Abstract: A retention for male and female structural members, including a self-locking selectively releasable locking spring wire or clip received in opposing grooves on the male and female members for locking the two members together, and interengaged threaded formations on the two members for absorbing a major portion of any force tending to axially separate the two members.

Abstract: A coupling assembly for fluid-flow systems is disclosed which includes both a coupler and a nipple. The mating or sealing surfaces of the coupler and nipple are protected from dirt and other deleterious substances by corresponding moveable covers. The moveable covers not only protect the mating surfaces but present flush faces for the coupler and nipple which are easily cleaned. The construction of the coupling assembly is designed so that connection of the coupler and nipple may be accomplished by using only one hand. The coupler is designed so as to render the adapter and the valve a one-piece structure.

Abstract: A cartridge type check valve which may be either pilot operated or of the free flow type. The pilot operated type includes in combination a generally cylindrically-shaped housing having first and second end portions and having internal wall means defining an opening extending axially therethrough. A valve seat is formed on the internal wall means and a valve member is movable into and out of engagement with the valve seat to selectively prohibit and permit fluid flow through the axially extending opening at the valve seat. A fluid port is provided in the first end portion of the housing and serves to provide for fluid entrance into the axially extending opening. A control piston is positioned in the second end portion of the housing and is movable between first and second positions as is a valve stem, which is connected to the valve member and extends axially to a position adjacent the control piston and is adapted to be engaged and moved by the control piston.