CN211078362U

CN211078362U - Four-section arm forklift telescopic pipeline system

Info

Publication number: CN211078362U
Application number: CN201920437838.5U
Authority: CN
Inventors: 徐迎莉; 何平; 肖超海; 何承元; 李金梅
Original assignee: Anhui Haoyun Machinery Co Ltd
Current assignee: Anhui Haoyun Machinery Co Ltd
Priority date: 2019-04-02
Filing date: 2019-04-02
Publication date: 2020-07-24
Anticipated expiration: 2029-04-02

Abstract

The utility model relates to the technical field of pipelines, and discloses a four-section arm forklift telescopic pipeline system, which comprises a telescopic arm for realizing pipeline telescopic, a pipeline and a transmission device for driving the telescopic arm, wherein the telescopic arm comprises a fixed arm, a middle one arm, a middle two arm and an inner arm; the pipeline comprises an outer arm steel pipe assembly fixedly arranged on the outer side of the fixed arm, a transition bent pipe assembly arranged at the front end of the fixed arm, a front high-pressure rubber pipe arranged on the inner side of the fixed arm, a rear high-pressure rubber pipe arranged on the inner side of the inner arm and an inner arm steel pipe assembly fixed on the inner side of the inner arm, which are sequentially communicated, wherein a drag chain is arranged outside the rear high-pressure rubber pipe, and part of pipelines of the telescopic pipeline system are arranged on the outer side of the fixed arm, so that the structural complexity in the telescopic arm is reduced, the peripheral size is limited, the inner space is increased, and the arrangement of; the high-pressure rubber tube and the chain are separately arranged, so that the rubber tube is prevented from being damaged by contact with the chain.

Description

Four-section arm forklift telescopic pipeline system

Technical Field

The utility model relates to the technical field of pipelines, concretely relates to flexible pipe-line system of four section arm fork truck.

Background

Pipelines are channels through which a hydraulic system transmits a working medium, and are often used for equipment driven by the hydraulic system due to flexibility in pipeline arrangement.

The telescopic boom forklift has a telescopic boom, and the telescopic boom needs to be stretched back and forth when carrying out goods handling, wherein the four-section boom cross-country forklift contains a fixed arm, a middle boom and an inner boom, and a telescopic pipeline system is needed to be provided for tipping forks, accessories and the like to provide high-pressure hydraulic oil.

SUMMERY OF THE UTILITY MODEL

In order to solve the technical problem, the utility model provides a four-section fork truck telescopic pipeline system, which arranges partial pipelines of the telescopic pipeline system outside a fixed arm, reduces the structural complexity inside the telescopic arm, limits the peripheral dimension, increases the internal space at the same time, and facilitates the arrangement of the internal structure; the high-pressure rubber tube and the chain are separately arranged, so that the rubber tube is prevented from being damaged by contact with the chain.

In order to solve the technical problem, the utility model adopts the following technical scheme:

a four-section forklift telescopic pipeline system comprises a telescopic arm for realizing pipeline telescopic, a pipeline and a transmission device for driving the telescopic arm, and is characterized in that the telescopic arm comprises a fixed arm, a middle first arm, a middle second arm and an inner arm; the pipeline is including the outer arm steel pipe component that sets firmly in the fixed arm outside, set up in the transition return bend subassembly of fixed arm front end, arrange the inboard preceding high-pressure rubber pipe of fixed arm in, arrange the inboard back high-pressure rubber pipe of inner arm in and be fixed in the inboard inner arm steel pipe component of inner arm in, back high-pressure rubber pipe is equipped with the tow chain outward.

Further, the transmission device comprises a telescopic oil cylinder assembly for driving one arm to move in the fixed arm, a middle two-arm front driving assembly for driving the two arms to move forwards in the middle one arm, a middle two-arm rear driving assembly for driving the two arms to move backwards in the middle one arm, an inner arm front driving assembly for driving the inner arm to move forwards in the middle two arm and an inner arm rear driving assembly for driving the inner arm to move backwards in the middle two arm.

Furthermore, the telescopic oil cylinder assembly comprises a telescopic oil cylinder, an oil cylinder protection plate arranged at the front end of the telescopic oil cylinder and an oil cylinder pin shaft arranged at the rear end of the telescopic oil cylinder, and the front end of the telescopic oil cylinder is fixedly connected with one of the arms.

Furthermore, the middle-two-arm front drive assembly comprises a middle-two-arm upper chain, a middle-two-arm upper chain wheel wound with the middle-two-arm upper chain and fixedly arranged at the front end of the middle-two-arm, and a middle-two-arm upper chain seat fixed on the middle-two-arm, wherein one end of the middle-two-arm upper chain is fixedly connected with the middle-two-arm upper chain seat, and the other end of the middle-two-arm upper chain is fixedly connected with the fixed arm; the middle two-arm rear drive assembly comprises a middle two-arm lower chain, a middle two-arm lower chain wheel wound with the middle two-arm lower chain and fixedly arranged at the rear end of the middle one arm, and a middle two-arm lower chain seat fixed on the middle two arms, wherein one end of the middle two-arm lower chain is fixedly connected with the middle two-arm lower chain seat, and the other end of the middle two-arm lower chain is fixedly connected with the fixed arm.

Furthermore, the inner arm front driving assembly comprises an inner arm upper chain, an inner arm upper chain wheel which is wound with the inner arm upper chain and is fixedly arranged at the front ends of the middle two arms, and an inner arm upper chain seat fixed on the inner arm, wherein one end of the inner arm upper chain is fixedly connected with the inner arm upper chain seat, and the other end of the inner arm upper chain is fixedly connected with the middle one arm; the inner arm rear-drive assembly comprises an inner arm return chain, an inner arm return chain wheel and an inner arm return chain seat, wherein the inner arm return chain wheel is wound on the inner arm return chain and is fixedly arranged at the rear end of the middle two arms, the inner arm return chain seat is fixed on the inner arm, one end of the inner arm return chain is fixedly connected with the inner arm return chain seat, and the other end of the inner arm return chain is fixedly connected with the middle arm.

Further, the rear end of the middle arm is fixedly provided with a pulley block assembly, the pulley block assembly comprises a pulley block support, a large pulley and a small pulley, the large pulley and the small pulley are wound with a high-pressure rubber pipe, the large pulley and the small pulley are fixed on the pulley block support through pin shafts, and the large pulley, the small pulley and the pulley block support limit the high-pressure rubber pipe together.

Furthermore, a four-way welding part assembly is fixed at the rear ends of the two middle arms and comprises a four-way welding part and partition plate joints which are fixedly arranged on the four-way welding part and used for connecting the front high-pressure rubber pipe and the rear high-pressure rubber pipe, and the partition plate joints are distributed in two rows.

Further, be provided with tow chain tray subassembly in the inner arm, tow chain tray subassembly is including setting firmly in the preceding fixed bent plate of well two arms and with preceding fixed bent plate through the tow chain tray weldment of round pin hub connection, tow chain tray lower surface middle part is fixed with the fixed platelet of tow chain and front end is fixed with the nylon cushion.

Furthermore, one end of the drag chain is fixed on the upper surface of the drag chain tray weldment, and the other end of the drag chain is fixed at the rear end of the inner side of the inner arm.

Furthermore, the inner arm steel pipe assembly comprises a U-shaped bent plate, a pipe clamp and steel pipes fixed on two sides in the inner arm through the U-shaped bent plate and the pipe clamp.

Compared with the prior art, the utility model has the advantages that:

1. the pipeline and the chain wheel and the chain are separately arranged, so that the high-pressure rubber pipe is prevented from being damaged due to the contact with the chain, the service life of the rubber pipe is prolonged, and the maintenance cost is reduced.

2. Partial pipelines of the telescopic oil cylinder and the telescopic pipeline system are arranged outside the telescopic arm, so that the structural complexity inside the telescopic arm is reduced, the peripheral size of the telescopic arm can be effectively controlled, and the internal space of the telescopic arm is increased.

3. The pulley seat assembly is arranged at the rear end of the middle arm, the high-pressure rubber pipe is limited by the large pulley, the small pulley and the pulley support, when the telescopic arm performs telescopic motion, the high-pressure rubber pipe can be guaranteed to move along with the telescopic arm, jumping is small, and stable work of a pipeline system is guaranteed.

4. The front high-pressure rubber pipe and the rear high-pressure rubber pipe are connected through the partition plate joint on the four-way welding part assembly, the four-way welding part assembly is fixed on the middle two arms, the situation that the rear high-pressure rubber pipe is pulled by the front high-pressure rubber pipe to bear force when the middle two arms move relative to the middle one arm is avoided, the service life of the rear high-pressure rubber pipe is prolonged, and the maintenance cost is reduced.

5. The rear high-pressure rubber pipe is arranged inside the drag chain, so that the inner arm is compact in structure while the rear high-pressure rubber pipe is protected, and the peripheral size of the telescopic arm is limited.

Drawings

FIG. 1 is a schematic structural view of the pipeline of the present invention;

fig. 2 is a schematic structural view of the telescopic boom of the present invention;

fig. 3 is a schematic structural view of the telescopic pipeline system of the present invention;

FIG. 4 is an enlarged view taken at A in FIG. 3;

FIG. 5 is an enlarged view at B in FIG. 3;

fig. 6 is a schematic structural view of the pulley seat assembly of the present invention;

FIG. 7 is a schematic structural view of the four-way weldment assembly of the present invention;

fig. 8 is a schematic structural view of the telescopic cylinder assembly of the present invention;

fig. 9 is a schematic structural view of the tow chain tray assembly of the present invention.

Detailed Description

A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

As shown in fig. 1 and 2, a telescopic pipeline system of a four-section forklift comprises a telescopic arm for realizing pipeline telescopic, a pipeline and a transmission device for driving the telescopic arm, and is characterized in that the telescopic arm comprises a fixed arm 100, a middle first arm 200, a middle second arm 300 and an inner arm 400; the pipeline comprises an outer arm steel pipe component 510 fixedly arranged on the outer side of the fixed arm, an excessive bent pipe component 520 arranged at the front end of the fixed arm, a front high-pressure rubber pipe 530 arranged on the inner side of the fixed arm, a rear high-pressure rubber pipe 540 arranged on the inner side of the inner arm, a drag chain 550 and an inner arm steel pipe component 560 fixed on the inner side of the inner arm, which are sequentially communicated.

As shown in fig. 2, 4 and 5, the transmission includes a telescopic cylinder assembly 650 for driving the one of the arms 200 to move in the fixed arm, a middle two-arm forward drive assembly 610 for driving the two of the arms 300 to move forward in the one of the arms 200, a middle two-arm backward drive assembly 620 for driving the two of the arms to move backward in the one of the arms, an inner arm forward drive assembly 630 for driving the inner arm to move forward in the middle two of the arms, and an inner arm backward drive assembly 640 for driving the inner arm to move backward in the middle two of the arms.

As shown in fig. 2 and 8, the telescopic cylinder assembly 650 includes a telescopic cylinder 651, a cylinder protection plate 652 at the front end of the telescopic cylinder, and a cylinder pin 653 at the rear end of the telescopic cylinder, the telescopic cylinder base 110 is mounted on the upper surface of the fixed arm 100, the telescopic cylinder protection plate 652 is mounted on the upper surface of the fixed arm through a bolt, the telescopic cylinder 110 is fixed on the telescopic cylinder base 110 through the cylinder pin 653, the front end of the telescopic cylinder is fixedly connected with the first arm 200, and the telescopic cylinder 651 can drive the first arm to move forward or backward in the fixed arm.

As shown in fig. 4 and 5, the middle-two-arm front-drive assembly 610 includes a middle-two-arm upper chain 612, a top chain wheel 611 wound around the middle-two-arm upper chain and fixed at the front end of the middle-two-arm, and a middle-two-arm top chain holder 613 fixed on the middle-two-arm, one end of the middle-two-arm top chain is fixedly connected with the middle-two-arm top chain holder and the other end is fixedly connected with the fixing arm 100, the middle-two-arm rear-drive assembly 620 includes a middle-two-arm lower chain 622, a middle-two-arm lower chain wheel 621 wound around the middle-two-arm lower chain and fixed at the rear end of the middle-two-arm, and a middle-two-arm lower chain holder 623 fixed on the middle-two-arm, one end of the middle-two-arm lower chain 622 is fixedly connected with the middle-two.

As shown in fig. 4 and 5, the inner arm forward driving assembly 630 includes an inner arm upper chain 632, an inner arm upper chain wheel 631 wound around the inner arm upper chain and fixed to the front end of the middle two arms, and an inner arm upper chain seat 633 fixed to the inner arm, the inner arm upper chain wheel having one end fixedly connected to the inner arm upper chain seat and the other end fixedly connected to the middle one arm 200, the inner arm rear driving assembly 640 includes an inner arm return chain 642, an inner arm return chain wheel 641 wound around the inner arm lower chain and fixed to the rear end of the middle two arms, and an inner arm return chain seat 643 fixed to the inner arm, and the inner arm return chain 642 has one end fixedly connected to the inner arm return chain seat 643 and the other end fixedly connected to the middle one arm 200.

As shown in fig. 1 and 2, the outer arm steel tube assembly 510 includes four steel tubes with different lengths and fixed to the outer side of the fixing arm by using tube clamps, and the different lengths of the steel tubes facilitate the arrangement of the transition elbow assembly because the steel tubes need to be communicated with the transition elbow assembly 520.

As shown in fig. 1 and 2, the transition elbow assembly 520 includes four curved steel tubes and is fixed to the front end of the fixed arm using a tube clamp, and one end of the transition elbow assembly 520 is communicated with the outer arm steel tube assembly 510 and the other end is communicated with the front high pressure hose 530.

As shown in fig. 1, the front high-pressure hose 530 is disposed inside the fixed arm 100, one end of the front high-pressure hose is communicated with the transition elbow assembly 520, and the other end of the front high-pressure hose is communicated with the rear high-pressure hose 540 through the partition joint 312 on the four-way weldment assembly, and when the telescopic arm extends forward, the four-way weldment assembly 310 moves forward along with the middle two arms, so as to drive the front high-pressure hose to move forward.

As shown in fig. 1 and 6, a pulley seat assembly 210 is fixedly arranged at the rear end of the middle arm 200, the pulley seat assembly includes a pulley seat support 211, a large pulley 212 and a small pulley 213 which are wound with a front high-pressure rubber hose 530, the large pulley and the small pulley are fixed on the pulley seat support by using a pin, the front high-pressure rubber hose 530 is wound around the large pulley and passes through a space formed by the pulley seat support, the large pulley and the small pulley together, when the telescopic arm works, the front high-pressure rubber hose 530 can slide in the space, the front high-pressure rubber hose slides more stably, the swing amplitude is small, and the working pressure of an oil path is stable.

As shown in fig. 1 and 7, a four-way weldment assembly 310 is fixed at the rear end of the middle two arms, and comprises a four-way weldment 311 and a partition plate joint 312 which is fixedly arranged on the four-way weldment and used for communicating a front high-pressure rubber pipe 530 with a rear high-pressure rubber pipe 540, so that the rear high-pressure rubber pipe is prevented from being pulled by the front high-pressure rubber pipe when the middle two arms 300 move relative to the middle one arm 200, the service life of the rear high-pressure rubber pipe is prolonged, and the maintenance cost is reduced; the partition plate joints 312 are arranged in two rows, so that the space of the four-way welding part assembly is fully utilized, the size of parts in the telescopic arm is reduced, and the peripheral size of the telescopic arm is reduced.

As shown in fig. 1 and 9, be provided with tow chain tray subassembly 410 in the inner arm 400, tow chain tray subassembly is including setting firmly in the preceding fixed bent plate 411 of two well arms and the tow chain tray weldment 412 of passing through the round pin hub connection with preceding fixed bent plate, tow chain tray bottom surface middle part is fixed with the fixed platelet 413 of tow chain and the front end is fixed with nylon cushion 414, makes the one end that tow chain tray weldment 412 is close to preceding fixed bent plate 411 can be around moving and the fine motion about the other end, guarantees the transmission hydraulic pressure force that the tow chain can be steady during telescopic boom work, has guaranteed the job stabilization nature of pipeline.

As shown in fig. 1 and 7, the rear high-pressure rubber pipe 540 is placed on the tow chain tray weldment 412, one end of the rear high-pressure rubber pipe is communicated with the partition plate joint 312, the other end of the rear high-pressure rubber pipe is communicated with the inner arm steel pipe assembly 560, the rear high-pressure rubber pipe is arranged in the tow chain 550, one end of the tow chain is fixed to the upper surface of the tow chain tray weldment 412, the other end of the tow chain is fixed to the inner rear end of the inner arm 400, the bending radius of the tow chain 550 is selected to be equal to the minimum bending radius of the rear high-pressure rubber pipe 540, the rear high-pressure rubber pipe is.

As shown in fig. 1, the tow chain 550 is fixed to the inner side of the inner arm by a tow chain fixing bent plate 420, and the front end of the tow chain fixing bent plate is provided with a side limiting plate 421 for limiting the rear end of the inner arm steel pipe assembly 560, so that the positioning and installation of the inner arm steel pipe assembly are more stable.

As shown in fig. 1, the inner arm steel tube assembly 560 includes a U-shaped bent plate 561, a tube clamp, and steel tubes fixed to both sides of the inner arm by the U-shaped bent plate and the tube clamp, and when the steel tubes are installed, a certain space is required to be left on both sides of the steel tubes, and the symmetrical arrangement is favorable for making full use of the space in the inner arm on both sides of the inner arm, and the left and right steel tubes are respectively connected to different hydraulic devices, and separately installed to facilitate the connection of corresponding control cylinders nearby.

The utility model discloses the theory of operation as follows: when the telescopic arm extends, the telescopic oil cylinder assembly 650 drives the middle arm 200 to move forwards relative to the fixed arm 100, the chain wheel 611 on the middle arm moves forwards along with the middle arm, and then acts on the chain seat 613 on the middle arm through the chain 612 on the middle arm, so that the middle arm 300 moves forwards relative to the middle arm 200, meanwhile, the chain wheel 631 on the inner arm moves forwards along with the middle arm, and further acts on the chain seat 633 on the inner arm through the chain 632 on the inner arm, so that the inner arm 400 moves forwards relative to the middle arm 300, and thus the extension of the telescopic arm is realized; when flexible arm contracts, the relative fixed arm 100 rearward movement of an arm 200 in the flexible cylinder subassembly 650 drive, well two underarm sprocket 621 is along with well one backward movement, and then acts on well two underarm chain seat 623 through well two underarm chain 622, and one 200 backward movement in two arms 300 is relative in the realization, and simultaneously inner arm time chain wheel 641 moves backward along with well two arms, and then acts on inner arm time chain seat 643 through inner arm time chain 642, realizes that two arms 300 backward movement in the arm 400 is relative in, and then realizes the shrink of flexible arm, the utility model discloses separately arrange pipeline and transmission's sprocket and chain, prevent because of causing the damage of high-pressure rubber tube with the chain contact, improve the life of rubber tube, reduced the maintenance cost.

It is obvious to a person skilled in the art that the invention is not restricted to details of the above-described exemplary embodiments, but that it can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein, and any reference signs in the claims are not intended to be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims

1. A telescopic pipeline system of a four-section forklift comprises a telescopic arm for realizing pipeline telescopic, a pipeline and a transmission device for driving the telescopic arm, and is characterized in that the telescopic arm comprises a fixed arm (100), a first middle arm (200), a second middle arm (300) and an inner arm (400); the pipeline is including setting firmly outer arm steel pipe component (510) in the fixed arm outside, setting up in transition return bend subassembly (520) of fixed arm front end that communicate in proper order, arranging the inboard preceding high-pressure rubber pipe (530) of fixed arm in, arranging the inboard back high-pressure rubber pipe (540) of inner arm in and be fixed in the inboard inner arm steel pipe component (560) of inner arm, back high-pressure rubber pipe is equipped with tow chain (550) outward.

2. The telescopic pipe system of a four-section forklift according to claim 1, wherein: the transmission device comprises a telescopic oil cylinder assembly (650) for driving one arm (200) to move in a fixed arm, a middle two-arm front driving assembly (610) for driving the middle two arm (300) to move forwards in the middle one arm (200), a middle two-arm rear driving assembly (620) for driving the middle two arm to move backwards in the middle one arm, an inner arm front driving assembly (630) for driving the inner arm to move forwards in the middle two arm, and an inner arm rear driving assembly (640) for driving the inner arm to move backwards in the middle two arm.

3. The telescopic pipe system of a four-section forklift according to claim 2, wherein: the telescopic oil cylinder assembly (650) comprises a telescopic oil cylinder (651), an oil cylinder protection plate (652) arranged at the front end of the telescopic oil cylinder and an oil cylinder pin shaft (653) arranged at the rear end of the telescopic oil cylinder, and the front end of the telescopic oil cylinder is fixedly connected with the middle arm (200).

4. The telescopic pipe system of a four-section forklift according to claim 2, wherein: the middle two-arm front drive assembly (610) comprises a middle two-arm upper chain (612), a middle two-arm upper chain wheel (611) wound with the middle two-arm upper chain and fixedly arranged at the front end of the middle one arm, and a middle two-arm upper chain seat (613) fixed on the middle two arm, wherein one end of the middle two-arm upper chain (612) is fixedly connected with the middle two-arm upper chain seat, and the other end of the middle two-arm upper chain (612) is fixedly connected with the fixing arm (100); the middle-two-arm rear drive assembly (620) comprises a middle-two-arm lower chain (622), a middle-two-arm lower chain wheel (621) wound with the middle-two-arm lower chain and fixedly arranged at the rear end of the middle-two arm, and a middle-two-arm lower chain seat (623) fixed on the middle-two arm, wherein one end of the middle-two-arm lower chain (622) is fixedly connected with the middle-two-arm lower chain seat (623), and the other end of the middle-two-arm lower chain (622) is fixedly connected with the fixing arm (100).

5. The telescopic pipe system of a four-section forklift according to claim 2, wherein: the inner arm front drive assembly (630) comprises an inner arm upper chain (632), an inner arm upper chain wheel (631) wound with the inner arm upper chain and fixedly arranged at the front ends of the middle two arms, and an inner arm upper chain seat (633) fixed on the inner arm, wherein one end of the inner arm upper chain is fixedly connected with the inner arm upper chain seat, and the other end of the inner arm upper chain is fixedly connected with the middle one arm (200); the inner arm rear drive assembly (640) comprises an inner arm return chain (642), an inner arm return chain wheel (641) wound with the inner arm return chain and fixedly arranged at the rear ends of the two middle arms and an inner arm return chain seat (643) fixed on the inner arm, wherein one end of the inner arm return chain (642) is fixedly connected with the inner arm return chain seat (643), and the other end of the inner arm return chain (643) is fixedly connected with the one middle arm (200).

6. The telescopic pipe system of a four-section forklift according to claim 1, wherein: the middle arm (200) is fixedly provided with a pulley seat component (210) at the rear end, the pulley seat component comprises a pulley seat support (211), a large pulley (212) and a small pulley (213) which are wound with a high-pressure rubber pipe, the large pulley and the small pulley are fixed on the pulley seat support through a pin shaft, and the large pulley, the small pulley and the pulley seat support limit the high-pressure rubber pipe together.

7. The telescopic pipe system of a four-section forklift according to claim 1, wherein: the middle arm and the middle arm are fixed with a four-way welding part assembly (310) at the rear end, the four-way welding part assembly comprises a four-way welding part (311) and partition plate joints (312) fixedly arranged on the four-way welding part and used for connecting a front high-pressure rubber pipe and a rear high-pressure rubber pipe, and the partition plate joints are distributed in two rows.

8. The telescopic pipe system of a four-section forklift according to claim 1, wherein: be provided with tow chain tray subassembly (410) in inner arm (400), tow chain tray subassembly is including setting firmly preceding fixed bent plate (411) of two arms in and tow chain tray weldment (412) through the round pin hub connection with preceding fixed bent plate, tow chain tray lower surface middle part is fixed with tow chain fixed platelet (413) and front end and is fixed with nylon cushion (414).

9. The telescopic pipe system of a four-section forklift according to claim 7, wherein: one end of the drag chain (550) is fixed on the upper surface of the drag chain tray weldment (311) and the other end of the drag chain is fixed at the rear end of the inner side of the inner arm.

10. The telescopic pipe system of a four-section forklift according to claim 1, wherein: the inner arm steel pipe assembly (560) comprises a U-shaped bent plate (561), a pipe clamp and steel pipes which are fixed on two sides in the inner arm through the U-shaped bent plate and the pipe clamp.