• The HP4 supply pump component parts and functions are basically the same as for the HP3. The explanations below
only cover those points on which the HP4 differs from the HP3. For other parts, see the appropriate item in the explanation of the HP3.
Pump Unit (Eccentric Cam, Ring Cam, Plunger)
• A triangular ring cam is installed on the eccentric cam on the drive shaft, and three plungers are installed to the ring cam at intervals of 120°.
• Because the rotation of the camshaft makes the eccentric cam rotate eccentrically, the ring cam follows this and this moves the three plungers reciprocally. (The ring cam itself does not rotate.)