the invention relates to a piston pump with a piston , which is guided so that the piston can move axially in a liner that has been inserted into a pump housing and is driven into a reciprocating stroke motion by means of a cam that is driven to rotate . the invention uses a liner that is manufactured as an injection - molded plastic part . the plastic liner has advantages with regard to manufacture , damping behavior when there are pressure changes , and noise generation . furthermore , the invention proposes affixing a filter integral with the liner when the liner is injection molded .