Automatic pressure release mechanism for caulk gun

Claim 1

In a caulking gun comprising: (a) a housing for holding a caulking tube, said housing having a rear wall and an intermediate wall, (b) a piston rod having a piston at one end thereof for driving caulk compound from a tube of caulk, (c) a handle secured to said housing, (d) a trigger pivotally mounted to said handle for rotation about a pivot member, (e) a driving dog means cooperating with said trigger and said rod for forwardly driving said rod a finite distance each time the trigger is rotated in a counterclockwise direction, the improvement comprising: (a) a deformable resilient pressure release means having a central bore therein, aligned with the path of travel of said rod and being adapted for engagement by said rod during forward travel, (b) said pressure release means being moveable from a first relaxed position to a compressed deformed position upon engagement of said rod therewith, (c) said release means also being adapted upon cessation of the forwardly driving of said rod, and clockwise rotation of said trigger to relax and return to the relaxed uncompressed position, (d) said rod being moveable to a position opposite its initial direction of travel upon decompression of said release means, (e) a spring carried by said rod, disposed behind said pressure release means, said deformable resilient pressure release means being disposed between the intermediate wall of said housing and the rear wall thereof and being compressed by the impingement of the spring therefrom upon trigger rotation, said pressure release means, and said spring cooperating to urge the driving dog means rearwardly to reset same into its at rest position and rendering it available for cooperation with said trigger by tensing the spring against said dog, said release means releasably gripping said rod and moving forwardly with said rod upon relaxation of said spring after reset of said dog means.