Hydraulic motor with low-pressure and low-speed operation function and engineering transport vehicle

Abstract

The present invention discloses a hydraulic motor and an engineering transport vehicle with low-pressure and low-speed operation functions. The distribution plate of the hydraulic motor is movably arranged between the motor rear cover and the rotor assembly. A movable valve core is arranged in the motor rear cover. A push rod is arranged on the movable valve core. The push rod is inserted into the distribution plate and drives the distribution plate to rotate an angle a in the opposite direction of the rotation of the rotor assembly. The hydraulic oil discharge port of the distribution plate is displaced in the opposite direction of the rotation of the rotor assembly. The advantage is that the hydraulic oil discharge port on the distribution plate is aligned with the hydraulic oil inlet port in advance for infusion, so that the hydraulic oil is filled in advance in the rotor assembly. The rotor assembly is forced to rotate in advance when rotating, thereby compensating for the influence of the low-pressure and low-speed starting difficulty of the motor caused by the relatively small height difference of the curve on the stator.

Description

Technical Field

[0001] The present invention relates to the field of motors, and in particular to a hydraulic motor with low-pressure and low-speed operation functions and an engineering transport vehicle. Background Art

[0002] Hydraulic motors are a common type of drive device. They typically consist of a front cover, a rear cover, a stator, and a rotor assembly connected to a rotating shaft. Multiple radially movable plunger assemblies are located around the rotor assembly. A valve plate is located within the rear cover, and hydraulic oil inlet and outlet channels are located within the rear cover and valve plate. Different hydraulic motors require different characteristics for different applications. For example, in road marking and line painting operations on highways or urban roads, the marking vehicle and equipment must be able to move slowly and precisely to ensure accurate, aesthetically pleasing lines with a high success rate. Similarly, in cargo lifting, transportation, and installation operations at industrial and mining sites, the lifting vehicle must be able to move at ultra-low speeds, requiring high precision in positioning and the ability to operate at low speeds under heavy loads. In both of these scenarios, a high-torque hydraulic motor with low-speed control capabilities is essential.

[0003] The internal structure of a traditional low-speed, high-torque hydraulic motor utilizes the flow distribution principle of a valve plate to achieve hydraulic drive. However, under low pressure and low speed conditions, starting at low pressure and low speed can be difficult or even impossible. The low-speed start-up shock is significant, meaning that the speed cannot be gradually increased from low to high. This cannot meet the low-speed starting requirements of vehicles such as line drawing vehicles or heavy-load lifting vehicles. Hydraulic motors with small stator curve height differences are particularly difficult to start at low pressure and low speed. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a hydraulic motor and an engineering transport vehicle with low-pressure and low-speed operation function, which is suitable for hydraulic motors with small stator curve height difference, ensuring normal starting at low pressure and low speed.

[0005] Principle analysis: The general low-speed, high-torque hydraulic motor is driven by the hydraulic distribution of the hydraulic distribution plate to convert hydraulic energy into mechanical energy output of the hydraulic motor to realize the rotation of the hydraulic motor to drive the vehicle movement; this type of motor generally requires a certain height difference between the large diameter and small diameter of the curve on the stator of the motor. The size of this height difference will affect the low-pressure and low-speed starting performance of the motor. For motors with a small height difference, the component force toward rotation of the motor plunger is reduced under the push of hydraulic pressure, and the motor is difficult to start at low pressure. If forced to start, the pressure output of the hydraulic pump needs to be increased, but the pressure increase will cause the speed of the hydraulic motor to increase suddenly, rather than a smooth linear increase, which cannot meet the actual needs of the above-mentioned load-bearing lifting vehicles and road line painting vehicles.

[0006] The difficulty that this patent needs to solve is: the hydraulic motors equipped on such vehicles are all motors with relatively small displacement, that is, the height difference between the major diameter and minor diameter of the stator curve on the motor is relatively small. When the motor is started, the rotational potential energy obtained by the plunger pair under the same conditions is relatively small, and the motor acceleration performance is not good enough, which makes it difficult to start the motor.

[0007] The problem that this patent needs to solve is how to change the existing method when the height difference between the large and small diameters of the curve on the motor stator is relatively small, so that the plunger on the motor can immediately give the plunger pair an accelerating force after the zero-speed zone of the stator (the zero-speed zone is the top and bottom positions of the motor stator) ends to make the rotor rotate quickly, increase the motor's rotational potential energy, and thus enable the motor to start quickly.

[0008] When the hydraulic motor rotates, the valve plate does not, while the rotor assembly rotates relative to it. The hydraulic oil outlet of the valve plate and the hydraulic oil inlet of the rotor assembly intermittently overlap and separate. In a conventional hydraulic motor operating in the zero-speed range, the hydraulic oil inlet is located midway between two adjacent hydraulic oil outlets, preventing hydraulic oil from entering the rotor assembly from the valve plate. The rotor assembly must rotate a certain angle to re-overlap the hydraulic oil inlet and outlet. The present invention utilizes a structure that rotates the valve plate a certain angle, reducing the rotation angle at which the rotating assembly causes the hydraulic oil inlet and outlet to re-overlap. This allows hydraulic oil to be filled into the rotor assembly earlier, forcing the rotor assembly to rotate earlier during rotation. This compensates for the difficulty in starting the motor at low pressure and low speed due to the relatively small height difference of the stator curve. This achieves a smooth and linear increase in motor speed, ensuring smooth operation of such vehicles under low-pressure and low-speed conditions, ensuring vehicle operational stability, and improving the accuracy and reliability of construction operations.

[0009] The technical solution adopted by the present invention to solve the above-mentioned technical problems is a hydraulic motor with low-pressure and low-speed operation function, including a motor front cover, a motor rear cover, a stator and a rotor assembly connected to the rotating shaft, a plurality of radially movable plunger assemblies are arranged on the periphery of the rotor assembly, a distribution plate is arranged in the motor rear cover, a hydraulic oil inlet channel and a hydraulic oil discharge channel are arranged in the motor rear cover and the distribution plate, a plurality of hydraulic oil inlets are arranged on the rotor assembly, and a hydraulic oil discharge port corresponding to the hydraulic oil inlet port is arranged on the distribution plate, which is characterized in that the distribution plate is movably arranged between the motor rear cover and the rotor assembly, a movable valve core is arranged in the motor rear cover, a push rod is arranged on the movable valve core, the push rod is inserted into the distribution plate and drives the distribution plate to rotate an angle a in the opposite direction of the rotation of the rotor assembly, and the hydraulic oil discharge port of the distribution plate is displaced in the opposite direction of the rotation of the rotor assembly.

[0010] A further preferred embodiment of the present invention is that the a is greater than 0 and less than 20.

[0011] A further preferred solution of the present invention is that the movable valve core can perform bidirectional movement, thereby driving the distribution plate to rotate clockwise or counterclockwise through the push rod.

[0012] A further preferred solution of the present invention is that the movable valve core includes a transverse axis, an intermediate body with a larger diameter is provided in the middle of the transverse axis, return springs are sleeved on both sides of the transverse axis, and a push rod is provided on the intermediate body.

[0013] A further preferred solution of the present invention is: a valve core accommodating cavity is provided on the motor rear cover, the movable valve core is inserted into the valve core accommodating cavity, and the intermediate body divides the valve core accommodating cavity into two sealed first spaces and a second space.

[0014] A further preferred embodiment of the present invention is that the first space and the second space are connected to a hydraulic oil inlet channel or a hydraulic oil outlet channel; when the hydraulic oil inlet channel is connected to the first space, the movable valve core moves toward the second space; or when the hydraulic oil inlet channel is connected to the second space, the movable valve core moves toward the first space.

[0015] A further preferred solution of the present invention is that the distribution disc is provided with an elongated groove, the push rod is inserted into the elongated groove, and the push rod moves in the elongated groove and pushes the distribution disc to rotate forward or reverse.

[0016] A further preferred embodiment of the present invention is that the elongated groove is arc-shaped as a whole, a swing gap for the push rod to move is provided between the push rod and the upper end surface of the elongated groove, and a swing gap for the push rod to move is provided between the push rod and the lower end surface of the elongated groove.

[0017] A further preferred embodiment of the present invention is as follows: the inner wall of the stator includes a raised portion and a recessed portion, the top ends of the raised portion and the recessed portion are the zero-speed zone, and when the plunger assembly is located in the zero-speed zone, the hydraulic oil inlet is located in the middle position between two adjacent hydraulic oil outlets; after the movable valve core moves, the hydraulic oil outlet located in the rotation direction of the hydraulic oil inlet moves toward the hydraulic oil inlet located in the zero-speed zone under the drive of the movable valve core.

[0018] A further preferred embodiment of the present invention is that the number of the hydraulic oil inlets is 8 and they are evenly distributed in a circle on the side of the rotor assembly, and the number of the hydraulic oil outlets is 12 and they are evenly distributed in a circle on the side of the distribution plate.

[0019] A further preferred solution of the present invention is: a first positioning block and a second positioning block are provided on both sides of the distribution plate, a first positioning groove and a second positioning groove are provided on the inner cavity of the motor back cover, the first positioning block is inserted into the first positioning groove, and the second positioning block is inserted into the second positioning groove.

[0020] A further preferred solution of the present invention is that the width of the first positioning groove is two to three times the thickness of the first positioning block, and the width of the second positioning groove is two to three times the thickness of the second positioning block.

[0021] A further preferred embodiment of the present invention is as follows: the two pairs of positioning arms extending from the inner cavity of the motor rear cover toward the rotor assembly, each pair of positioning arms forming the first positioning groove and the second positioning groove.

[0022] A further preferred solution of the present invention is that guide blocks are provided at both ends of the horizontal axis, a lubrication gap is provided between the guide blocks and the valve core accommodating cavity, and a plurality of lubrication grooves are distributed on the surface of the guide blocks.

[0023] The present invention modifies the traditional fixed setting of the distribution plate into a movable setting, and provides a movable valve core on the rear cover of the motor. The movement of the movable valve core drives the distribution plate to rotate, and the rotation direction of the distribution plate is opposite to the rotation direction of the rotor assembly. When in use, the distribution plate and the rotor assembly rotate relative to each other, and the hydraulic oil discharge port on the distribution plate is aligned with the hydraulic oil inlet port in advance for infusion, so that the hydraulic oil is filled in advance in the rotor assembly. The rotor assembly is forced to rotate in advance when rotating, thereby compensating for the difficulty in starting the motor at low pressure and low speed due to the relatively small height difference of the curve on the stator. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the coordination of the hydraulic oil inlet and outlet of a traditional hydraulic motor;

[0025] Figure 2 Schematic diagram of the coordination of the hydraulic oil inlet and the hydraulic oil outlet of the present invention;

[0026] Figure 3 It is a structural schematic diagram of the present invention;

[0027] Figure 4 An exploded view of the present invention;

[0028] Figure 5 for Figure 4 Enlarged view of point A in the middle;

[0029] Figure 6 It is a structural schematic diagram of the movable valve core of the present invention;

[0030] Figure 7 It is a three-dimensional diagram of the valve plate and the movable valve core;

[0031] Figure 8 The figure is a three-dimensional diagram of the valve plate;

[0032] Figure 9 It is a three-dimensional diagram of the movable valve core;

[0033] Figure 10 This is a three-dimensional view of the motor rear cover. DETAILED DESCRIPTION

[0034] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0035] like Figure 1 Figure 2 shows the coordinated relationship between the hydraulic oil inlet 10 and the hydraulic oil outlet 11 of a conventional hydraulic motor. When the plunger is in the zero-speed range of the stator 3, the interior of the stator 3 exhibits a wavy shape, and a gap exists between the hydraulic oil inlet 10 and the hydraulic oil outlet 11. Because the hydraulic oil inlet 10 and the hydraulic oil outlet 11 are disconnected from each other, the rotor assembly 4 experiences a certain degree of power interruption during rotation, resulting in relatively low rotational potential energy, poor motor acceleration, and difficulty starting the motor.

[0036] like Figure 2-Figure 10 As shown, the technical solution of the present invention is: a hydraulic motor with low-pressure and low-speed operation function, including a motor front cover 1, a motor rear cover 2, a stator 3 and a rotor assembly 4 connected to a rotating shaft 5, a plurality of radially movable plunger assemblies 6 are arranged on the periphery of the rotor assembly 4, a distribution plate 7 is arranged in the motor rear cover 2, a hydraulic oil inlet channel 8 and a hydraulic oil outlet channel 9 are arranged in the motor rear cover 2 and the distribution plate 7, and the hydraulic oil inlet channel 8 and the hydraulic oil outlet channel 9 can be replaced as needed, a plurality of hydraulic oil inlet ports 10 are arranged on the rotor assembly 4, and a hydraulic oil outlet port 11 corresponding to the hydraulic oil inlet port 10 is arranged on the distribution plate 7. When in use, the rotor assembly 4 keeps rotating and the distribution plate 7 is fixed. Correspondingly, the hydraulic oil outlet port 11 does not move, and the hydraulic oil inlet port 10 rotates. When the plunger of the plunger assembly 6 is in the zero-speed zone, the hydraulic oil inlet port 10 is located in the middle position between two adjacent hydraulic oil outlet ports 11. The valve plate 7 is movably mounted between the motor rear cover 2 and the rotor assembly 4. A movable valve core 12 is mounted within the motor rear cover 2, and a push rod 13 is attached to the movable valve core 12. This push rod 13 is inserted into the valve plate 7 and drives the valve plate 7 to rotate by an angle a in the direction opposite to the rotation of the rotor assembly 4. This causes the hydraulic oil outlet 11 of the valve plate 7 to be displaced in the direction opposite to the rotation of the rotor assembly 4. This allows the hydraulic oil outlet 11 to connect with the hydraulic oil inlet 10 in advance, allowing hydraulic oil to be pre-charged into the rotor assembly 4. This forces the rotor assembly 4 to rotate earlier during rotation, thus compensating for the difficulty in starting the motor at low pressure and low speed caused by the relatively small height difference of the stator curve. This results in a smooth and linear increase in motor speed, ensuring smooth operation of this type of vehicle under low-pressure and low-speed conditions, ensuring vehicle operational stability, and improving the accuracy and reliability of construction operations.

[0037] a is greater than 0 and less than 20. The rotation amplitude of the distribution plate 7 can be adjusted according to the size of the hydraulic pressure, that is, the greater the hydraulic pressure, the greater the rotation amplitude of the distribution plate 7, and the smaller the hydraulic pressure, the smaller the rotation amplitude of the distribution plate 7. Preferably, a rotation of 11.5 degrees is adopted. The movable valve core 12 can move in both directions, thereby driving the distribution plate 7 to rotate clockwise or counterclockwise through the push rod 13. The bidirectional movement is to cope with the fact that some hydraulic motors can also rotate in both directions. For this purpose, a movable valve core 12 of a hydraulic motor that can cope with bidirectional movement is designed. The movable valve core 12 includes a horizontal axis 14, and an intermediate body 15 with a larger diameter is provided in the middle position of the horizontal axis 14. Reset springs 16 are sleeved on both sides of the horizontal axis 14, and the push rod 13 is provided on the intermediate body 15. The reset springs 16 on both sides apply pressure to the horizontal axis 14, so that the horizontal axis 14 can move to both sides and has a reset function. The motor rear cover 2 is provided with a valve core accommodating chamber 17, into which the movable valve core 12 is inserted. The intermediate body 15 divides the valve core accommodating chamber 17 into two sealed spaces: a first space 18 and a second space 19. When hydraulic oil enters the first space 18, the movable valve core 12 is pushed toward the second space 19; when hydraulic oil enters the second space 19, the movable valve core 12 is pushed toward the first space 18. The first and second spaces 18 and 19 connect to the hydraulic oil inlet channel 8 or the hydraulic oil outlet channel 9, effectively utilizing the hydraulic motor's inherent hydraulic pressure and eliminating the need for additional hydraulic configuration. Furthermore, the inherent hydraulic pressure of the hydraulic motor ensures that the movable valve core 12 automatically activates in conjunction with the hydraulic motor, eliminating the need for separate control. When hydraulic oil enters the channel 8 and connects to the first space 18, the movable valve core 12 moves toward the second space 19; or when hydraulic oil enters the channel 8 and connects to the second space 19, the movable valve core 12 moves toward the first space 18.

[0038] The port plate 7 is provided with an elongated groove 20, into which the push rod 13 is inserted. A buffer zone is provided between the push rod 13 and the inner wall of the elongated groove 20. The push rod 13 moves within the elongated groove 20 and propels the port plate 7 in either forward or reverse rotation. Because the movable valve core 12 is highly sensitive, a buffer zone must be provided for the push rod 13 as it moves from one end of the elongated groove 20 to the other. The elongated groove 20 is generally arc-shaped, with a swing clearance provided between the push rod 13 and the upper end surface of the elongated groove 20, and a swing clearance provided between the push rod 13 and the lower end surface of the elongated groove 20. Because the push rod moves back and forth along the movable valve core 12, the port plate 7 also rotates when subjected to force, resulting in an irregular motion trajectory. Therefore, a certain clearance is required for the push rod 13 to swing. The inner wall of the stator 3 includes a raised portion 31 and a recessed portion 32, the top ends of which represent the zero-speed zone. Before the movable valve core 12 moves, when the plunger assembly 6 is in the zero-speed zone, the hydraulic oil inlet 10 is located midway between two adjacent hydraulic oil outlets 11. After the movable valve core 12 moves, the corresponding hydraulic oil outlet 11 (the hydraulic oil outlet 11 that will be connected after rotation) is driven by the movable valve core 12 toward the hydraulic oil inlet 10 located in the zero-speed zone, allowing the hydraulic oil inlet 10 and hydraulic oil outlet 11 to connect in advance.

[0039] There are 8 hydraulic oil inlets 10 and they are evenly distributed in a circular shape on the side of the rotor assembly 4. There are 12 hydraulic oil outlets 11 and they are evenly distributed in a circular shape on the side of the distribution plate 7. The two side surfaces fit together to achieve communication between the hydraulic oil inlet 10 and the hydraulic oil outlet 11. A first positioning block 71 and a second positioning block are provided on both sides of the distribution plate 7. A first positioning groove 21 and a second positioning groove 22 are provided on the inner cavity of the motor rear cover 2. The first positioning block 71 is inserted into the first positioning groove 21, and the second positioning block is inserted into the second positioning groove 22. This ensures that the distribution plate 7 cannot rotate arbitrarily. The width of the first positioning groove 21 is two to three times the thickness of the first positioning block 71, and the width of the second positioning groove 22 is two to three times the thickness of the second positioning block 72, which controls the rotation amplitude of the distribution plate 7. This prevents the distribution plate 7 from excessively rotating due to a malfunction of the movable valve core 12. Two pairs of positioning arms 23 extend from the interior of the motor rear cover 2 toward the rotor assembly 4. Each pair of positioning arms 23 forms the first and second positioning slots 21 and 22. These two pairs of positioning arms 23 and the side surfaces of the rotor assembly 4 create a secure space for the first and second positioning blocks 71 and 72, simplifying installation of the port plate 7.

[0040] Guide blocks 24 are installed at both ends of the transverse axis 14. A lubrication gap is defined between the guide blocks 24 and the valve core accommodating cavity 17. Multiple lubrication grooves 25 are also distributed on the surface of the guide blocks 24. On the one hand, the guide blocks 24 fill the valve core accommodating cavity 17, preventing the movable valve core 12 from shaking and ensuring smoother operation. On the other hand, they allow a certain gap for the hydraulic oil to flow, allowing the hydraulic oil to enter the sliding grooves and effectively lubricate the movable valve core 12 and the valve core accommodating cavity 17.

[0041] An engineering transport vehicle comprises a hydraulic motor of any one of the above structures with a low-pressure and low-speed control function.

[0042] The above describes in detail the hydraulic motor and engineering transport vehicle with low-pressure and low-speed operation provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is intended only to facilitate understanding of the present invention and its core concepts. It should be noted that those skilled in the art may make various improvements and modifications to the present invention without departing from the principles of the present invention, and such improvements and modifications fall within the scope of protection of the claims of the present invention.

Claims

1. A hydraulic motor with low-pressure, low-speed operation, comprising a motor front cover, a motor rear cover, a stator, and a rotor assembly connected to a rotating shaft; a plurality of radially movable plunger assemblies are disposed on the periphery of the rotor assembly; a port plate is disposed within the motor rear cover; hydraulic oil inlet and outlet channels are disposed within the motor rear cover and the port plate; a plurality of hydraulic oil inlet ports are disposed on the rotor assembly; and a hydraulic oil outlet port corresponding to the hydraulic oil inlet ports is disposed on the port plate. The distribution plate is movably arranged between the motor rear cover and the rotor assembly. A movable valve core is arranged in the motor rear cover. A push rod is arranged on the movable valve core. The push rod is inserted into the distribution plate and drives the distribution plate to rotate an angle a in the opposite direction of rotation of the rotor assembly. The hydraulic oil discharge port of the distribution plate is displaced in the opposite direction of rotation of the rotor assembly.

2. A hydraulic motor with low pressure and low speed operation function according to claim 1, characterized in that The a is greater than 0 degrees and less than 20 degrees.

3. A hydraulic motor with low pressure and low speed operation function according to claim 1, characterized in that The movable valve core can perform bidirectional movement, thereby driving the distribution plate to rotate clockwise or counterclockwise through the push rod.

4. A hydraulic motor with low pressure and low speed operation function according to claim 1, characterized in that The movable valve core comprises a transverse axis, an intermediate body with a larger diameter is arranged at the middle position of the transverse axis, return springs are sleeved on both sides of the transverse axis, and a push rod is arranged on the intermediate body.

5. A hydraulic motor with low pressure and low speed operation function according to claim 4, characterized in that The motor rear cover is provided with a valve core accommodating cavity, the movable valve core is inserted into the valve core accommodating cavity, and the intermediate body divides the valve core accommodating cavity into two sealed first spaces and a second space.

6. A hydraulic motor with low pressure and low speed operation function according to claim 5, characterized in that The first space and the second space are connected to the hydraulic oil inlet channel or the hydraulic oil outlet channel; when the hydraulic oil inlet channel is connected to the first space, the movable valve core moves toward the second space; or when the hydraulic oil inlet channel is connected to the second space, the movable valve core moves toward the first space.

7. The hydraulic motor with low pressure and low speed operation function according to claim 1, characterized in that The distribution plate is provided with a long strip groove, the push rod is inserted into the long strip groove, a buffer area is provided between the push rod and the inner wall of the long strip groove, the push rod moves in the long strip groove and pushes the distribution plate to rotate forward or reverse.

8. A hydraulic motor with low pressure and low speed operation function according to claim 7, characterized in that The long strip groove is arc-shaped as a whole, and a swing gap for the push rod to move is provided between the push rod and the upper end surface of the long strip groove, and a swing gap for the push rod to move is provided between the push rod and the lower end surface of the long strip groove.

9. The hydraulic motor with low pressure and low speed operation function according to claim 1, characterized in that The inner wall of the stator includes a raised portion and a recessed portion, the top ends of the raised portion and the recessed portion are the zero-speed zone. When the plunger assembly is located in the zero-speed zone, the hydraulic oil inlet is located in the middle position between two adjacent hydraulic oil outlets; after the movable valve core moves, the corresponding hydraulic oil outlet moves toward the hydraulic oil inlet located in the zero-speed zone under the drive of the movable valve core.

10. The hydraulic motor with low pressure and low speed operation function according to claim 1, characterized in that There are 8 hydraulic oil inlets and they are evenly distributed in a circle on the side of the rotor assembly. There are 12 hydraulic oil outlets and they are evenly distributed in a circle on the side of the distribution plate.

11. The hydraulic motor with low pressure and low speed operation function according to claim 1, characterized in that The first positioning block and the second positioning block are provided on both sides of the distribution plate, and the first positioning groove and the second positioning groove are provided on the inner cavity of the motor rear cover. The first positioning block is inserted into the first positioning groove, and the second positioning block is inserted into the second positioning groove.

12. A hydraulic motor with low pressure and low speed operation function according to claim 11, characterized in that The width of the first positioning groove is two to three times the thickness of the first positioning block, and the width of the second positioning groove is two to three times the thickness of the second positioning block.

13. A hydraulic motor with low pressure and low speed operation function according to claim 11, characterized in that The two pairs of positioning arms extend from the inner cavity of the motor rear cover toward the rotor assembly, and each pair of positioning arms forms the first positioning groove and the second positioning groove.

14. A hydraulic motor with low pressure and low speed operation function according to claim 5, characterized in that Guide blocks are provided at both ends of the transverse axis, a lubrication gap is provided between the guide blocks and the valve core accommodating cavity, and a plurality of lubrication grooves are distributed on the surface of the guide blocks.

15. Engineering transport vehicle, characterized by It comprises a hydraulic motor with low-pressure and low-speed operation function as described in any one of claims 1-14.

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