JPH074340A - Brake device of hydraulic motor - Google Patents

Abstract

PURPOSE:To provide the brake device of a hydraulic motor of which the construction is simple, the cost is low, and the output shaft can be stopped by a small torque. CONSTITUTION:This brake device is provided with a Geroler assembly 17 in which an annular ring 23 and an annular rotor 24 are engaged with each other, and the axis of the ring 23 is eccentrically arranged to the axis of the rotor 24. Working oil is supplied in order into the chamber between the ring 23 and the rotor 24, the rotor 24 rotates along the internal teeth of the ring 23 and revolves around the axis of the ring 23. A drive shaft 25 is connected between the rotor 24 and an output shaft 12, and an engaging means obstructing revolution of the drive shaft 25 is provided on the end face on the rotor 24 side of the drive shaft 25. When torque is reversely transmitted from the load to the output shaft 25 so as to revolve the drive shaft, revolution of the drive shaft 25 is obstructed by the engaging means, and hence rotation of the output shaft 12 is stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake device for a hydraulic motor.

[0002]

2. Description of the Related Art Conventionally, an orbit type hydraulic motor has a rotor provided with external teeth and a ring provided with internal teeth whose number of teeth is slightly larger than the number of teeth of the external teeth. The rotor is rotated about its axis while being revolved to generate a large torque in the rotor, and the rotor can output the torque to a load via an output shaft connected to the rotor.

A brake device consisting of a mechanical brake is arranged in the hydraulic motor to selectively stop the output shaft and prevent torque from being reversely transmitted from the load to the output shaft (Japanese Patent Publication No. 60-53193). FIG. 2 is a sectional view of a conventional hydraulic motor. In the figure, 11 is a cylindrical housing, and an output shaft 12 is rotatably supported in the housing 11,
One end of the output shaft 12 is connected to a load (not shown). The end of the housing 11 on the load side (left side in the figure) (hereinafter,
It is called the "load side end". ), A flange mounting 13 is fixed by a bolt 14, and a spacer plate 16 is provided at an end portion (hereinafter, referred to as “non-load side end portion”) of the housing 11 on the side opposite to the load side (right side in the drawing). ,
Jiroller assembly 17, bearing housing 18
Then, the end cap 19 is arranged in order, and is fixed by the bolt 21.

The giro roller assembly 17 meshes with an annular ring 23 having internal teeth (not shown) having a number of teeth a and an annular rotor 24 having external teeth not shown having a number of teeth b. The axis of the ring 23 and the axis of the rotor 24 are eccentric. Then, a drive shaft 25 is arranged to transmit the rotation of the large torque generated by the giro roller assembly 17 to the output shaft 12, and the load side end of the drive shaft 25 is inside the output shaft 12. The non-load side end portion is arranged in the bearing housing 18.

A spline groove (not shown) is formed on the inner periphery of the rotor 24, and spline teeth (not shown) are formed on the outer periphery of the drive shaft 25 in the vicinity of the end on the non-load side.
And the drive shaft 25 are concentrically spline-fitted. Further, a spline groove 26 is formed on the inner circumference of the output shaft 12, and spline teeth (not shown) are formed on the outer circumference of the load side end of the drive shaft 25 so that the output shaft 12 and the drive shaft 25 are concentrically spline-fitted. It

A plurality of chambers (not shown) which are separated from each other are formed between the inner teeth of the ring 23 and the outer teeth of the rotor 24, and high pressure is applied to the chambers in a preset order via a distribution valve (not shown). When the hydraulic oil is supplied, the rotor 24 rotates in the direction of increasing the volume of the chamber while meshing with the ring 23. Also, the rotor 2
The axis of No. 4 revolves around the axis of the ring 23 and moves.

Here, when the number of teeth a of the inner teeth of the ring 23 is 7 and the number of teeth b of the outer teeth of the rotor 24 is 6, the working oil is supplied to each chamber to set the rotor 24 to 1 When revolved only by rotation, the rotor 24 rotates about 1 / b = 1/6 rotation.

Since the rotor 24 and the output shaft 12 are connected via the drive shaft 25, the rotor 24
The rotational speed of 1 can be reduced to 1 / b = 1/6 and transmitted to the output shaft 12. That is, the number of rotations of the rotor 24 is set to the number of external teeth of the rotor 24 b
Can be transmitted to the output shaft 12 after decelerating to the rotational speed of the value subtracted by the above, and a torque obtained by multiplying the torque of the rotor 24 by the number of external teeth t of the rotor 24 is generated and output to the output shaft 12. be able to.

By the way, in order to selectively stop the output shaft 12 and prevent the torque from being reversely transmitted from the load to the output shaft 12, a brake device including a mechanical brake is provided. Therefore, the non-load side end of the drive shaft 25 is projected and supported by the rotating shaft 31 via the bush 32. The rotating shaft 31 is further provided with a bearing 3
3 is rotatably supported by the bearing housing 18 via the bearing 3 and the end cap 19 via the bearing 34. Moreover, the rotary shaft 31 is supported on the same axis as the output shaft 12.

In this way, the rotation of the drive shaft 25 can be transmitted to the rotary shaft 31. In addition, an annular friction plate 38 is slidable in the axial direction of the rotating shaft 31 around a predetermined portion of the rotating shaft 31 and does not rotate relatively in the rotating direction. Is installed in. An annular mating plate 39 is fixed to the end cap 19 by a pin 41 at a position facing the non-load side end of the friction plate 38. On the other hand, an annular push plate 43 is arranged at a position facing the load side end of the friction plate 38, and further,
A spring 44 is arranged to face the load side end of the push plate 43. Therefore, the push plate 43 is pressed by the spring 44 so that the friction plate 3 is constantly operated.
8 is urged to the mating plate 39 side.

An annular pressure chamber 47 is formed in the end cap 19 in order to cancel the biasing force applied to the friction plate 38 by the push plate 43.
An annular piston 48 is slidably disposed in the inside of 7. The load side end of the piston 48 is brought into contact with the push plate 43. Next, the operation of the brake device for the hydraulic motor configured as described above will be described.

During operation of the hydraulic motor, the shaft center of the drive shaft 25 revolves around the shaft center of the rotary shaft 31 in association with the revolution of the rotor 24. Rotate through 34. Therefore, the friction plate 38 also rotates at the same speed as the revolution of the rotor 24. At this time, since hydraulic oil is supplied to the pressurizing chamber 47 and the piston 48 is moved forward, the urging force applied to the friction plate 38 by the push plate 43 is offset, and the friction plate 38 is replaced by the counter plate 39. Away from, the mechanical brake is released. Therefore, the rotating shaft 31 can freely rotate, and accordingly, the output shaft 12 can also freely rotate.

Next, when stopping the output shaft 12,
The supply of hydraulic oil to the pressurizing chamber 47 is stopped. As a result, the piston 48 retracts and the push plate 4
When 3 applies an urging force to the friction plate 38, the friction plate 38 is pressed against the mating plate 39, and the mechanical brake is engaged. Therefore, the rotating shaft 31 is stopped, and the output shaft 12 is stopped accordingly.

Then, torque is reversed from the load to the output shaft 12
Is transmitted to the friction plate 38 via the drive shaft 25 and the rotating shaft 31, but the rotation direction of the rotating shaft 31 is opposite to that of the output shaft 12 because the rotor 24 operates. The number of rotations is equal to the number of external teeth of the rotor 24, that is, b times. Therefore, the torque is 1 / b times the number of external teeth of the rotor 24, that is, 1 / b times.

Therefore, the brake device is directly connected to the output shaft 1.
It is possible to stop the output shaft 12 with a smaller torque than in the case where the output shaft 12 is attached to the shaft 2. When an oil passage (not shown) for supplying hydraulic oil to the pressurizing chamber 47 and an oil passage (not shown) for supplying hydraulic oil to the chamber are connected, the hydraulic oil is supplied to the chamber and the pressurizing chamber 47 at the same time. The rotation of the rotor 24 can be started, the piston 48 can be moved forward, the friction plate 38 can be separated from the mating plate 39, and the mechanical brake can be released. Further, the rotor 24 can be stopped, the piston 48 can be retracted, and the friction plate 38 can be pressed against the mating plate 39 to engage the mechanical brake.

[0016]

However, in the conventional brake device for a hydraulic motor, the revolution of the drive shaft 25 is transmitted to the rotary shaft 31, and the rotation of the rotary shaft 31 is transmitted to the friction plate 38. The friction plate 38 and the counter plate 39
Since it is stopped by the friction generated between and, not only the structure is complicated, but also the cost becomes high.

The present invention solves the problems of the conventional hydraulic motor braking device, and provides a hydraulic motor braking device having a simple structure, low cost, and capable of stopping the output shaft with a small torque. The purpose is to do.

[0018]

Therefore, in the brake device for a hydraulic motor according to the present invention, an annular ring having internal teeth and an annular rotor having external teeth are meshed with each other, and the axial center of the ring is engaged. And a roller assembly in which the rotor axis is eccentric, a means for sequentially supplying hydraulic oil to the chamber between the ring and the rotor to cause the rotor to rotate and revolve, and between the rotor and the output shaft. It has a drive shaft that is connected and that transmits the rotation of the rotor to the output shaft, and an engagement means that is disposed on the rotor-side end surface of the drive shaft and that blocks the revolution of the drive shaft.

[0019]

According to the present invention, as described above, in the brake device of the hydraulic motor, the annular ring having the inner teeth and the annular rotor having the outer teeth are engaged with each other, and the axial center of the ring and the rotor. Has a jellore assembly having an eccentric shaft center. Then, when hydraulic oil is sequentially supplied to the chamber between the ring and the rotor, the rotor rotates along the inner teeth of the ring and revolves around the axis of the ring.

In this case, the rotational speed of the rotor is the rotational speed of the revolution reduced by the number of external teeth of the rotor. A drive shaft is connected between the rotor and the output shaft,
Rotation of the rotor is transmitted to the output shaft. Therefore, a large torque can be transmitted to the output shaft.

An engaging means for preventing the drive shaft from revolving is provided on the end surface of the drive shaft on the rotor side. Therefore, when torque is transmitted from the load to the output shaft, the torque is transmitted to the drive shaft and tries to revolve the drive shaft. However, the torque is 1 / the number of external teeth of the rotor. Become. As a result, the output shaft can be stopped with a smaller torque than when the brake device is directly attached to the output shaft.

[0022]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a sectional view of a hydraulic motor according to a first embodiment of the present invention. In the drawing, 11 is a cylindrical housing, and an output shaft 12 is rotatably supported in the housing 11, and the output shaft 12 is
Is connected to a load (not shown). Further, 61 is a thrust bearing race which receives an axial force applied to the output shaft 12, 62 is a thrust bearing needle, 6
3 is an oil seal, and 64 is a key for connecting the output shaft 12 and the load side.

A flange mounting 13 is fixed to the load-side end of the housing 11 with bolts 14, and a spacer plate 16, a roller assembly 17, and an end cap 65 are sequentially mounted to the non-load-side end of the housing 11. It is arranged and fixed by bolts 67. A piston cover 68 is fixed to a non-load side end portion of the end cap 65 with a bolt 69.

The giro roller assembly 17 is meshed with an annular ring 23 having internal teeth (not shown) having a number of teeth a and an annular rotor 24 having external teeth (not shown) having a number of teeth b. The axis of the ring 23 and the axis of the rotor 24 are eccentric. Then, the rotation of the large torque generated by the roller assembly 17 is applied to the output shaft 12
A drive shaft 25 is disposed for transmission to the drive shaft 25, the load side end of the drive shaft 25 is disposed inside the output shaft 12, and the non-load side end is disposed inside the rotor 24.

A spline groove 71 is formed on the inner circumference of the rotor 24.
However, spline teeth 72 are formed on the outer periphery of the end portion of the drive shaft 25 on the non-load side, and the rotor 24 and the drive shaft 25 are concentrically spline fitted. In addition, the output shaft 12
Of the drive shaft 25 and spline teeth 73 are formed on the outer periphery of the load side end of the drive shaft 25 so that the output shaft 12 and the drive shaft 25 are concentrically fitted to each other.

The inner teeth of the ring 23 and the rotor 2
4, a plurality of chambers (not shown) separated from each other are formed, and when high-pressure hydraulic oil is supplied to the chambers in a preset order via a distribution valve (not shown), the rotor 24 meshes with the ring 23 and Rotate in the direction of increasing the volume of the chamber. The axis of the rotor 24 revolves around the axis of the ring 23 to move.

When the number a of internal teeth of the ring 23 is 7 and the number b of external teeth of the rotor 24 is 6, the working oil is supplied to each chamber so that the rotor 24 is 1 When revolved only by rotation, the rotor 24 rotates about 1 / b = 1/6 rotation.

Since the rotor 24 and the output shaft 12 are connected via the drive shaft 25, the rotor 24
The rotational speed of 1 can be reduced to 1 / b = 1/6 and transmitted to the output shaft 12. That is, the number of rotations of the rotor 24 is set to the number of external teeth of the rotor 24 b
Can be transmitted to the output shaft 12 after decelerating to the rotational speed of the value subtracted by the above, and a torque obtained by multiplying the torque of the rotor 24 by the number of external teeth t of the rotor 24 is generated and output to the output shaft 12. be able to.

By the way, in order to selectively stop the output shaft 12 and prevent the torque from being reversely transmitted from the load to the output shaft 12, a brake device composed of a mechanical brake is provided. Therefore, the piston cover 68
A cylinder chamber 74 is formed therein, and a piston pin 78 is slidably arranged in the cylinder chamber 74. At the load side end of the piston pin 78, the engagement protrusion 7 protruding toward the load side is provided.
8a is integrally formed. And the drive shaft 2
5, a brake engaging hole 75 is formed at the end portion on the non-load side, and a through hole 76 is formed at a set position of the end cap 65, and the piston pin 78 is formed in the through hole 76.
Of the brake engaging hole 7
5 can be selectively inserted.

Here, the axis of the rotor 24 is the ring 2
As the axis of the drive shaft 25 revolves around the axis of the ring 23 as it revolves around the axis of 3.
The brake engagement hole 75 also revolves around the axis of the ring 23. Therefore, the through hole 76 is formed at a set position on the locus of the brake engagement hole 75 in the end cap 65, and the piston pin 78 is formed.
Is arranged at a position eccentric from the shaft center of the hydraulic motor in accordance with the amount of eccentricity of the jroller assembly 17.

In order to slide the piston pin 78 in the cylinder chamber 74, a spring 80 is arranged on the non-load side of the piston pin 78, and the spring 80 urges the piston pin 78 to the load side. A port 81 is opened in the end cap 65 so that the port 81 communicates with the load side end of the cylinder chamber 74 via an oil passage 82. Therefore, the port 8
1 and the oil passage 82 to selectively supply the hydraulic oil to the cylinder chamber 7
No. 4, and the piston pin 78 can be moved to the non-load side.

Next, the operation of the brake device for the hydraulic motor having the above construction will be described. During operation of the hydraulic motor, the axis of the drive shaft 25 revolves around the axis of the ring 23 in conjunction with the revolution of the rotor 24. At this time,
Since the hydraulic oil is supplied to the cylinder chamber 74 via the port 81 and the oil passage 82, the piston pin 78 moves to the non-load side against the urging force of the spring 80, and the engagement protrusion 78a is It is pulled out from the brake engagement hole 75. Therefore, the mechanical brake is released, the drive shaft 25 can freely rotate, and accordingly, the output shaft 12 can also freely rotate.

Next, when the output shaft 12 is stopped with the hydraulic motor stopped, the port 81 is depressurized,
The hydraulic oil in the cylinder chamber 74 is drained through the oil passage 82. As a result, the piston pin 78 moves to the load side, the engagement protrusion 78a is fitted into the brake engagement hole 75, and the mechanical brake is engaged. Therefore,
The drive shaft 25 is stopped, and the output shaft 12 is also stopped accordingly.

When the piston pin 78 moves to the load side, the position of the engagement protrusion 78a and the position of the brake engagement hole 75 do not match, and the engagement protrusion 78a is moved to the brake engagement hole 75. If it cannot be fitted into the output shaft 12, the torque is transmitted to the output shaft 12 by the load and the output shaft 12
When is rotated, the position of the engagement protrusion 78a and the position of the brake engagement hole 75 are aligned.

As described above, since the engagement projection 78a is fitted into the brake engagement hole 75 to prevent the drive shaft 25 from revolving, it is smaller than when the brake device is directly attached to the output shaft 12. Output shaft 12 with torque
Can be stopped. Therefore, the mechanical brake can be downsized. Although the above-described embodiment describes the brake device of the pressure release type (negative brake) that releases the mechanical brake when the pressure of the hydraulic oil is increased, the urging force by the spring 80 is generated in the opposite direction, It is also possible to use a pressurizing type (positive brake) in which the mechanical brake is engaged when the pressure of the hydraulic oil is increased. In this case, when the hydraulic oil in the cylinder chamber is drained through the port, the mechanical brake is released, and when the hydraulic oil is supplied to the cylinder chamber, the mechanical brake is engaged.

Cylinder chambers are formed on both sides of the piston pin 78 without using the spring 80.
It is also possible to supply and discharge the hydraulic oil to and from the cylinder chamber and engage and disengage the mechanical brake. By the way, in the above-described embodiment, the hydraulic oil for releasing the mechanical brake is supplied from the outside of the hydraulic motor, and has an external pilot type configuration. On the other hand, an internal pilot type configuration may be used in which the mechanical brake is released by utilizing the pressure of the hydraulic oil supplied to drive the hydraulic motor.

Next, a second embodiment of the present invention will be described. FIG. 3 is a sectional view of a hydraulic motor according to the second embodiment of the present invention. In the figure, 11 is a cylindrical housing, an output shaft 12 is rotatably supported in the housing 11, and one end of the output shaft 12 is connected to a load (not shown).

A flange mounting 13 is fixed to the load-side end of the housing 11 by bolts 14, and a spacer plate 16, a roller assembly 17, and an end cap 65 are sequentially installed at the non-load-side end of the housing 11. It is arranged and fixed by bolts 67. A piston cover 68 is fixed to a non-load side end portion of the end cap 65 with a bolt 69.

In the giro roller assembly 17, an annular ring 23 and an annular rotor 24 are engaged with each other, and the axial center of the ring 23 and the axial center of the rotor 24 are eccentric. Then, a drive shaft 25 is arranged to transmit the rotation of the large torque generated by the giro roller assembly 17 to the output shaft 12, and the load side end of the drive shaft 25 is inside the output shaft 12. The rotor 2 is on the non-load side end
It is arranged in 4.

When high-pressure hydraulic oil is supplied to a chamber (not shown) formed between the ring 23 and the rotor 24, the rotor 24 rotates while rotating with the ring 23 so as to expand the volume of the chamber. The axis of the rotor 24 revolves around the axis of the ring 23 to move. Therefore, the rotation speed of the rotor 24 is
Can be reduced to the number of revolutions of the outer teeth of the external tooth b to be transmitted to the output shaft 12, and the torque of the rotor 24 is multiplied by the number b of the outer teeth of the rotor 24 to generate a torque, It can be output to the output shaft 12.

In addition, a brake device including a mechanical brake is provided to selectively stop the output shaft 12 and prevent the torque from being reversely transmitted from the load to the output shaft 12. Therefore, a cylinder chamber 74 is formed in the piston cover 68, and a piston pin 78 is slidably arranged in the cylinder chamber 74. An engagement protrusion 78a that protrudes toward the load side is integrally formed at the load side end of the piston pin 78. Then, a brake engaging hole 75 is formed at the non-load side end of the drive shaft 25, and
A through hole 76 is provided at a set position of the end cap 65.
The engaging projection 78a of the piston pin 78 is passed through the through hole 76 so that it can be selectively fitted into the brake engaging hole 75.

Here, the axial center of the rotor 24 is the ring 2
As the axis of the drive shaft 25 revolves around the axis of the ring 23 as it revolves around the axis of 3.
The brake engagement hole 75 also revolves around the axis of the ring 23. Therefore, the through hole 76 is formed at a set position on the locus of the brake engagement hole 75 in the end cap 65, and the piston pin 78 is formed.
Is arranged at a position eccentric from the shaft center of the hydraulic motor in accordance with the amount of eccentricity of the jroller assembly 17.

In order to slide the piston pin 78 in the cylinder chamber 74, a spring 80 is provided on the non-load side of the piston pin 78, and the spring 80 urges the piston pin 78 to the load side. The port 83 is opened toward the chamber between the ring 23 and the rotor 24, and the port 83 is communicated with the load side end of the cylinder chamber 74 via the oil passage 84.
Therefore, the hydraulic oil can be selectively supplied to the cylinder chamber 74 via the port 83 and the oil passage 84, and the piston pin 78 can be moved to the non-load side. Moreover, since a valve or the like is not required to selectively supply the hydraulic oil to the cylinder chamber 74, the structure of the mechanical brake can be simplified.

In this case, the drive shaft 25 when the engagement protrusion 78a is fitted into the brake engagement hole 75
The stop position of is always the same. Further, when starting the hydraulic motor, the chamber to which hydraulic oil is first supplied via a distribution valve (not shown) is always the same. Therefore, the port 83 is first opened to the chamber to which the hydraulic oil is supplied.

Next, the operation of the brake device for the hydraulic motor configured as described above will be described. During operation of the hydraulic motor, the axis of the drive shaft 25 revolves around the axis of the ring 23 in conjunction with the revolution of the rotor 24. At this time,
Since the hydraulic oil is supplied to the cylinder chamber 74 via the port 83 and the oil passage 84, the piston pin 78 moves to the non-load side against the urging force of the spring 80, and the engagement protrusion 78a is It is pulled out from the brake engagement hole 75. Therefore, the mechanical brake is released, the drive shaft 25 can freely rotate, and accordingly, the output shaft 12 can also freely rotate.

Next, when the output shaft 12 is stopped with the hydraulic motor stopped, when the supply of hydraulic oil to the chamber is stopped, the drive shaft 25 stops at any position, and Decompress port 83, oil passage 8
The hydraulic oil in the cylinder chamber 74 is drained through the valve 4. As a result, the piston pin 78 moves to the load side,
The engagement protrusion 78a is fitted into the brake engagement hole 75,
The mechanical brake is engaged. Therefore, the drive shaft 25 is stopped, and accordingly, the output shaft 12 is stopped.
Is also stopped.

When the piston pin 78 moves to the load side, the position of the engagement protrusion 78a and the position of the brake engagement hole 75 do not match, and the engagement protrusion 78a is moved to the brake engagement hole 75. If it cannot be fitted into the output shaft 12, the torque is transmitted to the output shaft 12 by the load and the output shaft 12
When is rotated, the position of the engagement protrusion 78a and the position of the brake engagement hole 75 are aligned.

It should be noted that the present invention is not limited to the above-described embodiments, but various modifications can be made based on the spirit of the present invention, and they are not excluded from the scope of the present invention.

[0049]

As described above in detail, according to the present invention, in the brake device for the hydraulic motor, the annular ring having the inner teeth and the annular rotor having the outer teeth are engaged with each other, and the ring is provided. And a z-roller assembly in which the shaft center of the rotor and the shaft center of the rotor are eccentric. Then, when hydraulic oil is sequentially supplied to the chamber between the ring and the rotor,
The rotor rotates along the inner teeth of the ring,
Revolves around the axis of the ring.

In this case, the rotational speed of the rotor is the rotational speed of the revolution reduced by the number of external teeth of the rotor. A drive shaft is connected between the rotor and the output shaft,
Rotation of the rotor is transmitted to the output shaft. Therefore, a large torque can be transmitted to the output shaft.

An engaging means for preventing the drive shaft from revolving is provided on the end surface of the drive shaft on the rotor side. Therefore, when torque is transmitted from the load to the output shaft, the torque is transmitted to the drive shaft and tries to revolve the drive shaft. However, the torque is 1 / the number of external teeth of the rotor. Become. As a result, the output shaft can be stopped with a smaller torque than when the brake device is directly attached to the output shaft.

Further, since the friction plate and the mating plate are not required to prevent the drive shaft from revolving, the structure is simplified and the cost is reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of a hydraulic motor according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a conventional hydraulic motor.

FIG. 3 is a sectional view of a hydraulic motor according to a second embodiment of the present invention.

[Explanation of symbols]

 12 Output Shaft 17 Ji-Roller Assembly 23 Ring 24 Rotor 25 Drive Shaft 74 Cylinder Chamber 75 Brake Engagement Hole 78 Piston Pin 78a Engagement Projection 80 Spring 81, 83 Port 82, 84 Oil Path

Claims (1)

[Claims] 1. A jig roller assembly in which (a) an annular ring having internal teeth and an annular rotor having external teeth are meshed with each other, and the axial center of the ring and the axial center of the rotor are eccentric. (B) a means for sequentially supplying hydraulic oil to a chamber between the ring and the rotor to rotate and revolve the rotor, and (c) connected between the rotor and the output shaft to output the rotation of the rotor. A brake device for a hydraulic motor, comprising: a drive shaft that is transmitted to the shaft; and (d) engagement means that is disposed on the rotor-side end surface of the drive shaft and that blocks the revolution of the drive shaft.