A lubrication system typically used on critical machines due to its inherent high reliability. A basic circulating system is composed of a reservoir, a pump that is driven off either the machine shaft or an electric motor, a heater, a filter, a heat exchanger, and control valves to maintain system pressure and temperature. One or more of these system elements may be spared to improve system reliability. Pressure switches or transmitters are often used to alert operators to a loss of pressure, and the reservoir level is monitored with either a level transmitter or level glass. The pump takes oil from the reservoir and forces it through filters, heat exchangers, etc., until it reaches all the required machine lube points at the proper flow and temperature. Some or all the oil from the pump may bypass the heat exchanger to maintain the oil supply at the proper temperature. After providing the required lubrication, the oil gravity flows back to the reservoir to recirculate.
Also known as a Closed-Loop Lubrication System.