CN110847279B

CN110847279B - Loader buffer

Info

Publication number: CN110847279B
Application number: CN201911195373.8A
Authority: CN
Inventors: 陈艳艳; 张庆宇
Original assignee: Individual
Current assignee: Wang Lingzhi
Priority date: 2019-11-28
Filing date: 2019-11-28
Publication date: 2021-12-03
Anticipated expiration: 2039-11-28
Also published as: CN110847279A

Abstract

The invention discloses a loader buffering device, which comprises a hydraulic pump, a movable arm oil cylinder, an energy accumulator, an oil tank, a reversing pressure reducing valve and a multi-way control valve, wherein the multi-way control valve is connected with a rodless cavity and a rod cavity of the movable arm oil cylinder and is used for controlling the movable arm oil cylinder to extend out or retract; the outlet of the hydraulic pump is communicated with an X port of the reversing pressure-reducing valve, the energy accumulator is communicated with a P port of the reversing pressure-reducing valve, the oil tank is communicated with a T port of the reversing pressure-reducing valve, a rodless cavity of the movable arm oil cylinder is communicated with an A port of the reversing pressure-reducing valve, and a rod cavity is communicated with a B port of the reversing pressure-reducing valve; the buffering device of the loader not only has simple structure and compact volume, but also can effectively realize buffering and vibration reduction of the loader.

Description

Loader buffer

Technical Field

The invention belongs to the technical field of loaders, and particularly relates to a buffer device of a loader.

Background

The wheel-side support of the loader is rigidly connected with the frame, and the excitation vibration caused by uneven road surface is completely borne by four tires. When the loader runs or works, the movable arm oil cylinder does not act, the movable arm oil cylinder and the front frame are in rigid connection, the whole vehicle can swing around the front axle due to the road condition and the action of tires, the situation that the rear axle is separated from the ground can be caused sometimes, a driver swings along with the whole vehicle at the moment, the control is difficult, and the driving comfort is poor. Because the working device, heavy objects and other parts of the machine body react to bumpy bottom surfaces or obstacles, strong vibration and impact are generated, and the smoothness and the stability of the running of the whole machine are seriously influenced. Such vibrations during the travel of the loader can cause alternating stresses and fatigue damage to the working devices, the front and rear frames, the drive axles, and the like; meanwhile, as the working device is supported by the movable arm oil cylinder, the vibration impacts a hydraulic system, and adverse effects are generated on hydraulic elements and sealing; the vibration of the vehicle also causes bucket material to spill, the running speed cannot be provided, a driver is uncomfortable to ride, and driving batch is easy to generate, which all affect the working efficiency.

In the prior art, although the damping function of the loader during the running process can be realized to a certain extent as in the patent with application number 201210197132.9 entitled "damping device for a mobile arm of a skid steer loader" and the patent with application number 200420092138.0 entitled "running stabilizing device for a wheel loader", the following disadvantages exist:

(1) in the two technologies, because the energy accumulator is controlled to be communicated with the rodless cavity of the movable arm oil cylinder through the electromagnetic valve to charge liquid in a certain operation process, when the vibration reduction function is realized due to the fact that the size of each load is unequal, the pressure of the movable arm oil cylinder is unequal to the pressure of the energy accumulator, so that the movable arm oil cylinder is suddenly extended or retracted, and further bucket materials are scattered;

(2) in the two technologies, when the pressure of the energy accumulator is low, if the energy accumulator is filled with liquid in the operation process, the output flow of the hydraulic pump firstly enters the energy accumulator, and then the movable arm oil cylinder is driven to act, so that the movable arm is weak and cannot normally operate.

Disclosure of Invention

Technical problem to be solved

The invention aims to provide a buffer device which has simple structure and compact volume and can effectively realize the buffer and vibration damping functions of a loader.

(II) technical scheme

In order to achieve the purpose, the invention provides the following technical scheme: a loader buffer device comprises a hydraulic pump, a movable arm oil cylinder, an energy accumulator, an oil tank and a reversing pressure reducing valve; the outlet of the hydraulic pump is communicated with an X port of the reversing pressure-reducing valve, the energy accumulator is communicated with a P port of the reversing pressure-reducing valve, the oil tank is communicated with a T port of the reversing pressure-reducing valve, a rodless cavity of the movable arm oil cylinder is communicated with an A port of the reversing pressure-reducing valve, and a rod cavity is communicated with a B port of the reversing pressure-reducing valve.

In a further technical scheme, the reversing pressure-reducing valve comprises a valve sleeve, a threaded sleeve and a coil, wherein a reversing valve hole penetrating through the valve sleeve up and down is formed in the valve sleeve, and the threaded sleeve is in threaded connection with the upper end of the valve sleeve; the upper end of the threaded sleeve is provided with a detachable magnetic conduction pipe along the vertical direction, and the coil is sleeved on the outer circumference of the magnetic conduction pipe; the side surface of the valve sleeve is sequentially provided with an X port, a B port, a T port and a P port which are communicated with a reversing valve hole from top to bottom, the lower end of the reversing valve hole is an A port, a reversing valve core is connected in the reversing valve hole in a sliding mode, and the circumferential side surface of the reversing valve core is provided with a second annular groove communicated with the T port and a first annular groove communicated with the X port; the upper end of the reversing valve core is fixedly provided with an armature which penetrates through the threaded sleeve and extends into the magnetic conduction pipe, the valve sleeve is provided with a first shoulder at an opening at the upper end of the reversing valve hole, and the circumferential side surface of the reversing valve core close to the upper end is provided with a first shoulder; a first spring used for forcing the first shoulder to be pressed on the first shoulder is arranged above the armature in the magnetic conduction pipe; when the coil loses power, a first shoulder on the reversing valve core is pressed on the first shoulder under the action of a first spring, so that the port P is disconnected from the port A, and the port B is disconnected from the port T; when the coil is electrified, the armature moves upwards under the attraction action of the magnetic conduction pipe and compresses the first spring, so that the port P is communicated with the port A, and the port B is communicated with the port T through the first annular groove; and a pressure reducing component for controlling the pressure of the port P to be the same as the pressure of the port A is arranged in the reversing valve core.

In a further technical scheme, the pressure reducing assembly comprises a pressure reducing valve core, a second spring, a plunger, a plug, a mounting hole with an opening at the lower end is formed in the reversing valve core, an upward extending pressure reducing valve hole is formed in the top center of the mounting hole in the reversing valve core, a second shoulder matched with the second shoulder is formed between the pressure reducing valve hole and the mounting hole, and the second shoulder is arranged on the circumferential side of the lower end of the pressure reducing valve core; the pressure reducing valve core is connected in the pressure reducing valve hole in a sliding mode, the plug is in threaded connection with an opening at the lower end of the mounting hole, a plunger hole with an opening at the upper end is formed in the plug, the plunger is connected in the plunger hole in a sliding mode, and a plurality of oil holes communicated with the plunger hole are formed in the bottom of the plunger hole of the plug; the diameter of the plunger is the same as that of the pressure reducing valve core, and the second spring is positioned between the upper end of the plunger and the lower end of the pressure reducing valve core and used for forcing the plunger and the pressure reducing valve core to move back to back;

a first oil cavity is formed between the upper end of the plunger and the lower end of the pressure reducing valve core in the mounting hole, and a second oil cavity is formed between the upper end of the pressure reducing valve core and the upper end of the pressure reducing valve hole in the pressure reducing valve hole; a first through hole for communicating the first annular groove with the pressure reducing valve hole and a second through hole for communicating the second annular groove with the pressure reducing valve hole are formed in the reversing valve core; the circumferential side surface of the pressure reducing valve core is sequentially provided with a third annular groove and a fourth annular groove communicated with the second through hole from top to bottom; the upper end of the pressure reducing valve core is provided with an upper communicating hole communicated with the second oil cavity, and the lower end of the pressure reducing valve core is provided with a lower communicating hole communicated with the first oil cavity; a third through-flow hole for communicating the upper communication hole with the third annular groove and a fourth through-flow hole for communicating the lower communication hole with the fourth annular groove are formed in the pressure reducing valve core; a seventh through flow hole for communicating the second annular groove with the fourth annular groove is formed in the reversing valve core; a fifth annular groove is formed in the circumferential side face of the reversing valve core above the first annular groove, a fifth through-flow hole used for communicating the fifth annular groove with the second oil cavity is formed in the reversing valve core, and a sixth through-flow hole used for communicating the P port with the fifth annular groove is formed in the valve sleeve; when the pressure of the port P is less than the pressure of the port A, the third annular groove is communicated with the port X and is disconnected with the port T, when the pressure of the port P is equal to the pressure of the port A, the third annular groove is disconnected with the port X and the port T, and when the pressure of the port P is greater than the pressure of the port A, the third annular groove is communicated with the port T and is disconnected with the port X.

In a further technical scheme, a damper is arranged in the lower communication hole.

In a further technical scheme, the upper end of plunger is equipped with annular bulge, the lower extreme of second spring is contradicted on annular bulge.

In a further technical scheme, a limit clamp spring is arranged below a plunger on the inner side wall of the plunger hole, an annular valve plate matched with a plurality of oil holes is arranged below the limit clamp spring in the plunger hole, a damping hole is arranged at the bottom of the plunger hole in the plug, and the diameter of each oil hole is larger than that of the damping hole; this setting makes when fluid flows into the plunger hole by A mouth, with annular valve block jack-up, fluid can get into the plunger hole through damping hole and oilhole together and be equivalent to the check valve function this moment, and when fluid flowed into A mouth by the plunger hole, the downthehole fluid of plunger can only be flowed by the damping hole to annular valve block closure, consequently realizes the damping action.

(III) advantageous effects

Compared with the prior art, the technical scheme of the invention has the following advantages:

when the buffer device is used, automatic buffering in the running process of the loader can be realized, the pressure in the energy accumulator is controlled to be always equal to the pressure of the port A through the pressure reducing valve core, the movable arm oil cylinder cannot suddenly extend or retract when switching from operation to running buffering is carried out, and the buffering effect is better; and because the pressure reducing assembly controls the independent hydraulic pump to charge liquid, the phenomenon that the movable arm oil cylinder is weak and weak in the prior art is avoided; in addition, the invention is designed in a threaded plug-in mode, and has the advantages of high integration, compact volume, simple structure and low manufacturing cost.

Drawings

FIG. 1 is a front cross-sectional view of the reversing pressure relief valve element of the present invention;

FIG. 2 is a front cross-sectional view of the diverter valve cartridge and pressure relief assembly of the present invention;

FIG. 3 is a front cross-sectional view of the pressure relief valve cartridge of the present invention;

FIG. 4 is an enlarged view of the structure at A in FIG. 2;

FIG. 5 is a schematic diagram of the reversing pressure relief valve of the present invention;

fig. 6 is a schematic diagram of the loader cushioning device of the present invention.

Detailed Description

Referring to fig. 1 to 6, a buffering device of a loader includes a hydraulic pump 15, a boom cylinder 17, an accumulator 16, an oil tank 19, a reversing pressure reducing valve 66, and a multi-way control valve 18 connected to a rodless chamber and a rod chamber of the boom cylinder 17, where the multi-way control valve 18 is used to control extension or retraction of the boom cylinder 17; the outlet of the hydraulic pump 15 is communicated with an X port of a reversing pressure-reducing valve 66, the accumulator 16 is communicated with a P port of the reversing pressure-reducing valve 66, the oil tank 19 is communicated with a T port of the reversing pressure-reducing valve 66, a rodless cavity of the boom cylinder 17 is communicated with an a port of the reversing pressure-reducing valve 66, and a rod cavity is communicated with a B port of the reversing pressure-reducing valve 66, where the multi-way control valve 18 belongs to the prior art and is used for controlling the action of the boom cylinder 17, and is not described herein again.

The reversing pressure-reducing valve 66 comprises a valve sleeve 1, a threaded sleeve 2 and a coil 11, a reversing valve hole 108 which penetrates through the valve sleeve 1 up and down is arranged in the valve sleeve 1, and the threaded sleeve 2 is in threaded connection with the upper end of the valve sleeve 1; the upper end of the threaded sleeve 2 is provided with a detachable magnetic conduction pipe 3 along the vertical direction, and the coil 11 is sleeved on the outer circumference of the magnetic conduction pipe 3; an X port, a B port, a T port and a P port which are communicated with a reversing valve hole 108 are sequentially arranged on the side surface of the valve sleeve 1 from top to bottom, the lower end of the reversing valve hole 108 is an A port, a reversing valve core 6 is connected in the reversing valve hole 108 in a sliding mode, and a second annular groove 603 communicated with the T port and a first annular groove 602 communicated with the X port are arranged on the circumferential side surface of the reversing valve core 6; the upper end of the reversing valve core 6 is fixedly provided with an armature iron 4 which penetrates through the threaded sleeve 2 and extends into the magnetic conduction pipe 3, the opening of the upper end of the reversing valve hole 108 of the valve sleeve 1 is provided with a first shoulder 109, and the circumferential side surface of the reversing valve core 6 close to the upper end is provided with a first shoulder 605; a first spring 5 for forcing the first shoulder 605 to press against the first shoulder 109 is arranged in the magnetic conducting pipe 3 above the armature 4; when the coil 11 loses power, a first shoulder 605 on the reversing valve core 6 is pressed on the first shoulder 109 under the action of the first spring 5, so that the port P is disconnected from the port A, and the port B is disconnected from the port T; when the coil 11 is electrified, the armature 4 moves upwards under the attraction action of the magnetic conduction pipe 3 and compresses the first spring 5, so that the port P is communicated with the port A, and the port B is communicated with the port T through the first annular groove 602; and a pressure reducing component for controlling the pressure of the port P to be the same as that of the port A is arranged in the reversing valve core 6.

The pressure reducing assembly comprises a pressure reducing valve core 7, a second spring 8, a plunger 9, a plug 10, a mounting hole 611 with an opening at the lower end is arranged in the reversing valve core 6, a pressure reducing valve hole 612 extending upwards is arranged in the top center position of the mounting hole 611 in the reversing valve core 6, a second shoulder 613 is formed between the pressure reducing valve hole 612 and the mounting hole 611, and a second shoulder 711 matched with the second shoulder 613 is arranged on the lower end circumferential side surface of the pressure reducing valve core 7; the pressure reducing valve core 7 is connected in the pressure reducing valve hole 612 in a sliding manner, the plug 10 is connected to an opening at the lower end of the mounting hole 611 in a threaded manner, a plunger hole 1001 with an opening at the upper end is formed in the plug 10, the plunger 9 is connected in the plunger hole 1001 in a sliding manner, and the plug 10 is provided with a plurality of oil holes 102 communicated with the plunger hole 1001 at the bottom of the plunger hole 1001; the diameter of the plunger 9 is the same as that of the pressure reducing valve core 7, and the second spring 8 is positioned between the upper end of the plunger 9 and the lower end of the pressure reducing valve core 7 and used for forcing the plunger 9 and the pressure reducing valve core 7 to move back.

A first oil chamber 6a is formed between the upper end of the plunger 9 and the lower end of the pressure reducing valve core 7 in the mounting hole 611, and a second oil chamber 6b is formed between the upper end of the pressure reducing valve core 7 and the upper end of the pressure reducing valve hole 612 in the pressure reducing valve hole 612; a first through hole 63 for communicating the first annular groove 602 with the pressure reduction valve hole 612 and a second through hole 64 for communicating the second annular groove 603 with the pressure reduction valve hole 612 are formed in the direction valve core 6; the circumferential side surface of the pressure reducing valve core 7 is sequentially provided with a third annular groove 701 and a fourth annular groove 702 communicated with the second through hole 64 from top to bottom; the upper end of the pressure reducing valve core 7 is provided with an upper communication hole 71 communicated with the second oil chamber 6b, the lower end of the pressure reducing valve core is provided with a lower communication hole 72 communicated with the first oil chamber 6a, and a damper 13 is arranged in the lower communication hole 72; a third through hole 73 for communicating the upper communication hole 71 with the third annular groove 701 and a fourth through hole 74 for communicating the lower communication hole 72 with the fourth annular groove 702 are formed in the pressure reducing valve core 7; a seventh through hole 74 for communicating the second annular groove 603 with the fourth annular groove 702 is formed in the direction change valve core 6; a fifth annular groove 601 is formed in the circumferential side surface of the reversing valve core 6 above the first annular groove 602, a fifth through-flow hole 62 for communicating the fifth annular groove 601 with the second oil chamber 6b is formed in the reversing valve core 6, and a sixth through-flow hole 101 for communicating the P port with the fifth annular groove 601 is formed in the valve sleeve 1; when the pressure of the port P is smaller than the pressure of the port A, the third annular groove 701 is communicated with the port X and is disconnected with the port T, when the pressure of the port P is equal to the pressure of the port A, the third annular groove 701 is disconnected with the port X and the port T, and when the pressure of the port P is larger than the pressure of the port A, the third annular groove 701 is communicated with the port T and is disconnected with the port X.

The upper end of plunger 9 is equipped with annular bulge 91, the lower extreme of second spring 8 is contradicted on annular bulge 91. A limiting clamp spring 14 is arranged below the plunger 9 on the inner side wall of the plunger hole 1001, and an annular valve plate 12 matched with the oil holes 102 is arranged below the limiting clamp spring 14 in the plunger hole 1001; a damping hole 191 is formed in the plug 10 at the bottom of the plunger hole 1001, and the diameter of the oil hole 102 is larger than that of the damping hole 191; this setting makes when fluid flows into plunger hole 1001 by A mouth, with annular valve block 12 jack-up, fluid can get into the plunger hole 1001 simultaneously through damping hole 191 and oilhole 102 and be equivalent to the check valve function this moment in the plunger hole 1001, and when fluid flowed into A mouth by plunger hole 1001, annular valve block 12 closed the fluid in the plunger hole 1001 and can only flow out by damping hole 191, consequently realized the damping effect.

The specific functional process of the invention is as follows:

liquid filling stage: when the loader does not need buffering in normal operation, the coil 11 is powered off, the port P is blocked with the port A, and the port B is blocked with the port T. When the pressure in the accumulator 16 (i.e., at the port P) is lower than the pressure at the port a, the pressure reducing valve spool 7 is at the position shown in fig. 1 under the action of the second spring 8, and the oil delivered to the port X by the hydraulic pump 15 sequentially passes through the first annular groove 602, the first through-flow hole 63, the third annular groove 701, the third through-flow hole 73, the upper communication hole 71, the second oil chamber 6b, the fifth through-flow hole 62, the fifth annular groove 601, and the sixth through-flow hole 101, and then enters the accumulator 16 from the port P to charge the accumulator 16. When the pressure in the accumulator 16 (i.e. at the port P) is higher than the pressure at the port a, the pressure reducing valve core 7 moves downward, so that the oil in the accumulator 16 flows to the oil tank 19 through the port P, the sixth through hole 101, the fifth annular groove 601, the fifth through hole 62, the second oil chamber 6b, the upper through hole 71, the third through hole 73, the third annular groove 701, the second through hole 64, the second annular groove 603 and the port T to realize pressure reduction, and the control is performed until the pressure in the accumulator 16 is always equal to the pressure in the rodless chamber of the hydraulic cylinder, namely, the pressure at the port P is equal to the pressure at the port a.

A buffering stage: when the loader runs at a high speed, the coil 11 is electrified, the port P is communicated with the port A, the port B is communicated with the port T, namely, a rodless cavity of the movable arm oil cylinder 17 is communicated with the energy accumulator 16, a rod cavity of the movable arm oil cylinder 17 is communicated with the oil tank 19, and at the moment that the energy accumulator 16 is communicated with the rodless cavity of the movable arm oil cylinder 17, due to the fact that the pressure in the energy accumulator 16 is equal to the pressure in the rodless cavity, the movable arm oil cylinder 17 cannot extend or retract like the prior art. When the movable arm moves up and down along with the change of road conditions, when the movable arm moves up, oil in the energy accumulator 16 fills a rodless cavity of the movable arm oil cylinder 17 to jack the movable arm oil cylinder 17, and the oil in a rod cavity of the movable arm oil cylinder 17 returns to the oil tank 19 from the port B through the port T; when the boom cylinder 17 moves downward, the oil in the rodless chamber of the boom cylinder 17 flows into the accumulator 16, and the oil in the oil tank 19 flows into the rod chamber of the boom cylinder 17, thereby achieving a state similar to floating during traveling and achieving a buffering function.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the technical principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. A loader buffer device is characterized by comprising a hydraulic pump, a movable arm oil cylinder, an energy accumulator, an oil tank, a reversing pressure reducing valve and a multi-way control valve, wherein the multi-way control valve is connected with a rodless cavity and a rod cavity of the movable arm oil cylinder and is used for controlling the movable arm oil cylinder to extend out or retract; the outlet of the hydraulic pump is communicated with an X port of the reversing pressure-reducing valve, the energy accumulator is communicated with a P port of the reversing pressure-reducing valve, the oil tank is communicated with a T port of the reversing pressure-reducing valve, a rodless cavity of the movable arm oil cylinder is communicated with an A port of the reversing pressure-reducing valve, and a rod cavity is communicated with a B port of the reversing pressure-reducing valve;

the reversing pressure-reducing valve comprises a valve sleeve, a threaded sleeve and a coil, a reversing valve hole penetrating through the valve sleeve up and down is formed in the valve sleeve, and the threaded sleeve is in threaded connection with the upper end of the valve sleeve; the upper end of the threaded sleeve is provided with a detachable magnetic conduction pipe along the vertical direction, and the coil is sleeved on the outer circumference of the magnetic conduction pipe; the side surface of the valve sleeve is sequentially provided with an X port, a B port, a T port and a P port which are communicated with a reversing valve hole from top to bottom, the lower end of the reversing valve hole is an A port, a reversing valve core is connected in the reversing valve hole in a sliding mode, and the circumferential side surface of the reversing valve core is provided with a second annular groove communicated with the T port and a first annular groove communicated with the X port; the upper end of the reversing valve core is fixedly provided with an armature which penetrates through the threaded sleeve and extends into the magnetic conduction pipe, the valve sleeve is provided with a first shoulder at an opening at the upper end of the reversing valve hole, and the circumferential side surface of the reversing valve core close to the upper end is provided with a first shoulder; a first spring used for forcing the first shoulder to be pressed on the first shoulder is arranged above the armature in the magnetic conduction pipe; when the coil loses power, a first shoulder on the reversing valve core is pressed on the first shoulder under the action of a first spring, so that the port P is disconnected from the port A, and the port B is disconnected from the port T; when the coil is electrified, the armature moves upwards under the attraction action of the magnetic conduction pipe and compresses the first spring, so that the port P is communicated with the port A, and the port B is communicated with the port T through the first annular groove; a pressure reducing component for controlling the pressure of the port P to be the same as the pressure of the port A is arranged in the reversing valve core;

the pressure reducing assembly comprises a pressure reducing valve core, a second spring, a plunger, a plug, a mounting hole with an opening at the lower end is formed in the reversing valve core, an upward extending pressure reducing valve hole is formed in the top center of the mounting hole in the reversing valve core, a second shoulder is formed between the pressure reducing valve hole and the mounting hole, and a second shoulder matched with the second shoulder is formed on the circumferential side surface of the lower end of the pressure reducing valve core; the pressure reducing valve core is connected in the pressure reducing valve hole in a sliding mode, the plug is in threaded connection with an opening at the lower end of the mounting hole, a plunger hole with an opening at the upper end is formed in the plug, the plunger is connected in the plunger hole in a sliding mode, and a plurality of oil holes communicated with the plunger hole are formed in the bottom of the plunger hole of the plug; the diameter of the plunger is the same as that of the pressure reducing valve core, and the second spring is positioned between the upper end of the plunger and the lower end of the pressure reducing valve core and used for forcing the plunger and the pressure reducing valve core to move back to back;

a first oil cavity is formed between the upper end of the plunger and the lower end of the pressure reducing valve core in the mounting hole, and a second oil cavity is formed between the upper end of the pressure reducing valve core and the upper end of the pressure reducing valve hole in the pressure reducing valve hole; a first through hole for communicating the first annular groove with the pressure reducing valve hole and a second through hole for communicating the second annular groove with the pressure reducing valve hole are formed in the reversing valve core; the circumferential side surface of the pressure reducing valve core is sequentially provided with a third annular groove and a fourth annular groove communicated with the second through hole from top to bottom; the upper end of the pressure reducing valve core is provided with an upper communicating hole communicated with the second oil cavity, and the lower end of the pressure reducing valve core is provided with a lower communicating hole communicated with the first oil cavity; a third through-flow hole for communicating the upper communication hole with the third annular groove and a fourth through-flow hole for communicating the lower communication hole with the fourth annular groove are formed in the pressure reducing valve core; a seventh through flow hole for communicating the second annular groove with the fourth annular groove is formed in the annular groove; a fifth annular groove is formed in the circumferential side face of the reversing valve core above the first annular groove, a fifth through-flow hole used for communicating the fifth annular groove with the second oil cavity is formed in the reversing valve core, and a sixth through-flow hole used for communicating the P port with the fifth annular groove is formed in the valve sleeve; when the pressure of the port P is less than the pressure of the port A, the third annular groove is communicated with the port X and is disconnected with the port T, when the pressure of the port P is equal to the pressure of the port A, the third annular groove is disconnected with the port X and the port T, and when the pressure of the port P is greater than the pressure of the port A, the third annular groove is communicated with the port T and is disconnected with the port X.

2. The loader cushioning device of claim 1, wherein a damper is provided in said lower communication aperture.

3. The loader cushioning device of claim 1, wherein the upper end of said plunger is provided with an annular projection against which the lower end of said second spring abuts.

4. The loader buffering mechanism as claimed in claim 1, wherein a limit clamp spring is arranged below the plunger on the inner side wall of the plunger hole, an annular valve plate matched with a plurality of oil holes is arranged below the limit clamp spring in the plunger hole, a damping hole is arranged at the bottom of the plunger hole in the plug, and the diameter of the oil hole is larger than that of the damping hole.