JP3373963B2 - Multi-stage telescopic boom - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-stage telescopic boom used for a mobile crane or an aerial work vehicle, and more particularly to a multi-stage telescopic boom of a simultaneous telescopic type. 2. Description of the Related Art A conventional example of this type of multistage telescopic boom will be described with reference to FIGS. 2 and 3, the multistage telescopic boom A includes a multistage boom 1, a double-acting hydraulic cylinder 2, an extension tuning device, and a reduction tuning device. The multi-stage boom 1 is constructed by inserting a boom section 6 on a distal end side into a boom section 5 on a proximal end side so as to be able to expand and contract sequentially. The double-acting hydraulic cylinder 2 has a cylinder 8 whose head side and bottom side are closed by a head-side end wall 8a and a bottom-side end wall 8b, respectively. 9 and piston 9
And a piston rod 10 extending outside the cylinder 8 through an oil-tight slidable through the head-side end wall 8a. The head-side end of the cylinder 8 is attached to the head-side end wall 8a.
And a large diameter portion 8c having a large outer shape in order to incorporate the ear shaft 8d, and protruding from both sides of the large diameter portion 8c.
8d. The double-acting hydraulic cylinder 2 has the distal end of the piston rod 10 at the proximal end of the boom section 5 at the proximal end of the multi-stage boom 1 and the left and right ear shafts of the large-diameter portion 8c at the head-side end of the cylinder 8. 8d, 8d are respectively connected to the right and left side walls 6a, 6a at the base end of the boom section 6 on the front end side, so as to be interposed between the adjacent boom sections 5, 6 of the multi-stage boom 1. The boom section 7 on the straight distal end side is driven to expand and contract with respect to the base end boom section 5 by the extension and contraction movement. The extension / retraction movement of the double-acting hydraulic cylinder 2 drives the next-stage boom section 7 to extend / contract via the extension / contraction device 3 and the contraction / contraction device 4. The extension synchronizing device 3 is for transmitting the extension movement of the double-acting hydraulic cylinder 2 as the extension movement of the boom section 7, and is a folding pulley 3 a disposed at the tip of the boom section 6.
And an extension tuning wire rope 3 secured at one end to the distal end of the boom section 5 and at the other end to the proximal end of the boom section 7 and suspended around the folded pulley 3a in a U-shape.
b. The reduction synchronizing device 4 is for transmitting the reduction movement of the double-acting hydraulic cylinder 2 as the reduction movement of the boom section 7, and includes the left and right ear shafts 8d, 8c of the cylinder 8 of the double-acting hydraulic cylinder 2. 8d, and a pair of left and right sheaves 4a, 4a rotatably fitted to the outer periphery of the pair of sheaves 4a, 4a.
4a, each of which is formed of a reduction tuning wire rope 4b which is wound around the boom section 5 on the turn side and stretched between the boom section 5 on the proximal end side and the boom section 7 on the distal end side.
In the illustrated embodiment, the reduction tuning wire rope 4b is connected to the boom section 5 on the base end by connecting the base end to the base end of the boom section 5 on the base end and installed in the multi-stage boom 1. The connection to the boom section 7 is made at the base end of the boom section 7. [0007] The multi-stage telescopic boom A thus configured is
Since each boom section of the multi-stage boom 1 can be driven to expand and contract simultaneously by the double-acting hydraulic cylinder 2, it is frequently used for a mobile crane or an aerial work vehicle. By the way, the return pulleys 4a, 4a of the reduction tuning apparatus 4 in the conventional multistage telescopic boom A are boss portions rotatably fitted to the ear shafts 8d, 8d. Since the end surface of the cylinder 8 on the side of the cylinder 8 and the end surface of the outer peripheral portion b having the rope groove on the cylinder 8 side are located on the same plane, the end surface of the outer peripheral portion b on the cylinder 8 side has a large diameter. It is arranged so as to be located outside the portion 8c. Therefore, when the boss portion a is rotatably fitted to the corresponding ear shaft 8 d, the end surfaces of the outer peripheral portion b on the cylinder 8 side are larger than the side surfaces of the large-diameter portion 8 c of the cylinder 8 in the folded pulleys 4 a, 4 a. It is separated from the cylinder 8. For this reason, the left and right turn pulleys 4a, 4
a, the width of the boom section 6 to which the head-side end of the cylinder 8 is connected increases, and consequently the width of the multi-stage telescopic boom A increases. There was a problem of becoming larger. According to the present invention, the mounting structure of the left and right turn pulleys 4a, 4a of the reduction tuning device 4 to the end of the cylinder 8 head side is changed, and the head end of the cylinder 8 including the left and right turn pulleys 4a, 4a is changed. The width of the multi-stage telescopic boom A is reduced. In order to solve the above-mentioned problems, a multistage telescopic boom A of the present invention comprises a pair of right and left folded pulleys 4a, 4a in a reduction synchronizing device 4, which are connected to an outer peripheral portion having a rope groove. The width of the boss portion a is made smaller than the width of the boss portion b, and the cylinder 8 of the outer peripheral portion b having a rope groove is formed.
The end surface of the boss portion a on the cylinder 8 side is recessed from the side end surface. When the boss portion a is rotatably fitted to the corresponding ear shaft 8 d, the end surface of the outer peripheral portion b on the cylinder 8 side is the cylinder 8. Are arranged on the cylinder 8 side with respect to the side surface of the large diameter portion 8c. The multistage telescopic boom A of the present invention constructed as described above.
Are the right and left turn pulleys 4a at 4 on the reduction tuning device.
Since the width dimension of the head-side end of the cylinder 8 including the cylinder 4a can be made smaller than that of the related art,
The width of the boom section 6 of the double-acting hydraulic cylinder 2 to which the head-side end of the cylinder 8 is connected can be reduced, and the width of the multistage telescopic boom A can be reduced. An embodiment of the present invention will be described below with reference to FIG. The multi-stage telescopic boom A according to the present invention is different from the conventional multi-stage telescopic boom A shown in FIGS. Since the configuration of attachment to the device is different, the description of the above-described conventional technology is directly used for the other description. In FIG. 1, a pair of left and right folded pulleys 4a, 4a rotatably fitted to the left and right ear shafts 8d, 8d.
Each has a width t of the boss portion a smaller than a width T of the outer peripheral portion b having the rope groove,
The end face of the boss a on the cylinder 8 side is recessed from the end face of the outer peripheral part b having the rope groove on the cylinder 8 side. When the boss portion a is rotatably fitted to the corresponding ear shaft 8d, the end surface of the outer peripheral portion b on the cylinder 8 side is located closer to the cylinder 8 than the side surface of the large diameter portion 8c of the cylinder 8. are doing. With such a configuration, the width dimension of the head-side end of the cylinder 8 including the left and right turn pulleys 4a, 4a in the reduction tuning device 4 can be made smaller than that of the conventional one. . As a result, the width of the boom section 6 to which the head-side end of the cylinder 8 in the double-acting hydraulic cylinder 2 is connected can be reduced, and the width of the multistage telescopic boom A can be reduced. The multistage telescopic boom according to the present invention, which is constructed and operated as described above, has the advantage that the width of the multistage telescopic boom can be reduced while having a simple configuration in which a part of the conventional multistage telescopic boom is modified. This has the effect.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram of a main part of a multistage telescopic boom according to the present invention. FIG. 2 is a sectional view of a conventional multistage telescopic boom. FIG. 3 is an X sectional view of FIG. 2; DESCRIPTION OF THE SYMBOLS 1; Multi-stage boom, 2; Double-acting hydraulic cylinder, 3; Extension tuning device, 3a, 3a; Folding pulley, 3b, 3b; Extension tuning wire rope, 4; Reduction tuning device, 4a, 4a; Folded pulley, a: boss, t: width of boss, b: outer circumference, T: width of outer circumference, 4b, 4b; reduction tuning wire rope, 4c: rod member, 5, 6, 7; Boom section, 6a, 6a; side wall, 8; cylinder, 8a; head side end wall, 8b; bottom side end wall, 8c; large diameter portion, 8d,
8d; ear shaft, 9; piston, 10; piston rod,

Claims (1)

(1) A multi-stage boom (1) in which a boom section (6) and a boom section (7) on a distal end are sequentially inserted into a boom section (5) on a proximal end so as to be extendable and contractable. Head side end wall 8
a and a bottom end side wall 8b, a cylinder 8, a piston 9 slidably fitted in the cylinder 8, and a base end thereof connected to the piston 9 to seal the head side end wall 8a with oil. A double-acting hydraulic cylinder 2 comprising a piston rod 10 slidably penetrating and extending to the outside of the cylinder 8, particularly a head-side end of the cylinder 8 has a large external dimension for incorporating the head-side end wall 8a. The double-acting hydraulic cylinder 2 is configured with a large-diameter portion 8c, and is provided with ear shafts 8d, 8d protruding on both left and right sides of the large-diameter portion 8c. At the base end of the boom section 5 on the base end side of the multi-stage boom 1, the left and right ear shafts 8d, 8d of the large diameter portion 8c at the head end of the cylinder 8 are connected to the base end of the boom section 6 on the front end side. Left and right side walls a, 6a, the double-acting hydraulic cylinder 2 interposed between adjacent boom sections 5, 6 of the multi-stage boom 1; A multi-stage telescopic boom comprising an extension synchronizing device 3 for transmitting extension motion and a reduction synchronizing device 4 for transmitting the reducing motion of the double-acting hydraulic cylinder 2 to the reducing motion of the next-stage boom section 7. A pair of left and right folding pulleys 4a, 4a rotatably fitted to the left and right ear shafts 8d, 8d of the cylinder 8 of the double-acting hydraulic cylinder 2, and a pair of left and right folding pulleys 4a. , 4a in a folded state, respectively, and the base-side boom section 5 and the distal-side boom section 7
Wire ropes 4b, 4b stretched between
And a pair of left and right turn pulleys 4 in the reduction tuning device 4.
The width of the boss portion a is made smaller than the width of the outer peripheral portion b having the rope groove, and the width of the boss portion a is closer to the cylinder 8 than the end surface of the outer peripheral portion b having the rope groove on the cylinder 8 side. When the boss portion a is rotatably fitted on the corresponding ear shaft 8d, the outer peripheral portion b is formed.
The multi-stage telescopic boom characterized in that the end face of the cylinder 8 is located closer to the cylinder 8 than the side face of the large diameter portion 8c of the cylinder 8.