| 摘要 |
An annulus (19) is integrally rotatable with a shaft (13). First and second pistons (22), (23) are disposed between the shaft (13) and the annulus (19) in diametrically opposed relation. A plurality of pistons (17) are circumferentially spaced around the annulus (19) and are sequentially supplied with high pressure hydraulic fluid to exert driving force on the annulus (19) and shaft (13) in proportion to the eccentricity of the annulus (19). High pressure fluid is selectively applied to one of the first and second pistons (22), (23) to shift the annulus (19) and thereby vary the eccentricity thereof and the motor speed and torque. A pair of diametrically opposed, semicircular shoes (49), (51) are retained by the shaft (13) and movable perpendicular to a direction of movement of the first piston (22). An inner end of the first piston (22) is formed with a circular cutout (54). In response to high pressure applied to facing surfaces of the shoes (49), (51), the shoes (49), (51) move away from each other and abuttingly prevent the first piston (22) from moving closer to the shaft (13) beyond a limit position. In response to low pressure applied to the facing surfaces of the shoes (49), (51), the shoes (49), (51) move toward each other and fit inside the cutout (54). Thus, the first piston (22) is allowed to move closer to the shaft (13) than the limit position. This arrangement provides a three speed radial cylinder hydraulic motor (41).
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