Lubricating oil pump
Lubricating oil pumps are used to supply oil to lubrication points, e.g. for plain bearings.
In the case of circulation lubrication, the lubricating oil pump takes in an amount of oil from a reservoir, forces it through the lubrication points and then feeds it back to the reservoir. Gear pumps, which are able to generate high static pressure in the lubricating oil system, are preferably used for this purpose.
In a fresh oil or economy lubrication system, each lubrication point is supplied with a quantity of oil adequate for its needs. Special piston pumps are usually required for this purpose.
For the supply of oil to large plain bearings as in steam turbines or generators, single-stage volute casing or multistage pumps are used. They are submersible pumps which rest directly on the oil reservoir and have a throttling bush at the shaft passage, instead of a conventional shaft seal.
The oil leakage thus runs directly back into the oil reservoir.
The lubricating pump used for grease-lubricated plain bearings is also a piston pump. In this case the grease reservoir is situated above the pump to ensure that grease is always fed positively to the lubricating pump with the aid of a mechanically driven stirrer and slightly excessive pressure in the reservoir.