阅读说明：本技术 一种直臂起重机用双液压缸加拉索内置可调节的伸缩臂 (Telescopic boom with adjustable two hydraulic cylinders and inhaul cable are built in for straight boom crane ) 是由 商晓恒 蔡江哲 肖彦峰 任路遥 王舒 冯献录 余旋 于 2019-08-21 设计创作，主要内容包括：本发明公开一种直臂起重机用双液压缸加拉索内置可调节的伸缩臂,包括基本臂、一节伸臂、二节伸臂、三节伸臂；三节伸缩臂依次套入基本臂中；一伸液压缸缸杆连接到基本臂尾端；一伸液压缸缸杆连接到一节伸臂尾端；二伸液压缸缸杆连接到一伸液压缸缸筒上；二伸液压缸缸筒连接到二节伸臂尾部；一伸液压缸缸头下侧布置有半滑轮二和半滑轮一；二伸液压缸缸头支架两侧布置有伸出滑轮；缸头支架内布置伸出拉索调节机构；三节伸臂下侧布置半滑轮三,三节伸臂臂头内部下侧布置调节半滑轮。在一伸液压缸缸头下侧布置半滑轮和半滑轮,充分利用了两液压缸之间狭窄空间,降低了两液压缸之间的高度距离,使得臂体结构紧凑,臂体内空间利用率高。(The invention discloses a double-hydraulic cylinder and inhaul cable built-in adjustable telescopic boom for a straight boom crane, which comprises a basic boom, a first section of boom, a second section of boom and a third section of boom; three sections of telescopic arms are sleeved in the basic arm in sequence; a hydraulic cylinder rod is connected to the tail end of the basic arm; a hydraulic cylinder rod is connected to the tail end of a section of the extension arm; the two-extension hydraulic cylinder rod is connected to the cylinder barrel of the one-extension hydraulic cylinder; the cylinder barrel of the two-section hydraulic cylinder is connected to the tail part of the two-section extension arm; a half pulley II and a half pulley I are arranged on the lower side of the cylinder head of the first hydraulic cylinder; two sides of the cylinder head bracket of the secondary extension hydraulic cylinder are provided with extension pulleys; an extended stay rope adjusting mechanism is arranged in the cylinder head bracket; and a third half pulley is arranged on the lower side of the three-section extending arm, and a regulating half pulley is arranged on the lower side inside the arm head of the three-section extending arm. The half pulleys and the half pulleys are arranged on the lower side of the cylinder head of the first-extension hydraulic cylinder, so that the narrow space between the two hydraulic cylinders is fully utilized, the height distance between the two hydraulic cylinders is reduced, the structure of the arm body is compact, and the space utilization rate in the arm body is high.)

1. A double-hydraulic cylinder and pull rope built-in adjustable telescopic boom for a straight boom crane is characterized by comprising a basic boom (1), a section of extension boom (2), a section of extension boom (3), a section of extension boom (4), a section of extension hydraulic cylinder (5), a section of extension hydraulic cylinder (6), a recovery pull rope (7), a half pulley I (8), a half pulley II (9), an extension pull rope (10), an extension pulley (11), a cylinder head bracket (12), an adjustment half pulley (13), a pin shaft I (14), a pin shaft II (15), a pin shaft III (16), a pin shaft IV (17), a recovery pulley (18) and a half pulley III (19);

the first extension arm (2), the second extension arm (3) and the third extension arm (4) are sequentially sleeved in the basic arm (1); the rod of the hydraulic extending cylinder (5) is connected to the tail end of the basic arm (1) through a first pin shaft (14); a cylinder barrel of the first extension hydraulic cylinder (5) is connected to the tail end of the first extension arm (2) through a second pin shaft (15); the cylinder rod of the second-extension hydraulic cylinder (6) is connected to the cylinder barrel of the first-extension hydraulic cylinder (5) through a third pin shaft (16); a cylinder barrel of the secondary extension hydraulic cylinder (6) is connected to the tail part of the secondary extension arm (3) through a pin shaft four (17);

a half pulley II (9) for fixing an extending guy cable (10) and a half pulley I (8) for fixing a recovering guy cable (7) are arranged on the lower side of the cylinder head of the first extending hydraulic cylinder (5); two sides of a cylinder head bracket (12) of the secondary extension hydraulic cylinder (6) are provided with extension pulleys (11); an extending inhaul cable adjusting mechanism is arranged in the cylinder head bracket (12); and a half pulley III (19) for fixing the extending cable (10) is arranged on the lower side of the arm tail of the three-section extending arm (4), and an adjusting half pulley (13) is arranged on the lower side inside the arm head of the three-section extending arm (4).

2. The double-hydraulic-cylinder stay-cable built-in adjustable telescopic boom for the straight boom crane according to claim 1, characterized in that the extension stay cable adjusting mechanism comprises a cylinder head bracket (12), an extension pulley (11), a pulley shaft (20), an adjusting bolt (21), a bolt fixing plate (22), a screw (24) and a washer (23);

the cylinder head bracket (12) is provided with a rectangular hole; the middle of the pulley shaft (20) is provided with a stepped shaft shoulder and cylindrical shafts at two sides, the center of the shaft shoulder is provided with a threaded hole, the pulley shaft (20) is arranged in a rectangular hole of the cylinder head bracket (12), and the shaft shoulder part can slide back and forth in the rectangular hole of the cylinder head bracket (12); the extended pulley (11) is arranged on cylindrical shafts on two sides of the pulley shaft (20); the extending inhaul cable (10) is an annular inhaul cable which is connected end to end, the extending inhaul cable (10) bypasses the extending pulleys (11) on the two sides of the cylinder head support (12), turns back for 180 degrees, and two ends of the extending inhaul cable are respectively fixed on a half pulley II (9) on the lower side of the cylinder head support (12) of the hydraulic cylinder (5) and a half pulley III (19) on the lower side of the arm tail of the three-section extending arm (4); a bolt guide hole (25) is formed in the cylinder head support (12), an adjusting bolt (21) is installed from a circular hole in the front end of the cylinder head support (12), screwed into a threaded hole in the shaft shoulder of the pulley shaft (20), and then penetrates into the guide hole (25), the pulley shaft (20) is moved back and forth by screwing or unscrewing the adjusting bolt (21), and the two sides of the extending pulley (11) are driven to move back and forth, so that the extending inhaul cable (10) is adjusted; the bolt fixing plate (22) is arranged on the upper side of the head of the adjusting bolt (21), and the hexagonal side of the head of the adjusting bolt (21) is pressed by the lower side of the bolt fixing plate (22).

3. The telescopic boom with the built-in adjustable double hydraulic cylinders and the guy cable for the straight boom crane according to claim 1 is characterized in that the recovery guy cable adjusting mechanism comprises: the device comprises a recovery inhaul cable (7), an adjusting half pulley (13), an adjusting bolt I (26), a bolt fixing plate I (27), a gasket I (28), a screw I (29) and a three-section extension arm (4);

the arm head of the three-section extending arm (4) is provided with a guide slideway; the lower side of the half pulley (13) is welded with a cube block, a threaded hole is formed in the middle of the cube block, the adjusting half pulley (13) is placed in a guide slideway of the three-section extending arm (4), the cube block is just embedded into the guide slideway, an adjusting bolt I (26) is placed in an arm head hole of the three-section extending arm (4) and screwed into the threaded hole of the cube block on the lower side of the adjusting half pulley (13), and the adjusting half pulley (13) moves back and forth by screwing or unscrewing the adjusting bolt I (26), so that the adjustment of the recovery inhaul cable (7) is realized; the first bolt fixing plate (27) is arranged on the upper side of the head of the first adjusting bolt (26), and the lower side edge of the first bolt fixing plate (27) is tightly attached to the hexagonal edge of the head of the first adjusting bolt (26).

Technical Field

The invention relates to a double-hydraulic-cylinder and pull-rope built-in adjustable telescopic boom for a straight boom crane, and belongs to the technical field of lorry-mounted cranes.

Background

The lorry-mounted crane transport vehicle is a special vehicle which is provided with a lorry-mounted crane and can realize self loading, unloading and transportation of goods. The crane has the transportation function of a common truck and the hoisting and loading and unloading function of a crane, and can complete the loading and unloading operation of the truck cargo and the loading and unloading of the cargo between the trucks; therefore, the vehicle-mounted hoisting transport vehicle is used, so that the transport efficiency can be greatly improved, the transport cost is reduced, the labor intensity is reduced, and the operation safety is ensured. Therefore, the device is widely applied to the conditions of cargo unloading, emergency rescue, long-distance cargo transfer and the like in traffic transportation, civil construction, electric power, telecommunication, field operation, stone industry, wharf and the like.

The telescopic boom structure is the most important part of a straight boom crane, the prior boom body telescopic boom structure is technically upgraded from a single hydraulic cylinder with multiple sets of guys to a double hydraulic cylinder with guys, the boom body loading telescopic capacity and the hanging load capacity of the double hydraulic cylinder and the multi hydraulic cylinder structure are greatly improved, but the arrangement of the double hydraulic cylinder and the multi hydraulic cylinder also increases the cross section of the boom body, particularly when the application of the double hydraulic cylinder technology is gradually expanded to a small-tonnage crane, the small-tonnage straight boom crane has a small cross section, the contradiction between the small space of the boom body and the large space required by the arrangement of the double hydraulic cylinder structure is more and more prominent, and therefore, the problem that how to arrange the double hydraulic cylinder guys with the guys in the inner space of the boom body with the small cross section and the small space becomes an urgent need to be solved is solved.

The existing double-cylinder telescopic arm structure of the straight-arm lorry-mounted crane is provided with a guy cable, the guy cable extending out is in two forms, the guy cable extending out is connected by a rope row, an extending pulley is positioned at the front end of a cylinder head support of a two-extending hydraulic cylinder, the upper side of the rope row is wound around the pulley and extends backwards through the space between the two hydraulic cylinders, a rope row joint is fixed at the tail part of one-section extending arm, and the lower side of the rope row is wound around the extending pulley and rotates 180 degrees to be connected to the structural part of. The second kind, when stretching out the cable and adopting the cable of both ends bandeau screw rod to connect, stretch out the cable and arrange in the adjacent arm body space of arm body upside, arm head upside need set up and stretch out the pulley, stretch out the cable fifty percent discount, walk around arm head upside pulley and turn back 180, the screw rod end need be connected to last section arm head connecting plate on, the other end pass with next section between the arm body clearance, on the half pulley of the afterbody upside of the next section arm body of fixing.

The double hydraulic cylinders of the rope row are adopted to be provided with the guy cable telescopic arm structure, the rope row needs to penetrate through the whole telescopic hydraulic cylinder between the two hydraulic cylinders, and a larger height space needs to be reserved in front of the two hydraulic cylinders, so that the height size of the arm body is larger; joints of the rope rows need to be connected with a structural member of the arm tail of the telescopic arm, so that the structure of the arm tail of the telescopic arm is complex and loose, and the length of an arm body is increased when the telescopic arm is fully contracted; the overlap joint of the arm body is reduced during full extension, and the hanging load capacity and the extension length of the arm body are reduced; and the length of the rope row cannot be adjusted.

The telescopic arm structure of the stretching guy cable with the screw rods at two ends is adopted, the stretching pulley and the guy cable connecting plate are required to be arranged in the outer space at the upper side of the arm head, and allowance is required to be reserved for adjusting the screw rods, so that the arm body arranged by the guy cable has high arm head structure height and is complex and loose in arm head structure in length, and the arm head structure cannot be compact and simple; meanwhile, because the extension cable needs to pass through the upper side space of the arm body of two adjacent sections of arms, the section height of the whole arm body is also passively increased.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a double-hydraulic cylinder and pull rope built-in adjustable telescopic arm for a straight arm crane, which is used for solving the problem of complex nose head structure and improving the lifting capacity and the extension length of an arm head.

In order to achieve the purpose, the invention adopts the technical scheme that: a double hydraulic cylinder and pull rope built-in adjustable telescopic boom for a straight boom crane comprises a basic boom, a section of telescopic hydraulic cylinder, a recovery pull rope, a half pulley I, a half pulley II, an extension pull rope, an extension pulley, a cylinder head bracket, an adjustment half pulley, a pin shaft I, a pin shaft II, a pin shaft III, a pin shaft IV, a recovery pulley;

the first extension arm, the second extension arm and the third extension arm are sleeved in the basic arm in sequence; a cylinder rod of the hydraulic extension cylinder is connected to the tail end of the basic arm through a pin shaft; a cylinder barrel of the first extension hydraulic cylinder is connected to the tail end of the first extension arm through a second pin shaft; the cylinder rod of the second-extension hydraulic cylinder is connected to the cylinder barrel of the first-extension hydraulic cylinder through a third pin shaft; a cylinder barrel of the second-extension hydraulic cylinder is connected to the tail part of the second-extension arm through a pin shaft IV;

a half pulley II for fixing an extending inhaul cable and a half pulley I for fixing a recovering inhaul cable are arranged on the lower side of the cylinder head of the first extending hydraulic cylinder; two sides of a cylinder head bracket of the secondary extension hydraulic cylinder are provided with extension pulleys; an extended stay cable adjusting mechanism is arranged in the cylinder head bracket; and a third half pulley for fixing the extending inhaul cable is arranged on the lower side of the arm tail of the three-section extending arm, and a regulating half pulley is arranged on the lower side inside the arm head of the three-section extending arm.

Furthermore, the extending inhaul cable adjusting mechanism comprises a cylinder head bracket, an extending pulley, a pulley shaft, an adjusting bolt, a bolt fixing plate, a screw and a gasket;

the cylinder head bracket is provided with a rectangular hole; the middle of the pulley shaft is provided with a stepped shaft shoulder and cylindrical shafts at two sides, the center of the shaft shoulder is provided with a threaded hole, the pulley shaft is arranged in a rectangular hole of the cylinder head bracket, and the shaft shoulder part can slide back and forth in the rectangular hole of the cylinder head bracket; the extended pulleys are arranged on cylindrical shafts on two sides of the pulley shaft; the extending stay cable is an annular stay cable connected end to end, the extending stay cable bypasses the extending pulleys on two sides of the cylinder head bracket and turns back for 180 degrees, and two ends of the extending stay cable are respectively fixed to a half pulley II on the lower side of the cylinder head bracket of the extending hydraulic cylinder and a half pulley III on the lower side of the tail of the three-section extending arm; a bolt guide hole is formed in the cylinder head support, an adjusting bolt is installed from a circular hole at the front end of the cylinder head support, is screwed into a threaded hole in a shaft shoulder of the pulley shaft and then penetrates into the guide hole, the pulley shaft is moved back and forth by screwing or unscrewing the adjusting bolt, and the two sides of the pulley shaft are driven to extend out of the pulleys to move back and forth, so that the adjustment of the extending stay cable is realized; the bolt fixing plate is arranged on the upper side of the head of the adjusting bolt, and the lower side of the bolt fixing plate compresses the hexagonal side of the head of the adjusting bolt.

Further, retrieve cable adjustment mechanism include: the method comprises the following steps of (1) recovering a guy cable, an adjusting half pulley, an adjusting bolt I, a bolt fixing plate I, a gasket I, a screw I and three-section extending arms;

the arm head of the three-section extending arm is provided with a guide slideway; the lower side of the half pulley is welded with a cube block, a threaded hole is formed in the middle of the cube block, the adjusting half pulley is placed in a guide slideway of the three-section extending arm, the cube block is just embedded into the guide slideway, an adjusting bolt I is installed in a head hole of the three-section extending arm and screwed into the threaded hole of the cube block on the lower side of the adjusting half pulley, and the adjusting half pulley is made to move back and forth by screwing or unscrewing the adjusting bolt I, so that the adjustment of the recovery inhaul cable is realized; the first bolt fixing plate is arranged on the upper side of the head of the first adjusting bolt, and the lower side edge of the first bolt fixing plate is tightly attached to the hexagonal edge of the head of the adjusting bolt.

The invention has the beneficial effects that:

1) the half pulley for fixing the extending guy cable and the half pulley for fixing the recovery guy cable are arranged at the lower side of the cylinder head of the hydraulic cylinder, so that the narrow space between the two hydraulic cylinders is fully utilized, the height distance between the two hydraulic cylinders is reduced, the structure of the arm body is compact, and the utilization rate of the space in the arm body is high;

2) the stretching out inhaul cable and the recycling inhaul cable are connected end to form an annular inhaul cable, the structure is simple, and the defect that the height size and the width size of the arm body need to be increased due to the fact that corresponding connecting plates or cylindrical pin shafts need to be arranged in the arm body when an inhaul cable joint is made into a screw rod or a pull ring is overcome;

3) the extending stay cable bypasses the extending pulleys on the two sides of the cylinder head bracket and turns back for 180 degrees, the upper end of the extending stay cable is fixed on a half pulley on the lower side of the cylinder head of a hydraulic extending cylinder (different from the arrangement of a rope row, the upper end of the extending stay cable needs to penetrate through the whole length between two hydraulic cylinders and is fixed on a structural member of a section of extending arm tail), the structural design of the arm tail is compact, and the space in the arm body is fully utilized;

4) the extension cable adjusting mechanism is arranged in the cylinder head support, and a structure that the extension pulley shaft is connected through a bolt is adopted, so that the extension cable is completely internally arranged, the arm head sealing plate is opened, the adjusting bolt is loosened or screwed, the length of the extension cable can be adjusted, and the adjustment is simple and convenient.

5) The recovery inhaul cable adjusting mechanism adopts an arrangement mode that one bolt is connected with the half pulley, the arm head sealing plate is opened, the tightness of the recovery inhaul cable bypassing the half pulley can be adjusted by screwing or unscrewing the bolt, and the adjustment is simple and convenient.

6) The guy cable is stretched out, the guy cable is recycled, and the guy cable adjusting mechanism is completely arranged inside the arm body, so that the arm body is compact in structure, and the arm head is concise and attractive in appearance.

Drawings

FIG. 1 is a schematic cross-sectional view of the structure of the present invention;

FIG. 2 is an exploded view of the extension cable adjustment mechanism of the present invention;

FIG. 3 is an exploded view of the adjusting mechanism of the retractable cable of the present invention;

fig. 4 is a schematic three-dimensional structure diagram of the adjusting mechanism of the recovery cable of the invention.

In the figure: 1. basic arm, 2, one-section extension arm, 3, two-section extension arm, 4, three-section extension arm, 5, one-section extension hydraulic cylinder, 6, two-section extension hydraulic cylinder, 7, recovery cable, 8, half-pulley one, 9, half-pulley two, 10, extension cable, 11, extension pulley, 12, cylinder head bracket, 13, adjustment half-pulley, 14, pin shaft one, 15, pin shaft two, 16, pin shaft three, 17, pin shaft four, 18, recovery pulley, 19, half-pulley three, 20, pulley shaft, 21, adjusting bolt, 22, bolt fixing plate, 23, gasket, 24, screw, 25, guide hole, 26, adjusting bolt one, 27, gasket one, 28, gasket one, 29 and screw one.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood, however, that the description herein of specific embodiments is only intended to illustrate the invention and not to limit the scope of the invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, and the terms used herein in the specification of the present invention are for the purpose of describing particular embodiments only and are not intended to limit the present invention.

The following are specific examples:

as shown in fig. 1, fig. 2, fig. 3 and fig. 4, a double-hydraulic cylinder and pull cable built-in adjustable telescopic boom for a straight boom crane comprises a basic boom 1, a section of boom 2, a section of boom 3, a section of boom 4, a section of hydraulic cylinder 5, a section of hydraulic cylinder 6, a recovery pull cable 7, a half pulley I8, a half pulley II 9, a stretching pull cable 10, a stretching pulley 11, a cylinder head bracket 12, an adjusting half pulley 13, a pin shaft I14, a pin shaft II 15, a pin shaft III 16, a pin shaft IV 17, a recovery pulley 18 and a half pulley III 19;

the first extension arm 2, the second extension arm 3 and the third extension arm 4 are sleeved in the basic arm 1 in sequence; the rod of the hydraulic extending cylinder 5 is connected to the tail end of the basic arm 1 through a pin shaft I14; the cylinder barrel of the first extension hydraulic cylinder 5 is connected to the tail end of the first extension arm 2 through a second pin shaft 15; the cylinder rod of the second-extension hydraulic cylinder 6 is connected to the cylinder barrel of the first-extension hydraulic cylinder 5 through a third pin shaft 16; the cylinder barrel of the second extension hydraulic cylinder 6 is connected to the tail part of the second extension arm 3 through a pin shaft four 17;

a half pulley II 9 for fixing an extending guy cable 10 and a half pulley I8 for fixing a recovery guy cable 7 are arranged on the lower side of the cylinder head of the first extending hydraulic cylinder 5; two sides of a cylinder head bracket 12 of the secondary extension hydraulic cylinder 6 are provided with extension pulleys (11); an extended cable adjusting mechanism is arranged in the cylinder head bracket 12; and a half pulley III 19 for fixing the extending inhaul cable 10 is arranged at the lower side of the arm tail of the three-section extending arm 4, and an adjusting half pulley 13 is arranged at the lower side inside the arm head of the three-section extending arm 4.

The extending cable adjusting mechanism comprises a cylinder head bracket 12, an extending pulley 11, a pulley shaft 20, an adjusting bolt 21, a bolt fixing plate 22, a screw 24 and a washer 23;

the cylinder head bracket 12 is provided with a rectangular hole; the middle of the pulley shaft 20 is a cylindrical shaft with a step shoulder and two sides, the center of the shaft shoulder is provided with a threaded hole, the pulley shaft 20 is arranged in the rectangular hole of the cylinder head bracket 12, and the shaft shoulder part can slide back and forth in the rectangular hole of the cylinder head bracket 12; the extended pulley 11 is arranged on the cylindrical shafts at two sides of the pulley shaft 20; the extending guy cable 10 is an annular guy cable connected end to end, the extending guy cable 10 bypasses the extending pulleys 11 at two sides of the cylinder head bracket 12 and turns back for 180 degrees, and two ends of the extending guy cable are respectively fixed on a second half pulley 9 at the lower side of the cylinder head bracket 12 of the hydraulic extending cylinder 5 and a third half pulley 19 at the lower side of the arm tail of the three-section extending arm 4; a bolt guide hole 25 is formed in the cylinder head support 12, an adjusting bolt 21 is installed from a round hole in the front end of the cylinder head support 12, screwed into a threaded hole in the shaft shoulder of the pulley shaft 20 and then penetrates into the guide hole 25, the pulley shaft 20 is moved back and forth by screwing or unscrewing the adjusting bolt 21, and the two sides of the pulley shaft are driven to extend out of the pulleys 11 to move back and forth, so that the adjustment of the extending inhaul cable 10 is realized; the bolt guide hole 25 in the cylinder head bracket 12 prevents the extended pulley 11 from moving laterally due to the left and right offset of the adjusting bolt 21, the bolt fixing plate 22 is installed on the upper side of the head of the adjusting bolt 21, and the lower side of the bolt fixing plate 22 presses the hexagonal side of the head of the adjusting bolt 21.

Retrieve cable adjustment mechanism include: the cable recovery device comprises a recovery cable 7, an adjusting half pulley 13, an adjusting bolt I26, a bolt fixing plate I27, a gasket I28, a screw I29 and a three-section extension arm 4;

the head of the three-section extending arm 4 is provided with a guide slideway; the lower side of the half pulley 13 is welded with a cube block, a threaded hole is formed in the middle of the cube block, the adjusting half pulley 13 is placed in a guide slideway of the three-section extending arm 4, the cube block is just embedded into the guide slideway, an adjusting bolt I26 is installed from an arm head hole of the three-section extending arm 4 and screwed into the threaded hole of the cube block on the lower side of the adjusting half pulley 13, and the adjusting half pulley 13 moves back and forth by screwing or unscrewing the adjusting bolt I26, so that the adjustment of the recovery cable 7 is realized; the first bolt fixing plate 27 is arranged on the upper side of the head of the first adjusting bolt 26, and the lower side edge of the first bolt fixing plate 27 tightly clings to the hexagonal edge of the head of the first adjusting bolt 26 to prevent the first adjusting bolt 26 from loosening.

The working principle of the whole device is as follows:

the extending process of the arm body comprises the following steps: when the large cavity of the hydraulic cylinder is filled with oil, a cylinder barrel of a first hydraulic stretching cylinder 5 extends firstly to drive a section of stretching arm 2 to extend, meanwhile, a second section of stretching arm 3 and a third section of stretching arm 4 are pushed out together with the first section of stretching arm 2, after the first hydraulic stretching cylinder 5 extends completely, a valve core of a head stroke valve of the first hydraulic stretching cylinder 5 is opened, the large cavity of the second hydraulic stretching cylinder 6 is filled with oil, the cylinder barrel of the second hydraulic stretching cylinder 6 extends outwards to drive the second section of stretching arm 3 to extend, meanwhile, a stretching pulley 11 on a cylinder head support 12 of the second hydraulic stretching cylinder 6 extends out, a stretching inhaul cable 10 is an annular inhaul cable which is connected end to end, the stretching inhaul cable 10 is folded back 180 degrees around two ends of the stretching pulley 11 and is respectively connected to a half pulley 9 on the lower side of the cylinder head of the first hydraulic stretching cylinder 5 and.

The arm retraction process: when oil enters the small cavity of the hydraulic cylinder, the valve core of the stroke valve is in an open state, the cylinder barrel of the second-extension hydraulic cylinder 6 retracts first to drive the second-section extension arm 3 to retract, meanwhile, the recovery pulley 18 at the tail part of the second-extension hydraulic cylinder 6 retracts, the recovery cable 7 is an annular cable which is connected end to end, the recovery cable 7 bypasses two ends of the recovery pulley 18 to return for 180 degrees and is respectively connected to the half pulley 8 at the lower side of the cylinder head of the first-extension hydraulic cylinder 5 and the adjusting half pulley 13 at the lower side of the arm tail of the third-section extension arm 4, and then the third-section extension arm 4.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents or improvements made within the spirit and principle of the present invention should be included in the scope of the present invention.