Coupling and transmission mechanism for window covering assembly

A manually operable window covering assembly comprising:

• a headrail having window covering suspended therefrom;
• a shaft disposed in said headrail on rotation of which the positions of the window covering may be adjusted said shaft having a predetermined cross-sectional shape defining driven formations and having a shaft axis;
• a transmission mechanism which in turn comprises:
• a housing disposed in said headrail;
• a drive gear supported by said housing and having a drive axis co-axial with said shaft axis;
• resilient arm means extending from said drive gear defining drive surfaces of predetermined cross-sectional shape;
• support means on said housing, engaging said headrail, and positioning said housing so that said drive gear is located co-axial with said shaft axis;
• a coupling defining two ends and coupled to said drive gear for transmission rotational movement of said drive gear to said shaft;
• a driven recess at one end of said coupling, said driven recess defining driven surface formations therein said resilient arm means of said drive gear being received therein and being resiliently biassed to engage said driven surface formations to transmit rotational movement thereto;
• a drive recess at said other end of said coupling having drive formations complementary to said shape of said shaft, for receiving said shaft;
• a stop member on said coupling;
• an abutment member in said headrail of rigid inflexible construction adapted to engage and stop said stop member on rotation of said coupling to a predetermined rotational position thereby then to prevent further rotation of said coupling;
• whereby upon manual rotation of said coupling to said predetermined rotational position and stopping of said stop member by said abutment member further manual rotation of said coupling and said shaft is halted, and, if excessive torque is then applied by continued manual rotation of said drive gear, said abutment member will resist further rotation of said coupling, while said resilient arm means will flex against said biassing within said recess in said coupling thereby in turn permitting said drive gear to continue to rotate, and said drive recess, and said resilient arm means being coaxial with one another and with said drive gear axis and said shaft axis.

A manually operable window covering assembly comprising:

• a head rail having window coverings suspended therefrom;
• a shaft disposed in said head rail on rotation of which the positions of the window coverings may be adjusted, said shaft having a predetermined cross-sectional shape defining driven formations and defining a shaft axis;
• a transmission mechanism which in turn comprises:
• a housing disposed in said head rail;
• drive gear supported by said housing and having a drive axis;
• support means on said housing, engaging the headrail and positioning said housing so that said drive gear is located co-axial with said shaft;
• a coupling coupled to said shaft for transmitting manual rotational movement of said drive gear to said shaft;
• a drive recess defined by said coupling having drive formations complementary to said shaft and coaxial therewith, for receiving said shaft;
• a stop member on said coupling;
• a rigid inflexible abutment member adapted to engage and stop said stop member on rotation of said coupling to a predetermined rotational position thereby then to prevent further rotation of said coupling;
• a recess in said drive gear of regular cross-section and having internal drive surfaces of predetermined cross-sectional shape;
• a co-axial adaptor coupled to said drive gear for co-rotation therewith and defining an acircular recess;
• an acircular axial extension of said adaptor being received in said recess in said drive gear, and,
• resilient arm means on said coupling adapted to be received in said acircular recess and formed to be complementary to said acircular recess and being resiliently biassed to engage said adapted to transmit rotational movement therebetween for rotation of said shaft and whereby, upon rotation of said coupling to said predetermined rotational position and engagement of said stop member with said abutment member further rotation of said drive gear, said resilient arm means will flex against said biassing thereby in turn permitting said drive gear and said adaptor to continue to rotate, and said drive recess, and said resilient arm means and said adaptor being coaxial with one another and with said drive gear axis and said shaft axis.