Radial piston pump

Radial piston pumps are used in hydraulic systems involving high pressure, above 480 bar and of up to 700 bar. It is used in press, metalworking machines, lifting machines.

The pistons, in a radial piston pump, extend in a radial direction symmetrically around the drive shaft.

Types

The stroke of each piston, in a radial piston pump, is caused by:

• an eccentric drive shaft (outside impinged radial piston pump),
• an external eccentric tappet (inside impinged radial piston pump).

Eccentric drive shaft pump design

In fig. 1 is a inside impinged radial piston pump.

Most swashplate radial pumps consist of a few basic components:

• Shaft,
• Base,
• Piston,
• Rotor,
• Shaft,
• Cap.

As the drive shaft rotates, the connecting rods push the pistons back and forth in the cylinders to develop the pumping action.

External eccentric tappet design

In fig. 2 is a valve controlled radial piston pump with eccentric shaft.

• Housing,
• Piston,
• Pivot,
• Pressure valve,
• Shaft,
• Spring,
• Suction valve,
• Cylinder sleeve.

As the drive shaft rotates, when the piston moves in the direction of the centre axis of the eccentre, the chamber becomes larger and the suction valve opens due to the negative pressure produced, fluid flows into chamber.

When the piston is moved in the direction of the pivot, fluid is compressed in the chamber, the pressure valve in the pivot opens, fluid flows into the high pressure line.

Radial pump flow

• Shaft speed - n,
• Displacement volume - V,
• Eccentricity - e, eccentricity determines the stroke of the pistons,
• z - number of pistons,
• d - diameter of piston.