Patent ID: 7137792

Claim:
A piston pump for transporting highly viscous media from a storage reservoir to a spray gun, the pump having a differential piston positioned in a cylindrical housing and translationally drivable, the pump having a first pressure chamber connected to a second pressure chamber via a connecting line having a check valve therein, the pump further being connected with a storage reservoir via an inlet valve, wherein the differential piston is provided with a dipping piston that dips into the medium to be transported, the dipping piston being attached to an aligned piston rod, wherein a pass-through of the piston rod from the first pressure chamber is closed fluid-tight by at least one seal, and wherein a transport line is disposed in the vicinity of the pass-through of the piston rod; wherein the pass-through of the piston rod is provided with at least a portion of said transport line provided in a connecting piece connected with the housing of said differential piston, and wherein an extension piece receives the dipping piston and is attached to the connecting piece; wherein the inlet valve is located upline from the first pressure chamber; and wherein the first pressure chamber is in the connecting piece.