A pump is a machine that uses moving mechanical parts (rotary or alternative rectilinear) to lift or move or collect fluid material.

A pump operates in a confined space, between a suction duct and a supply one.

Pump usually means the device used to move liquids.

The pumps features are:

  • capacity Q – the volume of fluid moved in a unit of time, usually expressed in m3/s;
  • pumping speed (the volume of substance moved in time function);
  • prevalence H – the maximum lifting height, normally expressed in meters.

Some physical and hydraulic features can influence the pumps choice, such as viscosity, density and temperature.

Pumps differ not only in function of the prevalence, in the capacity of the features of liquid to be pumped, but also according to the applied motive power (e.g. electrical pumps or pumps with combustion engine).

The pumps can be divided in:

  • Volumetric
  • Fluid dynamic or hydraulic

Volumetric pumps types:

  • gear
  • lobes
  • blades
  • screws
  • pistons

Volumetric pumps use the volume variation or a room movement to provoke an aspiration or a boost on the fluid.

The fundamental feature is that the supplied capacity is constant for each working cycle and does not depend on the prevalence, but only on the number of effected cycles in the time unit.

They can be rotary or alternative. The gear pumps are rotary ones.

In gear pump, it is the volume variation caused by meshing of the teeth of two cogwheel to be exploited. They are widely used to pump lubrication oil in the vehicles engines, to pump oil in the hydraulic circuit of  earth moving machines, and generally in all those applications where the fluid is viscous, providing it is not harmful to the pump itself, in function of the sliding between the component parts.