| 摘要 |
<p>PURPOSE:To prevent the generation of disengagement sound by housing two kinds of springs only by slightly changing the structure of a conventional housing chamber. CONSTITUTION:The housing section 24 of a metallic-coil large spring 16 is formed on the inner part side of the housing section 23 of a metallic-coil small spring 12 besides the housing section 23, and the metallic-coil small spring 12 is housed in the housing section 23 and the metallic-coil large spring 16 in the housing section 24. Since the elastic force of the metallic-coil large spring 16 is hardly affected by a temperature at that time, the effect of the elastic force of the spring 16 is not changed. Since only the metallic-coil small spring 12 is shrunk, the door of a gate is operated lightly as seen in conventional devices at the beginning of the operation of the door of the gate, and the metallic-coil large spring 16 works when a circular corner section 14 and a corner section 15 are separated, thus preventing disengagement sound.</p> |
