This consists of a hydraulic pressure pump which is connected to the butterfly valve. Engine speed is low but the butterfly valve is fully open. The butterfly valve is actuated through hydraulic linkages. Examples of high recovery valve - butterfly valve, ball valve, plug valve, gate valve etc. Many diesel engines do not have butterfly valve throttles. When closed, it acts exactly like a butterfly valve and is tight. Rotary control valves, butterfly valve and ball valves are good examples. The throttle on a gasoline engine is typically a butterfly valve. James Watt used a butterfly valve in his steam engine prototypes. The butterfly valve has been in use since the late 18th century. A butterfly valve is from a family of valves called quarter-turn valves. The valve best suited for high-pressure systems is the triple offset butterfly valve. A butterfly valve is a valve that isolates or regulates the flow of a fluid. A hand-controlled butterfly valve was located in the hollow crankshaft to regulate throttle. External wastegates can also use a butterfly valve, though that is far less common.