摘要 |
A portable power supply assembly ( 24 ) capable of providing electrical power to an electric motor of a flexible shutter assembly ( 13 ) and a torsion spring assembly ( 21 ) capable of reducing load on the electric motor of a shutter assembly. The portable power supply assembly includes a portable supply of power ( 26 ), a detachable body ( 24 ) capable of electrically connecting the portable supply of power ( 26 ) to the receiving port( 25 ) and a means of controlling the portable supply of power ( 29 ). The torsion spring assembly ( 21 ) includes a housing ( 57, 58 ) able to be mounted at or towards one end of the shaft; a torsion spring ( 56 ) mounted within the housing, one end ( 63 ) of the torsion spring being held with respect to the housing ( 57, 58 ) and a shaft adapter ( 64 ) rotatably mounted with respect to the housing, the other end ( 67 ) of the torsion spring being held with respect to the shaft adapter. |