The 5H oil pump is a positive displacement vane-type pump used to move oil from a reservoir to the engine. It is typically used in diesel engines to provide lubrication to the engine components. The 5H pump is designed to maintain a constant pressure within the system, ensuring that the oil is delivered at an optimal rate. It is particularly suited to engines with high RPMs, as it can maintain a consistent flow of oil even when the engine is running at high speeds.