A closed series anti-skid hydraulic system for railway engineering machinery

Abstract

A closed series anti-skid running hydraulic system for railway engineering machinery includes a running oil pump, an oil replenishment valve group, a hydraulic motor 1 and a hydraulic motor 2; the hydraulic motor 1 and the hydraulic motor 2 are connected in series to the running oil pump through an oil supply pipeline and an oil return pipeline; the hydraulic motor 1 and the hydraulic motor 2 are connected to the running wheel pair; the oil replenishment valve group is an integrated valve group, the X1 port on the valve seat of the oil replenishment valve group is connected to the A2 port of the hydraulic motor 1, the X2 port on the valve seat of the oil replenishment valve group is connected to the B3 port of the hydraulic motor 2, and the X3 port on the valve seat of the oil replenishment valve group is connected to the A3 port of the hydraulic motor 2; the oil replenishment valve group includes a three-way flow valve and a control valve group, the output port A10 of the three-way flow valve is connected to the X3 port on the valve seat of the oil replenishment valve group, and the input port A8 and the control port A9 of the three-way flow valve are respectively connected to the control valve group. The oil replenishment valve group provides a certain amount of oil replenishment flow between the series motors to prevent the hydraulic motor from being pulled and slipping due to air suction.

Description

Technical Field

[0001] The invention relates to the technical field of hydraulic control, in particular to a closed series anti-skid running hydraulic system for railway engineering machinery. Background Art

[0002] Railway engineering machinery is often large in structure and equipped with various operating mechanisms. Due to structural and space limitations, it is not convenient to use mechanical transmission to achieve the travel of the entire machine. The hydraulic system has the characteristics of small component size, high power density, flexible and convenient layout, and good speed regulation performance. At the same time, compared with the open hydraulic system, the closed hydraulic system has the advantages of high integration, compact structure, simple pipelines, and small oil tank size. Therefore, the closed hydraulic system has been widely used in the travel transmission of railway engineering machinery.

[0003] At present, the hydraulic drive system for railway engineering machinery usually adopts a closed parallel hydraulic system, which is composed of a running oil pump installed on the prime mover and multiple drive motors installed on the axle gearbox connected in parallel to form a closed parallel hydraulic system. The inlet and outlet of each drive motor are connected in parallel and connected to the inlet and outlet of the running oil pump. The vehicle running speed is controlled by giving the running oil pump input signal and is infinitely adjustable to provide the vehicle with the maximum traction. However, the closed parallel hydraulic system can only be used in situations where the road conditions are smooth. If the road conditions are poor, the loads borne by multiple drive motors on different wheel sets are different, the instantaneous flow and pressure of the inlet and outlet of each drive motor are also different, and the traction provided by the drive motor is also different, causing the motor to fail to work in the best working condition, the hydraulic system is unstable and cannot work continuously for a long time; and the oil flowing through the long hydraulic pipeline between the motors will cause a high pressure loss, resulting in uneven flow distribution of the parallel motors and thus a pressure difference, causing an unbalanced driving force and wheel slippage, causing a single wheel set to be towed. Summary of the invention

[0004] The purpose of the present invention is to solve the above-mentioned deficiencies in the prior art, thereby providing a closed series anti-skid running hydraulic system for railway engineering machinery.

[0005] The technical solution of the present invention is: a closed series anti-skid running hydraulic system for railway engineering machinery, comprising a running oil pump, an oil replenishment valve group, a hydraulic motor 1 and a hydraulic motor 2; the hydraulic motor 1 and the hydraulic motor 2 are connected in series with the running oil pump through an oil supply pipeline and an oil return pipeline to form a closed series circuit;

[0006] The running oil pump is connected to the prime mover;

[0007] The hydraulic motor 1 and the hydraulic motor 2 are connected to the running wheel pair;

[0008] The oil replenishment valve group is an integrated valve group, the X1 port on the valve seat of the oil replenishment valve group is connected to the A2 port of the hydraulic motor 1, the X2 port on the valve seat of the oil replenishment valve group is connected to the B3 port of the hydraulic motor 2, and the X3 port on the valve seat of the oil replenishment valve group is connected to the A3 port of the hydraulic motor 2;

[0009] The oil replenishing valve group includes a three-way flow valve and a control valve group for providing pilot pressure to the three-way flow valve. The output port A10 of the three-way flow valve is connected to the X3 port on the valve seat of the oil replenishing valve group, and the input port A8 and the control port A9 of the three-way flow valve are respectively connected to the control valve group.

[0010] The A1 port of the traveling oil pump is connected to the A2 port of the hydraulic motor one, the B1 port of the traveling oil pump is connected to the B3 port of the hydraulic motor two, and the B2 port of the hydraulic motor one is connected to the A3 port of the hydraulic motor two, forming a closed series circuit.

[0011] The control valve group includes a bridge circuit composed of four one-way valves connected end to end, the A4 port of the bridge circuit is connected to the X1 port on the valve seat of the oil replenishing valve group, the A6 port of the bridge circuit is connected to the X2 port on the valve seat of the oil replenishing valve group, the A5 port of the bridge circuit is connected to the damping hole 1 on the valve seat through a filter, the A7 port of the bridge circuit is connected to the damping hole 2 on the valve seat through a filter, the A7 port of the bridge circuit is also connected to the input port A8 of the three-way flow valve, the damping hole 1 is connected to the damping hole 2 and is connected to the control port A9 of the three-way flow valve.

[0012] The diameter of the damping hole 1 is smaller than that of the damping hole 2.

[0013] The filter, one-way valve and three-way flow valve are all threaded cartridge valves, and the damping hole is a fixed damping hole, which provides a stable pilot pressure for the three-way flow valve.

[0014] The working principle of the closed series anti-skid running hydraulic system for railway vehicles described in the present invention is:

[0015] Vehicle forward working condition:

[0016] The prime mover drives the running oil pump to work. Assuming that the A1 port of the running oil pump is the oil outlet and B1 is the oil return port, the hydraulic oil flows from the A1 port of the running oil pump to the A2 port of the hydraulic motor, the B2 port of the hydraulic motor to the A3 port of the hydraulic motor, the B3 port of the hydraulic motor to the B1 port of the running oil pump, the A2 port of the hydraulic motor to the X1 port on the valve seat of the oil replenishing valve group, the B3 port of the hydraulic motor to the X2 port on the valve seat of the oil replenishing valve group, and the X3 port on the valve seat of the oil replenishing valve group to the A3 port of the hydraulic motor; the hydraulic motor and the hydraulic motor are installed on the running wheel set and are rigidly connected, and their theoretical rotation speeds are the same; when the vehicle operates normally, the output speed and resistance of the hydraulic motor and the hydraulic motor are the same, and the two motors evenly share the running system load. After the high-pressure oil passes through the hydraulic motor, a pressure drop occurs, that is, the A2 port of the hydraulic motor is the high-pressure port of this system, and the pressures of the B2 port of the hydraulic motor and the A3 port of the hydraulic motor inlet are equal and less than the pressure of the A2 port of the hydraulic motor. The B3 port of the hydraulic motor is the low-pressure port of this system and is connected to the B1 port of the running oil pump; the force of the A9 port of the three-way flow valve in the oil replenishment valve group is equal to the spring force plus the force of the X3 port. At this time, the three forces are in a balanced state and the three-way flow valve is in a closed state; when the line condition is poor, the hydraulic motor and the vehicle running resistance suffered by the hydraulic motor are unevenly distributed, resulting in a pressure difference between the B2 port of the hydraulic motor and the A3 port of the hydraulic motor. The oil flowing into the A3 port of the hydraulic motor is less than the oil flowing into the A2 port of the hydraulic motor, causing the speed of the hydraulic motor to be lower than that of the hydraulic motor. The hydraulic motor is in a towed working condition, and the pressure of the A3 port of the hydraulic motor is reduced, that is, the pressure of the X3 port of the three-way flow valve is reduced. At this time, the force of the A9 port of the three-way flow valve is greater than the spring force plus the force of the X3 port. The three-way flow valve opens, and the oil flows in through the X1 port, and flows into the A3 port of the hydraulic motor through the A7, A8, A10, and X3 ports to replenish the hydraulic motor. Under the joint action of the forces at port X3 and port A9, the valve core of the three-way flow valve is always in a dynamic equilibrium state. The lower the pressure at port X3, the greater the displacement of the valve core of the three-way flow valve under the pressure at port A9, and the greater the valve opening, that is, the greater the oil flow from port A8 to port X3, and the greater the oil replenishment amount to port A3 of the hydraulic motor, so that the hydraulic motor and the hydraulic motor maintain the same speed to achieve stable running traction and prevent wheel slippage.

[0017] Vehicle reverse condition:

[0018] The prime mover drives the running oil pump to work. Assuming that the B1 port of the running oil pump is the oil outlet and A1 is the oil return port, the hydraulic oil flows from the B1 port of the running oil pump to the B3 port of the hydraulic motor, the A3 port of the hydraulic motor to the B2 port of the hydraulic motor, the A2 port of the hydraulic motor to the A1 port of the running oil pump, the B3 port of the hydraulic motor to the X2 port on the valve seat of the replenishing valve group, the A2 port of the hydraulic motor to the X1 port on the valve seat of the replenishing valve group, and the X3 port on the valve seat of the replenishing valve group to the A3 port of the hydraulic motor; the hydraulic motor and the hydraulic motor are installed on the running wheel set and are rigidly connected, and their theoretical rotation speeds are the same; when the vehicle operates normally, the output speed and resistance of the hydraulic motor and the hydraulic motor are the same, and the two motors evenly share the running system load. After the high-pressure oil passes through the hydraulic motor, a pressure drop occurs, that is, the B3 port of the hydraulic motor is the high-pressure port of this system, and the pressures of the A3 port of the hydraulic motor and the B2 port of the hydraulic motor are equal and less than the pressure of the B3 port of the hydraulic motor. The A2 port of the hydraulic motor is the low-pressure port of this system and is connected to the A1 port of the running oil pump; the force of the A9 port of the three-way flow valve in the oil replenishment valve group is equal to the spring force plus the force of the X3 port. At this time, the three forces are in a balanced state and the three-way flow valve is in a closed state; when the line condition is poor, the hydraulic motor and the vehicle running resistance suffered by the hydraulic motor are unevenly distributed, resulting in a pressure difference between the A3 port of the hydraulic motor and the B2 port of the hydraulic motor. The oil flowing into the B2 port of the hydraulic motor is less than the oil flowing into the B3 port of the hydraulic motor, causing the speed of the hydraulic motor to be lower than the hydraulic motor. The hydraulic motor is in a towing condition, and the pressure of the B2 port of the hydraulic motor is reduced, that is, the pressure of the X3 port of the three-way flow valve is reduced. At this time, the force of the A9 port of the three-way flow valve is greater than the spring force plus the force of the X3 port. The three-way flow valve opens, and the oil flows in through the X2 port, and flows into the B2 port of the hydraulic motor through the A7, A8, A10, and X3 ports to replenish the hydraulic motor. Under the joint action of the forces at port X3 and port A9, the valve core of the three-way flow valve is always in a dynamic equilibrium state. The lower the pressure at port X3, the greater the displacement of the valve core of the three-way flow valve under the pressure at port A9, and the greater the valve opening, that is, the greater the oil flow from port A8 to port X3, and the greater the oil replenishment amount to port A3 of the hydraulic motor, so that the hydraulic motor and the hydraulic motor maintain the same speed to achieve stable running traction and prevent wheel slippage.

[0019] When the vehicle is in the forward working condition, the X1 port on the valve seat of the oil replenishing valve group is high-pressure oil. When the vehicle is in the reverse working condition, the X2 port on the valve seat of the oil replenishing valve group is high-pressure oil. The bridge circuit always allows the high-pressure oil to flow into the A9 port of the three-way flow valve through the filter and the damping hole 2, and maintain a dynamic balance with the spring force and the pressure of the X3 port to replenish oil for the hydraulic motor and the hydraulic motor; the aperture of the damping hole 1 is smaller than that of the damping hole 2, which provides a certain pilot pressure for the A9 port of the three-way flow valve, so that the three-way flow valve can operate stably.

[0020] The present invention can provide stable traction force for railway vehicles and prevent wheels from slipping when the vehicles are running.

[0021] The present invention proposes that a running oil pump and a plurality of motors constitute a series hydraulic system, and are matched with an oil replenishment valve group, which can detect the pressure difference between the series motors in real time, and act on the pilot port of the three-way flow valve in the oil replenishment valve group. The opening degree of the three-way flow valve is controlled by the pilot flow, and a stable oil replenishment flow is provided for the hydraulic motor located at the rear end of the system, so that the working speed and pressure of the series motors are equal, avoiding the working condition that one motor is towed due to different motor speeds, affecting the service life of the motor; at the same time, the series motors evenly distribute the running resistance of the whole vehicle, provide stable traction for the running wheelset, prevent it from slipping, so as to drive the railway vehicle to run stably and ensure the operation safety of the whole vehicle.

[0022] The present invention proposes to use a closed series hydraulic system in railway engineering machinery vehicles, a running oil pump and a driving motor adopt a closed hydraulic system, and the driving motor is connected in series, the oil output of the front motor is connected to the oil inlet of the rear motor, and an oil replenishment valve group is set on the circuit to form a closed series running hydraulic system. Based on the above invention, this system can make the hydraulic oil flow through each hydraulic motor completely equal in theory, and prevent the wheel from slipping due to uneven flow distribution caused by the inherent leakage characteristics of the oil pump motor, the pressure flow loss of the pipeline, and the line conditions. This system has the advantages of good road condition adaptability, high system efficiency, simple and reliable structure, etc., and has better traction characteristics and adaptability applications on railway vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention is further described in detail below based on the accompanying drawings and examples.

[0024] Figure 1 It is one of the principle diagrams of the present invention;

[0025] Figure 2 It is the second schematic diagram of the present invention. Implementation

[0026] like Figure 1 As shown, the running oil pump 1 is connected to the prime mover 10, and the hydraulic motor 1 3 and the hydraulic motor 2 4 are rigidly connected to the running wheel pair 11; the A1 port of the running oil pump 1 is connected to the A2 port of the hydraulic motor 1 3, the B1 port of the running oil pump 1 is connected to the B3 port of the hydraulic motor 2 4, and the B2 port of the hydraulic motor 1 3 is connected to the A3 port of the hydraulic motor 2 4, forming a closed series circuit. The oil replenishment valve group 2 is an integrated valve group, the X1 port on the valve seat of the oil replenishment valve group 2 is connected to the A2 port of the hydraulic motor 1 3, the X2 port on the valve seat of the oil replenishment valve group 2 is connected to the B3 port of the hydraulic motor 2 4, and the X3 port on the valve seat of the oil replenishment valve group 2 is connected to the A3 port of the hydraulic motor 2 4.

[0027] like Figure 2As shown, the oil replenishing valve group 2 includes a three-way flow valve 8 and a control valve group for providing a pilot pressure 2 to the three-way flow valve 8. The output port A10 of the three-way flow valve 8 is connected to the X3 port on the valve seat of the oil replenishing valve group 2, and the input port A8 and the control port A9 of the three-way flow valve 8 are respectively connected to the control valve group. The control valve group includes a bridge loop 9 composed of four one-way valves connected end to end, the A4 port of the bridge loop 9 is connected to the X1 port on the valve seat of the oil replenishing valve group 2, the A6 port of the bridge loop 9 is connected to the X2 port on the valve seat of the oil replenishing valve group 2, the A5 port of the bridge loop 9 is connected to the damping hole 1 5.1 on the valve seat through the filter 6.1, the A7 port of the bridge loop 9 is connected to the damping hole 2 5.2 on the valve seat through the filter 6.2, the A7 port of the bridge loop 9 is also connected to the input port A8 of the three-way flow valve 8, the damping hole 1 5.1 is connected to the damping hole 2 5.2 and is connected to the control port A9 of the three-way flow valve 8. The aperture of the damping hole 1 5.1 is smaller than that of the damping hole 2 5.2.

[0028] No matter whether the X1 port or the X2 port on the valve seat of the oil replenishing valve group 2 is high-pressure oil, the bridge circuit 9 always allows the high-pressure oil to flow into the A9 port of the three-way flow valve 8 through the filter 6.2 and the damping hole 2 5.2, and maintain a dynamic equilibrium state with the spring force and the pressure of the X3 port, so as to replenish oil for the hydraulic motor 1 3 and the hydraulic motor 2 4; the aperture of the damping hole 1 5.1 is smaller than that of the damping hole 2 5.2, so as to provide a certain pilot pressure for the A9 port of the three-way flow valve 8, so that the three-way flow valve 8 can operate stably.

[0029] The operation mode of the closed series anti-skid running hydraulic system for railway vehicles is:

[0030] Working condition 1: vehicle moving forward

[0031] The prime mover 10 drives the traveling oil pump 1 to work. At this time, the A1 port of the traveling oil pump 1 is the oil outlet, and B1 is the oil return port. The hydraulic oil flows from the A1 port of the traveling oil pump 1 to the A2 port of the hydraulic motor 3, the B2 port of the hydraulic motor 3 to the A3 port of the hydraulic motor 4, the B3 port of the hydraulic motor 4 to the B1 port of the traveling oil pump 1, the A2 port of the hydraulic motor 3 to the X1 port on the valve seat of the oil replenishing valve group 2, the B3 port of the hydraulic motor 4 to the X2 port on the valve seat of the oil replenishing valve group 2, and the The X3 port of the hydraulic motor 1 is connected to the A3 port of the hydraulic motor 2 4; the hydraulic motor 1 3 and the hydraulic motor 2 4 are installed on the running wheel pair 11 and are rigidly connected to drive the vehicle to run, and their theoretical rotation speeds are the same; when the vehicle is running normally, the output speed and resistance of the hydraulic motor 1 3 and the hydraulic motor 2 4 are the same, and the two motors share the running system load. The high-pressure oil produces a pressure drop after passing through the hydraulic motor, that is, the B3 port of the hydraulic motor 2 4 is the high-pressure port of this system, and the A3 port of the hydraulic motor 2 4 and the B2 port of the hydraulic motor 1 3 are the high-pressure ports of this system. The force is equal to and less than the pressure of the B3 port of the hydraulic motor 2 4. The A2 port of the hydraulic motor 1 3 is the low-pressure port of this system, which is connected to the A1 port of the running oil pump 1; the force of the A9 port of the three-way flow valve 8 in the oil replenishment valve group 2 is equal to the spring force plus the force of the X3 port. At this time, the three forces are in a balanced state, and the three-way flow valve 8 is in a closed state; when the hydraulic oil flows through the hydraulic motor 1 3, due to the volumetric efficiency loss and the pressure drop loss of the pipeline between the hydraulic motor 1 3 and the hydraulic motor 2 4, the oil flowing into the A3 port of the hydraulic motor 2 4 The total pressure is less than the oil flowing into the A2 port of the hydraulic motor 1 3, causing the speed of the hydraulic motor 2 4 to be lower than that of the hydraulic motor 1 3. The hydraulic motor 2 4 is in the traction condition, and the pressure of the A3 port of the hydraulic motor 2 4 is reduced, that is, the pressure of the X3 port of the three-way flow valve 8 is reduced. At this time, the force of the A9 port of the three-way flow valve 8 is greater than the spring force plus the force of the X3 port. The three-way flow valve 8 opens, and the oil flows in through the X1 port, and flows into the A3 port of the hydraulic motor 2 4 through the A7, A8, A10, and X3 ports to replenish the oil for the hydraulic motor 2 4. The three-way flow valve 8 can adjust the opening amount according to the pressure of the A3 port, compared with the pressure of the A2 port of the hydraulic motor 1 3, to provide different replenishment oil quantities. The lower the pressure of the A3 port of the hydraulic motor 2 4, the greater the replenishment oil quantity, so that the hydraulic motor 1 3 and the hydraulic motor 2 4 maintain the same speed, prevent the wheels from slipping, and achieve stable running traction.

[0032] Working condition 2: Vehicle moving backwards

[0033] The prime mover 10 drives the traveling oil pump 1 to work. At this time, the B1 port of the traveling oil pump 1 is the oil outlet, and A1 is the oil return port. The hydraulic oil flows from the B1 port of the traveling oil pump 1 to the B3 port of the hydraulic motor 2 4, the A3 port of the hydraulic motor 2 4 to the B2 port of the hydraulic motor 1 3, the A2 port of the hydraulic motor 1 3 to the A1 port of the traveling oil pump 1, the B3 port of the hydraulic motor 2 4 to the X2 port on the valve seat of the oil replenishing valve group 2, the A2 port of the hydraulic motor 1 3 to the X1 port on the valve seat of the oil replenishing valve group 2, and the valve seat of the oil replenishing valve group 2 The X3 port on the vehicle is connected to the A3 port of the hydraulic motor 2 4; the hydraulic motor 1 3 and the hydraulic motor 2 4 are installed on the running wheel pair 11 and are rigidly connected, and their theoretical rotation speeds are the same; when the vehicle is operating normally, the output speed and resistance of the hydraulic motor 1 3 and the hydraulic motor 2 4 are the same, and the two motors evenly share the running system load. The high-pressure oil produces a pressure drop after passing through the hydraulic motor, that is, the B3 port of the hydraulic motor 2 4 is the high-pressure port of this system, and the pressure of the A3 port of the hydraulic motor 2 4 and the B2 port of the hydraulic motor 1 3 are equal and The pressure at the B3 port of hydraulic motor 2 is less than that at the B3 port of hydraulic motor 4. The A2 port of hydraulic motor 1 is the low-pressure port of the system and is connected to the A1 port of the travel oil pump 1. The force at the A9 port of the three-way flow valve 8 in the replenishing valve group 2 is equal to the spring force plus the force at the X3 port. At this time, the three forces are in a balanced state and the three-way flow valve 8 is in a closed state. After the hydraulic oil flows through hydraulic motor 2, due to the loss of volumetric efficiency and the pressure drop loss of the pipeline between hydraulic motor 1 and hydraulic motor 2, the total amount of oil flowing into the B2 port of hydraulic motor 1 is less than that at the B3 port of hydraulic motor 4. The oil flowing into the B3 port of the hydraulic motor 2 4 causes the speed of the hydraulic motor 1 3 to be lower than that of the hydraulic motor 2 4. The hydraulic motor 1 3 is in the traction condition, and the pressure of the B2 port of the hydraulic motor 1 3 is reduced, that is, the pressure of the X3 port of the three-way flow valve 8 is reduced. At this time, the force of the A9 port of the three-way flow valve 8 is greater than the spring force plus the force of the X3 port. The three-way flow valve 8 opens, and the oil flows in through the X2 port, and flows into the B2 port of the hydraulic motor 1 3 through the A7, A8, A10, and X3 ports to replenish the oil for the hydraulic motor 1 3. The three-way flow valve 8 can adjust the opening amount according to the pressure of the B2 port of the hydraulic motor 1 3 and the pressure of the B3 port of the hydraulic motor 2 4 to provide different replenishment oil amounts. The lower the pressure of the B2 port of the hydraulic motor 1 3, the greater the replenishment oil amount, so that the hydraulic motor 1 3 and the hydraulic motor 2 4 maintain the same speed, prevent the wheels from slipping, and achieve stable running traction.

Claims

1. A closed series anti-skid hydraulic system for railway engineering machinery, characterized in that: It comprises a running oil pump (1), an oil replenishment valve group (2), a hydraulic motor 1 (3) and a hydraulic motor 2 (4); the hydraulic motor 1 (3) and the hydraulic motor 2 (4) are connected in series to the running oil pump (1) through an oil supply pipeline and an oil return pipeline to form a closed series circuit; The running oil pump (1) is connected to the prime mover (10); The hydraulic motor 1 (3) and the hydraulic motor 2 (4) are connected to the running wheel pair (11); The oil replenishing valve group (2) is an integrated valve group, the X1 port on the valve seat of the oil replenishing valve group (2) is connected to the A2 port of the hydraulic motor one (3), the X2 port on the valve seat of the oil replenishing valve group (2) is connected to the B3 port of the hydraulic motor two (4), and the X3 port on the valve seat of the oil replenishing valve group (2) is connected to the A3 port of the hydraulic motor two (4); The oil replenishment valve group (2) comprises a three-way flow valve (8) and a control valve group for providing a pilot pressure to the three-way flow valve (8), the output port A10 of the three-way flow valve (8) being connected to the port X3 on the valve seat of the oil replenishment valve group (2), and the input port A8 and the control port A9 of the three-way flow valve (8) being connected to the control valve group respectively; The control valve group comprises a bridge circuit (9) formed by four one-way valves connected end to end, wherein the A4 port of the bridge circuit (9) is connected to the X1 port on the valve seat of the oil replenishing valve group (2), the A6 port of the bridge circuit (9) is connected to the X2 port on the valve seat of the oil replenishing valve group (2), the A5 port of the bridge circuit (9) is connected to the damping hole 1 (5.1) on the valve seat via a filter (6.1), the A7 port of the bridge circuit (9) is connected to the damping hole 2 (5.2) on the valve seat via a filter (6.2), the A7 port of the bridge circuit (9) is also connected to the input port A8 of the three-way flow valve (8), the damping hole 1 (5.1) is connected to the damping hole 2 (5.2) and is connected to the control port A9 of the three-way flow valve (8).

2. According to claim 1, a closed series anti-skid running hydraulic system for railway engineering machinery is characterized by: The A1 port of the traveling oil pump (1) is connected to the A2 port of the hydraulic motor 1 (3), the B1 port of the traveling oil pump (1) is connected to the B3 port of the hydraulic motor 2 (4), and the B2 port of the hydraulic motor 1 (3) is connected to the A3 port of the hydraulic motor 2 (4), forming a closed series circuit.

3. According to claim 1, a closed series anti-skid running hydraulic system for railway engineering machinery is characterized by: The diameter of the damping hole 1 (5.1) is smaller than that of the damping hole 2 (5.2).

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