CN220865517U

CN220865517U - Automatic limiting device and engineering machinery chassis

Info

Publication number: CN220865517U
Application number: CN202322613241.0U
Authority: CN
Inventors: 张波; 吕阳; 郭春雷; 许金州; 李春翔; 李广; 林志伟
Original assignee: Xuzhou Xugong Caterpillar Base Plate Co ltd
Current assignee: Xuzhou Xugong Caterpillar Base Plate Co ltd
Priority date: 2023-09-26
Filing date: 2023-09-26
Publication date: 2024-04-30
Anticipated expiration: 2033-09-26

Abstract

The utility model belongs to the technical field of engineering machinery chassis, and in particular relates to an automatic limiting device and an engineering machinery chassis, wherein the automatic limiting device comprises a cylinder body, an elastic piece, a limiting pin shaft and a cylinder seat; one end of the cylinder is provided with a containing cavity, a sliding rail is arranged on the circumference of the cylinder along the axial direction, and the sliding rail is communicated with the containing cavity; the elastic piece is arranged in the accommodating cavity of the cylinder body; a pin shaft positioning hole is formed in the circumference of one end of the limiting pin shaft, one end provided with the pin shaft positioning hole compresses the elastic piece and is arranged in the accommodating cavity of the cylinder, a third limiting piece penetrating through the sliding track is movably connected to the pin shaft positioning hole, and the pin shaft positioning hole is slidably arranged in the accommodating cavity of the cylinder through the third limiting piece; the cylinder seat is connected with target equipment and is used for movably fixing the cylinder body. The automatic limiting device is used without repeated centering of operators, and can automatically realize quick centering.

Description

Automatic limiting device and engineering machinery chassis

Technical Field

The utility model belongs to the technical field of engineering machinery chassis, and particularly relates to an automatic limiting device and an engineering machinery chassis.

Background

The crawler chassis is more and more applied to engineering machinery because of small grounding pressure and strong stability and trafficability. In particular, for large or work machines with a high center of gravity, the track pan is generally designed to be longer and have a larger track gauge in order to ensure work safety, but this presents difficulties and challenges for short-distance transfer (e.g., via narrower roadways) and long-distance transportation of the machine.

In view of this, more chassis designs into telescopic structure now, and telescopic track chassis mainly includes left track frame, right track frame, center frame and flexible hydro-cylinder etc. the stiff end of flexible hydro-cylinder links to each other with the center frame, and the extension end links to each other with the track frame. When the telescopic crawler belt rack works, the telescopic oil cylinder stretches to drive the left crawler belt rack and the right crawler belt rack to be far away from the center frame, and at the moment, the track gauge of the chassis is maximum; when the truck is transported in a transition mode, the telescopic oil cylinder is retracted to drive the left crawler frame and the right crawler frame to be close to the center frame, and at the moment, the track gauge of the chassis is minimum.

After the telescopic action of the telescopic oil cylinder is finished, the left and right crawler frames are required to be limited and locked, so that the left and right crawler frames can be prevented from moving again during working or transferring transportation. The current common operations are: when the pin holes on the track frame are aligned with the limit holes on the center frame, the limit pins are manually inserted. The operation mode needs manual repetition of hole alignment, the operation efficiency is low, and when the telescopic oil cylinder stretches, a person approaches the chassis to wait for the bolt, so that a certain danger exists.

Disclosure of Invention

In order to overcome the defects of the prior art, the utility model provides the automatic limiting device which is applied to the chassis of the engineering machinery, when the chassis of the engineering machinery needs to be adjusted in track gauge, firstly, an operator takes down a cylinder body with a limiting pin shaft of the automatic limiting device, after the operator is far away from the chassis of the engineering machinery, the telescopic cylinder acts to drive a side bracket to move for a certain distance and then stop the telescopic action, the operator installs the cylinder body with the limiting pin shaft on a cylinder seat again, after the operator is far away from the chassis of the engineering machinery, the telescopic cylinder acts again, and after the telescopic cylinder stretches into the positioning pin shaft hole automatically under the action of an elastic piece, the limiting pin shaft of the automatic limiting device realizes the locking of the side bracket and the center frame.

The utility model is realized by the following technical scheme: an automatic limiting device, comprising:

One end of the cylinder is provided with a containing cavity, a sliding track is arranged on the circumference of the cylinder along the axial direction, and the sliding track is communicated with the containing cavity;

The elastic piece is arranged in the accommodating cavity of the cylinder body;

The circumference of one end of the limiting pin shaft is provided with a pin shaft positioning hole, one end provided with the pin shaft positioning hole compresses the elastic piece and is arranged in the accommodating cavity of the cylinder, the pin shaft positioning hole is movably connected with a third limiting piece penetrating through the sliding track, and the third limiting piece is slidably arranged in the accommodating cavity of the cylinder; and

The cylinder seat is connected with target equipment and used for movably fixing the cylinder body.

In some embodiments, the cylinder seat is a hollow cylinder body, a cylinder seat positioning hole is formed in the circumference of one end of the cylinder seat, and the cylinder seat is movably fixed with the cylinder body through a connecting piece penetrating through the cylinder seat positioning hole.

In some embodiments, the cylinder seat positioning hole is an L-shaped positioning hole, the connecting piece comprises a first limiting piece and a second limiting piece, and a cylinder body first positioning hole and a cylinder body second positioning hole which are connected with the first limiting piece and the second limiting piece are formed in the cylinder body.

In some embodiments, the cylinder seat is provided with two cylinder seat positioning holes, and the two cylinder seat positioning holes are symmetrically arranged;

The cylinder body is movably fixed with the cylinder seat through two groups of connecting pieces which respectively penetrate through two cylinder seat positioning holes.

In some embodiments, an observation window is arranged on the circumference of the cylinder seat along the axial direction, and after the cylinder seat is movably fixed with the cylinder body, the observation window faces the sliding track.

In some embodiments, the cylinder seat is provided with a T-shaped hole, and after the cylinder seat is movably fixed with the cylinder body, the end surface of the cylinder body contacts with a shaft shoulder formed by the T-shaped hole.

In some embodiments, the limiting pin shaft is provided with two pin shaft positioning holes matched with the third limiting piece, and the two pin shaft positioning holes are symmetrically arranged;

The cylinder body is provided with two sliding rails which are symmetrically arranged;

The limiting pin shafts are slidably arranged in the accommodating cavity of the cylinder body through two third limiting parts.

In some embodiments, a guide fillet is provided at an end of the limit pin remote from the pin positioning hole.

In some embodiments, the elastic member is still in a compressed state when the limit pin is in a maximum extended state.

The utility model also provides an engineering machinery chassis, which comprises the automatic limiting device;

The engineering machinery chassis comprises a center frame and side brackets positioned at two sides of the center frame, wherein the two sides of the center frame are respectively provided with a telescopic arm, the side brackets are sleeved on the telescopic arms through sliding rail sleeves, and the telescopic arms are provided with at least two positioning pin holes in a straight line along the sliding direction of the sliding rail sleeves;

the automatic limiting device is arranged on the sliding rail sleeve, and a cylinder seat of the automatic limiting device is fixedly connected with the sliding rail sleeve.

In some embodiments, the telescopic arm is provided with a guide band plate, the middle part of the guide band plate is provided with a straight slot, and each locating pin shaft hole on the telescopic arm is positioned in the straight slot.

The beneficial effects of the utility model are as follows: 1) When the chassis track gauge of the engineering machinery needs to be adjusted, firstly, an operator takes down the cylinder body with the limiting pin shaft of the automatic limiting device, after the operator is far away from the chassis of the engineering machinery, the telescopic oil cylinder acts to drive the side bracket to move a distance and then stop the telescopic action, the operator installs the cylinder body with the limiting pin shaft on the cylinder seat again, after the operator is far away from the chassis of the engineering machinery, the telescopic oil cylinder acts again, and after the telescopic oil cylinder stretches out and draws in place, the limiting pin shaft of the automatic limiting device automatically stretches into the positioning pin shaft hole under the action of the elastic piece, so that the locking of the side bracket and the center frame is realized. The process does not need repeated centering of operators, and can automatically realize quick centering; in addition, the operator does not need to repeatedly center on site, so that the operator does not need to stand beside the chassis of the engineering machinery in the centering process, and safe operation is realized.

2) The cylinder seat positioning hole on the cylinder seat adopts an L-shaped structure, and the cylinder body and the cylinder seat can be conveniently and rapidly movably fixed by matching with the first limiting piece and the second limiting piece.

3) The arrangement of the observation window on the cylinder seat can be used for checking whether the limiting pin shaft is fixed in place or not, so that the safety is improved.

Drawings

FIG. 1 is a schematic view of the structure of a barrel, an elastic member and a limit pin of the automatic limit device of the present utility model;

FIG. 2 is a schematic view of a cartridge seat of the automatic limiting device according to the present utility model;

FIG. 3 is a schematic view of the automatic limiting device of the present utility model applied to a chassis of an engineering machine;

FIG. 4 is a partial schematic view of a work machine chassis;

FIG. 5 is a partial schematic view of an automatic limiting device applied to a chassis of a work machine;

In the figure, 1, an automatic limiting device, 11, a barrel, 11-1, a first barrel positioning hole, 11-2, a second barrel positioning hole, 11-3, a sliding rail, 11-4, a first limiting piece, 11-5, a second limiting piece, 12, an elastic piece, 13, a limiting pin, 13-1, a pin positioning hole, 13-2, a guiding round corner, 13-3, a third limiting piece, 14, a barrel seat, 14-1, a barrel seat positioning hole, 14-2, an observation window, 14-3, a T-shaped hole, 2, a side bracket, 2-1, a sliding rail sleeve, 3, a center frame, 3-1, a telescopic arm, 3-2, a positioning pin hole, 3-3, a round corner, 3-4, a guiding band plate, 3-41 and a linear groove.

Description of the embodiments

The utility model is further described below with reference to the drawings and examples.

As shown in fig. 1, 2 and 5, an automatic limiting device 1 comprises a cylinder 11 with a containing cavity at one end, a sliding rail 11-3 is axially arranged on the circumference of the cylinder 11, and the sliding rail 11-3 is communicated with the containing cavity. The automatic limiting device 1 further comprises an elastic piece 12, a limiting pin shaft 13 and a cylinder seat 14. Wherein the elastic element 12 is preferably a spring, and the elastic element 12 is arranged in the accommodating cavity of the cylinder 11.

The circumference of one end of the limiting pin shaft 13 is provided with a pin shaft positioning hole 13-1, when the assembly is carried out, one end of the limiting pin shaft 13 provided with the pin shaft positioning hole 13-1 compresses the elastic piece 12 to be placed in the accommodating cavity of the cylinder 11 and can linearly slide in a limited range in the accommodating cavity of the cylinder 11, and in order to realize the linear sliding of the limiting pin shaft 13 in the accommodating cavity of the cylinder 11 and in the limited range, the structure is as follows: the limiting pin shaft 13 is provided with a pin shaft positioning hole 13-1 matched with the third limiting piece 13-3, the third limiting piece 13-3 penetrates through the sliding track 11-3 to be connected with the pin shaft positioning hole 13-1 on the limiting pin shaft 13, a part of the limiting pin shaft 13 is located in the sliding track 11-3, the limiting pin shaft 13 is slidably arranged in a containing cavity of the cylinder 11 by means of guiding matching of the third limiting piece 13-3 and the sliding track 11-3, and the sliding track 11-3 is used for limiting the movement range of the third limiting piece 13-3 so as to limit the linear movement range of the limiting pin shaft 13. As an improvement of the above embodiment, the limiting pin shaft 13 is provided with two pin shaft positioning holes 13-1 matched with the third limiting piece 13-3, and the two pin shaft positioning holes 13-1 are symmetrically arranged; the cylinder 11 is provided with two sliding rails 11-3, and the two sliding rails 11-3 are symmetrically arranged; the limiting pin shaft 13 is slidably arranged in the accommodating cavity of the cylinder 11 through two third limiting pieces 13-3, so that the linear motion of the limiting pin shaft 13 in the accommodating cavity of the cylinder 11 is more stable. In the above, the third limiting member 13-3 may be a screw, and the pin positioning hole 13-1 may be a threaded hole.

The cylinder seat 14 is connected with target equipment and is used for movably fixing the cylinder 11.

The automatic limiting device 1 is applied to a chassis of engineering machinery, and the working principle of the automatic limiting device 1 is specifically described with specific reference to fig. 1-5. The engineering machinery chassis comprises a center frame 3 and side frames 2 positioned on two sides of the center frame 3, and if the engineering machinery chassis is a crawler chassis, the side frames 2 on two sides of the center frame 3 are respectively a left crawler frame and a right crawler frame. The two sides of the center frame 3 are respectively provided with a telescopic arm 3-1, and specifically as shown in fig. 3, the left side and the right side of the center frame 3 are respectively provided with two telescopic arms 3-1, and the two telescopic arms 3-1 positioned on the same side of the center frame 3 are matched with a side bracket 2 for assembly. The linear motion of the side bracket 2 relative to the center bracket 3 is realized by a telescopic oil cylinder, the fixed end of the telescopic oil cylinder is connected with the center bracket 3, and the extending end of the telescopic oil cylinder is connected with the side bracket 2; the track gauge of the chassis is adjusted through the telescopic action of the telescopic oil cylinder.

The side support 2 is sleeved on the telescopic arm 3-1 through the sliding rail sleeve 2-1, the sliding rail sleeve 2-1 is matched with the telescopic arm 3-1 in a guiding manner, and the side support 2 can linearly approach or depart from the center frame 2 under the telescopic action of the telescopic oil cylinder. The telescopic arm 3-1 is provided with at least two locating pin shaft holes 3-2 in a straight line arrangement along the sliding direction of the sliding rail sleeve 2-1; as shown in fig. 4, the chassis of the engineering machinery has chassis gauges of two sizes, so that two positioning pin shaft holes 3-2 are arranged, and if more than three chassis gauges exist, the corresponding positioning pin shaft holes 3-2 are added. For the purpose of fig. 4, the chassis of the engineering machine comprises two chassis gauges of maximum gauge and minimum gauge, before the engineering machine is adjusted between the maximum gauge and the minimum gauge, the fixed connection between the side bracket 2 and the center frame 3 needs to be released, and after the maximum gauge and the minimum gauge are adjusted in place, the side bracket 2 and the center frame 3 need to be fixed again.

The automatic limiting device 1 is arranged on the sliding rail sleeve 2-1, and a cylinder seat 14 of the automatic limiting device 1 is fixedly connected with the sliding rail sleeve 2-1. The cylinder seat 14 and the slide rail sleeve 2-1 can be fixed by welding, screw thread, etc. The cylinder body 11 provided with the limiting pin shaft 13 and the cylinder seat 14 are assembled, and when the limiting pin shaft 13 is clamped into the positioning pin shaft hole 3-2 under the action of the elastic piece 12, the side bracket 2 and the center bracket 3 can be fixed.

Assuming that the automatic limiting device 1 locks the chassis of the construction machine at the maximum gauge (as shown in fig. 4, the automatic limiting device 1 is fixed in the locating pin shaft hole 3-2 on the right side, i.e. the locating pin shaft hole 3-2 farthest from the center frame 3), the chassis of the construction machine needs to be adjusted to the minimum gauge (as shown in fig. 4, the automatic limiting device 1 needs to be fixed in the locating pin shaft hole 3-2 on the left side), the specific operation steps are as follows: firstly, an operator removes the cylinder 11 with the limiting pin shaft 13 of the automatic limiting device 1, so that the locking of the side bracket 2 and the center frame 3 is released, after the operator is far away from the chassis of the engineering machine, the telescopic oil cylinder acts to drive the side bracket 2 to move a certain distance and then stop the telescopic action, at the moment, the operator installs the cylinder 11 with the limiting pin shaft 13 on the cylinder seat 14 again, the limiting pin shaft 13 is propped against by the telescopic arm 3-1, the limiting pin shaft 13 cannot stretch out under the action of the elastic piece 12, after the operator is far away from the chassis of the engineering machine, the telescopic oil cylinder acts again, after the telescopic oil cylinder stretches out and draws in place, the limiting pin shaft 13 of the limiting device 1 stretches into the left locating pin shaft hole 3-2 shown in the figure 4 under the action of the elastic piece 12, and after the limitation of the telescopic arm 3-1 is lost, the limiting pin shaft 13 of the automatic limiting device 1 stretches into the left locating pin shaft hole 3-2 shown in the figure 4, so that the locking of the side bracket 2 and the center frame 3 is realized. The operation principle of adjusting the engineering machinery chassis from the minimum track gauge to the maximum track gauge is the same as that of the engineering machinery chassis, and the description is omitted here.

In the engineering machinery chassis, the telescopic arm 3-1 is provided with the guide band plate 3-4, the middle part of the guide band plate 3-4 is provided with the straight slot 3-41, each locating pin shaft hole 3-2 on the telescopic arm 3-1 is located in the straight slot 3-41, the two locating pin shaft holes 3-2 are respectively located at two ends of the straight slot 3-41, the free end of the limiting pin shaft 13 is located in the straight slot 3-41, and when the limiting pin shaft 13 slides to the end part of the straight slot 3-41, the limiting pin shaft hole is just aligned with the corresponding locating pin shaft hole 3-2.

For the automatic limiting device 1, in some embodiments, as shown in fig. 2, the cylinder seat 14 is a hollow cylinder, a cylinder seat positioning hole 14-1 is provided on the circumference of one end of the cylinder seat 14, and the cylinder seat 14 is movably fixed with the cylinder 11 by a connecting piece passing through the cylinder seat positioning hole 14-1. The specific steps can be as follows: the cylinder seat positioning hole 14-1 is a threaded hole, the cylinder 11 with the limiting pin shaft 13 is inserted into the cylinder seat 14, and then a screw serving as a connecting piece penetrates through the cylinder seat positioning hole 14-1 to be connected with a corresponding threaded hole on the cylinder 11, so that the movable fixation of the cylinder 11 and the cylinder seat 14 is realized. However, the above structure requires blind alignment of the positioning hole 14-1 of the cylinder seat with the corresponding threaded hole on the cylinder 11, which is inconvenient to fix, and in addition, the axial force applied by the elastic member 12 is inconvenient to assemble the cylinder 11 during the alignment, which is time-consuming and labor-consuming. For this purpose, as an improvement, the cylinder seat positioning hole 14-1 is an L-shaped positioning hole, the connecting piece comprises a first limiting piece 11-4 and a second limiting piece 11-5, and the cylinder 11 is provided with a cylinder first positioning hole 11-1 and a cylinder second positioning hole 11-2 connected with the first limiting piece 11-4 and the second limiting piece 11-5. The first limiting piece 11-4 and the second limiting piece 11-5 are screws, and the first cylinder positioning hole 11-1 and the second cylinder positioning hole 11-2 are threaded holes; before the cylinder 11 is connected to the cylinder seat 14, the first limiting piece 11-4 is fixed in the cylinder first positioning hole 11-1, then the first limiting piece 11-4 on the cylinder 11 extends along the axial direction of the cylinder seat 14 along the cylinder seat positioning hole 14-1, and then the cylinder 11 is rotated, so that the first limiting piece 11-4 is clamped in the cylinder seat positioning hole 14-1 to realize the axial limiting of the cylinder 11, and the influence of the elastic piece 12 on the assembly of the cylinder 11 in the axial direction is overcome; and then the second limiting piece 11-5 is fixed in the second positioning hole 11-2 of the cylinder body, the first limiting piece 11-4 and the second limiting piece 11-5 are matched to limit the circumferential rotation of the cylinder body 11, and further the movable fixation of the cylinder body 11 and the cylinder seat 14 is realized, so that the cylinder body 11 and the cylinder seat 14 are assembled more conveniently due to the structure.

For the automatic limiting device 1, in some embodiments, as shown in fig. 1 and 2, two cartridge seat positioning holes 14-1 are provided on the cartridge seat 14, and the two cartridge seat positioning holes 14-1 are symmetrically arranged; the cylinder 11 is movably fixed with the cylinder seat 14 by two groups of connecting pieces respectively passing through two cylinder seat positioning holes 14-1. The scheme realizes the symmetrical fixation of the cylinder 11 and the cylinder seat 14, and the fixation is firmer.

For the automatic limiting device 1, as shown in fig. 2, in some embodiments, an observation window 14-2 is disposed on the circumference of the cylinder seat 14 along the axial direction, and after the cylinder seat 14 is movably fixed with the cylinder 11, the observation window 14-2 faces the sliding rail 11-3. A sensor can be arranged on the observation window 14-2, and after the limiting pin shaft 13 and the locating pin shaft hole 3-2 are limited, safety prompt is given to an operator; it is also possible to manually visually check whether the spacing between the spacing pin 13 and the locating pin hole 3-2 is completed.

In some embodiments, as shown in fig. 2, the cylinder seat 14 is provided with a T-shaped hole 14-3, and after the cylinder seat 14 is movably fixed with the cylinder 11, the end surface of the cylinder 11 contacts with a shoulder formed by the T-shaped hole 14-3. The above structure facilitates the assembly of the cylinder 11 and the cylinder seat 14 when assembled, and when the end surface of the cylinder 11 contacts with the shaft shoulder formed by the T-shaped hole 14-3, the cylinder 11 is assembled in place in the axial direction.

In some embodiments, a guiding fillet 13-2 is arranged at one end of the limiting pin 13 away from the pin positioning hole 13-1, so as to facilitate centering of the limiting pin 13 and the positioning pin hole 3-2; in addition, a round corner 3-3 can be arranged at the port of the locating pin shaft hole 3-2 to serve as a guide centering.

In some embodiments, when the limiting pin 13 is in the maximum extending state, the elastic member 12 is still in a compressed state, i.e. after the limiting pin 13 is clamped into the positioning pin hole 3-2, the elastic member 12 still applies an elastic force to the limiting pin 13, so as to ensure that the limiting pin 13 stably fixes the side bracket 2 and the center bracket 3

The foregoing description is only a preferred embodiment of the present utility model, and is not intended to limit the present utility model in any way, and any simple modification, equivalent variation and modification made to the above embodiments according to the technical principles of the present utility model are within the scope of the technical solutions of the present utility model.

Claims

1. An automatic limiting device, comprising:

One end of the cylinder body (11) is provided with a containing cavity, a sliding track (11-3) is arranged on the circumference of the cylinder body (11) along the axial direction, and the sliding track (11-3) is communicated with the containing cavity;

an elastic piece (12) arranged in the accommodating cavity of the cylinder body (11);

A pin shaft positioning hole (13-1) is formed in the circumference of one end of the limiting pin shaft (13), one end provided with the pin shaft positioning hole (13-1) compresses the elastic piece (12) to be placed in the accommodating cavity of the cylinder body (11), a third limiting piece (13-3) penetrating through the sliding track (11-3) is movably connected to the pin shaft positioning hole (13-1), and the elastic piece is slidably arranged in the accommodating cavity of the cylinder body (11) through the third limiting piece (13-3); and

And the cylinder seat (14) is connected with target equipment and is used for movably fixing the cylinder body (11).

2. The automatic limiting device according to claim 1, wherein the cylinder seat (14) is a hollow cylinder body, a cylinder seat positioning hole (14-1) is formed in the circumference of one end of the cylinder seat (14), and the cylinder seat (14) is movably fixed with the cylinder body (11) through a connecting piece penetrating through the cylinder seat positioning hole (14-1).

3. The automatic limiting device according to claim 2, wherein the cylinder seat positioning hole (14-1) is an L-shaped positioning hole, the connecting piece comprises a first limiting piece (11-4) and a second limiting piece (11-5), and the cylinder (11) is provided with a cylinder first positioning hole (11-1) and a cylinder second positioning hole (11-2) which are connected with the first limiting piece (11-4) and the second limiting piece (11-5).

4. An automatic limiting device according to claim 2 or 3, wherein the cartridge (14) is provided with two cartridge positioning holes (14-1), and the two cartridge positioning holes (14-1) are symmetrically arranged;

The cylinder body (11) is movably fixed with the cylinder seat (14) through two groups of connecting pieces which respectively penetrate through two cylinder seat positioning holes (14-1).

5. The automatic limiting device according to claim 2, wherein an observation window (14-2) is arranged on the circumference of the cylinder seat (14) along the axial direction, and the observation window (14-2) faces the sliding rail (11-3) after the cylinder seat (14) is movably fixed with the cylinder body (11).

6. The automatic limiting device according to claim 2, wherein the cylinder seat (14) is internally provided with a T-shaped hole (14-3), and after the cylinder seat (14) is movably fixed with the cylinder body (11), the end surface of the cylinder body (11) is contacted with a shaft shoulder formed by the T-shaped hole (14-3).

7. The automatic limiting device according to claim 1, wherein two pin positioning holes (13-1) matched with the third limiting piece (13-3) are formed in the limiting pin (13), and the two pin positioning holes (13-1) are symmetrically formed;

The cylinder body (11) is provided with two sliding rails (11-3), and the two sliding rails (11-3) are symmetrically arranged;

the limiting pin shaft (13) is slidably arranged in the accommodating cavity of the cylinder body (11) through two third limiting pieces (13-3).

8. Automatic limiting device according to claim 1, characterized in that the end of the limiting pin (13) remote from the pin positioning hole (13-1) is provided with a guiding fillet (13-2).

9. Automatic limiting device according to claim 1, characterized in that the elastic element (12) is still in compression when the limiting pin (13) is in its maximum extension.

10. An engineering machinery chassis, characterized by comprising the automatic limiting device of any one of claims 1-9;

The engineering machinery chassis comprises a center frame (3) and side supports (2) positioned at two sides of the center frame (3), wherein telescopic arms (3-1) are respectively arranged at two sides of the center frame (3), the side supports (2) are sleeved on the telescopic arms (3-1) through sliding rail sleeves (2-1), and the telescopic arms (3-1) are provided with at least two locating pin shaft holes (3-2) in a straight line along the sliding direction of the sliding rail sleeves (2-1);

The automatic limiting device is arranged on the sliding rail sleeve (2-1), and a cylinder seat (14) of the automatic limiting device is fixedly connected with the sliding rail sleeve (2-1).

11. The engineering machinery chassis according to claim 10, wherein the telescopic arm (3-1) is provided with a guide band plate (3-4), a straight slot (3-41) is arranged in the middle of the guide band plate (3-4), and each locating pin shaft hole (3-2) on the telescopic arm (3-1) is located in the straight slot (3-41).