A means for mounting a diaphragm in an accumulator-reservoir device or the like in which the gland receiving the diaphgram bead has faces formed to oppose such pull on the bead as will break the sealing contact between gland faces and the bead. Back draft angles and grooved surfaces are used in conjunction...http://www.google.com.tw/patents/US3983902?utm_source=gb-gplus-share專利 US3983902 - Means for mounting a diaphragm in an accumulator-reservoir device
