Abstract: A clutch includes two coupling members respectively secured or coupled to two transmission shafts and each coupling member having a plurality of coupling teeth formed with arcuate or round tip portions for a smooth engaging of the two coupling members, and an electromagnetic controller electromagnetically driving a thrusting cam in relation to a stationary cam mounted on a base housing of the clutch, so that the clutch can be coupled or uncoupled smoothly, instantly and lightly.

Abstract: A variable bed includes a foldable bed having a plurality of bed units pivotally joined with one another normally lying on a bed frame positioned under the foldable bed; a central jack capable of raising a bed unit of a back portion of the foldable bed for forming a reclining bed or a folding chair on the frame; two end jacks for raising a head portion and a foot portion of the bed for forming a concave bed or for suspending the bed above the frame for serving as a hammock; and a driving motor as controlled by several clutches for driving the jacks or for moving the bed units frontwardly for converting a reclining bed to a folding chair to allow several front bed units to be pendant on a front end wall of the bed frame.

Abstract: A collapsible table and chair set includes a base platform, a driving motor driving a main transmission shaft rotating a master bevel gear rotatably mounted in a central portion of the platform, a reel having a wire rope wound on the reel and driven by the motor for rotating the reel to wind the rope of which an upper rope end is hanged on a wall for vertically erecting a folded table and a chair set, a table and a plurality of chairs radially disposed about the table pivotably supported by a plurality of links which are driven by a plurality of worms radially disposed on the platform and driven by the master bevel gear for raising the links for extending the table and the chairs, or for lowering the links for folding the same.