A radial piston hydraulic motor comprising a box frame with a cam ring connected thereto, pistons in a piston frame and press rollers 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 of the cam ring. The piston frame comprises connections between the interior space and passages, and a shutter valve is provided within each connection for controlling the hydraulic fluid flow through the connection between the passages and the interior space. The shutter valve is arranged to allow hydraulic fluid to flow from the passage into the interior space, when the pressure in the working pressure inlet passage, in the return passage and in the interior space is equal, i.e. the motor is in free-rotating state.

A radial piston hydraulic motor comprising a box frame with a cam ring connected thereto, pistons in a piston frame and press rollers 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 of the cam ring. The piston frame comprises connections between the interior space and passages, and a shutter valve is provided within each connection for controlling the hydraulic fluid flow through the connection between the passages and the interior space. The shutter valve is arranged to allow hydraulic fluid to flow from the passage into the interior space, when the pressure in the working pressure inlet passage, in the return passage and in the interior space is equal, i.e. the motor is in free-rotating state.

Provided is a liquid supply system that can suppress a functional decline of relief valves and improve cooling efficiency. The system includes a sealed container (110), a pump (120) disposed in a cryogenic liquid (L) contained inside the sealed container (110) and driven by a linear actuator (130), a first conduit (K1) for directing the cryogenic liquid (L) pumped out by the pump (120) to a cooled device (300) provided outside the sealed container (110), a second conduit (K2) for returning the cryogenic liquid (L) from the cooled device (300) into the sealed container (110), and a relief valve (170) that is connected to the first conduit (K1) within the sealed container (110) and releases the cryogenic liquid (L) into the sealed container (110).