This is a seven piston pump driven by two belts at half engine speed.

An oscillating plate, driven from an eccentric shaft, drives the pistons in an alternating rectilinear motion by pushrods.

Half-turn of plate: Pushrod advancing (fig.3).

The piston (a) pushed by the rod (b) compresses the spring (R), closing the inlet valves of its cylinder (c) and pushing out the contained fluid.

This liquid pushes the valve (d) and moves towards the pressure regulator: Compression.

Half-turn of plate: Pushrod returning (fig.2).

Spring (R) pushes back the piston (a), the valve (d) is closed again under the action of its spring (R) and creates a depression in the cylinder.

The inlet valves are uncovered by the piston and the liquid enters the cylinder (c): Intake.