Method of Improving Performance of Existing Lubrication System

A lubricant injector comprising a body having an inlet for lubricant under pressure, an outlet, a measuring chamber for receiving lubricant from the inlet, a piston movable though a stroke in the measuring chamber for the discharge of a measured volume of lubricant from the measuring chamber and thence through the outlet, and a valve responsive to pressure conditions in the inlet to move between a first position for transmission of lubricant to said measuring chamber and a second position for said discharge, said valve being configured to be urged from said second position toward said first position by back pressure of lubricant in the outlet.