Geared pump

Geared pumps are centrifugal pumps with a gear drive fitted between the pump shaft and the drive. A special variant is the high-pressure gear pump, a high-speed pump which is used to generate large heads (up to 1000 m) at small flow rates and high efficiencies. If used with a normal 2 or 4 pole electric motor a transmission gear is required to achieve a rotational speed of approximately 15,000 rpm, which is unusually high for a centrifugal pump. Such pumps comprise of a pump casing (in-line version), an open impeller with radial vanes and inducer, two mechanical seals for sealing off the fluid handled and the gear oil, and a radial and axial bearing supporting the sun gear (central gear) of the transmission gear (power split transmission) arranged above.

The motor is firmly flanged to the gear housing and fitted with a coupling, at its shaft end. The coupling meshes with the annulus, which drives the planet gears of the gear drive Decisive factors for the wear resistance of gears are the manufacturing quality, the lubrication of bearings and gear wheels, and the correct lubricant maintenance for cooling and cleaning purposes. See Fig.1 Geared pump

The single-stage back-pull out design, enables the complete rotating assembly to be pulled out towards the top and minimises any downtimes required for assembly work.

The in-line design (see In-line pump) only requires a minimum foundation size and allows for straightforward installation. Gentle speed changes can be achieved by selecting sufficiently small gear steps from the modular system. Each casing design is usually assigned a variety of impeller diameters and a corresponding diffuser design.

Thanks to the variation options by changing the input speed, transmission ratio, inducer, diffuser size, impeller size and trimmed impeller diameter any required operating point in the characteristic curves selection chart depending on the suction-side inlet conditions can be attained economically for a high-pressure geared pump.