Abstract: A main body has a partition wall provided in the interior of the main body and a communication hole formed in the wall. A valve body is disposed in the main body to be movable between a first position and a second position. At the first position the valve body closes the hole, and at the second position the valve body opens the hole. A spring urges the valve body into the second position. An operating lever is connected in a universal-joint fashion to the main body. A cam is formed on the lever and slidably contact with a cam contact element disposed on the valve body in a position away from a plane including a center axis of the main body. A pair of grooves are formed on the lever at each side of the cam and extend along the plane. A pair of projections are provided on the valve body and inserted into the grooves. When the lever is rotated in one or the other direction in the plane by an external force, the valve body is moved between the first and the second position by the action of the cam.