A telescopically extendable and collapsible ladder assembly having a bottom ladder section, a top ladder section, and one or more intermediate ladder sections,
- wherein each of the ladder sections comprises two tubular stile members, each tubular stile member having a bottom end and a top end and each tubular stile member defining an inner space, which tubular stile members are arranged parallel to each other and are interconnected at the top end by a ladder rung to form a U-shaped ladder section, wherein the tubular stile members of the bottom ladder section are furthermore connected by a bottom ladder rung,
- wherein the top ladder section and the one or more intermediate ladder sections are collapsible ladder sections, each collapsible ladder section having the bottom end of the tubular stile members telescopically inserted into the top end of the tubular stile members of an adjacent ladder section, the adjacent ladder section being the bottom ladder section or an intermediate ladder section, such that each collapsible ladder section can be moved relative to the adjacent ladder section between;
- a collapsed position, in which the bottom end of the tubular stile members of the collapsible ladder section are located near the bottom end of the tubular stile members of the adjacent ladder section;
- and
- an extended position, in which the bottom end of the tubular stile members of the collapsible ladder section are located away from the bottom end of the tubular stile members of the adjacent ladder section;
- wherein the ladder assembly comprises latch mechanisms for locking the telescopically inserted tubular stile members of the collapsible ladder sections relative to the adjacent ladder sections when the collapsible ladder section are in the extended position, the latch mechanisms being associated with actuators for unlocking the tubular stile members in order to allow for collapsing of the ladder assembly, and moving all collapsible ladder sections into the collapsed position,
- wherein the collapsible ladder sections are each provided with an air damper at the bottom end of at least one of the tubular stile members, which air dampers provide retardation of gravity induced velocity of the collapsible ladder sections upon collapse of the ladder sections on the basis of throttling an airflow flowing out of the inner space of the tubular stile member of the adjacent ladder section into the inner space of the tubular stile member of the collapsible ladder section being inserted into the inner space of the tubular stile member of the adjacent ladder section,
- wherein each of the air dampers comprises:
- an air damper body defining a throttle opening, which throttle opening provides an air path that enables air to flow out of the tubular stile member of the adjacent ladder section into the tubular stile member of the collapsible ladder section on which the air damper is mounted and vice versa;
- a throttle valve, which throttle valve is located at the throttle opening, and which throttle valve is movable relative to the throttle opening between:
- a release position, in which release position the throttle valve is located away from the throttle opening to allow for a maximum air flow to flow through the throttle opening out of the stile member on which the air damper is mounted, and thus, upon extending the ladder section, to enable aerating of the inner space of the stile member of the adjacent ladder section out of which the collapsing ladder section is moved;
- and
- a throttle position, in which throttle position the throttle valve is located adjacent to or in the throttle opening to throttle or block an air flow flowing through the throttle opening into the stile member of the collapsible ladder section on which the air damper is mounted, and thus, upon collapsing of the collapsible ladder section, enabling a pressure build up in the inner space of the stile member of the adjacent ladder section into which the collapsible ladder section is being inserted;
- wherein the ladder assembly further comprises:
- a throttle valve securing device, located at the bottom end of the adjacent ladder section, for cooperating with the throttle valve of the air damper when the collapsible ladder section is in the collapsed position, to secure the throttle valve in its throttle position and to thus enable the throttle valve to throttle or block, an air flow flowing through the throttle opening out of the tubular stile member on which the air damper is mounted, and thus, allow for a pressure build up in the inner space of the tubular stile member on which the air damper is mounted when a stile member of a collapsing ladder section is inserted in the inner space of that stile member.