A combination valve for relieving pressure and vacuum conditions in a pressurizable tank includes an elongated rod with a spring seat thereon, a body member sealingly securable to the tank, a cover member secured for axial movement with the rod, a spring mounted between the body member and rod so as to yieldably urge the rod and cover member toward the body member, and an O-ring rollably disposed in a groove in the body member. The width of the O-ring is substantially less than the width of the groove such that the O-ring is rollable within the groove between the body member and the cover member. A seal member mounts on the rod and extends between the cavity and the cover member so as to normally sealingly engage the cover member and cover the vent. In a vacuum venting mode, the flexible seal member is suctioned away from the cover member and the vents therein in response to a predetermined vacuum present in the tank. The air can then be drawn into the tank through the vent. In a pressure relieving mode, the pressure in the tank overcomes the force of the spring so as to move the cover member upwardly with respect to the body member. This relative movement causes the O-ring to roll upwardly and eventually stop on an upper shoulder of the groove. Thereafter, movement of the cover member relative to the body member causes the cover member to slide past the O-ring and open an annular pressure relieving passage between the cover member and the O-ring.
An internal combustion engine includes a combination intake and exhaust valve assembly. The combination intake and exhaust valve assembly includes an intake valve and an exhaust valve which are disposed in a coaxial relationship. The intake valve has an annular rim portion which is movable into and out of engagement with an intake valve seat. The exhaust valve has a head end portion with an annular rim which is movable into and out of engagement with a valve seat disposed on the intake valve. When the intake valve is operated from a closed position to an open position, the intake and exhaust valves move together. A pair of rocker arms may be used to move the intake valve from its closed position to its open position. A single rocker arm may be used to move the exhaust valve from its closed position to its open position.
