Hydraulic device, hydraulic motor and construction machine

A hydraulic device comprising:

• a first block having a block inner circumferential portion and a plurality of internal teeth on the block inner circumferential portion;
• a second block configured to rotate relative to the first block;
• an oscillatory rotating body having a plurality of external teeth, the external teeth being smaller in number than the internal teeth, the oscillatory rotating body being provided inside the first block such that the oscillatory rotating body is oscillatorily rotatable, the oscillatory rotating body having an inner circumferential portion, the internal teeth and the external teeth defining a working chamber therebetween;
• a rotation restricting shaft extending from the inner circumferential portion of the oscillatory rotating body in a direction intersecting a radial direction, the rotation restricting shaft coupling the oscillatory rotating body and the second block such that the oscillatory rotating body and the second block are not allowed to rotate relative to each other while allowing the oscillatory rotating body to oscillatorily rotate;
• a first friction plate configured to rotate together with the oscillatory rotating body;
• a second friction plate restricted from rotating by the second or first block;
• and
• a press mechanism configured to press the first and second friction plates against each other.