is a once-through lubrication device comprising a battery of individual pumps that continuously meter oil to each of a number of moving parts. It is typically used in steam engines, gas engines, diesel engines and large compressors. The oil is pumped into a sight-feed bowl containing an inert, dense, transparent fluid (see sight fluid) through which the oil floats upward to the feed line. Mechanical lubrication is similar to centralized lubrication, the principal distinction being that a centralized system is served by a single pump, or by two or more pumps discharging into a common manifold.