| 摘要 |
A radial piston hydraulic motor (4) comprises a cam ring provided with a wave-shaped inner surface and radial cylinders provided in the inner part inside the cam ring and pistons that move therein as well as rollers coupled to the pistons so as to follow the inner surface of the cam ring. By the effect of the working pressure of hydraulic oil conveyed to the cylinders, the rollers that are pressed against the inner surface of the cam ring provide a rotating movement of the cam ring and the inner part relative to each other. The hydraulic motor (4) is provided with means disengaging the rollers coupled to the pistons from contact to the inner surface of the cam ring when the working pressure stops acting in the cylinders for bringing the hydraulic motor (4) into freewheeling. The hydraulic motor (4) is provided with a control coupling which, when the prevailing pressure of hydraulic oil in the working pressure line (5) that leads to the cylinders drops below a specific level, automatically disengages the cylinders from the working pressure line (5) and couples the hydraulic motor (4) into freewheeling. |
