| 摘要 |
A door closing device 951, of the type which applies a force to push a door towards a closed position is configured so that the force may he isolated from the door. In this passive mode (Fig. 9a) the door is freely pivotable without effect from the door closer. The device is arranged so that in response to a control signal, such as the acoustic signal emitted by a smoke detector or fire alarm system, it changes to an active mode (Fig, 9b) in which the force is applied to close the door. Isolation of the force may be by means of a clutch mechanism or by a catch mechanism which holds an actuating arm in the door open position. A device for attachment to a standard prior art door closer, in order to convert it to a door closer having active and passive modes, is also disclosed. <IMAGE> |
