CN117466212A

CN117466212A - Balance bridge structure, balance bridge and forklift

Info

Publication number: CN117466212A
Application number: CN202210869095.5A
Authority: CN
Inventors: 请求不公布姓名
Original assignee: Zhuoyi Industrial Robot Suzhou Co ltd
Current assignee: Zhuoyi Industrial Robot Suzhou Co ltd
Priority date: 2022-07-21
Filing date: 2022-07-21
Publication date: 2024-01-30

Abstract

The invention provides a balance bridge structure, which comprises a frame and a balance bridge; the balance bridge includes: a cross member assembly, a front axle, a rear axle, and a pair of drive wheel assemblies; the driving wheel assemblies are arranged at two ends of the beam assembly, and when the horizontal plane of the landing points of the driving wheels of the driving wheel assemblies changes, the end parts of the beam assembly are driven to swing; the front shaft and the rear shaft are respectively fixedly arranged on two outer surfaces of the beam assembly, which are opposite; the front shaft and the rear shaft are respectively provided with a bearing part at one end deviating from the beam assembly; the frame is provided with a mounting part which is fixedly connected with the bearing part. Simple structure, convenient assembly and maintenance, low cost, high reliability and practicality, and good safety. The balance bridge and the forklift provided by the invention have corresponding advantages.

Description

Balance bridge structure, balance bridge and forklift

Technical Field

The invention belongs to the technical field of forklifts, and particularly relates to a balance bridge structure, a balance bridge and a forklift.

Background

The forklift generally has a body system with single-point driving and rear double-driving and multiple-driving systems. The driving of the single pivot cannot meet the requirement of large tonnage forklift trucks due to the limited bearing capacity. In the vehicle body system of the rear double-drive and multi-drive system, if the fulcra of the four wheels are rigidly connected, the tires of the vehicle cannot be fully landed due to manufacturing errors and uneven road surfaces, and at the moment, the running and the stability of the vehicle cannot be guaranteed. Balance bridges are components of forklifts that are used to accommodate or adjust for uneven ground, and are typically mounted to the frame of the truck to maintain the wheels of the truck in place while they are in operation.

The balance bridge structure design in the prior art adopts a whole shaft to penetrate through a cross beam of the balance bridge as a connecting part of the balance bridge and a frame. The matching precision requirement of the center shaft and the hole of the existing balance bridge structure is very high, the error requirement of related welding parts is also very high, the difficulty of assembly and maintenance work is high, and the relative movement of the connecting parts is ensured by lubricating at regular intervals. After the outer shaft and the hole are matched, various abnormal sounds are often caused due to the fact that the degree of freedom of enough dimensions is not available, and the difficulty of adjusting and controlling the gap of the shaft hole is quite high. Specifically, the frame and the balance bridge are generally welded parts, and welding errors and deformation exist, which also cause abnormal difficulties in assembly. The method of connecting the bearing or the large shaft is adopted, the requirements on machining and matching precision of the welded vehicle body and the holes and shafts on the balance bridge are very high, the assembly efficiency is low, and the disassembly is more difficult, especially for vehicles with larger tonnage. In the prior art, the problem that a certain driving wheel cannot land when a balance bridge jolts up and down along with a road surface is solved by utilizing a hydraulic cylinder and other modes, but the structural design of the balance bridge greatly improves the manufacturing cost and has a complex structure, the circuit control of a hydraulic system is needed, and a corresponding electric control circuit is also needed to lock the hydraulic circuit for pressure maintaining, so that the balance bridge can adapt to the common road surface (such as relatively flat road surfaces in a factory building, an indoor environment road surface and the like) and the working condition that jolts are not severe, but the problem that the left and right heights of two driving wheels are inconsistent and the left and right side of the balance bridge are drastic when the road surface is continuously hollow in outdoor work of a forklift cannot be effectively solved.

It can be seen that the existing balance bridge structure has the following disadvantages: 1. the matching precision requirement of the shaft and the hole is high, the assembly and maintenance difficulty is high, the manufacturing and later maintenance cost is high, and the continuous cost reduction of enterprises is limited; 2. the large-tonnage forklift is large in structural size, machining errors of parts and errors of integral welding are large, and the existing balance bridge structure is difficult to adapt; 3. the forward and backward swinging range of the balance bridge is uncontrollable; 4. the existing structure is adopted to ensure that the driving wheels are all grounded, the cost is high, the structure and the control are too complex, and the application scene has limitation.

Disclosure of Invention

The invention provides a balance bridge structure, a balance bridge and a forklift, which are used for solving all or part of the problems in the prior art, and realizing the effects of cost and balance, so that the driving wheel can be fully grounded and stably run under various road surface working conditions.

The invention relates to a balance bridge structure, which comprises a frame and a balance bridge; the balance bridge includes: a cross member assembly, a front axle, a rear axle, and a pair of drive wheel assemblies; the length direction of the beam assembly is marked as a first direction, and the length direction of the beam assembly is horizontally orthogonal to the first direction and is marked as a second direction; the driving wheel assemblies are arranged at two ends of the beam assembly in the first direction, and when the horizontal plane of the driving wheel landing points of the driving wheel assemblies changes, the end parts of the beam assembly are driven to swing; the front shaft and the rear shaft are respectively fixedly arranged on two outer surfaces of the beam assembly, which are opposite; the front shaft and the rear shaft are respectively provided with a bearing part at one end deviating from the beam assembly; the frame is provided with a mounting part which is fixedly connected with the bearing part.

Through set up front axle and rear axle of separation respectively in crossbeam subassembly outside both sides, on the one hand structural design flexibility is higher, has more abundant allowed swing space to the swing of balanced bridge in each direction under the actual condition, more importantly can be in fork truck work, when the balanced bridge meets the resistance, when two drive wheel subassembly atress sizes are inconsistent and violent change, because front axle, rear axle are not an integral axle, so can not produce violent alternating load and transmit epaxial, avoided producing conditions such as alternating bending moment, abnormal sound of friction, extrusion, frequent change. The front axle and the rear axle are separated, the generated alternating load is borne by the whole rigid bridge structure of the balance bridge, the front axle and the rear axle only transmit the force to the whole rigid structure of the balance bridge by the freedom degree of the bearing when being stressed, and the front axle and the rear axle have high overall controllability of the stress of the forklift in the working process.

The bearing part is a joint bearing; and adjusting washers are respectively arranged between the knuckle bearing and the front shaft and between the knuckle bearing and the rear shaft. Compared with other types of bearings, such as deep groove ball bearings and round roller bearings, the spherical ball bearing has only a small radial or axial clearance, and the spherical ball bearing can have a floating amount in a 360-degree range. Utilize the characteristics that possess a plurality of degrees of freedom in the different dimensionalities of joint bearing, front axle, rear axle and joint bearing cooperation, joint bearing fixes realize the fixed mounting of balanced bridge and frame in the installation department, compare other types of bearing or wear the mode that big axle linked, the balanced bridge is more nimble with the connection of frame, and the reliability is stronger, and the assembly is simpler.

The mounting part comprises an upper shaft seat and a lower shaft seat fixed on the frame; the upper shaft seat and the lower shaft seat are fixedly connected in a Half (Half) structure, and the anchor ear is used for the bearing part.

The coaxiality of the front shaft and the rear shaft is within 1 mm; the upper shaft seat and the lower shaft seat are two groups, the upper shaft seat and the lower shaft seat which are positioned on the same side of the beam assembly in the second direction are one group, and the coaxiality of the two groups of upper shaft seats and the lower shaft seat is within 1 mm.

The upper shaft seat and the lower shaft seat are fixedly connected through a quick assembly disassembly structure; the quick assembly disassembly structure comprises a fixing bolt and screw holes correspondingly formed in the upper shaft seat and the lower shaft seat.

The balance bridge and the frame can be quickly and fixedly connected through the upper shaft seat and the lower shaft seat of the Half (Half) structure and the quick assembly and disassembly structure, so that the balance bridge is convenient to install and maintain.

The beam assembly comprises a beam, a front connecting plate and a rear connecting plate which are fixedly connected to the two sides of the beam in the first direction; the front shaft is welded on the front connecting plate, and the rear shaft is welded on the rear connecting plate; the front connecting plate and/or the rear connecting plate are/is provided with reinforcing plates at two ends in the first direction. Through set up preceding, back link plate and reinforcing plate in the crossbeam outside, played the effect of strengthening, further improved the rigidity of balanced bridge, do benefit to the stability and the reliability of guarantee balanced bridge structure at work.

The beam assembly further comprises drive mounting plates arranged at two ends of the beam; the driving wheel assembly is arranged at the lower part of the driving mounting plate, and a steering driving assembly is arranged at the upper part of the driving mounting plate and used for driving the driving wheel assembly to steer.

The drive wheel of the drive wheel assembly is a rubber tire. Compared with the existing polyurethane tire commonly used, the rubber tire can be more suitable for the road surface working condition of outdoor load, and the buffer performance of the rubber material is superior to that of the polyurethane material, and the rubber material is matched with the balance bridge, so that the overall advantage of the balance bridge structure is more obvious in the working condition of outdoor road surface pothole. Preferably, the rubber tyre is a solid rubber tyre.

In a general case, the balance bridge structure further comprises a first limiting component and/or a second limiting component; the first limiting assembly is used for limiting the front-back swing of the cross beam assembly relative to the frame, and the second limiting portion is used for limiting the up-down swing of the cross beam assembly relative to the frame.

And correspondingly setting a first limiting component and/or a second limiting component according to the degree of freedom of the bearing part, wherein if the bearing part can only move forwards and backwards, only the first limiting component is set, and if the bearing part can only move up and down, only the second limiting component is set. The first limiting component can prevent the bearing from being permanently damaged beyond the limit dimension of the bearing due to overlarge swinging range, and the second limiting component can prevent the different tire rotating speed differences from being seriously worn or the direction consistency deviation from being overlarge due to overlarge relative dislocation of tires of the driving wheel component. Through setting up the damage when can preventing bearing limit dimension can prevent effectively again that the excessive deviation from top to bottom from leading to the fact balance bridge and frame chassis to take place to interfere the collision.

And taking the center of the beam assembly as a vertex, wherein the amplitude of the back-and-forth swing and/or the up-and-down swing is correspondingly limited within +/-5 degrees by the first limiting assembly and/or the second limiting assembly. The limited range is correspondingly set according to the degree of freedom of the bearing part, so that the application of the forklift in the working condition of a hollow pavement is required to be met, the excessive swing is avoided, the stability of the vehicle is affected, parts are damaged, the swing amplitude of the beam assembly is limited through the first limiting assembly and the second limiting assembly, and the bearing is not stressed in the swing process.

The first limiting component comprises front limiting blocks and rear limiting blocks which are arranged on the frame in opposite directions on two sides of the first direction; the surfaces of the front limiting block, the rear limiting block and the beam assembly, which are contacted, are provided with buffer pieces; the second limiting assembly comprises limiting shaft seats arranged on two sides of the beam assembly in the second direction and limiting shaft heads correspondingly arranged on the frame; and a buffer piece is arranged between the limiting shaft seat and the limiting shaft head. Through the corresponding spacing spindle nose that sets up of frame, the crossbeam subassembly is around the front axle the back axle is swung from top to bottom to extreme position, and spacing spindle nose card is in the arc wall of spacing axle bed, has restricted the scope of balance bridge swing from top to bottom.

The invention provides a balance bridge, which comprises a beam assembly, a front shaft, a rear shaft and a pair of driving wheel assemblies; the length direction of the beam assembly is marked as a first direction, and the length direction of the beam assembly is horizontally orthogonal to the first direction and is marked as a second direction; the driving wheel assemblies are arranged at two ends of the beam assembly in the first direction, and when the horizontal plane of the driving wheel landing points of the driving wheel assemblies changes, the end parts of the beam assembly are driven to swing; the front shaft and the rear shaft are respectively fixedly arranged on two outer surfaces of the beam assembly, which are opposite; the front axle and the rear axle are both provided with bearing parts at one ends facing away from the beam assembly.

And adjusting washers are respectively arranged between the bearing part and the front shaft and between the bearing part and the rear shaft. The adjusting washer can better protect the damage of the bearing part during working, and the smoothness of the bearing movement is improved.

The bearing part is a knuckle bearing. The characteristics that the joint bearing has a plurality of degrees of freedom in different dimensions are effectively utilized, and the design that the front shaft and the rear shaft correspond to the front joint bearing and the rear joint bearing respectively is used, so that compared with the joint bearing with the whole shaft being matched with the front joint bearing and the rear joint bearing, the structure is more flexible, and the balance bridge has more sufficient allowable swinging space for swinging in all directions under the actual working condition.

The coaxiality of the front shaft and the rear shaft is within 1 mm. The process error can be controlled within 1mm generally, and the coaxiality can also meet the requirements of the front shaft and the rear shaft in application, so that the process is optimized reasonably, and the manufacturing difficulty is reduced.

The beam assembly comprises a beam, a front connecting plate and a rear connecting plate which are fixedly connected to the two sides of the beam in the first direction; the front shaft is welded on the front connecting plate, and the rear shaft is welded on the rear connecting plate; the front connecting plate and/or the rear connecting plate are/is provided with reinforcing plates at two ends in the first direction.

Another aspect of the present invention provides a forklift, including the balance bridge structure of one aspect of the present invention or the balance bridge of the present invention.

Compared with the prior art, the invention has the main beneficial effects that:

1. the balance bridge structure disclosed by the invention realizes the structure of the rear axle of the large-tonnage rear double-drive forklift in a mode of simple structure, convenience in assembly and maintenance and cost saving and production efficiency, and solves the problem that the forklift is difficult to adapt to pain points of various complex working conditions. The front axle and the rear axle are matched with the bearing in a connecting mode, so that relatively large welding errors can be tolerated, the welding process difficulty is reduced, the operation reliability of the balance bridge structure and the feasibility of production and application are improved, the balance bridge structure is suitable for large-tonnage carrying vehicles in the forklift industry, particularly under the working condition that outdoor road bumps are severe, the advantages are particularly obvious, and a feasible scheme is provided for solving the problem that how the rear bridge structure of a multi-drive forklift with ultra-tonnage (5 tons and above) is suitable for the pits of the outdoor road; through the cooperation the corresponding spacing subassembly that sets up of bearing portion degree of freedom, can prevent that control drive wheel difference in height from being too big, make balanced bridge back-and-forth swinging's scope in controllable scope, further improved fork truck operation's security.

2. The balance bridge provided by the invention has the advantages of low assembly difficulty, simple structure, high processing and production efficiency and low cost, and can practically and effectively meet the application requirements under the condition of bumpy road surfaces.

3. The forklift truck has corresponding advantages due to the balance bridge structure or the balance bridge.

Drawings

Fig. 1 is a schematic view of a balance bridge and a frame according to an embodiment of the present invention.

Fig. 2 is a schematic limiting diagram of a balance bridge and a frame according to an embodiment of the present invention.

Fig. 3 (a) and 3 (b) are schematic diagrams of a balance bridge portion according to an embodiment of the present invention.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and fully, and it is apparent that the embodiments described are only some, but not all, of the embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

In the embodiment of the invention, referring to fig. 1 and 2 in combination, a balance bridge structure is provided, which comprises a frame 1 and a balance bridge 2. The balance bridge 2 provided in this embodiment includes: a cross member assembly 21, a front axle 22a, a rear axle 22b, and a pair of drive wheel assemblies 23. The drive wheel assemblies 23 are arranged in pairs, one drive wheel assembly 23 comprising one drive wheel. One driving wheel assembly 23 may have more driving wheels, and is not limited to the actual application.

In the present embodiment, the longitudinal direction of the beam assembly 21 is referred to as a first direction X (i.e., the left-right direction of the frame 1 in the case of fig. 1), and a second direction Y (i.e., the front-rear direction of the beam assembly 21 in the case of fig. 1, i.e., the direction perpendicular to X and in the same horizontal plane) that is horizontally orthogonal to the first direction X. The driving wheel assemblies 23 are installed at two ends of the beam assembly 21 in the first direction, and when the horizontal plane where the driving wheel landing points of the driving wheel assemblies 23 are located changes, the ends of the beam assembly 21 are driven to swing, and the front shaft 22a and the rear shaft 22b are arranged in a back-to-back mode in the second direction Y (the ends of the front shaft 22a and the rear shaft 22b deviate from the center O of the beam assembly 21), and are fixedly installed on the outer surfaces of the beam assembly 21, which are opposite to each other, respectively. The front axle 22a and the rear axle 22b are each provided with a bearing portion 22c at an end facing away from the cross member assembly 21. The frame 1 is provided with a mounting portion 10, and the mounting portion 10 is fixedly connected to a bearing portion 22c.

In the case of the example of fig. 1, the bearing portion 22c is a knuckle bearing. An adjusting washer 22d is provided between the knuckle bearing and each of the front and rear shafts 22a and 22 b. The adoption of the knuckle bearing is a good example in the embodiment, the degree of freedom that the knuckle bearing can provide has more dimensions, and the swing in multiple directions in the complex road surface working condition can be met to the greatest extent so as to ensure that the driving wheel is all grounded. In some embodiments, the bearing portion 22c may be implemented by using other types of bearings such as deep groove ball bearings and roller bearings, which are not limited to the specific case.

Referring to fig. 1 and 2 in combination, in the illustrated case, the mounting portion 10 includes an upper axle seat 10a and a lower axle seat 10b fixed to the frame 1. The upper shaft seat 10a and the lower shaft seat 10b are in a Half (halof) structure, and are fixedly connected, and a hoop bearing part 22c. In the illustrated case, the upper axle seat 10a and the lower axle seat 10b are arranged in groups, and a group of front upper axle seat 10a and front lower axle seat 10b, and a group of rear upper axle seat 10a and rear lower axle seat 10b are respectively arranged on the front side and the rear side of the beam assembly 21, so that the front axle 22a and the rear axle 22b are respectively pressed to realize the fixed connection of the balance bridge 2 and the frame 1. In the case of the example of fig. 1, the upper shaft seat 10a and the lower shaft seat 10b are fixedly connected through a quick-dismantling structure, and the quick-dismantling structure example comprises that screw holes and a plurality of groups of fixing bolts are formed in the upper shaft seat 10a and the lower shaft seat 10b, and the quick-dismantling is realized through the cooperation of the bolt screw holes, so that the upper shaft seat 10a and the lower shaft seat 10b are separated or folded. Although the front axle 22a and the rear axle 22b are separate from each other, not the whole axle, they have a high requirement for coaxiality, and the upper axle seat 10a and the lower axle seat 10b have a high requirement for coaxiality. The coaxiality of the front shaft 22a and the rear shaft 22b in a preferred example is within 1 mm. The coaxiality of the front upper shaft seat 10a and the front lower shaft seat 10b, and the rear upper shaft seat 10a and the rear lower shaft seat 10b, which correspond to the embodiment, is also within 1 mm.

The balance bridge structure of the embodiment is formed by splicing and welding steel plates with various thicknesses and shapes. Referring to fig. 3 (a) and 3 (b) in combination, the example beam assembly 21 includes a beam 211, a front link plate 212a and a rear link plate 212b welded to both sides of the beam 211 in the first direction. The front link plate 212a and the rear link plate 212b are provided with reinforcing plates 213 at both ends in the first direction. The front axle 22a is welded to the front link plate 212a and the rear axle 22b is welded to the rear link plate 212b. The welding error can be controlled within 1mm generally, and is in order of magnitude different from five to ten wires required by machining, so that the process difficulty is greatly reduced. The coaxiality of the front shaft 22a and the rear shaft 22b, that is, the coaxiality required to be ensured by welding is within 1 mm.

The beam assembly 21 of the example of fig. 3 (a) and 3 (b) further includes drive mounting plates 214 disposed at both ends of the beam 211. Referring to fig. 1 in combination, the drive wheel assembly 23 is mounted on a lower portion of the drive mounting plate 214, and a steering drive assembly 215 is provided on an upper portion of the drive mounting plate 214 for providing a steering force required by the drive wheel assembly 23 to steer the drive wheel. The drive wheel of the example drive wheel assembly 23 is a large wheel diameter solid rubber tire. The large-wheel-diameter rubber tire has excellent buffering performance, and the rear axle structure of the large-tonnage (more than five tons) multi-drive forklift truck provided with the large-wheel-diameter solid rubber tire can be better adapted to outdoor diversified topography and landform and stably work under the jolt working condition.

The beam 211 is provided with a riser 216 at each end, and the drive mounting plate 214 is welded to the riser 216. The standing plate 216 also functions to strengthen the overall strength in the second direction Y.

In cooperation with the degrees of freedom provided by the bearing portion 22c, in some preferred embodiments, the balanced bridge structure further includes a first stop assembly 24 and a second stop assembly 25. The first limiting assembly 24 is used to limit the fore-and-aft swing of the cross member assembly 21 relative to the frame 1. The second limiting assembly 25 is used for limiting the up-and-down swing of the cross member assembly 21 relative to the frame 1. In the case of the example of fig. 2, the bearing portion 22c employs a knuckle bearing, and the balance bridge swings a certain amount in the front, rear, left and right directions, and the example first stopper assembly 24 includes front and rear stoppers 24a and 24b disposed opposite to each other on the frame 1 on both sides in the first direction X. The surfaces of the front stopper 24a, the rear stopper 24b and the beam assembly 21 that contact are provided with cushioning members so as not to cause damage due to rigid collision between the components. The second spacing assembly 25 includes spacing axle seats 25a provided on both sides (on the reinforcement plate 213) of the cross member assembly 21 in the second direction Y and corresponding spacing axle heads 25b provided on the frame 1. A buffer is also arranged between the limit shaft seat 25a and the limit shaft head 25b to avoid collision. The first limiting assembly 24 and the second limiting assembly 25 may have other specific designs, for example, the movement of the beam assembly 21 is limited by using the steel frame structure of the frame 1, and the like, which is not limited to the specific designs.

The swing range of the beam assembly 21 is limited in multiple directions by the first limiting assembly 24 and the second limiting assembly 25, and the center of the beam assembly 21 is taken as a vertex in the example, and the amplitude of the back-and-forth swing and the up-and-down swing is correspondingly limited within +/-5 degrees by the first limiting assembly 24 and/or the second limiting assembly 25. Preferably, the back-and-forth swing amplitude is within + -2 DEG, and the up-and-down swing amplitude is within + -3 deg. An exemplary limit point is the limit position to which the knuckle bearing can move, and the knuckle bearing is unstressed when swinging.

It can be seen that the balance bridge structure of this embodiment is assembled simpler, and limit setting about upper, lower, front, back, left and right is cooperated, can satisfy the fork truck of large-tonnage and bear, and cooperation rubber tyre can adapt to the road surface operating mode of outdoor load more.

The embodiment also provides a forklift with the balance bridge structure of the embodiment or the balance bridge of the embodiment.

Relational terms such as "first" and "second", and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. It should be noted that it will be apparent to those skilled in the art that various improvements and modifications can be made to the present invention without departing from the principles of the invention, and such improvements and modifications fall within the scope of the appended claims.

Claims

1. A balanced bridge construction, characterized in that: comprises a frame (1) and a balance bridge (2);

the balance bridge (2) comprises: a cross member assembly (21), a front axle (22 a), a rear axle (22 b), and a pair of drive wheel assemblies (23);

the length direction of the beam assembly (21) is marked as a first direction, and the length direction is horizontally orthogonal to the first direction and is marked as a second direction; the driving wheel assemblies (23) are arranged at two ends of the beam assembly (21) in the first direction, and when the horizontal plane of the driving wheel landing points of the driving wheel assemblies (23) changes, the end parts of the beam assembly (21) are driven to swing;

the front shaft (22 a) and the rear shaft (22 b) are respectively fixedly arranged on two outer surfaces of the beam assembly (21) which are opposite;

the front shaft (22 a) and the rear shaft (22 b) are respectively provided with a bearing part (22 c) at one end which is far away from the beam assembly (21);

the frame (1) is provided with an installation part (10), and the installation part (10) is fixedly connected with the bearing part (22 c).

2. The balanced bridge configuration according to claim 1, wherein: the bearing part (22 c) is a knuckle bearing; and adjusting washers (22 d) are respectively arranged between the knuckle bearing and the front shaft (22 a) and between the knuckle bearing and the rear shaft (22 b).

3. The balanced bridge configuration according to claim 1, wherein: the mounting part (10) comprises an upper shaft seat (10 a) and a lower shaft seat (10 b) fixed on the frame (1); the upper shaft seat (10 a) and the lower shaft seat (10 b) are fixedly connected in a half structure, and the bearing part (22 c) is hooped.

4. A balanced bridge construction according to claim 3, characterized in that: -the coaxiality of the front axle (22 a) and the rear axle (22 b) is within 1 mm; the upper shaft seat (10 a) and the lower shaft seat (10 b) are two groups, the upper shaft seat (10 a) and the lower shaft seat (10 b) which are positioned on the same side of the beam assembly (21) in the second direction are one group, and the coaxiality of the upper shaft seat (10 a) and the lower shaft seat (10 b) is within 1 mm.

5. A balanced bridge construction according to claim 3, characterized in that: the upper shaft seat (10 a) and the lower shaft seat (10 b) are fixedly connected through a quick-dismantling structure; the quick assembly disassembly structure comprises a fixing bolt and screw holes correspondingly formed in the upper shaft seat (10 a) and the lower shaft seat (10 b).

6. The balanced bridge configuration according to claim 1, wherein: the beam assembly (21) comprises a beam (211), and a front connecting plate (212 a) and a rear connecting plate (212 b) which are fixedly connected to the beam (211) at two sides of the first direction; the front axle (22 a) is welded on the front connecting plate (212 a), and the rear axle (22 b) is welded on the rear connecting plate (212 b);

the front connecting plate (212 a) and/or the rear connecting plate (212 b) are provided with reinforcing plates (213) at both ends in the first direction.

7. The balanced bridge configuration of claim 6, wherein: the beam assembly (21) further comprises drive mounting plates (214) arranged at two ends of the beam (211); the driving wheel assembly (23) is installed at the lower part of the driving installation plate (214), and a steering driving assembly (215) is arranged at the upper part of the driving installation plate (214) and used for driving the driving wheel assembly (23) to steer.

8. The balanced bridge structure according to any one of claims 1-7, characterized in that: the drive wheel of the drive wheel assembly (23) is a rubber tyre.

9. The balanced bridge structure according to any one of claims 1-7, characterized in that: the device also comprises a first limiting component (24) and/or a second limiting component (25);

the first limiting assembly (24) is used for limiting the front-back swing of the cross beam assembly (21) relative to the frame (1);

the second limiting assembly (25) is used for limiting the up-and-down swing of the cross beam assembly (21) relative to the frame (1).

10. The balanced bridge configuration according to claim 9, wherein: and taking the center of the beam assembly (21) as a vertex, and correspondingly limiting the amplitude of the back-and-forth swing and/or the up-and-down swing to be within +/-5 degrees by the first limiting assembly (24) and/or the second limiting assembly (25).

11. The balanced bridge configuration according to claim 9, wherein: the first limiting component (24) comprises a front limiting block (24 a) and a rear limiting block (24 b) which are oppositely arranged on the frame (1) at two sides in the first direction; the surfaces of the front limiting block (24 a), the rear limiting block (24 b) and the beam assembly (21) which are contacted are provided with buffer pieces;

the second limiting assembly (25) comprises limiting shaft seats (25 a) arranged on two sides of the beam assembly (21) in the second direction and limiting shaft heads (25 b) correspondingly arranged on the frame (1); a buffer piece is arranged between the limiting shaft seat (25 a) and the limiting shaft head (25 b).

12. A balance bridge, characterized by: comprises a beam assembly (21), a front axle (22 a), a rear axle (22 b) and a pair of driving wheel assemblies (23);

the front axle (22 a) and the rear axle (22 b) are each provided with a bearing portion (22 c) at one end facing away from the cross member assembly (21).

13. The balance bridge of claim 12, wherein: an adjusting washer (22 d) is provided between the bearing portion (22 c) and the front shaft (22 a) and between the bearing portion and the rear shaft (22 b).

14. The balance bridge of claim 12, wherein: the bearing portion (22 c) is a knuckle bearing.

15. The balance bridge of claim 12, wherein: the coaxiality of the front shaft (22 a) and the rear shaft (22 b) is within 1 mm.

16. Balance bridge according to any one of claims 12-15, characterized in that: the beam assembly (21) comprises a beam (211), and a front connecting plate (212 a) and a rear connecting plate (212 b) which are fixedly connected to the beam (211) at two sides of the first direction; the front axle (22 a) is welded on the front connecting plate (212 a), and the rear axle (22 b) is welded on the rear connecting plate (212 b); the front connecting plate (212 a) and/or the rear connecting plate (212 b) are provided with reinforcing plates (213) at both ends in the first direction.

17. The balance bridge of claim 16, wherein: the beam assembly (21) further comprises drive mounting plates (214) arranged at two ends of the beam (211); the driving wheel assembly (23) is installed at the lower part of the driving installation plate (214), and a steering driving assembly (215) is arranged at the upper part of the driving installation plate (214) and used for driving the driving wheel assembly (23) to steer.

18. A forklift truck, characterized in that: comprising a balance bridge structure according to any one of claims 1 to 11 or a balance bridge according to any one of claims 12 to 17.