| 摘要 |
The invention relates to a telescopically extendable and collapsible ladder assembly having a bottom ladder section, a top ladder section, and one or more intermediate ladder sections. The top ladder section and the one or more intermediate ladder sections are collapsible ladder sections,multiple of which are provided with air dampers, being mounted on a bottom end of tubular stile members of the collapsible ladder sections. The air damper comprises a barrier member that defines one or more throttle openings,a valve member, and an actuator member. The actuator member pushes the valve member into the throttle position during collapse of the collapsible ladder section, and pushes the valve member into the non-throttle position during extension of the collapsible ladder section. |
