Patent ID: 8578653

Claim:
A drive assembly for a moveable closure selected from a door, gate and barrier, comprising: a track; a trolley for connection to the moveable closure, the trolley mountable to run along the track; a longitudinal drive comprising a chain or belt, connectable in a closed loop arrangement around or within the track, said closed loop defining a plane; the trolley provided with an engagement mechanism for selective engagement between the trolley and the longitudinal drive; the engagement mechanism including an engagement member arranged for selective movement in a direction substantially transverse to the longitudinal direction of the longitudinal drive and in a direction less than 45° from the plane of the loop of the longitudinal drive; the engagement member including or cooperating with a cam part a cam part which rotates about the engagement member, and a camming cooperation between the cam part and the trolley body which converts rotation of the cam part about the engagement member into the required movement of the engagement member.