The impulse turbine was one of the basic steam turbines. It involved striking of the blades by a stream or a jet of high pressure steam, which caused the blades of the turbine to rotate. The direction of the jet was perpendicular to the axis of the blade. It was realized that the impulse turbine was not very efficient and required high pressures, which is also quite difficult to maintain. The impulse turbine has nozzles that are fixed to convert the steam to high pressure steam before letting it strike the blades.