| 摘要 |
A closure apparatus, comprising: a sub body having an annular opening; a closure door carried by the sub body and movable thereto between an open position and a closed position; a plurality of arcuate segments arranged between the closure door and the sub body in the closed position; wherein bracketless gaps are defined between adjacent arcuate segments; a drive hub rotatably mounted to the closure door for rotation about a drive axis; and a plurality of cross bars, each cross bar having a first end pivotably mounted to the drive hub and a second end pivotably mounted to one of the arcuate segments; wherein the arcuate segments are directly mounted to the cross bars and pivotable relative to the cross bars via fasteners, each fastener pivotably connecting one of the arcuate segments with one of the crossbars. |
