Dispenser-gun assembly for viscous fluids and dispenser therefor

摘要

A dispenser for viscous fluids includes a tubular cylindrical barrel member, a dispensing nozzle on one end of the barrel member and a piston element which is sealingly received in the barrel member and slidable therein in a direction toward the nozzle for dispensing a viscous fluid from the barrel member. The barrel member and the piston element are constructed so that the piston element is freely slidable in a reverse direction in the barrel member to relieve the pressure on the fluid in the barrel member after a dispensing operation has been completed and to thereby eliminate post extrusion from the dispenser. The dispenser is operative in combination with a dispenser gun which includes a drive plunger and an advancing mechanism which is operative for advancing the drive plunger in order to advance the piston element of the dispenser in the barrel member thereof. The advancing mechanism is further operative for automatically retracting the drive plunger after a dispensing operation has been completed so that the piston element is free to move rearwardly in the barrel member to relieve the pressure on the fluid in the barrel member.