摘要 |
<p>A mechanism for driving the two halves (5) of a centrally-opening door at a substantially constant speed along an arc of a circle, where the door aperture is wide and said mechanism takes up limited vertical space, particularly in lift, building or vehicle doors. Each half (5) of the door is connected to a pivot arm (13) linked at one point (P, Q) to a secondary drive (20) using a chain or a synchronous belt (21) which is slightly elongatable by means of a resilient compensating element (24). Both secondary drives (20) are driven by a motor (17) via a common primary drive including two stages (18 and 19) separated by a frictional torque limiter (33).</p> |