CN210218266U

CN210218266U - Hand pilot valve for bulldozer and bulldozer with hand pilot valve

Info

Publication number: CN210218266U
Application number: CN201821825587.XU
Authority: CN
Inventors: Wei'an Jiang; 江卫安; Baolin Zhu; 朱宝麟; Chongqing Liao; 廖崇庆
Original assignee: Liugong Changzhou Machinery Co Ltd
Current assignee: Liugong Changzhou Machinery Co Ltd
Priority date: 2018-11-07
Filing date: 2018-11-07
Publication date: 2020-03-31
Anticipated expiration: 2028-11-07

Abstract

The utility model relates to a bull-dozer that is used for hand pilot valve of bull-dozer and has it belongs to bull-dozer technical field, in order to solve the problem that how to utilize hand pilot valve and normal close formula braking clutch cooperation to realize the bull-dozer walking and turn to, a bull-dozer that is used for the hand pilot valve of bull-dozer and has it is provided, the hand pilot valve includes valve body and handle operating device, handle operating device can swing and connect on the valve body, be formed with oil inlet and oil return opening on the valve body, inject the oil feed chamber that has the intercommunication oil inlet and the oil return chamber's of intercommunication oil return opening in the valve body, be formed with intercommunication oil feed chamber and the open pressure boost valve opening in oil return chamber and the top and reduce the pressure chamber, inject the pressure chamber that has the pressure boost chamber. The utility model discloses increased the function of hand pilot valve, for controlling the bull-dozer provides convenience, can adjust the pressure variation curve in decompression chamber moreover, promoted the variety of hand pilot valve.

Description

Hand pilot valve for bulldozer and bulldozer with hand pilot valve

Technical Field

The utility model belongs to the technical field of the bull-dozer technique and specifically relates to a bull-dozer that is used for hand pilot valve of bull-dozer and has it.

Background

The hand pilot valve among the prior art is the control form that the relief pressure valve is the prototype mostly, through the handle of swing pilot valve, the pilot valve case removes, and the hydraulic fluid port that corresponds increases along with the angle of handle wobbling, and the pressure of hydraulic fluid port output increases gradually until reaching system maximum pressure, but this kind of pilot valve can't accurate control realize the walking machinery of braking and turning to through normal close formula braking clutch, consequently, the urgent need develop a hand pilot valve for bull-dozer in order to solve above-mentioned technical problem.

SUMMERY OF THE UTILITY MODEL

The utility model discloses a solve the problem that how to utilize hand pilot valve and normal close formula braking clutch cooperation to realize the bull-dozer walking and turn to, provide a hand pilot valve for bull-dozer.

The utility model adopts the technical scheme as follows:

a hand pilot valve for a bulldozer, comprising a valve body and a handle operating mechanism, said handle operating mechanism comprising: the steering mechanism comprises a driving handle, a steering knuckle and a pressure plate, and is characterized in that a handle operation structure is connected to a valve body in a swinging manner, an oil inlet and an oil return opening are formed in the valve body, an oil inlet cavity communicated with the oil inlet and an oil return cavity communicated with the oil return opening are defined in the valve body, a pressurization valve hole and a decompression valve hole which are communicated with the oil inlet cavity and the oil return cavity and open in top are formed in the valve body, and a pressurization cavity communicated with the pressurization valve hole and a decompression cavity communicated with the decompression valve hole are defined between the oil inlet cavity and the oil return cavity; the hand pilot valve further comprises: the upper end of the first type valve core is abutted with the pressure plate, the upper end of the second type valve core is abutted with the pressure plate, the first type valve core is slidably arranged in the pressure increasing valve hole between the first upper end and the first lower end, and the second type valve core is slidably arranged in the pressure reducing cavity between the second upper end and the second lower end; when the first type valve core is positioned at the first upper end, the pressurizing cavity is communicated with the oil return cavity, and when the first type valve core is positioned at the first lower end, the pressurizing cavity is communicated with the oil inlet cavity; and an upper oil guide groove and a lower oil guide groove which extend along the axial direction of the second type valve core are formed on the side wall of the second type valve core, when the second type valve core is positioned at the upper end of the second, the lower oil guide groove is communicated with the decompression cavity and the oil inlet cavity, and when the second type valve core is positioned at the lower end of the second, the upper oil guide groove is communicated with the decompression cavity and the oil return cavity.

According to the utility model discloses an embodiment, the second upper end with intermediate position has between the second lower extreme, works as type two valves are located during the intermediate position, lead oil groove intercommunication down the decompression chamber with the oil feed chamber just lead oil groove intercommunication on the top the decompression chamber with return oil chamber.

According to an embodiment of the present invention, there are two pressure-increasing valve holes, there are two first-type valve cores, and the two first-type valve cores are disposed in the two pressure-increasing valve holes in a one-to-one correspondence manner; the two pressure reducing valve holes are formed, the two valve cores are two, and the two valve cores are arranged in the two pressure reducing valve holes in a one-to-one correspondence mode.

According to an embodiment of the present invention, the two pressure-increasing valve holes are respectively a first pressure-increasing valve hole and a second pressure-increasing valve hole, the bottom of the first pressure-increasing valve hole is communicated with the locking flow channel, and the other end of the locking flow channel is communicated with the pressure-increasing cavity of the second pressure-increasing valve hole; and a locking position is arranged above the first upper end of the first-type valve core, and when the first-type valve core in the second pressurizing valve hole moves to the first lower end, the first-type valve core in the first pressurizing valve hole moves to the locking position and is in contact with the handle operating mechanism in a stopping way.

According to the utility model discloses an embodiment, two types of spools include: the second type upper sealing boss surrounds the second type valve post, when the second type valve post is located at the first upper end, the second type upper sealing boss seals a channel between the oil return cavity and the decompression cavity, and when the second type valve post is located at the second lower end, the second type upper sealing boss seals a channel between the oil inlet cavity and the decompression cavity.

According to the utility model discloses an embodiment, on lead the oil groove with lead the oil groove down and all establish on the sealed boss of second type, just on lead the upper end of oil groove and open, the lower extreme of leading the oil groove down opens.

According to the utility model discloses an embodiment, go up lead the oil groove with lead the oil groove down and be in spaced apart setting in the axial of class two valve posts, just go up lead the oil groove with lead the distance between the oil groove down and be less than the decompression chamber is in class two valve posts are ascending height in the axial.

According to the utility model discloses an embodiment, the sealed boss is in on the second type the ascending height of second type valve post axial is greater than the decompression chamber is in the ascending height of second type valve post axial adds the second upper end with the distance sum between the second lower extreme.

According to the utility model discloses bull-dozer of second aspect, include: according to the hand pilot valve for the bulldozer, the power supply device, the rotating device, the traveling device and the normally closed type braking clutch are arranged, the power supply device is communicated with the oil inlet and the oil return opening, the rotating device is communicated with the pressurization cavity, the traveling device is communicated with the decompression cavity, and the normally closed type braking clutch is arranged between the traveling device and the decompression cavity.

The utility model discloses beneficial effect: the utility model relates to a bull-dozer that is used for hand pilot valve of bull-dozer and has it, through set up pressure boost valve opening and decompression valve opening on the valve body, utilize one type of case and the working process that pressure boost valve opening cooperation control turned to the device, the bull-dozer driver can increase gradually and turn to the drive power of device, utilize the working process of two types of case and decompression valve opening cooperation control running gear, the bull-dozer driver can reduce running gear's drive effort gradually, and then advance or retreat with normal close formula braking clutch cooperation drive bull-dozer. From this, not only increased the function of hand pilot valve, for the bull-dozer driver control bull-dozer provides convenience, the pressure variation curve in decompression chamber can be adjusted in the cooperation of second class case and decompression valve hole moreover, has promoted the variety of hand pilot valve.

Drawings

Fig. 1 is a schematic structural diagram of a hand pilot valve according to an embodiment of the present invention;

fig. 2 is a top view of a hand pilot valve according to an embodiment of the present invention;

FIG. 3 is a cross-sectional view taken along line A-A of FIG. 2;

FIG. 4 is a top view of a type of valve cartridge for a hand pilot valve according to an embodiment of the present invention;

FIG. 5 is a cross-sectional view taken along line B-B of FIG. 2;

fig. 6 is a top view of a type two valve element of a hand pilot valve according to an embodiment of the present invention.

In the figure:

100: a hand pilot valve; 1: a valve body; 2: an oil inlet cavity; 3: an oil return cavity; 4: a booster valve hole; 5: a relief valve aperture; 6: a pressurizing cavity; 7: a decompression chamber; 8: a type of valve core; 9: a second type valve core; 10: locking the flow channel; 11: a handle operating mechanism; 12: a type of return spring; 13: a class II return spring; 14: a kind of valve spool; 15: a lower sealing boss; 16: a kind of upper sealing boss; 17: a second-type spool; 18: a second type upper sealing boss; 19: an upper oil guide groove; 20: and a lower oil guide groove.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are exemplary only for the purpose of explaining the present invention, and should not be construed as limiting the present invention.

As shown in fig. 1 to 6, a hand pilot valve 100 for a bulldozer comprises a valve body 1 and a handle operating mechanism 11, wherein the handle operating mechanism is swingably connected to the valve body 1, an oil inlet and an oil return port are formed on the valve body 1, an oil inlet chamber 2 communicating with the oil inlet and an oil return chamber 3 communicating with the oil return port are defined in the valve body 1, a pressurization valve hole 4 and a decompression valve hole 5 communicating with the oil inlet chamber 2 and the oil return chamber 3 and having open tops are formed in the valve body 1, and a pressurization chamber 6 communicating with the pressurization valve hole 4 and a decompression chamber 7 communicating with the decompression valve hole 5 are defined between the oil inlet chamber 2 and the oil return chamber 3; the hand pilot valve 100 further comprises: the first-class valve core 8 of which the upper end is connected with the handle operating mechanism 11 and the second-class valve core 9 of which the upper end is connected with the handle operating mechanism 11 are arranged in the pressure increasing valve hole 4 in a sliding way between the first upper end and the first lower end of the first-class valve core 8, and the second-class valve core 9 of which the second upper end and the second lower end of the second-class valve core are arranged in the pressure reducing cavity 7 in a sliding way; when the first-class valve core 8 is positioned at the first upper end, the pressurizing cavity 6 is communicated with the oil return cavity 3, and when the first-class valve core 8 is positioned at the first lower end, the pressurizing cavity 6 is communicated with the oil inlet cavity 2; an upper oil guide groove 19 and a lower oil guide groove 20 which extend along the axial direction of the second-type valve core 9 are formed on the side wall of the second-type valve core 9, when the second-type valve core 9 is positioned at the second upper end, the lower oil guide groove 20 is communicated with the decompression cavity 7 and the oil inlet cavity 2, and when the second-type valve core 9 is positioned at the second lower end, the upper oil guide groove 19 is communicated with the decompression cavity 7 and the oil return cavity 3; and an intermediate position is formed between the second upper end and the second lower end, when the second-type valve core 9 is positioned at the intermediate position, the lower oil guide groove 20 is communicated with the decompression cavity 7 and the oil inlet cavity 2, and the upper oil guide groove 19 is communicated with the decompression cavity 7 and the oil return cavity 3.

According to the utility model discloses bull-dozer of second aspect, include: the hand pilot valve 100 for the bulldozer, the power supply device, the rotating device, the traveling device, and the normally closed brake clutch described in the above embodiments, the power supply device communicates with the oil inlet and the oil return port, the rotating device communicates with the pressurizing chamber 6, the traveling device communicates with the depressurizing chamber 7, and the normally closed brake clutch is provided between the traveling device and the depressurizing chamber 7.

According to the utility model discloses bulldozer, in the course of the work, driver's manipulator pilot valve 100, when handle operating device 11 pushes down a type of case 8, the sectional area subassembly increase of the intercommunication passageway between pressurization chamber 6 intercommunication oil feed chamber 2 and pressurization chamber 6 and the oil feed chamber 2, and then can increase the oil pressure in pressurization chamber 6 gradually, can increase rotating device's rotation effort gradually from this. Under the matching action of the second-class valve core 9 and the pressure reducing valve hole 5, the pressure reducing cavity 7 is always in a high-pressure state, the transmission of acting force is controlled by matching with a normally closed brake clutch, the oil pressure in the pressure reducing cavity 7 can be gradually reduced by utilizing the second-class valve core 9, the oil pressure does not change like the traditional linear change, and a certain curve change is formed.

According to the utility model discloses a bull-dozer that is used for hand pilot valve 100 of bull-dozer and has it, through set up pressure boost valve opening 4 and decompression valve opening 5 on valve body 1, utilize one type of case 8 and the working process that pressure boost valve opening 4 cooperation control turned to the device, the bull-dozer driver can increase gradually and turn to the drive power of device, utilize the working process of two types of

case

9 and 5 cooperation control running gear of decompression valve opening, the bull-dozer driver can reduce running gear's driving force gradually, and then advance or retreat with normal close formula braking clutch cooperation drive bull-dozer. From this, not only increased the function of hand pilot valve 100, for the bulldozer driver control bulldozer provides convenience, the pressure variation curve of decompression chamber 7 can be adjusted in the cooperation of second class case 9 and decompression valve opening 5 moreover, has promoted the variety of hand pilot valve 100.

According to an embodiment of the present invention, there are two pressure-increasing valve holes 4, two first-type valve cores 8, and the two first-type valve cores 8 are disposed in the two pressure-increasing valve holes 4 in a one-to-one correspondence manner; the two pressure reducing valve holes 5 are provided, the two second-type valve cores 9 are provided, and the two second-type valve cores 9 are arranged in the two pressure reducing valve holes 5 in a one-to-one correspondence mode.

All set up two through setting up one kind of case 8, two kinds of case 9, pressure boost valve opening 4 and decompression valve opening 5, can increase the control range of hand pilot valve 100, that is to say, the work of four mechanisms can be controlled simultaneously to the hand pilot valve 100 of this embodiment, provides convenience for the driver control bull-dozer.

According to an embodiment of the present invention, the two pressure-increasing valve holes 4 are respectively a first pressure-increasing valve hole 4 and a second pressure-increasing valve hole 4, the bottom of the first pressure-increasing valve hole 4 is communicated with the locking flow channel 10, and the other end of the locking flow channel 10 is communicated with the pressure-increasing cavity 6 of the second pressure-increasing valve hole 4; and when the valve core 8 in the second pressurization valve hole 4 moves to the first lower end, the valve core 8 in the first pressurization valve hole 4 moves to the locking position and is in contact with the handle operating mechanism 11.

Through setting up locking runner 10, when second pressure boost valve hole 4 is in operating condition, pressure increase in pressure cavity 6, the oil pressure of first pressure boost valve hole 4 bottom increases, and a class of case 8 in first pressure boost valve hole 4 is upwards removed under the effect of oil pressure, utilizes the drive effect of a class of case 8 to handle operating device 11, can lock handle operating device 11, prevents that handle operating device 11 from reseing.

According to the utility model discloses an embodiment, the equidistant setting of circumference along valve body 1 of pressure boost valve opening 4 and decompression valve opening 5.

According to an embodiment of the present invention, the handle operating mechanism 11 includes: the valve comprises a driving handle, a steering knuckle and a pressing plate, wherein the steering knuckle is connected to the lower end of the driving handle, the steering knuckle is connected to the top of the valve body 1 in a swinging mode, the pressing plate is arranged around the steering knuckle and extends outwards along the radial direction of the valve body 1, and the lower surface of the pressing plate is in contact with the upper ends of the first-class valve core 8 and the second-class valve core 9 in a stopping mode.

The handle operating mechanism 11 with the structure has a simple structure, can not only provide convenience for driving the first-class valve core 8 or the second-class valve core 9 by the pressure plate, but also provide convenience for driving the handle by swinging of a driver.

According to an embodiment of the present invention, the hand pilot valve 100 further includes a first type of return spring 12 sleeved on the first type of valve element 8, an upper end of the first type of return spring 12 is engaged with an outer peripheral wall of the first type of valve element 8, a lower end of the first type of return spring 12 is engaged with an inner peripheral wall of the pressure increasing valve hole 4, and the first type of return spring 12 always pushes the first type of valve element 8 to move to a position of a first upper end; the hand pilot valve 100 further comprises a second type return spring 13 sleeved on the second type valve core 9, the upper end of the second type return spring 13 is matched with the outer peripheral wall of the second type valve core 9, the lower end of the second type return spring 13 is matched with the inner peripheral wall of the pressurization valve hole 4, and the second type return spring 13 normally pushes the second type valve core 9 to move to the position of the second upper end.

By arranging the first-class reset spring 12 and the second-class reset spring 13, the first-class valve core 8 and the second-class valve core 9 can be promoted to reset after moving, and the condition that the normal work of the hand pilot valve 100 is influenced because the first-class valve core 8 and the second-class valve core 9 cannot reset after moving is prevented.

According to an embodiment of the present invention, one type of valve element 8 includes: the first-type spool 14, the first-type lower seal boss 15, and the first-type upper seal boss 16, the first-type spool 14 extending in the axial direction of the pressure-increasing valve hole 4 and being connected to the handle operating mechanism 11, the first-type spool 14 moving between the first upper end and the first lower end, the first-type lower seal boss 15 being provided at the lower end of the first-type spool 14, the first-type lower seal boss 15 closing a passage between the oil inlet chamber 2 and the pressure-increasing chamber 6 when the first-type spool 14 is located at the first upper end, the first-type upper seal boss 16 being provided around the first-type spool 14, and the first-type spool 14 closing a passage between the oil return chamber 3 and the pressure-increasing chamber 6 when the first-type spool 14 is located at the.

According to the utility model discloses an embodiment, second type case 9 includes: the second-class valve column 17 and the second-class upper sealing boss 18, the second-class valve column 17 extends along the axial direction of the pressure reducing valve hole 5 and is connected with the handle operating mechanism 11, the second-class valve column 17 moves between the second upper end and the second lower end, the second-class upper sealing boss 18 is arranged around the second-class valve column 17, when the second-class valve column 17 is located at the first upper end, a channel between the closed oil return cavity 3 of the second-class upper sealing boss 18 and the pressure reducing cavity 7 is formed, and when the second-class valve column 17 is located at the second lower end, a channel between the closed oil inlet cavity 2 of the second-class upper sealing boss 18 and the pressure reducing cavity 7 is formed. The upper oil guide groove 19 and the lower oil guide groove 20 are both arranged on the second-class sealing boss, the upper end of the upper oil guide groove 19 is opened, and the lower end of the lower oil guide groove 20 is opened.

The second-class valve core 9 with the structure is simple in structure, oil pressure change between the oil inlet cavity 2, the oil return cavity 3 and the decompression cavity 7 is controlled by matching the second-class sealing boss, the upper oil guide groove 19 and the lower oil guide groove 20, and a curve between the oil pressure of the decompression cavity 7 and the swing angle of the handle operating mechanism 11 can be adjusted by adjusting the length and the position of the upper oil guide groove 19 and the lower oil guide groove 20.

Specifically, at the initial stage of the swing of the handle operating mechanism 11, the lower oil guide groove 20 is always communicated with the oil inlet cavity 2 and the decompression cavity 7, the upper oil guide groove 19 is in sealing fit with the decompression cavity 7, the oil pressure of the decompression cavity 7 is equal to the oil pressure of the oil inlet cavity 2 at the moment, the upper oil guide groove 19 is gradually communicated with the decompression cavity 7 along with the continuous swing of the handle operating mechanism 11, but the sectional area of a flow channel between the oil inlet cavity 2 and the decompression cavity 7 is far larger than that of a flow channel between the oil return cavity 3 and the decompression cavity 7 at. The second-class valve core 9 continues to move downwards, the sectional area of a flow channel between the oil inlet cavity 2 and the decompression cavity 7 is gradually smaller, the sectional area of the flow channel between the oil return cavity 3 and the decompression cavity 7 is gradually increased, the oil pressure of the decompression cavity 7 is gradually reduced in a curve mode until the space between the lower oil guide groove 20 and the decompression cavity 7 is sealed, the upper oil guide groove 19 is completely communicated with the decompression cavity 7 and the oil return cavity 3, and the oil pressure of the decompression cavity 7 becomes zero.

According to the utility model discloses an embodiment, lead oil groove 19 on with lead oil groove 20 down and separate the setting in the axial of class II valve post 17, and lead the oil groove 19 on with lead the distance between the oil groove 20 down and be less than decompression chamber 7 at class II valve post 17 axial height. Therefore, in the downward movement process of the second-class valve core 9, a state exists to enable the decompression cavity 7 to be communicated with the oil return cavity 3 and the oil inlet cavity 2 at the same time, and pressure balance among the oil inlet cavity 2, the oil return cavity 3 and the decompression cavity 7 is guaranteed.

According to an embodiment of the present invention, the height of the second type upper sealing boss 18 in the axial direction of the second type spool 17 is greater than the sum of the height of the decompression chamber 7 in the axial direction of the second type spool 17 and the distance between the second upper end and the second lower end.

The above is the preferred embodiment of the present invention, and the technical personnel in the field of the present invention can also change and modify the above embodiment, therefore, the present invention is not limited to the above specific embodiment, and any obvious improvement, replacement or modification made by the technical personnel in the field on the basis of the present invention all belong to the protection scope of the present invention.

Claims

1. A hand pilot valve (100) for a bulldozer, comprising a valve body (1) and a handle operating mechanism (11), said handle operating mechanism (11) comprising: the hydraulic control valve is characterized in that a handle operating mechanism (11) is connected to a valve body (1) in a swinging mode, an oil inlet and an oil return opening are formed in the valve body (1), an oil inlet cavity (2) communicated with the oil inlet and an oil return cavity (3) communicated with the oil return opening are defined in the valve body (1), a pressurization valve hole (4) and a decompression valve hole (5) which are communicated with the oil inlet cavity (2) and the oil return cavity (3) and open in top are formed in the valve body (1), and a pressurization cavity (6) communicated with the pressurization valve hole (4) and a decompression cavity (7) communicated with the decompression valve hole (5) are defined between the oil inlet cavity (2) and the oil return cavity (3);

the hand pilot valve (100) further comprises: the upper end of the first-type valve core (8) is abutted to the pressure plate, the upper end of the second-type valve core (9) is abutted to the pressure plate, the first-type valve core (8) is slidably arranged in the pressure increasing valve hole (4) between the first upper end and the first lower end, and the second-type valve core (9) is slidably arranged in the pressure reducing cavity (7) between the second upper end and the second lower end;

when the first type valve core (8) is positioned at the first upper end, the pressurizing cavity (6) is communicated with the oil return cavity (3), and when the first type valve core (8) is positioned at the first lower end, the pressurizing cavity (6) is communicated with the oil inlet cavity (2);

an upper oil guide groove (19) and a lower oil guide groove (20) are formed in the side wall of the second type valve core (9) and extend along the axial direction of the second type valve core (9), when the second type valve core (9) is located at the upper end of the second, the lower oil guide groove (20) is communicated with the decompression cavity (7) and the oil inlet cavity (2), and when the second type valve core (9) is located at the lower end of the second, the upper oil guide groove (19) is communicated with the decompression cavity (7) and the oil return cavity (3).

2. The hand pilot valve (100) for a bulldozer according to claim 1, in which said second upper end and said second lower end have an intermediate position therebetween, and when said type two spool (9) is in said intermediate position, said lower oil guide groove (20) communicates said decompression chamber (7) with said oil feed chamber (2) and said upper oil guide groove (19) communicates said decompression chamber (7) with said oil return chamber (3).

3. The hand pilot valve (100) for a bulldozer according to claim 1, wherein there are two said booster valve holes (4), there are two said one-type valve spools (8), and two said one-type valve spools (8) are provided in one-to-one correspondence in the two booster valve holes (4);

the two pressure reducing valve holes (5) are formed, the two valve cores (9) are two, and the two valve cores (9) are correspondingly arranged in the two pressure reducing valve holes (5) one by one.

4. The hand pilot valve (100) for a bulldozer according to claim 3, wherein said two pressurization valve holes (4) are a first pressurization valve hole and a second pressurization valve hole, respectively, a bottom of said first pressurization valve hole communicates with a lock flow passage (10), and the other end of said lock flow passage (10) communicates with a pressurization cavity (6) of said second pressurization valve hole;

and a locking position is arranged above the first upper end of the valve core (8), and when the valve core (8) in the second pressurizing valve hole moves to the first lower end, the valve core (8) in the first pressurizing valve hole moves to the locking position and stops contacting the handle operating mechanism (11).

5. The hand pilot valve (100) for a bulldozer according to claim 2, characterised in that said type two spool (9) comprises:

a second-type spool (17), the second-type spool (17) extending in the axial direction of the pressure-reducing valve hole (5) and being connected to the handle operation mechanism (11), the second-type spool (17) moving between the second upper end and the second lower end;

sealing boss (18) in the second kind, sealing boss (18) centers on in the second kind two kind valve post (17) set up, works as when second kind valve post (17) are located when first upper end, the closure of sealing boss (18) in the second kind oil return chamber (3) with passageway between decompression chamber (7), works as when second kind valve post (17) are located when the second lower extreme, the closure of sealing boss (18) in the second kind oil feed chamber (2) with passageway between decompression chamber (7).

6. The hand pilot valve (100) for a bulldozer according to claim 5, in which said upper oil guide groove (19) and said lower oil guide groove (20) are both provided on said class II upper seal boss (18), and an upper end of said upper oil guide groove (19) is open and a lower end of said lower oil guide groove (20) is open.

7. The hand pilot valve (100) for a bulldozer according to claim 6, in which said upper oil guide groove (19) and said lower oil guide groove (20) are provided spaced apart in an axial direction of said type two spool (17), and a distance between said upper oil guide groove (19) and said lower oil guide groove (20) is smaller than a height of said decompression chamber (7) in the axial direction of said type two spool (17).

8. A bulldozer, characterized by comprising:

the hand pilot valve (100) for a bulldozer according to any one of claims 1-7;

the power supply device is communicated with the oil inlet and the oil return port;

the rotating device is communicated with the pressurizing cavity (6);

the walking device is communicated with the decompression cavity (7);

and the normally closed type braking clutch is arranged between the traveling device and the decompression chamber (7).