| 摘要 |
A back chock and door closure delaying device for a door closure comprises a rotational shaft 3 sealed in a casing 1 having a pair of chambers 5, 6. The rotational shaft 3 is formed with a pair of rotary blades 7 which define high pressure chambers 5a, 6a and low pressure chambers 5b, 6b within the casing, which is filled with a viscous fluid. The rotational shaft 3 has a narrow passage 12 which connects both high pressure chambers 5a, 6a to both low pressure chambers 5b, 6b, a wide passage 10 which connects the two high pressure chambers 5a, 6a and is provided with a regulating valve 14 to regulate the fluid flow through the passage depending on the force applied to the rotational shaft 3. Thus when a strong wind blows the door, the valve 14 closes restricting the flow of fluid through passage 10 thereby limiting the speed at which the door closes. <IMAGE>
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