Hydraulic drive type portal frame forward moving structure and forklift

Abstract

The invention relates to the technical field related to warehouse logistics, discloses a hydraulic drive type portal frame forward moving structure and a forklift, and aims to solve the problem that the overall length of a forklift is too large due to the fact that a fork assembly adopts an oil cylinder push-out mode. The pulley frame can extend / retract according to the positioning and guiding of the transmission chain, the displacement length of the pulley frame completely depends on the actual set length of the transmission chain, and the driving component is completely integrated on the pulley frame, so that the whole machine is more compact, and the pulley frame can extend and retract for a long distance while being ensured to move. And the length of the whole machine can be reduced, so that the chassis of the vehicle body can flexibly move in a narrow space, and the aim of propelling and stretching through motor-gear transmission and chain wheel-chain transmission is finally achieved.

Description

Technical Field

[0001] This invention relates to the field of warehousing and logistics technology, and in particular to a hydraulically driven gantry forward-moving structure and forklift. Background Technology

[0002] With the unprecedented rapid development of the modern logistics industry and the active promotion of upgrading and transformation strategies by domestic enterprises, the warehousing and logistics sector is undergoing profound changes. Against this backdrop, the demand for diversified handling and stacking within factories and warehouses is showing a significant upward trend.

[0003] Currently, land resources are becoming increasingly scarce, and land use costs are continuously rising, especially in urban warehousing areas where land is extremely valuable, posing numerous challenges for businesses. To achieve efficient operations within limited warehousing space, companies urgently need material handling and stacking operations with higher efficiency, greater flexibility, more economical costs, and higher space utilization. For example, during peak e-commerce logistics periods, warehouses need to complete large-scale inbound and outbound operations within a short period, requiring handling equipment to quickly and accurately complete loading, unloading, and stacking of goods. Simultaneously, with continuously rising warehouse rents, companies hope to optimize warehouse layouts to increase the storage capacity per unit area, thereby reducing logistics costs.

[0004] In this context, reach trucks have gained widespread application in these complex usage scenarios due to their unique advantages. The lifting system of a reach truck is ingeniously designed, with its mast extending forward. When storing or retrieving goods, the extended mast provides the stability of a counterbalance forklift, ensuring the vehicle remains stable while handling heavy loads and preventing goods from slipping and causing safety hazards; it also boasts broad pallet adaptability, accommodating various pallet sizes to meet the handling needs of different goods. During transport, when the mast retracts, the reach truck combines the flexibility of a stacker forklift and a pallet truck, maneuvering nimbly through narrow aisles. Furthermore, it requires smaller stacking aisles, significantly reducing warehouse aisle width compared to traditional forklifts, thereby increasing the number of racking storage positions and effectively improving warehouse capacity. These advantages allow reach trucks to significantly reduce logistics costs for businesses and improve the overall efficiency of warehouse operations.

[0005] Currently, the main mast-moving mechanism in reach trucks on the market employs double-acting piston cylinders with angled thrust, enabling the forks to move forward and backward. However, in practical applications, the limited length of the cylinders restricts the mast's forward movement distance, failing to meet the demands of scenarios with high handling distance requirements. Furthermore, the increased cylinder length leads to a larger turning radius. These issues make reach trucks using direct-acting mast thrust difficult to maneuver in narrow aisles, severely impacting their efficiency and adaptability in specific warehousing environments. Summary of the Invention

[0006] This invention proposes a hydraulically driven mast forward-moving structure and forklift, which integrates the propulsion advantages of motor-gear transmission and sprocket-chain transmission, aiming to effectively solve the problem of excessive overall vehicle length caused by the use of hydraulic cylinders for pushing out, as mentioned in the background art.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a hydraulically driven mast forward-moving structure, comprising: a vehicle chassis, a trolley frame movably mounted on its surface, and a control assembly mounted on its top; a fork assembly fixedly connected to the top of the trolley frame, and a balance valve mounted on the back of the trolley frame, the output end of which is connected to a hydraulic motor fixedly mounted on the back of the trolley frame, and a drive gear fixedly mounted on the output shaft of the hydraulic motor; a drive shaft assembly movably mounted on the side of the trolley frame, and a driven shaft gear meshing with the external teeth of the drive gear mounted on the side of the drive shaft assembly; a drive shaft sprocket mounted at the end of the drive shaft assembly, and a drive chain connected to the front and rear ends of the vehicle chassis, the drive chain being connected to the drive shaft sprocket; and a driven sprocket fixedly mounted on the side of the trolley frame for reversing the drive chain.

[0008] Furthermore, the drive chain fixed to the front end of the vehicle chassis is fixedly connected to a chain adjustment shaft, and the chain adjustment shaft is inserted into a sleeve set at the front end of the vehicle chassis; an anti-reverse groove is provided on the outer side of the chain adjustment shaft, and a stop rod is inserted into the anti-reverse groove at the front end of the vehicle chassis and located in the sleeve.

[0009] Furthermore, the anti-reverse groove is shaped like a right-angled trapezoid.

[0010] Furthermore, a top plate is threadedly connected to the end of the chain adjusting shaft away from the drive chain, and a push spring is provided between the top plate and the sleeve.

[0011] Furthermore, the transmission shaft assembly is divided into a drive main shaft and a transmission driven shaft. The drive main shaft and the driven shaft gears are coaxially fastened. The drive main shaft has a transmission driven shaft movably mounted on the trolley frame at both ends. Both ends of the driven shaft gear are fixedly connected to a drive end face gear row. The driven end face gear row is movably mounted at the end of the transmission driven shaft. The end of the driven end face gear row is movably mounted with a transmission push rod that is pushed by a spring towards the drive end face gear row.

[0012] Furthermore, a stepped groove is provided at the end of the drive shaft, and the end of the drive shaft is elliptical.

[0013] Furthermore, an electromagnet is fixedly installed at the end of the drive end face toothed rack. When the electromagnet is energized, it attracts the driven end face toothed rack. The drive shaft sprocket is movably installed on the trolley frame, and there is a protrusion extending towards the central axis on the inner side of the drive shaft sprocket. Detection switches are symmetrically arranged on both sides of the protrusion. A top block located inside the drive shaft sprocket is fixedly installed at the end of the driven shaft. The top block presses against the detection switch to activate the electromagnet.

[0014] Furthermore, the inner side of the drive shaft sprocket is provided with protruding teeth at equal angles, and the outer side of the top block has a tensioning rod that is pushed into the inner side of the drive shaft sprocket by a spring.

[0015] Furthermore, a warning bell located at the end of the chain adjustment shaft is fixedly installed at the front of the vehicle chassis.

[0016] The present invention has the following beneficial effects:

[0017] This invention provides a hydraulically driven mast forward-moving structure and forklift, which utilizes a hydraulic motor, driven shaft gear, driving gear, drive shaft sprocket, and drive chain working in concert. During operation, the hydraulic motor acts as a power source, converting hydraulic energy into mechanical energy to drive the driving gear. The driving gear meshes with the driven shaft gear, achieving the initial power transmission. Subsequently, the driven shaft drives the drive shaft sprocket to rotate, and the drive shaft sprocket further transmits power through the drive chain, enabling the trolley frame to smoothly and reliably extend or retract under the precise positioning and guidance of the drive chain.

[0018] Because the displacement length of the trolley frame depends entirely on the actual set length of the drive chain, this design ensures the precision and controllability of the displacement. Simultaneously, the drive components are fully integrated into the trolley frame, greatly optimizing the overall structural layout. This innovative design effectively reduces the overall length of the machine while ensuring the trolley frame can achieve stable long-distance telescopic movement. The shorter overall length gives the chassis greater flexibility and maneuverability in confined spaces, easily handling various complex working environments. Attached Figure Description

[0019] The accompanying drawings, which form part of this specification, illustrate embodiments of the invention and, together with the specification, serve to explain the principles of the invention.

[0020] The invention will be more clearly understood with reference to the accompanying drawings and the following detailed description, wherein:

[0021] Figure 1 This is a schematic diagram of the overall side view and partial cross-sectional planar structure of the present invention;

[0022] Figure 2 For the present invention Figure 1 Enlarged structural diagram of section E in the middle;

[0023] Figure 3 This is a schematic diagram showing the positions and three-dimensional structure of various components on the trolley frame of the present invention;

[0024] Figure 4 This is a schematic diagram of the design and structure of the first type of transmission shaft assembly of the present invention;

[0025] Figure 5 This is a schematic diagram of the design and structure of the second type of drive shaft assembly of the present invention;

[0026] Figure 6 This is a schematic diagram of the installation position and three-dimensional structure of the driving end face toothed row and the driven end face toothed row of the present invention;

[0027] Figure 7 This is a schematic diagram of the transmission driven shaft end structure of the present invention;

[0028] Figure 8 This is a schematic diagram of the internal three-dimensional structure of the drive shaft sprocket of the present invention.

[0029] In the diagram: 1. Tractor frame; 2. Balance valve; 3. Drive shaft assembly; 300. Drive spindle; 301. Driven shaft; 4. Hydraulic motor; 5. Driven shaft gear; 6. Drive gear; 7. Drive shaft sprocket; 701. Protrusion; 702. Protruding tooth; 703. Detection switch; 8. Driven sprocket; 9. Drive chain; 10. Chain adjusting shaft; 1001. Top plate; 1002. Anti-reverse groove; 1003. Push spring; 11. Fork assembly; 12. Chassis; 13. Control assembly; 14. Drive end face gear row; 140. Driven end face gear row; 141. Drive push rod; 142. Electromagnet; 15. Top block; 151. Tensioning push rod; 16. Stop rod; 17. Warning bell. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1, please refer to Figure 1 As can be seen, a stand-up reach forklift is generally used. The trolley frame 1 is movably mounted on the chassis 12. The trolley frame 1 can extend and retract horizontally along the chassis 12, and is positioned and guided by rollers on both sides to ensure the stability of its horizontal movement. A control assembly 13 for controlling the entire machine is fixedly installed on the chassis 12. A fork assembly 11 for lifting goods is fixedly connected to the top of the trolley frame 1. The left and right movement of the trolley frame 1 can drive the fork assembly 11 to move horizontally; at the same time, the vertical movement of the fork assembly 11 can realize the vertical transport of goods.

[0032] Combination Figure 1 , Figure 3 and Figure 4 It can be seen that the components used to drive the movement of the trolley frame 1 are fully integrated onto the trolley frame 1, thereby reducing the space occupied by the components driving the movement of the trolley frame 1, facilitating a shorter overall length of the chassis 12, and making the chassis 12 easier to maneuver in narrow passageways. The balance valve 2 is fixedly installed on the back of the trolley frame 1, and the balance valve 2 is connected to the hydraulic system in the control assembly 13 via a pipe. The output end of the balance valve 2 is connected to a hydraulic motor 4 fixedly installed on the back of the trolley frame 1. According to the regulation of the balance valve 2, hydraulic oil enters the hydraulic motor 4, forcing the hydraulic motor 4 to rotate and providing power to the subsequent structure.

[0033] The output shaft of the hydraulic motor 4 is fixedly mounted with a drive gear 6, from which... Figure 3 As can be seen, a drive shaft assembly 3 is movably mounted on the side of the trolley frame 1, located above the hydraulic motor 4, and a driven shaft gear 5 that meshes with the external teeth of the drive gear 6 is mounted on the side of the drive shaft assembly 3. When the hydraulic motor 4 drives the drive gear 6 to perform forward and reverse movements, the meshing transmission between the driven shaft gear 5 and the drive gear 6 can control the drive shaft assembly 3 to rotate synchronously.

[0034] A drive shaft sprocket 7 is mounted at one end of the drive shaft assembly 3. Depending on actual needs, the drive shaft sprocket 7 can be mounted at one or both ends. Meanwhile, according to... Figure 1It can be seen that a drive chain 9 is connected to the front and rear ends of the chassis 12, and the drive chain 9 is connected to the drive shaft sprocket 7. A driven sprocket 8 for reversing the drive chain 9 is fixedly installed on the side of the trolley frame 1. Based on the above, it can be seen that during application, the hydraulic motor 4 drives the drive shaft assembly 3 to rotate, and the drive shaft assembly 3, based on the rotation of the drive shaft sprocket 7, moves in a directional manner along the drive chain 9. At this time, by setting the length of the drive chain 9, the actual forward extension length of the trolley frame 1 can be achieved.

[0035] In summary, the transmission method provided in this application utilizes gear transmission, which offers a higher transmission ratio while maintaining high torque output. The coaxial transmission in the middle ensures high synchronization of the transmission chains on both sides of the trolley frame 1, making the forward movement of the trolley frame 1 more stable and smooth. The arrangement of the sprockets and chains saves more lateral space, effectively shortening the overall width of the machine. Furthermore, the drive components are integrated into the back of the trolley frame 1, further reducing its footprint. Ultimately, this shortens the overall length and width of the machine, making it more compact and flexible.

[0036] Example 2 is a further improvement on Example 1. Please refer to Example 1. Figure 1 and Figure 2 As can be seen, the drive chain 9 can be configured in one or two ways, depending on the actual load conditions. Taking the use of one drive chain 9 as an example, the drive chain 9 fixed to the front end of the chassis 12 is fixedly connected to a chain adjusting shaft 10, and the chain adjusting shaft 10 is inserted into a sleeve located at the front end of the chassis 12. Simultaneously, an anti-reverse groove 1002 is provided on the outer side of the chain adjusting shaft 10, and the anti-reverse groove 1002 is a right-angled trapezoid. Correspondingly, a stop rod 16 is inserted into the anti-reverse groove 1002 at the front end of the chassis 12, located in the sleeve, thereby restricting the chain adjusting shaft 10 from moving to the right, with the direction referenced... Figure 2 .

[0037] The end of the chain adjusting shaft 10 away from the transmission chain 9 is threadedly connected to a top plate 1001, and a push spring 1003 is provided between the top plate 1001 and the sleeve. The push spring 1003 pushes the chain adjusting shaft 10 so that it always tends to move away from the transmission chain 9, thus ensuring that the transmission chain 9 is always in a taut state.

[0038] In practical applications, combined with Figure 1 and Figure 2 As shown, when the trolley frame 1 extends forward, the drive shaft sprocket 7 rotates counterclockwise, thus moving along the drive chain 9. During this process, the drive shaft sprocket 7 tends to drag the drive chain 9 to the right, but is stopped by the stop rod 16 pressing against the anti-reverse groove 1002, which locks the chain adjusting shaft 10 in place.

[0039] When the extended trolley frame 1 needs to retract to the right, the drive shaft sprocket 7 rotates clockwise. At this time, the drive shaft sprocket 7 tends to push the drive chain 9 to the left. On the one hand, the right end of the drive chain 9 needs to be tightly pulled to the rear end of the chassis 12, while the left end of the drive chain 9 tends to be pushed to the left under the force of the push spring 1003. If the drive chain 9 loosens, the push spring 1003 will push the top plate 1001, causing the top plate 1001 to pull the drive chain 9 to the left via the chain adjusting shaft 10, thus bringing the drive chain 9 back to a taut state. The leftward movement of the chain adjusting shaft 10 will cause the anti-reverse groove 1002 to move to the left relative to the stop rod 16, forcing the stop rod 16 to abut against the next anti-reverse groove 1002, thereby further limiting the chain adjusting shaft 10.

[0040] Therefore, it can be seen that by using the solution described in Embodiment 2, it is possible to ensure that the transmission chain 9 is always in a taut state during operation, and to prevent the chain from failing or slipping.

[0041] Example 3 is a further improvement on Example 2. When using a dual-chain drive, if one chain has insufficient tension, due to the synchronous rotation of the two drive shaft sprockets 7, only one drive shaft sprocket 7 will apply force to the drive chain 9. This will cause the taut drive chain 9 to overwork, while the slack drive chain 9 will have reduced working strength or even fail directly. This not only reduces the overall load-bearing capacity of the machine, but may also lead to accelerated wear of the overworked drive chain 9, resulting in rapid damage.

[0042] To address this issue, this third embodiment provides an alternative transmission method. Compared to the direct impact of the transmission shaft assembly 3 in the first embodiment, this third embodiment divides the transmission shaft assembly 3 into a drive shaft 300 and a driven shaft 301. The drive shaft 300 and the driven shaft gear 5 are coaxially fastened, and the driven shaft gear 5 and the drive gear 6 are always in external gear meshing. Driven shafts 301 are movably mounted on the trolley frame 1 at both ends of the drive shaft 300. The two driven shafts 301 can restrict the installation position of the drive shaft 300, but the drive shaft 300 and the driven shafts 301 can rotate relative to each other.

[0043] from Figures 5-7It can be seen that both ends of the driven shaft gear 5 are fixedly connected to drive end face gear rows 14. Correspondingly, a driven end face gear row 140 is movably mounted at the end of the driven shaft 301 near the driven shaft gear 5. This end has a stepped groove, and its outer side is elliptical, thus restricting the driven end face gear row 140 to move only left and right along the axis of the driven shaft 301. A transmission push rod 141, which is pushed by a spring towards the drive end face gear row 14, is movably mounted at the end of the driven end face gear row 140. The transmission push rod 141 abuts against the outer teeth at the end of the drive end face gear row 14. Under normal conditions, since the spring is placed between the transmission push rod 141 and the driven end face gear row 140, the transmission push rod 141 is forced to abut against the drive end face gear row 14, and the driven end face gear row 140 is relatively far away from the drive end face gear row 14. At this time, the outer teeth between the driven end face gear row 140 and the drive end face gear row 14 are relatively far apart.

[0044] An electromagnet 142 is fixedly mounted on the end of the drive end face toothed rack 14. When the electromagnet 142 is energized, it can attract the driven end face toothed rack 140, causing the driven end face toothed rack 140 to move towards the drive end face toothed rack 14 until the external teeth of the two engage and transmit power. Regarding the energization control of the electromagnet 142, combined with... Figure 5 and Figure 8 It can be seen that the drive shaft sprocket 7 is movably mounted on the trolley frame 1, and there is a protrusion 701 extending towards the central axis on the inner side of the drive shaft sprocket 7. Detection switches 703 are symmetrically arranged on both sides of the protrusion 701. Correspondingly, a top block 15 located inside the drive shaft sprocket 7 is fixedly mounted on the end of the driven shaft 301. When the driven shaft 301 drives the top block 15 to rotate and bring it close to the detection switch 703, the detection switch 703 is pressed, which will activate the electromagnet 142. However, it should be noted that there are two drive shaft sprockets 7 and two electromagnets 142. Figure 5 For example, electromagnets 142 are provided on both the left and right sides of the driven shaft gear 5. When the detection switch 703 on the right side of the driven shaft gear 5 is pressed, the electromagnet 142 on the left side will be turned on. Similarly, when the detection switch 703 on the left side of the driven shaft gear 5 is pressed, the electromagnet 142 on the right side will be turned on.

[0045] The advantage of this design is that, during actual handling, the forward and backward movement of the trolley frame 1 is primarily based on the forward and reverse rotation of the drive shaft assembly 3. Therefore, during the extension / retraction of the trolley frame 1, the drive shaft 301 will cause the drive shaft sprocket 7 to rotate in the opposite direction. Figure 8For example, if the driven shaft 301 rotates clockwise, the top block 15 abuts against the detection switch 703 below, and the trolley frame 1 is in a forward-extended state. However, when the trolley frame 1 needs to retract, the driven shaft gear 5 will drive the driven shaft 301 to rotate counterclockwise. At this time, the top block 15 and the protrusion 701 move away from each other. At this time, the electromagnet 142 is de-energized, and the driven end face gear 140 is disengaged from the driving end face gear 14. However, during the rotation of the driven shaft gear 5, because the transmission top rod 141 abuts against the outer tooth spacing of the driving end face gear 14, the driving end face gear 14 still has the tendency to drive the driven end face gear 140 to rotate, forcing the driven shaft 301 to continue to rotate counterclockwise. During this process, neither the transmission shaft sprocket 7 nor the driven sprocket 8 applies resistance to the transmission chain 9. When the drive chain 9 is relaxed, the push spring 1003 will push the chain adjusting shaft 10 away from the drive chain 9, and put the drive chain 9 back into a taut state.

[0046] After the drive shaft 301 drives the top block 15 to rotate counterclockwise, if both top blocks 15 simultaneously contact the detection switch 703, the top blocks 15 push the protrusion 701 to rotate the drive shaft sprocket 7 counterclockwise, causing the trolley frame 1 to retract. If the drive chain 9 is loosened, causing it to tighten and pull the drive shaft sprocket 7 to rotate, the two top blocks 15 will contact the corresponding detection switches 703 in sequence. The top block 15 that contacts the detection switch 703 first will activate its corresponding electromagnet 142. However, as mentioned above, the activation of the detection switch 703 will magnetize the electromagnet 142 that is relatively far away from it. But since the drive shaft 301 in this part still needs to deflect counterclockwise and move the top block 15 towards the protrusion 701, the activated electromagnet 142 will not affect the movement of the drive shaft 301 that has not yet contacted the detection switch 703. Subsequently, when the relatively lagging top block 15 contacts the detection switch 703, the corresponding electromagnet 142 will also be activated. At this time, the electromagnets 142 on both sides of the driven shaft gear 5 will be activated simultaneously, and both transmission chains 9 will be in a taut state. When the transmission shaft sprocket 7 and the transmission chain 9 are in motion, both transmission chains 9 provide power for the movement of the trolley frame 1, thereby avoiding the problem of the taut transmission chain 9 overworking due to slackness.

[0047] Example 4 is a supplement to Example 3. Please refer to Example 3. Figure 8 It can be seen that the inner side of the drive shaft sprocket 7 has protruding teeth 702 arranged at equal angles. Correspondingly, the outer side of the top block 15 has a tensioning push rod 151 that is pushed inward by a spring towards the inner side of the drive shaft sprocket 7. The significance of this design is that, as Figure 2As shown, a warning bell 17 is fixedly installed at the front end of the chassis 12, located at the end of the chain adjusting shaft 10. When the anti-reverse groove 1002 completely disengages from the stop rod 16, it indicates that the chain adjusting shaft 10 can no longer independently adjust the tension of the transmission chain 9. Therefore, the push spring 1003 pushes the chain adjusting shaft 10 towards the warning bell 17, causing the chain adjusting shaft 10 to strike the warning bell 17. Figure 1 As shown, if the drive shaft sprocket 7 retracts and needs to rotate clockwise, the top block 15 will cause the tightening rod 151 to move along the inner side of the drive shaft sprocket 7. During the movement, the tightening rod 151 abuts against the tooth 702, causing the drive shaft sprocket 7 to tend to drive the drive chain 9 to move synchronously to the right. The drive chain 9 moves to the right and pulls the chain adjusting shaft 10 to compress and store force on the push spring 1003. When the chain adjusting shaft 10 cannot move to the right, the resistance to the movement of the drive chain 9 will increase, forcing the tightening rod 151 to pass over the tooth 702. Then, pushed by the elastic force of the push spring 1003, the chain adjusting shaft 10 strikes the warning bell 17 and produces a sound. When the tightening rod 151 passes the next tooth 702 again, the chain adjusting shaft 10 compresses and stores force on the push spring 1003 again. Then, according to the above, the chain adjusting shaft 10 continuously strikes the warning bell 17 to make a sound, thereby warning the operator that the transmission chain 9 is too loose and needs to be inspected and adjusted.

Claims

1. A hydraulically driven gantry forward-moving structure, characterized in that, include: The vehicle chassis (12) has a movably mounted sled frame (1) on its surface and a control assembly (13) mounted on its top. The top of the trolley frame (1) is fixedly connected to a fork assembly (11), and a balance valve (2) is installed on the back of the trolley frame (1). The output end of the balance valve (2) is connected to a hydraulic motor (4) fixedly installed on the back of the trolley frame (1), and a drive gear (6) is fixedly installed on the shaft of the output end of the hydraulic motor (4). A drive shaft assembly (3) is movably mounted on the side of the trolley frame (1), and a driven shaft gear (5) that meshes with the external teeth of the drive gear (6) is mounted on the side of the drive shaft assembly (3). A drive shaft sprocket (7) is installed at the end of the drive shaft assembly (3). A drive chain (9) is connected to the front and rear ends of the chassis (12). The drive chain (9) is connected to the drive shaft sprocket (7). A driven sprocket (8) for reversing the drive chain (9) is fixedly installed on the side of the trolley frame (1).

2. The hydraulically driven gantry forward-moving structure according to claim 1, characterized in that, The transmission chain (9) fixed to the front end of the vehicle chassis (12) is fixedly connected to the chain adjustment shaft (10), and the chain adjustment shaft (10) is inserted into the sleeve set at the front end of the vehicle chassis (12); the chain adjustment shaft (10) is provided with an anti-reverse groove (1002) on the outside, and the front end of the vehicle chassis (12) and the sleeve have a stop rod (16) inserted into the anti-reverse groove (1002).

3. The hydraulically driven gantry forward-moving structure according to claim 2, characterized in that, The anti-reverse groove (1002) is in the shape of a right trapezoid.

4. The hydraulically driven gantry forward-moving structure according to claim 2, characterized in that, The end of the chain adjusting shaft (10) away from the transmission chain (9) is threaded with a top plate (1001), and a push spring (1003) is provided between the top plate (1001) and the sleeve.

5. The hydraulically driven gantry forward-moving structure according to claim 2, characterized in that, The drive shaft assembly (3) is divided into a drive main shaft (300) and a drive driven shaft (301). The drive main shaft (300) and the driven shaft gear (5) are coaxially fastened. The drive main shaft (300) has drive driven shafts (301) that are movably mounted on the trolley frame (1) at both ends. Both ends of the driven shaft gear (5) are fixedly connected to the drive end face gear row (14), and the driven end face gear row (140) is movably installed at the end of the transmission driven shaft (301). The end of the driven end face gear row (140) is movably installed with a transmission push rod (141) that is pushed by a spring towards the drive end face gear row (14).

6. The hydraulically driven gantry forward-moving structure according to claim 5, characterized in that, The drive shaft (301) has a stepped groove at its end, and the end of the drive shaft (301) is elliptical.

7. The hydraulically driven gantry forward-moving structure according to claim 5, characterized in that, An electromagnet (142) is fixedly installed at the end of the drive end face toothed rack (14). When the electromagnet (142) is energized, it attracts the driven end face toothed rack (140). The drive shaft sprocket (7) is movably installed on the trolley frame (1). There is a protrusion (701) extending towards the central axis on the inner side of the drive shaft sprocket (7). Detection switches (703) are symmetrically arranged on both sides of the protrusion (701). A top block (15) located inside the drive shaft sprocket (7) is fixedly installed at the end of the drive shaft (301). The top block (15) presses the detection switch (703) to activate the electromagnet (142).

8. The hydraulically driven gantry forward-moving structure according to claim 7, characterized in that, The inner side of the drive shaft sprocket (7) has teeth (702) arranged at equal angles, and the outer side of the top block (15) has a tensioning rod (151) that is pushed out by a spring towards the inner side of the drive shaft sprocket (7).

9. The hydraulically driven gantry forward-moving structure according to claim 8, characterized in that, A warning bell (17) located at the end of the chain adjustment shaft (10) is fixedly installed at the front end of the chassis (12).

10. A forklift, characterized in that, Includes the hydraulically driven gantry forward movement structure as described in any one of claims 1-9.

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