Patent ID: 8672162

Claim:
A power tool comprising: a reservoir reserving oil, said reservoir comprising: a rim surrounding an opening and having; an interior having an interior pressure; and, an exterior having an exterior pressure; a cap attached to the opening, said cap comprising: a cap body having a communicating path extending between the interior and the exterior; a valve covering the communicating path, the valve comprising: an integral sealing flange for sealing the cap to the rim of the reservoir; a central portion having a projecting part with a slit, the slit deforming between a closed position to an open position, and the central portion elastically deforming between: a non-bulging orientation wherein the central portion has not significantly deformed and the slit remains in the closed position, the non-bulging orientation occurring when the exterior pressure and the interior pressure are in equilibrium; an inward bulging orientation wherein the central portion extends away from the exterior of the reservoir toward the interior of the reservoir and the slit outwardly deforms to the open position, the inward bulging orientation occurring when the exterior pressure substantially exceeds the interior pressure; and, an outward bulging orientation wherein the central portion extends away from the interior of the reservoir toward the exterior of the reservoir and the slit inwardly deforms to the open position, the outward bulging orientation occurring when the interior pressure substantially exceeds the exterior pressure; a supporting plate arranged between the cap body and the rim of the reservoir, the supporting plate capable of swinging relative to the cap body; a biasing member biasing the supporting plate toward the rim, the biasing member being disposed between the cap body and the supporting plate; and, wherein the supporting plate and the biasing member cooperate to allow the integral sealing flange of the cap to sealingly engage the rim of the reservoir.