RETRACTABLE BOARDING LADDER

摘要

RETRACTABLE BOARDING LADDER A boarding stairway moves relative to fixed structure in front of it between a raised retracted position and a lowered operative position. Rollers at the top of the stairway are guided in a fixed track that is straight and vertical along most of its length from its top but curves into a short downwardly-rearwardly inclined bottom section. The stringers of the stairway rest against a roller rotatable on a fixed horizontal axis that is below and to the rear of the track; hence the bottom of the stairway swings rearward as it moves down. A counterweight that moves vertically is connected with the stairway by a cable that has a vertical front stretch extending up from the counterweight to a cable guide above the stairway and a rear oblique stretch extending down from the guide to a connection on the stairway that is spaced below its top. As the stairway moves up and down, the inclination of the rear cable stretch so changes that the stairway can be manually started from each position towards the other and moves to the destination position by momentum, coming to a gradual stop at the destination position. ' , ,'