Hydraulic motor
AssigneeOy Partek AB
InventorIlmari Louhio
Life of this patent
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Abstract
The invention relates to a hydraulic motor with two cylinder sets of different diameters and with a slide valve for directing a pressure medium simultaneously to both cylinder sets or to either one of them. In order to achieve smooth shifting from one driving state to another, the slide valve comprises means for connecting the pressure openings of the disconnected cylinder set to a space wherein return pressure prevails, whereby the pistons of the said cylinder set passively will follow the rolling space of the cam ring of the motor. The valve structure further comprises means for connecting the pressure openings of both cylinder sets with the said space of return pressure, if the work pressure of the motor approaches the return pressure.
Claims9
A hydraulic motor provided with two cylinder sets arranged around a shaft and having diameters of different sizes with a sliding spindle valve structure, having fluid pressure reactive surfaces thereon, controlled by the pressure medium being arranged in a bore formed in the motor shaft for directing the pressure medium alternatively to both cylinder sets, to the larger-diameter cylinder set only or to the smaller-diameter cylinder set only, characterized in that the valve spindle structure comprises means for connecting the pressure openings of the cylinder set remaining without pressure medium to a space in which return pressure prevails, and means for connecting the pressure openings in both cylinder sets to the return pressure when the working pressure of the motor approaches the return pressure, said connecting means including said sliding spindle valve which slides in response to a pressure differential thereacross, on fluid pressure reactive surfaces of the spindle valve, between the working pressure and the return pressure.
A hydraulic motor as claimed in any of the preceding claims, characterized in that the return channel and a casing space are interconnected by a pump which is connected to the rotation of the casing part so that, as the casing part rotates forwards, the pump functions as a hydraulic motor while assisting the rotation of the casing parts, and while transferring pressure medium by means of dosing, according to the rate of rotation from the return space, to the casing space and when the entire hydraulic system is in a pressureless condition with respect to the hydraulic motor and when the pressure and return lines are connected to the tank line, pressure is produced in the casing space up to the pressure value determined by a valve for pushing the pistons to their innermost positions in their cylinders, whereby the cam rings of the motor are, while rotating, disengaged from the roller means of the pistons and the casing parts of the motor can rotate freely while the motors operate as conventional load-carrying wheels.
Dependencies are inferred from the claim text.