JP2003063394A - Suspension system of railway rolling stock and damper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a suspension system of a railway rolling stock improving ride quality by preventing wear and running-off of a wheel or the like without receiving restriction of an attaching space of and to provide yaw damper used therefore. SOLUTION: A yaw damper A generating attenuation force depending on a stroke of a piston 2 is horizontally or substantially horizontally arranged between a bogie B and a body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension system for a railway vehicle in which a yaw damper is interposed between a bogie of the railway vehicle and a vehicle body, and a suspension system for the railway vehicle.

[0002]

2. Description of the Related Art Generally, a railroad vehicle has a bogie traveling on a rail and a vehicle body mounted on the bogie, and a vehicle is suspended by a yaw damper vertically arranged between the bogie and the vehicle body. It prevents the carriage from meandering when traveling at high speed in a straight line.

As the above-mentioned yaw damper, for example, the one shown in FIG. 10 is used, and this yaw damper is a so-called position-dependent damper that generates a predetermined damping force near the neutral position of the piston and over the entire expansion / contraction operation stroke. Is said to be.

The yaw damper P comprises a cylinder 101, a piston rod 103 movably inserted into the cylinder 101 via a piston 102, and an outer shell 106 arranged outside the cylinder 101. In the cylinder 101, a piston 102 is provided in the rod-side oil chamber 10
7 is separated from the oil chamber 108 on the side opposite to the rod, and the cylinder 101
A reservoir 109 having an upper air chamber is defined between the outer shell 106 and the outer shell 106.

The two oil chambers 107 and 108 are pistons 10.
2 is opened and closed via the expansion side damping valve 104 and the compression side damping valve 105, and the non-rod side oil chamber 108 is opened and closed to the reservoir 109 via the base valve 110.

The cylinder 101 has a central thick portion 101A.
And the groove portions 101B and 101C formed above and below with this as a boundary
The outer periphery of the piston 102 is in contact with the inner periphery of the thick portion 101A when the piston 102 is neutral.

In the expansion and contraction operation, the expansion side damping valve 104 generates expansion side compression force and the compression side damping valve 105 generates base side compression force during compression, respectively.
In this case, when the piston 102 is in contact with the thick portion 101A, a high damping force is generated due to the slight amplitude, and the groove portion 101
When a stroke is made at the positions of B and 101C, oil flows through these groove portions 101B and 101C to exert a soft damping force.

[0008]

However, with the yaw damper arranged vertically as described above, even if the yaw damper is effective against the vibration in the vertical direction by component force, the yaw motion in the horizontal direction or Since the vibration absorption rate becomes smaller with respect to the turning motion, it is necessary to set the damping force stronger (higher) in order to improve the effect as a yaw damper. For this reason, when a high damping force is generated while the railway vehicle is running, meandering of the bogie is prevented when traveling straight, but on the other hand, when the train travels on a curve of the rail, the attitude angle of the car body and the attitude of the bogie are The angle changes and the posture of the vehicle body cannot immediately follow the posture of the carriage. For this reason, the truck cannot turn smoothly, and the wheel weight acts as a pressing force on the rail.
Lateral pressure on the rail increases, causing excessive friction between the rail and the wheel, which causes wear of the rail and the wheel. In addition, the balance of the wheel weights of the left and right wheels may be lost and the vehicle may be derailed. Further, since the yaw damper makes a large stroke during traveling on a curve as described above, if the damping force of the yaw damper is large, disturbance vibration from the bogie side may be transmitted to the vehicle body and the riding comfort may be deteriorated.

Further, since the above-mentioned yaw damper is vertically arranged between the carriage and the vehicle body so that the air chamber of the reservoir is located above, the mounting space below the vehicle body is restricted, and depending on the vehicle, the vertical direction may occur. There is a problem that it is not attached to the vehicle and it is installed diagonally, and that the space under the vehicle body is taken up and the structure under the vehicle body becomes complicated.

In the yaw damper, the damping force on the extension side and the damping force on the compression side are separately provided.
It is difficult to design to generate the damping force with the same extension and compression.

Furthermore, since the piston 102 is separated from the grooves 101B and 101C at the time of piston stroke other than neutral, backlash occurs between the piston 102 and the cylinder 101, and a desired damping force cannot be obtained. Moreover, piston 10
When 2 passes through the upper and lower edges of the intermediate thick portion 101A of the cylinder, a shock is generated, which may damage the seal around the piston.

Therefore, a first object of the present invention is to avoid wear of wheels and rails and derailment without being restricted by the mounting space and improving the followability of the posture between the bogie and the vehicle body during curved traveling. It is an object of the present invention to provide a suspension system for a railway vehicle that can be prevented and can improve riding comfort.

A second object is that a damping force depending on the stroke of the piston can be obtained, and the same damping force can be obtained by the relief valve that is commonly used for extension, so that there is no rattling of the piston and a desired stable damping is obtained. It is to provide a yo-damper that can always obtain power.

[0014]

In order to achieve the above object, the means for suspension of a railway vehicle of the present invention is a suspension system for a railway vehicle in which a yaw damper is interposed between a bogie and a vehicle body. , A yaw damper that generates a damping force depending on the stroke position of the piston is arranged horizontally or substantially horizontally, one end of the yaw damper is connected to the dolly side, and the other end is erected upward through a bracket. It is characterized in that it is connected to the side.

In this case, a pair of horizontal or substantially horizontal left and right yaw dampers are provided on both sides of the chassis frame of the bogie in the front-rear direction, and a central yaw damper is also horizontally or substantially horizontal in the center of the chassis frame. It is preferable to provide a pair of the two facing each other.

Similarly, in the means of the yaw damper of the present invention, a piston rod is movably inserted into a cylinder which is horizontally or substantially horizontally arranged via a piston, and the piston has a rod side chamber and a non-rod side chamber in the cylinder. The outer shell is placed outside the cylinder, the reservoir is provided between the cylinder and the outer shell, and the piston is provided with a piston side check valve that allows oil flow only from the rod side chamber to the rod side chamber. Stretching the piston by connecting the rod-side chamber to the reservoir via a relief valve that is also used for expansion and the anti-rod-side chamber to the reservoir via a base-side check valve that allows oil flow only from the reservoir side. The hydraulic oil that accompanies the above is configured to flow in one direction through the relief pipe, and An inner tube is inserted between the inner tube and the cylinder to form an axial oil passage isolated from the reservoir between the inner tube and the cylinder, and one end of this oil passage is formed through a communication hole formed at the end of the cylinder. Opening to the rod side chamber, and forming first and second throttles each having one or a plurality of orifices on the upper side and the lower side of the cylinder intermediate portion corresponding to the piston neutral position, and the first throttle is the above oil The other end of the passage is characterized in that the second throttle opens and closes the reservoir selectively to the rod-side chamber or the non-rod-side chamber corresponding to the expansion and contraction operation position of the piston through some or all of the orifices. It is a thing.

In this case, a single orifice forming the first and second throttles is formed in one or in parallel along the axial direction at the intermediate portion of the cylinder corresponding to the neutral position of the piston, and the expansion and contraction operation of the piston is performed. At times, it is preferable that each orifice is opened and closed sequentially by a piston in correspondence with the stroke position.

Similarly, an orifice group consisting of a single orifice forming the first and second throttles and a plurality of orifices formed along the circumferential direction is axially formed in the middle portion of the cylinder corresponding to the piston neutral position. A plurality of parallel lines may be formed along the line.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the suspension system according to the present invention is a suspension system for a railway vehicle in which a yaw damper is interposed between a carriage B and a vehicle body (not shown). Yaw damper A that generates damping force depending on
Is arranged in a horizontal or substantially horizontal state, one end of the yaw damper A is connected to the dolly B side, and the other end is connected to the vehicle body side via a bracket D standing upright.

The yaw damper A is a front and rear yaw damper A.
And a lateral yaw damper A2. That is, the left and right yaw dampers A which are horizontal or substantially horizontal in the front-rear direction via the brackets on both sides of the chassis frame E of the carriage B.
Similarly, a pair of horizontal center yaw dampers A2 and A2 are provided in the center of the chassis frame E so as to face each other in the lateral direction. However, it is also possible to use only by mounting either one of the yaw dampers A1 or A2.

The yaw damper A1 in the front-rear direction and the yaw damper A2 in the lateral direction are arranged horizontally or substantially horizontally, so that they can be mounted in the mounting space below the vehicle body without being restricted so much.

Each of the yaw dampers A connects the carriage B and the vehicle body and suspends the vehicle body, and holds the postures of the carriage B and the vehicle body in the same direction during straight traveling to prevent the carriage B from meandering. When the vehicle travels on a curve, the posture of the vehicle body is controlled by following the carriage B.

In the present invention, these yaw dampers A generate hard and soft damping forces according to the positions of the expansion and contraction operation strokes of the piston and the piston rod. That is, when traveling straight, as described above, only a slight vibration of the piston produces a hard damping force, while on the other hand, when the vehicle travels on a curve of the rail, the piston and piston rod make a large stroke. The soft damping force that depends on the stroke position is generated so that the posture of the vehicle body can be smoothly followed even when the posture of the truck changes.

The basic structure of the above-mentioned yaw damper A is shown in FIG.
As shown in FIG. 3, a piston rod 3 is movably inserted into a cylinder 1 via a piston 2, and the piston 2 defines a rod side chamber 4 and a non-rod side chamber 5 inside the cylinder 1 and is outside the cylinder 1. The outer shell 6 is disposed in the outer shell 6 and the reservoir R is provided between the cylinder 1 and the outer shell 6. The piston 2 is provided with a piston-side check valve 7 that allows the oil flow only from the non-rod-side chamber 5 to the rod-side chamber 4.

The rod-side chamber 4 communicates with the reservoir R via a relief valve 8 commonly used for expansion, and the non-rod-side chamber 5 communicates with the reservoir R via a base-side check valve 9 which allows oil flow only from the reservoir R side. It communicates with R.
This constitutes a one-way flow in which the hydraulic oil accompanying the expansion and contraction operation of the piston 2 always flows in one direction from the rod side chamber 4 in the cylinder 1 toward the reservoir R via the relief valve 8. Further, an inner tube 10 is inserted between the cylinder 1 and the outer tube 6 to form an axial oil passage 11 isolated from the reservoir R between the inner tube 10 and the cylinder 1. One end is open to the rod side chamber 4 through a communication hole 12 formed at the end of the cylinder 1. Further, a first throttle P1 and a second throttle P2, each of which has one or a plurality of orifices a, b, c, ..., N, are provided on the upper side and the lower side of the intermediate portion of the cylinder 1 corresponding to the piston neutral position. Is forming. The first throttle P1 connects the other end of the oil passage 11 to the second throttle P1.
Reference numeral 2 denotes a reservoir which is selectively opened / closed by the rod side chamber 4 or the non-rod side chamber 5 corresponding to the expansion / contraction operation position of the piston 2 through some or all of the orifices a, b, c. . In this case, since the yaw damper A is arranged substantially horizontally or in a horizontal state, the second diaphragm P2 located below the yaw damper A is always in the working oil of the reservoir R and causes aeration without providing a diaphragm or the like. Therefore, there is no disturbance of the damping force. The combinations of the orifices a, b and c are shown in FIG. 6, FIG. 7, FIG. 8 and FIG.
There is a pattern shown in.

For example, as shown in FIG. 6, a single orifice a, b, c, ..., N is provided in the middle portion of the cylinder 1 corresponding to the piston neutral position or in parallel in the axial direction. The orifices a, b, c, ..., N are sequentially opened and closed by the piston 2 in correspondence with the stroke position when the piston expands and contracts.

Further, as shown in FIGS. 7 and 8, a single orifice a, b and a plurality of orifices C1, C2, ..., Cn formed along the circumferential direction form a piston neutral position. Are formed in parallel in the axial direction in the middle portion of the cylinder 1 corresponding to.

Further, as shown in FIG. 9, a plurality of orifices C1, C2, C3, C ..., C are arranged in a line along the circumferential direction.
An orifice group consisting of n may be provided in the middle portion of the cylinder 1 similarly to Cn.

The yaw damper A will be described in more detail.

The inner circumference of the cylinder 1 has a smooth surface along the axial direction, and the outer circumference of the piston 2 is in smooth sliding contact over the entire stroke without backlash.

A rod guide 31 is connected to one end of the cylinder 1, the inner tube 10 and the outer shell 6,
The piston rod 3 slides on the center of the rod guide 31 via a seal.

An eye 14 is attached to the outer end of the piston rod 3, and a body side bracket D (see FIG. 1) is attached to the eye 14.
A support rod 15a to which the lower bracket 16 of (see) is coupled is provided. On the other hand, a bottom 18 is provided at the other end of the cylinder 1 and the outer shell 6, and the sealing member 1
An eye 13 is connected via 7 and a support rod 15 to which the bracket C on the dolly B side is connected is provided on the eye 13 (see FIG. 1). One end of the inner tube 10 is connected to the guide rod 31. At the same time, it is connected to an annular mounting portion 19 that extends over the outer circumference of the cylinder 1.

A plurality of ports 20 are formed in the piston 2, and a piston-side check valve 7 consisting of a leaf valve is openably provided at the outlet end of the port 20, that is, the rod-side oil chamber 4 side. An oil passage 21 that connects the rod-side oil chamber 4 and the reservoir R is formed in the guide 31, and a relief valve 8 that is a poppet valve and is commonly used to open and close is provided in the middle of the oil passage 21.

The anti-rod side oil chamber 5 communicates with the reservoir R through an oil passage 22 formed in the bottom 18, and a base check valve 9 biased in the closing direction by a spring is provided in the middle of the oil passage 22. It is openable and closable.

Further, a reservoir R is provided at an annular mounting portion 19 at the end of the inner tube 10 and the intermediate portion of the cylinder 1.
A plug member 24 for isolating the oil passage 11 from the oil passage 11 is attached, and an oil hole 23 is formed in the plug member 24. The oil hole 23 is always open to the reservoir R, but is closed on the outer circumference of the piston 2 when the piston is neutral. Furthermore,
When the piston 2 is compressed, that is, when the piston 23 strokes rightward beyond the neutral position of the piston in FIG. 2, the oil hole 23 opens in the rod-side oil chamber 4 to communicate the rod-side oil chamber 4 and the reservoir R. On the contrary, at the time of the extension operation of making a stroke to the left, the anti-rod side oil chamber 5 is opened and the anti-rod side oil chamber 5 is communicated with the reservoir R.

Next, the operation of the yaw damper A will be described.

As shown in FIGS. 2 and 3, when the piston 2 is in the neutral position, the orifices a, b, c, ..., N forming the first and second throttles P1 and P2 are the piston 2 It is closed on the perimeter. Further, when the piston 2 expands or contracts or has a slight amplitude in a range in which the orifices a, b, c, ..., N are closed, as when the vehicle is traveling straight, the rod side oil chamber 4 and the opposite rod side. The oil in the oil chamber 5 flows out to the reservoir R from the relief valve 8, and at this time, the relief valve 8 exerts a hard high damping force to suppress the resonance of the vehicle body and maintain the running stability.

When the piston 2 that makes a large leftward stroke is extended, such as when the vehicle is traveling on a curved line, the piston-side check valve 7 is closed, and the oil in the rod-side oil chamber 4 is released from the oil passage 21 and is used as a relief valve. 8 to the reservoir R to generate a damping force. At this time, a part of the hydraulic oil flows into the oil passage 11 through the communication hole 12, and the oil in the oil passage 11 further has orifices a, b, ..., In the first throttle P1.
, n, and flows out to the opposite rod side oil chamber 5 and exerts a soft extension side damping force according to the number of orifices a, b, ..., N opened at this time (see FIGS. 4A and 4B). Oil corresponding to the withdrawal volume of the piston rod 3 is introduced from the reservoir R via the base side check valve 9. On the other hand, FIG. 4 (A)
As shown in (B), when the compression operation is performed in a state where the rod is leftwardly stroked from the neutral position, a part of the oil in the non-rod side oil chamber 5 is replaced with the rod side oil chamber 4 via the piston side check valve 7. Then, part of the oil corresponding to the piston rod intrusion volume flows out to the reservoir R via the relief valve 8 and also flows out to the reservoir R via the orifices a, b, ..., N in the second throttle P2 to reduce the damping force. At the same time, a part of the hydraulic oil generates a soft compression side damping force by the second throttle P2.

Next, as shown in FIG. 5, the oil in the oil chamber 5 opposite to the rod side flows out to the oil chamber 4 in the rod side through the piston side check valve 7 during the compression operation in which the stroke is made to the right from the neutral position. While the oil corresponding to the invading volume of the piston rod 3 flows out to the reservoir R via the relief valve 8 which is commonly used for the expansion, a compression side damping force is generated, while a part of the hydraulic oil in the rod side chamber 4 is part of the second throttle P2. , N to flow into the reservoir R and generate a soft compression-side damping force corresponding to the opening area of the orifices a, b, ..., N.

Further, when the compression position, which is raised from the neutral position, is switched to the extension operation, the piston side check valve 7
, And the oil in the rod-side oil chamber 4 flows out to the reservoir R via the orifices a, b, ..., N in the second throttle P2, and the softness according to the opening area of the orifices a, b ,. Generates damping force on the extension side. At this time, oil corresponding to the withdrawal volume of the piston rod 3 is introduced from the reservoir R into the anti-rod side oil chamber 5 via the base side check valve 9. This time,
Since the rod side chamber 4 and the oil passage 11 have the same pressure, the first throttle P
No hydraulic fluid flows through the first orifices a and bn.

By the way, the patterns of the orifices a, b, c, ..., N in the first and second diaphragms P1 and P2 are shown in FIG.
As shown in FIG. 9, there are various patterns, and soft damping force characteristics corresponding to each pattern can be obtained.

For example, as shown in FIG. 6A, when a single orifice a, b, ..., N is formed in parallel along the axial direction, all the orifices a, b ,. The extension / compression damping force characteristic is the hardest characteristic F1 when it is in motion, and is slightly softer when one orifice a or b is opened by making a stroke only on the extension side or compression side 11 from the neutral position.
2 and strokes more than 12 and all orifices a,
When b, ..., N are fully opened, the softest characteristic F5 is obtained. That is, as the piston 2 sequentially strokes l1, l2, ... In to open the orifices a, b, ..., N, the damping force is increased in accordance with the opening area of the orifice.
Change to medium or soft. In other words, it is possible to obtain a damping force characteristic depending on the piston position from the neutral position of the piston 2 according to the stroke.

Similarly, FIG. 7A shows a combination of the single orifices a, b and the central orifices C1, C2, C3, and the central orifices C1, C.
When 2 and C3 are opened, the characteristic becomes softer than the single orifice c in FIG. 6 (A), and the overall characteristic is shown in FIG. 7 (B).
The graphs F1 to F4 in FIG.

Further, FIG. 8 (A) shows a combination of the orifice groups on the left side with the orifices C1, C2, C3 and other single orifices a, b, and the characteristics at that time are shown in FIG.
It is shown by the graphs F1 to F4 in (B).

Further, FIG. 9A shows a single orifice C1,
, Cn are provided at one place in the circumferential direction, and when the orifice C1Cn is fully opened, the soft characteristic F2 of FIG. 9B is obtained.

The combination pattern of the orifices a, b, ..., N in the first and second diaphragms P1, P2 is not limited to that shown in the drawing, and various patterns can be formed based on the same idea.

[0048]

The present invention has the following effects.

(1) According to the suspension device of the first and second aspects of the invention, the yaw damper, which generates a damping force depending on the stroke position of the piston between the carriage and the vehicle body, is placed horizontally or substantially horizontally. Since it is interposed, the displacement between the bogie and the vehicle body can be directly transmitted as a damper stroke, and a functionally efficient low damping force can be set. Further, when the vehicle is traveling straight, a high damping force associated with the neutral position of the piston can prevent the vehicle from meandering, and when traveling on a curve, the posture of the vehicle body can follow the posture of the vehicle and the vehicle can smoothly turn. As a result, the wheel load of the wheels does not act on the rail side, and the wheels and rails can be prevented from wear and removal and the riding comfort is improved.

(2) Similarly, since the yaw damper is arranged in a horizontal or substantially horizontal state, there are few restrictions on the mounting space below the vehicle body and no special mounting method is required, and the assembling property is improved.

(3) According to the inventions of claims 3, 4 and 5, a high damping force can be generated by fully closing the first and second throttles at or near the neutral position of the piston. A soft damping force corresponding to the opening areas of the first and second diaphragms can be obtained at the expansion / contraction stroke position beyond. That is, it is possible to exert a position-dependent damping force corresponding to the stroke position of the piston.

(4) Similarly, since the one-way flow is used as the flow of hydraulic oil associated with the expansion and contraction operation of the damper, the damping force on the expansion side and the compression side can be obtained by the same first and second throttles as the same expansion relief valve. Since the same damping force can be obtained because it is generated, the design of the damping force generation mechanism is easy, and because the cylinder is placed horizontally or almost horizontally, there is no need to use a reservoir diaphragm or bellows. A horizontal damper can be constructed, and it can be manufactured at a low cost with a simpler structure than the conventional horizontal damper.

(5) Similarly, since the same damping force generating mechanism can generate the damping force over the entire stroke without forming a groove on the inner circumference of the cylinder, the piston can smoothly move in the cylinder without any step over the entire stroke. Can be stroked to
It is possible to prevent backlash and prevent damage to the seal around the piston.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a suspension system for a railway vehicle according to the present invention.

FIG. 2 is a vertical sectional front view of the yaw damper according to the present invention.

3 is a partially enlarged sectional view of FIG.

4 (A) and (B) are partially enlarged cross-sectional views of FIG. 1 in a state where a piston has an extension stroke.

5 is a partially enlarged cross-sectional view of FIG. 1 in a state in which the piston makes a compression stroke.

6A and 6B are a developed view of a combination pattern of orifices according to an embodiment and a graph of damping force characteristics thereof.

7A and 7B are a developed view of a combination pattern of orifices according to another embodiment and a graph of damping force characteristics thereof.

8A and 8B are a developed view of a combination pattern of orifices according to another embodiment and a graph of damping force characteristics thereof.

9A and 9B are a developed view of a combination pattern of orifices according to another embodiment and a graph of damping force characteristics thereof.

FIG. 10 is a vertical sectional front view of a conventional yaw damper.

[Explanation of symbols]

1 cylinder 2 pistons 3 piston rod 4 Rod side chamber 5 Anti-rod side chamber 6 Outer shell 7 check valves 8 relief valve 9 Base side check valve 10 Inner tube 11 oil passage 12 communication holes A Yodampa B trolley D bracket E chassis frame R reservoir P1, P2 diaphragm a, b, c, ..., n Orifice

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F16F 15/023 F16F 15/023 A

Claims (5)

[Claims] 1. In a suspension system for a railway vehicle in which a yaw damper is interposed between a bogie and a vehicle body, a yaw damper that generates a damping force depending on a stroke position of a piston is arranged horizontally or substantially horizontally. A suspension device for a rail vehicle, wherein one end of the yaw damper is connected to a dolly side, and the other end is connected to a vehicle body side through a bracket that stands upright. 2. A pair of horizontal or substantially horizontal left and right yaw dampers are provided on both sides of the chassis frame of the bogie in the front-rear direction, and a central yaw damper is also horizontally or substantially horizontal in the center of the chassis frame. The suspension system for a railway vehicle according to claim 1, wherein a pair is provided relatively. 3. A piston rod is movably inserted into a horizontally or substantially horizontally arranged cylinder via a piston, and the piston divides a rod side chamber and a non-rod side chamber into the cylinder and is provided outside the cylinder. An outer shell is installed to provide a reservoir between the cylinder and outer shell, and a piston has a piston check valve that allows oil flow only from the rod-side chamber to the rod-side chamber. Of the piston and the hydraulic fluid accompanying the expansion and contraction operation of the piston are communicated with the reservoir through a base side check valve that allows the flow of oil only from the reservoir side to communicate with the reservoir via the relief valve. So that it flows in one direction through the inner tube, and insert the inner tube between the cylinder and the outer tube. An axial oil passage isolated from the reservoir is formed between the inner tube and the cylinder, and one end of this oil passage is opened to the rod side chamber through a communication hole formed at the end of the cylinder to provide a piston neutral position. At the upper side and the lower side of the cylinder intermediate portion corresponding to, respectively, first and second throttles each having one or a plurality of orifices are formed. The first throttle restricts the other end of the oil passage to the second throttle. Is a yaw damper for railway vehicles, wherein the reservoir is selectively opened and closed to the rod side chamber or the non-rod side chamber corresponding to the expansion and contraction operation position of the piston through some or all of the orifices. 4. A single orifice, which constitutes the first and second throttles, is formed in a middle portion of the cylinder corresponding to the piston neutral position, or a plurality of orifices are arranged in parallel along the axial direction, and when the piston expands and contracts. The yaw damper for a railway vehicle according to claim 3, wherein each orifice is opened and closed sequentially by a piston in correspondence with a stroke position. 5. A single orifice that constitutes the first and second throttles and an orifice group consisting of a plurality of orifices formed along the circumferential direction are axially formed in the intermediate portion of the cylinder corresponding to the piston neutral position. A plurality of yaw dampers for railway vehicles according to claim 3, wherein a plurality of them are formed in parallel along each other.