0038] FIG. 1 shows a conventional stepladder for carrying out the present invention as an example of a high-altitude working device, in which a pair of legs 11, 11 are arranged opposite each other and their upper ends are pivotally connected to each other by a pivoting means, so that the stepladder can be opened and closed. When the stepladder is in the open position, it can be used for high-altitude working by engaging a detachable opening prevention means.

[0039] For this reason, in the following description, the mutually opposing sides of the pair of legs 11, 11 are referred to as a back side R, and the opposite side is referred to as a front side F on which a user as an operator ascends and descends.

[0040] The legs 11 form a ladder-like frame by installing multiple steps 13 on top and bottom of a pair of main legs 12, 12 arranged side by side on the left and right. In the illustrated example, a three-step configuration is provided with one upper step 13b and one lower step 13c above and below a middle step 13a, but a four-step or more configuration with multiple upper steps 13b and lower steps 13c may also be used.

[0041] To form a telescopic landing gear device, telescopic legs 14 are slidably inserted into the main landing gear 12, and a locking mechanism 15 is provided to releasably lock and fix the telescopic legs 14 in a stored position where almost the entire length of the telescopic legs 14 is inserted inside the main landing gear 12, a maximum extended position where the telescopic legs protrude the furthest from the main landing gear 12, and a position where the telescopic legs 14 are arbitrarily extended or retracted between these positions. The locking mechanism 15 is provided near both ends of the lower step bar 13c of the lowest step, and fixes the telescopic legs 14 so that they cannot slide when in a locked position by locking, and allows the telescopic legs 14 to slide freely when unlocked by releasing the locking.

[0042] (Embodiments of the present invention) 2 to 9 show one embodiment of the present invention.

[0043] The main leg 12, the telescopic leg 14, and the step bar 13 are each formed of an aluminum extrusion. The main leg 12 is formed of a groove-shaped member having a groove-shaped cross section that opens toward the inside facing the step bar 13, and as shown in FIG. 9(B), it has a bottom wall 12a that becomes the groove bottom of the groove and both side walls 12b, 12c, one side wall 12b faces the front side F, and the other side wall 12c faces the back side R. The both side walls 12b, 12c integrally form inward ribs 12d, 12d that are bent toward both sides of the groove opening. Although not shown, a guide cylinder is fixed to the lower end of the main leg 12, and the telescopic leg 14 is inserted through the guide cylinder and slidably inserted inside the main leg 12.

[0044] As shown in FIG. 2, the upper and lower stages of treads 13 are attached to and supported by arms of bracket fittings 16 fixed to both side walls 12b, 12c of the main landing gear 12, respectively.

[0045] The telescopic leg 14 is formed from an aluminum profile having a cylindrical cross section, and as shown in Figures 4 and 5, a number of rack teeth 17a are provided in the sliding direction relative to the main leg 12, and the rack teeth face the groove opening of the main leg 12. Specifically, a strip-shaped rack 17 with rack teeth 17a is inserted and fixed in the groove-shaped passage of the telescopic leg 14.

[0046] (Telescopic leg device) 2, a telescopic leg device 20 is made up of the telescopic leg 14, the locking mechanism 15, an operating mechanism 18 that activates the locking mechanism 15, and an interlocking mechanism 19 that interlocks the operating mechanism 18 and the locking mechanism 15. In this case, the locking mechanism 15 is provided near the end of the lower step 13c, while the operating mechanism 18 is provided on the upper step 13b, and the interlocking mechanism 19 is provided along the back side R of the main leg 12.

[0047] (locking mechanism) 3 to 5 show the locking mechanism 15. The locking mechanism 15 is inserted between the side plate portions of the bracket metal fitting 16 that connects the lower step 13c to the main landing gear 12, and is housed within a housing 22 that is fixed by a through bolt 21.

[0048] A locking body 23 is rotatably supported inside the housing 22 with the through bolt 21 as a support shaft 21a, and the locking body 23 has a locking arm 23a extending obliquely downward and provided with a plurality of locking teeth 23b at the tip end thereof.

[0049] When the locking body 23 rotates in a direction in which the locking arm 23a approaches the rack 17 (hereinafter, this rotation direction is referred to as the "normal direction"), the locking body 23 performs a locking operation in which the locking teeth 23b are engaged with the rack teeth 17a, and when the locking arm 23a rotates in a direction in which the locking arm 23a moves away from the rack 17 (hereinafter, this rotation direction is referred to as the "reverse direction"), the locking body 23 performs an unlocking operation in which the locking teeth 23b are disengaged from the rack teeth 17a. At this time, a locking spring 27 made of a coil spring that is inserted around the support shaft 21a is provided. The locking spring 27 is compressed by elastically contacting one end with the V-groove 23d of the locking body 23 and elastically contacting the other end with the housing 22 or the main leg 12, so that the locking body 23 is elastically biased in the normal direction by the locking spring 27 and always performs a locking operation, and when the locking arm 23 rotates in the reverse direction against the locking spring 27, the locking body 23 performs an unlocking operation.

[0050] An indicator means 24 that indicates whether the lock body 23 is in the locked state or the unlocked state is provided in the housing 22. The indicator means 24 is composed of a button 25 that is interlockingly connected to the lock body 23, and a pushing portion 25a at the tail end of the button 25 is brought into contact with an operating piece 23c of the lock arm 23a, and the pushing portion 25a is resiliently urged by a spring 26 toward the operating piece 23c.

[0051] As shown in Fig. 4, when the lock body 23 performs a locking operation, the button 25 is moved to a position where the pushing portion 25a follows the operating piece 23c, that is, to the locked position. As shown in Fig. 5, when the lock body 23 performs an unlocking operation, the operating piece 23c pushes the pushing portion 25a, so that the button 25 is moved to a position where it protrudes outside the housing 22, that is, to the unlocked position.

[0052] In the illustrated embodiment, the locked position of button 25 is a position where the tip of the button does not protrude significantly from housing 22 (in the illustrated example, the tip surface is nearly flush with the outer surface of the housing), and the unlocked position is a position where the tip of the button protrudes significantly from housing 22.

[0053] In this way, the indicator means 24 constitutes a safety confirmation device that enables the user to visually confirm the position of the button 25 and thereby confirm whether the lock mechanism 15 is in the locked state or the unlocked state.

[0054] (Motion transmission mechanism) A motion transmission mechanism is provided inside the housing 22 to enable the lock body 23 to be rotated in the reverse direction from the locked state to the unlocked state when it receives a pulling force from the interlocking mechanism 19 described later.

[0055] An unlock arm 28 extending obliquely upward in the opposite direction to the lock arm 23a is provided on the lock body 23, and when the unlock arm 28 is pulled up, the lock body 23 rotates in the reverse direction, and a relay member 29 is provided to perform this pulling.

[0056] The relay member 29 has a connecting cylinder portion 29a at its upper portion to which the interlocking mechanism 19 described below is connected, and is pivotally connected to the unlock arm 28 via a horizontal shaft portion 29b provided at its lower portion so as to be freely rotatable.

[0057] As a result, when an upward driving force is applied to the interlocking mechanism 19, the relay member 29 appropriately pulls up the unlock arm 28 and rotates the lock body 23 in the reverse direction, as shown in Fig. 5. When the upward driving force is released from the interlocking mechanism 19 in this state, the lock body 23 is rotated in the forward direction by the lock spring 27, as shown in Fig. 4, and at that time, the relay member 29 located between the unlock arm 28 and the interlocking mechanism 19 appropriately pulls down the interlocking mechanism 19 while changing its position.

[0058] The relay member 29, which is interlocked with the lock body 23 via the horizontal shaft portion 29a, has an unlock button 29E protruding from a portion near the horizontal shaft portion 29a and projecting to the outside through a window hole 22b of the housing 22. When the unlock button 29E is pressed from outside the housing 22, the horizontal shaft portion 29a of the relay member 29 rotates the unlock arm 28 in the clockwise direction in the figure, thereby rotating the lock body (23) in the reverse direction and performing an unlocking operation.

[0059] 4 and 5, when the lock body 23 is performing a locking operation, the unlock button 29E of the relay member 29 is moved to a locked position protruding largely from the window hole 22b (FIG. 4), and when the lock body 23 is performing an unlocking operation, the unlock button 29E is moved to an unlocked position retracted from the locked position (FIG. 5). Thus, the unlock button 29E functions as an indicator means 24a that indicates whether the lock body 23 is in the locked or unlocked state by allowing the user to visually recognize the position from outside the housing 22.

[0060] Therefore, in this way, when the indicator means 24a is constituted by the lock release button 29E, the indicator means 24 constituted by the above-mentioned button 25 does not necessarily need to be provided.

[0061] (operation mechanism) 6 to 8 show the operating mechanism 18, which is provided on the upper step 13b.

[0062] As shown in FIG. 6, the upper step bar 13b is made of a hollow member formed by a rear wall 30a facing the rear side R of the leg body 11, a front wall 30b facing the front side F, an upper wall 30c and a lower wall 30d. The step bar body 30 is formed with a hinge cavity 31 having an opening located between a rear wall 30a and a lower wall 30d inside the hollow shape member.

[0063] Therefore, as shown in Figures 6 and 7, the operating mechanism 18 is composed of an operating lever 32a of an operating body 32 pivotally supported on the tread body 30 for free rotation, a fixed body 33 attached to the rear wall 30a, and a movable body 34 attached to the operating lever 32a facing the fixed body 33.

[0064] The operating body 32 is pivotally supported around a pivot part 31a inside the hinge cavity 31, and a plate-shaped operating lever 32a formed integrally with the operating body 32 is extended to the back side R below the rear wall 30a. Therefore, by turning the fingers of the hand gripping the tread body 30 from the front side F to the back side R, the user can swing the operating lever 32a up and down with the fingertips.

[0065] In this case, the operating body 32 is provided with a stopper 32b that restricts rotation inside the hinge cavity 31, and is configured so that the upward movement stop position of the operating lever 32a shown in Figure 6(A) and the downward movement stop position of the operating lever 32a shown in Figure 6(B) are determined.

[0066] (Interlocking mechanism) 2 and 6(A), it is composed of a power transmission cable 35. The power transmission cable 35 is composed of a bendable cord in which an inner cable 37 made of a wire is slidably inserted into an outer cable 36 made of a flexible tube, and the inner cable 37 has slidable play inside the outer cable 36.

[0067] The transmission cable 35 has an operating side end 35a formed near the upper end, an actuating side end 35b formed near the lower end, and an intermediate portion 35c formed by the portion extending between the operating side end 35a and the actuating side end 35b.

[0068] Therefore, the operating side end portion 35a is connected to the operating mechanism 18 as shown in Figures 7 and 8, the actuation side end portion 35b is connected to the locking mechanism 15 as shown in Figures 3 to 5, and the intermediate portion 35c is routed along the back side R of the main landing gear 12.

[0069] The upper and lower ends of the outer cable 36 may be left bare, but as shown in the figure, it is preferable to cover them with a fixed tube made of a hard material to form upper end 36a and lower end 36b, and the inner cable 37 has upper end 37a and lower end 37b formed by the end that is pulled out of the outer cable 36.

[0070] (Operating end of transmission cable and operating mechanism) As shown in Figures 7 and 8, the operating side end 35a of the transmission cable 35 is bent from the middle portion 35c located on the back side R of the main leg 12 toward the rear wall 30a of the tread body 30 that constitutes the upper tread 13b, and the upper end portion 36a of the outer cable 36 is inserted and fixed into the cylindrical boss portion 33a of the fixed body 33.

[0071] The upper end 37a of the inner cable 37, which is inserted from the upper end 36a of the outer cable 36, is bent downward inside the fixed body 33 via a guide handle 33b formed by the shaft portion of a pin (not shown), and then fixed to the movable body 34.

[0072] A connector 38 made of a thick disk called a drum is fixed to an upper end 37a of the inner cable 37, and is rotatably inserted into a cylindrical hole 34a opening in the side of the movable body 34. At this time, the upper end 37a of the inner cable 37 located outside the connector 38 is inserted into a slit 34b formed in the upper surface of the movable body 34 and communicating with the cylindrical hole 34a.

[0073] As a result, when the operating lever 32a is moved downward from the upward stop position where it has been moved upward and stopped as shown in FIG. 8(A) to the downward stop position as shown in FIG. 8(B), the upper end portion 37a of the inner cable 37 is pulled a predetermined amount.

[0074] (Working end of power transmission cable and locking mechanism) As shown in Figures 3 to 5, the working side end 35b of the transmission cable 35 is slightly offset from the middle part 35c located on the back side R of the main landing gear 12 toward the upper part of the housing 22, and the lower end 36b of the outer cable 36 is inserted and fixed into the cylindrical boss portion 22a of the housing 22.

[0075] A lower end 37b of the inner cable 37 inserted from a lower end 36b of the outer cable 36 is fixed inside the housing 22 to a connecting tubular portion 29a of the relay member 29 located immediately below the boss portion 22a.

[0076] A connector 39 made of a thick disk called a drum is fixed to a lower end 37b of the inner cable 37, and is rotatably inserted into cylindrical holes 29c opening on both sides of the connecting tube portion 29a. At this time, the lower end 37b of the inner cable 37 located outside the connector 39 is inserted into a slit 29d formed in communication with the cylindrical hole 29c from the upper surface of the connecting tube portion 29a.

[0077] As described above, the lock body 23 is biased in the forward rotation direction by the lock return biasing means 27 so as to lock the lock teeth 23b with the rack teeth 17a, so that a downward pulling force is normally applied to the lower end portion 37b of the inner cable 37 via the unlock arm 28 and the relay member 29 as shown in Fig. 4. Therefore, in this state, the operating mechanism 18 holds the operating lever 32a in the upward movement stop position as shown in Fig. 8(A).

[0078] From this state, as shown in FIG. 8(B), when the user tilts the operating lever 32a with his / her finger to the downward movement stop position, the upper end 37a of the inner cable 37 is pulled, so that, as shown in FIG. 5, the lower end 37b pulls up the relay member 29 and the unlock arm 28, rotates the lock body 23 in the reverse direction against the lock return biasing means 27, and disengages the lock teeth 23b from the rack teeth 17a.

[0079] When the operating lever 32a is released from the user's fingers, the lock body 23 rotates in the normal direction due to the lock return biasing means 27, and in response to this, the lower end portion 37b of the inner cable 37 is pulled downward, and the operating lever 32a also returns to the upward movement stop position shown in Figure 8(A).

[0080] As shown in Figures 4 and 5, the relay member 29 interposed between the lower end 37b of the inner cable 37 and the unlock arm 28 of the locking body 23 changes its inclined position through the relative rotation of the connecting tube portion 29a and the connector 39 and the relative rotation of the horizontal shaft portion 29b and the unlock arm 28, so that the lower end 37b of the inner cable 37 can always maintain a straight position in the vertical direction.

[0081] (middle part of transmission cable) As shown in Figures 6 and 9, the middle portion 35c of the transmission cable 35 is arranged in a straight line along the outer surface of the side wall 12c of the main leg 12 located on the back side R of the leg body 11, and the outer cable 36 in the middle portion 35c is held in an unbendable state by a long holder 40 fixed to the side wall 12c of the main leg 12.

[0082] In this case, the length of the power transmission cable 35 is determined in relation to the length of the wiring path. The wiring path of the outer cable 36 is determined by the sum (Lc+La+Lb) of the distance Lc on a straight line corresponding to the intermediate portion 35c, the distance La on an arc line from the upper end of the intermediate portion 35c to the boss portion 33a of the operating mechanism 18, and the distance Lb on an inclined line from the lower end of the intermediate portion 35c to the boss portion 22a of the locking mechanism 15.

[0083] Therefore, the actual total length of the outer cable 36 is determined by adding a length α by which the outer cable 36 is compressed by a predetermined amount in the longitudinal direction to the length of the routing path. In this case, an optimum value is selected for α, which allows for an appropriate amount of play in the inner cable 37 and simultaneous interlocking of both ends as described above.

[0084] In contrast to this, the total length of the inner cable 37 is simply determined according to its effective length. That is, it is formed as a length obtained by adding the length of the routing path of the outer cable 36 (Lc+La+Lb) to the length of the bent path from the boss 33a to the connector 38 in the operating mechanism 18 and the length of the straight path from the boss 22a to the connector 39 in the locking mechanism 15.

[0085] As a result, the outer cable 36 of the power transmission cable 35 is compressed by a predetermined amount and the inner cable 37 has an appropriate amount of play, so that when the upper end 37a of the inner cable 37 is pulled by the operating mechanism 18, the lower end 37b can be simultaneously interlocked, providing excellent interlocking operability. Moreover, the sliding resistance of the inner cable 37 is appropriate, allowing operation with an appropriate operating force, and the cable has good sliding properties without any problems with durability.

[0086] The intermediate portion 35c of the power transmission cable 35 is held by a holder 40 so as to be unable to bend from a straight state. As shown in Fig. 9, the holder 40 integrally forms a band-shaped plate portion 41 which is secured by fasteners such as rivets or bolts in a state where it is superimposed on the outer surface of the side wall 12c of the rear side R of the main landing gear 12, and a grooved portion 42 which is bent from the band-shaped plate portion 41 into a substantially U-shaped cross section so as to surround the inward rib 12d of the side wall 12c, and the outer cable 36 of the intermediate portion 35c of the power transmission cable 35 is fitted into a retaining groove 42a formed by the grooved portion 42 to fixedly hold it.

[0087] As a result, the middle portion 35c of the transmission cable 35 is maintained in a straight state over the distance La, and repeated operation over a long period of time does not cause the compression of the outer cable 36 to loosen, and the above-mentioned interlocking operability and smooth sliding are not reduced.

[0088] Moreover, since the middle portion 35c of the transmission cable 35 is positioned on the back side R of the main leg 12, it does not get in the way when the user ascends or descends the leg body 11. Furthermore, since it is not subject to collision with foreign objects, there is no change in posture from a straight posture to a bent posture due to external forces, etc., and in this respect too, the above-mentioned interlocking operability and smooth sliding are not impaired.

[0089] In the illustrated embodiment, the retainer 40 is divided into an upper retainer 40a and a lower retainer 40b to avoid interference with the bracket fitting 16 of the middle step 13b, but the shape and number of the retainers can be designed arbitrarily, and in short, it is sufficient that the retainer as a whole is long enough to hold the middle portion 35c in the longitudinal direction.

[0090] With the above configuration, the telescoping leg device allows the user to operate the operating lever 32a from the upper position of the aerial work device to pull up the relay member 29 and the unlock arm 28 via the inner cable 37, thereby unlocking the locking body 23 and allowing the telescoping leg 14 to slide relative to the main leg 12. However, in the unlikely event that the inner cable 37 breaks and operation from the upper position is not possible, the locking body 23 can also be unlocked by pressing the unlock button 29E provided on the relay member 29 as described above, so there is no hindrance to use of the telescoping leg device. [Explanation of symbols]

[0091] 11 Legs 12 Main landing gear 12a Bottom wall 12b, 12c side wall 12d Inward Rib 13. Stepping Rail 13a Middle treadle 13b Upper step 13c Lower step 14 Telescopic legs 15 Locking mechanism 16 Bracket fittings 17 Rack 17a rack teeth 18 Operating mechanism 19 Interlocking mechanism 20 Telescopic leg device 21 Through bolt 21a Support shaft 22 Housing 22a Boss part 22b window hole 23 Locked 23a Lock Arm 23b locking teeth 23c Actuation piece 23d V groove 24, 24a Indicator means 25 Buttons 25a Push part 26 Spring 27 Rock Spring 28 Unlock Arm 29 Intermediate parts 29a Connecting cylinder part 29b Horizontal shaft 29c Cylindrical hole 29d Slit 29E Unlock button 30 Tread body 30a back wall 30b Front wall 30c upper wall 30d lower wall 31 Hinge cavity 31a Cardinal branch 32 Operation body 32a Operating lever 32b Stopper 33 Fixed body 33a Boss part 33b Guidance means 34 Mobile 34a Cylindrical hole 34b Slit 35 Power Transmission Cable 35a Operation side end 35b Working end 35c middle part 36 Outer cable 36a Upper end 36b Bottom end 37 Inner cable 37a Upper end 37b Lower end 38, 39 Connector 40, 40a, 40b retainer 41 Belt-shaped plate section 42 Groove section 42a Retaining groove

Claims

1. This is a high-altitude work device that is formed by installing multiple steps (13) on the upper and lower main legs (12) that are arranged side by side and have a groove-shaped cross section, forming a ladder-like leg body (11), and pivoting a pair of legs that are arranged opposite each other so that they can be opened and closed freely. The opposing sides of the pair of legs are the back side (R), and the opposite side is the front side (F) on which the user ascends and descends. The main landing gear (12) is provided with a telescopic leg (14) slidably inserted into the main landing gear, a locking mechanism (15) having a locking means for detachably locking the telescopic leg, an operating mechanism (18) having an operating means for actuating the locking means, and an interlocking mechanism (19) for interlocking the operating means and the locking means, thereby forming a telescopic landing gear device (20), The lock mechanism (15) is provided near both ends of the lower step bar (15c), and the operating mechanism (18) is provided near both ends of the upper step bar (13b), The interlocking mechanism (19) is composed of a flexible transmission cable (35) in which an inner cable (37) made of a wire is slidably inserted through an outer cable (36) made of a flexible tube, and a portion of the transmission cable near its lower end forms an actuating end (35b) and a portion of the transmission cable near its upper end forms an operating end (35a), The operating side end portion (35b) fixes a lower end portion (36b) of an outer cable to a fixing portion of the locking mechanism (15) and fastens a lower end portion (37b) of an inner cable to the locking means, The operating side end portion (35a) fixes an upper end portion (36a) of an outer cable to a fixing portion of the operating mechanism (18) and fastens an upper end portion (37a) of an inner cable to the operating means, an intermediate portion (35c) extending between the actuation side end portion (35b) and the operation side end portion (35a) of the transmission cable (35) is arranged in a straight line along the outer surface of the main leg (12) located on the rear side (R) of the leg body, and an outer cable in the intermediate portion is held unbendably by a long holder (40) fixed to the outer surface of the main leg (12).

2. The telescopic leg device for aerial work equipment according to claim 1, characterized in that the retaining device (40) is integrally formed with a band-shaped plate portion (41) which is secured by a fastener in a state of being overlapped with the outer surface of the main leg (12) located on the back side (R) of the leg body, and a retaining groove (42a) which is bent from the band-shaped plate portion into an approximately U-shaped cross section along the edge of the outer surface of the main leg facing the tread, and an outer cable at the intermediate portion (35c) of the transmission cable is fitted into the retaining groove.

3. The lock mechanism (15) is composed of a housing (22) provided at the end of the lower step bar (13c), a lock body (23) that is rotatably supported inside the housing and engages with the telescopic leg (14) when rotated forward and disengages when rotated reversely, a lock spring (27) that urges the lock body in the forward rotation direction, and a relay member (29) interlocked with the lock body via a horizontal shaft portion (29a) so as to drive the lock body in the reverse direction by receiving a pulling force, and a lower end (36b) of an outer cable at the operating side end (35b) of the transmission cable is fixed to the housing, and a lower end (37b) of an inner cable is fixed to the relay member, 3. The telescopic leg device for aerial work equipment according to claim 1 or 2, characterized in that the relay member (29) has an unlocking button (29E) protruding from a portion near the horizontal shaft portion (29a) and passing through the housing (22) to protrude to the outside, and when the relay member (29) is pushed from outside the housing (22) via the unlocking button (29E), the locking body (23) is rotated in the reverse direction.

4. The upper step (13b) on which the operating mechanism (18) is provided constitutes a step body (30) made of a hollow material formed of a rear wall (30a) facing the rear side (R) of the leg body, a front wall (30b) facing the front side, an upper wall (30c) and a lower wall (30d), The operating mechanism (18) is composed of an operating body (32) that is inserted into the tread body (30) in the longitudinal direction and pivotally supported in the vertical direction, an operating lever (32a) that is connected to the lower wall and extends from the rear wall so as to protrude from the rear wall, a fixed body (33) that is attached to the rear wall (30a), and a movable body (34) that faces the fixed body and is attached to the operating lever (32a), 4. The telescopic leg device for a high-altitude work device according to claim 1, 2 or 3, characterized in that an upper end (36a) of an outer cable at an operating side end (35a) of the transmission cable (35) is fixed to the fixed body (33), and an upper end (37a) of an inner cable is fixed to the movable body (34) in a state where it is bent downward via a guide means (33b) of the fixed body.

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