Patent ID: 7225720

Claim:
A radial piston hydraulic motor which includes a box frame ( 10 ) with a cam ring ( 11 ) connected thereto and pistons ( 13 a 1 , 13 a 2 . . . ) in a piston frame ( 12 ) and press rollers ( 14 a 1 , 14 a 2 . . . ) in the pistons, which press rollers can be pressed by means of the pressure of a hydraulic fluid, such as hydraulic oil, against an inner surface ( 11 ′) of the cam ring ( 11 ), and that the piston frame ( 12 ) is connected to a central shaft ( 17 ), and that there is a distributor valve ( 18 ) that includes bores ( 23 ) through which hydraulic oil can be passed into and out of connection with the pistons ( 13 a 1 , 13 a 2 . . . ), the device arrangement including a working pressure inlet passage (B) for the hydraulic fluid and a return passage (A) for the hydraulic fluid which is not under working pressure, wherein the radial piston hydraulic motor ( 100 ) includes a free rotation valve ( 50 ) which is built inside it and includes a spindle ( 19 ) which is disposed in a spindle cavity ( 20 ) and which is movable in the spindle cavity ( 20 ) such that, in a free rotation situation, shoulders of the spindle ( 19 ) block the working pressure inlet and outlet passages (A, B), so that, in a free rotation situation, springs (U 1 , U 2 . . . ) press the pistons ( 13 a 1 , 13 a 2 . . . ) and the press rollers ( 14 a 1 , 14 a 2 . . . ) associated therewith to a bottom position and out of contact with the cam ring ( 11 ).