Patent ID: 8113818

Claim:
A valve gate assembly for use with a hot manifold, the valve gate assembly formed around an axis and comprising: a piston and a cylinder, the piston actuable along the axis within the cylinder between a forward position and a rear position, the piston having a cylindrical wall having a forward end; a piston stop surface extending radially inwardly from the forward end of the first cylindrical wall and terminating in a radially inward end; a forward pressure surface extending radially inwardly from the inward end of the piston stop surface such that a fluid acting on the forward pressure surface will urge the piston in a rearward direction; the cylinder having a cylindrical first wall formed to be parallel to the axis, the piston axially displaceable along the wall; a forward opening for positioning adjacent the hot manifold and communicating with a hot manifold pin hole; a cylinder stop surface disposed to contact the piston stop surface with the piston in the forward position, the cylinder stop surface being radially outward of at least a portion of the forward pressure surface of the piston; a chamber disposed forwardly of the cylinder stop surface, an open gate supply port opening onto the chamber and in fluid communication with the forward pressure surface of the piston; and a shutoff pin substantially aligned with the axis and having an elongated shaft with a front end forward of the cylinder and a rear end affixed to the piston, the shaft passable through the forward opening and the hot manifold pin hole to a gate of a mold, the front end of the shutoff pin operable to open and close the gate.