Abstract: The present invention provides a method and apparatus for controlling the rate of flow of fluid in a high (e.g. 100 kg/sq cm) pressure hydraulic circuit such as is found in pneumatic piston and cylinder arrangements having hydraulic damping and which may be used to control the feed rate of a cutting tool. Control is achieved by incorporating into the fluid circuit, upstream of the flow control orifice, a pressure reducing valve designed to provide a controlled low (e.g. 7 kg/sq cm) pressure independently of changes in applied pressure or demanded flow rates and which further automatically clears itself of any silt deposited thereon from the hydraulic fluid.