JPH0478833B

It is proposed that a drive tappet of a pump piston be provided with an integrated hydraulic supply onset adjusting device. This device includes an adjusting piston, which is guided in a work cylinder and is joined to the piston base of the pump piston, and a pressure chamber. The delivery of the control fluid pumped into the pressure chamber is effected via a delivery conduit discharging into the cylinder bore and a connecting conduit extending inside the pump piston and leading to the pressure chamber. By means of the control point located at the discharge point of the delivery conduit, relatively high control pressures can be fed into the system without relatively large leakage losses. The apparatus is usable in all piston-type supply pumps in which a control face on the pump piston, in cooperation with the control opening in the cylinder bore, determines the onset of supply.