| 摘要 |
A fence line is provided including a pair of spaced posts between which a fence opening is defined and wherein a cattle guard is substantially centered in the opening and spans considerably less than the width of the opening. A pair of edge upstanding panel-like wing closure members are provided at opposite sides of the opening between the posts and the adjacent sides of the cattle guard and pivot structure pivotally mounts first corresponding upstanding base edge portions of the closure members at the opposite sides of the opening for angular displacement about upstanding axes and with the closure members including second free swinging upstanding edge portions opposite the first edge portions swingable toward and away from closed positions with the second edge portions at least closely adjacent the opposite sides of the cattle guard and an upstanding plane containing the fence line opening. The pivot structure is operative to yieldingly bias the wing closure members from open positions thereof toward the closed positions thereof and is also operative to yieldingly resist movement of the wing closure members from the closed positions toward the open positions with a greater resistance to movement of the closure members from the closed positions toward the open positions than the biasing force on the closure members to swing the latter from the open positions toward the closed positions.
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