Abstract: In an anti-reverse valve, a first communication passage that allows the first supply and discharge passage to communicate with the first pressure chamber and a second communication passage that allows the second supply and discharge passage to communicate with the second pressure chamber are provided inside the spool, a first restrictor is provided in the first communication passage, a second restrictor is provided in the second communication passage, and a first annular groove that allows the first supply and discharge passage to communicate with the drain passage when the spool is placed at the first communication position and a second annular groove that allows the second supply and discharge passage to communicate with the drain passage when the spool is placed at the second communication position are provided in an outer periphery of the spool.

Abstract: A brake system configured to brake a hydraulic motor includes a valve device configured to open and close supply passages through which working oil pressurized in a hydraulic pump is supplied to a brake device, the valve device has a first connection port to which the working oil is led from the hydraulic pump, a second connection port from which the working oil is led to the brake device, and a valve element provided with a pressure receiving surface facing the first connection port, and the valve element permits communication between the first connection port and the second connection port when pressure of the working oil led to the first connection port reaches predetermined pressure, and shuts off the communication between the first connection port and the second connection port when the pressure of the working oil led to the first connection port becomes less than the predetermined pressure.

Abstract: An optical waveguide of an optical deflector comprising a planar optical waveguide or an optical fiber type optical waveguide is cut while perpendicularly pressing a blade having a blade tip with an angle of inclination against the optical waveguide at a desired location thereof to form an oblique end face serviceable as an oblique end face mirror.