Grease Gun and Coupling

Author:  Everett Fox, J. Schaefer, R. Leliaert
Source:  US Patent 3,788,427
Doc ID:  1974008
Year of Publication:  1974
Abstract:  
An improved high pressure grease gun and coupling unit for connecting the gun to a grease fitting. The coupling comprises a piston actuated collet type clamp which is normally spring biased to a position in which the collet is compressed. An axially movable valve element extends through the collet clamp and is engageable with the end of the grease fitting when the coupling is clamped onto a fitting. This valve is automatically opened by engagement with the fitting and is automatically closed by the pressure of the grease contained within the coupling when the coupling is removed from the fitting. The gus has a pressure relief valve and a pressure relief valve safety which prevents actuation of the gun whenever the relief valve is open.