| 摘要 |
A pressure relief and venting closure cap for a filler neck of a vehicle gas or coolant system tank having an initial rotary drive which opens a vent valve in response to a differential movement between a cap shell and a vent valve actuator to vent the filler neck and wherein continued rotation of the cap shell causes disconnection of the cap shell and the filler neck. There are two separate drives from the cap shell, one to operate the vent valve and one to rotate a sealing element which screwingly connects the cap to the filler neck. A lost motion connection is provided for the drive to the sealing element so that disconnection can only take place after venting. A torque over-ride is provided for the closure to limit its rotary closing screwing movement after the vent valve is closed. A second drive between the lost motion connection and the vent valve is provided to stop differential rotation between the cap shell and the vent valve actuator when the closure member is rotated.
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