An hydraulic oil cooler is a device designed to prevent oil used in hydraulic systems from overheating. This is a critical function in hydraulic systems, as overheating of the oil can lead to a drop in system efficiency and excessive wear of the system components in general due to reduced oil viscosity. In most cases, the coolers allow the oil to shed accumulated thermal energy into a secondary medium, typically water or air, by passing the hot oil through a series of thin tubes exposed to a constant flow of low temperature cooling medium. The cooling medium absorbs heat from the oil and carries it away from the cooler, where it is typically shed into the atmosphere. Common hydraulic oil cooler designs include radiator, shell and tube, or plate and frame types.