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Cam and Groove Coupling

hose coupling method widely used in petroleum marketing operations.

The traditional method of connecting a hose to a faucet, or to another hose, has been through use of screw type couplings. This is a common way of connecting lengths of garden hose, for example.

With larger hoses, such as 4-inch delivery hose used to transfer petroleum products from a tank vehicle to storage tanks, screw type connections would be excessively slow and cumbersome. To make it possible for fuel delivery truck drivers to make quick connections between faucets on their tank vehicles and the hose that carries product into storage tanks, and between the hose and tank, cam and groove couplings have been developed.

The coupling is a two-piece assembly. In a typical application, one section of the coupling is fitted directly onto a tank delivery vehicle beneath the product compartment. This section has a shallow groove running all the way around its outer perimeter.

The other section of the coupling is attached directly to one end of a delivery hose that is to be connected to the tank delivery vehicle. This section is a round piece of machined metal, usually brass or aluminum, with two ear-like cam arms projecting from opposite sides. Inside the section is a gasket made of Buna-N, Neoprene, or similar material.

To make a connection between the two sections of the coupling, the operator inserts the hose end of the coupling into the opposing section mounted on the tank vehicle. He then pulls down on the two ear-like cam arms. This pulling motion causes the arms to rotate. Curved sections on the inside ends of the cam arms seat themselves in the groove on the tank truck portion of the coupling. When the cam ends fully engage themselves in the groove, they pull the inner gasket into firm contact with a lip on the opposing section of the coupling. This creates a liquid-tight seal.

The hose can later be uncoupled from its connection to the tank vehicle by reversing the process–pulling up on the cam arms.