A fastening apparatus includes: a base having a first sliding groove; a rotation member pivotally connected to the base and having at least two locking states, the rotation member has a second sliding groove; a locking member having a locked state and an unlocked state, in the locked state, the rotation member is located in both the first sliding groove and the second sliding groove; in the unlocked state, the locking member is withdrawn from the first sliding groove or the second sliding groove to allow the rotation member to rotate relative to the base; an elastic element configured to maintain the locking member in the locked state; and a releasing member configured to drive the locking member to move against an elastic force of the elastic element, such that the locking member is switched from the locked state to the unlocked state.

A modular linking system provides a positioning and supporting structure for mounting various components, particularly on a wheelchair structure. A wheelchair kit includes such a modular linking system and further wheelchair includes at least one modular linking system or at least one wheelchair kit.

A plate folding and unfolding device and a solar panel structure are provided. The plate folding and unfolding device includes a cam fixed with first plate piece, and a rotating shaft is disposed inside the cam in an axial direction of the cam; a connecting rod, where the connecting rod includes a first end and a second end that are opposite to each other, the first end is connected vertically to the rotating shaft, and the second end is fixed to a second plate piece; a positioning shaft, where the positioning shaft is disposed, on the connecting rod; and an elastic piece, where the elastic piece is disposed on the connecting rod, one end of the elastic piece is connected to the positioning shaft, where a groove that accommodates the positioning shaft is disposed at at least one location of the outer peripheral surface of the cam.

A plate folding and unfolding device and a solar panel structure are provided. The plate folding and unfolding device includes a cam fixed with first plate piece, and a rotating shaft is disposed inside the cam in an axial direction of the cam; a connecting rod, where the connecting rod includes a first end and a second end that are opposite to each other, the first end is connected vertically to the rotating shaft, and the second end is fixed to a second plate piece; a positioning shaft, where the positioning shaft is disposed, on the connecting rod; and an elastic piece, where the elastic piece is disposed on the connecting rod, one end of the elastic piece is connected to the positioning shaft, where a groove that accommodates the positioning shaft is disposed at at least one location of the outer peripheral surface of the cam.

A child play yard includes a frame that includes legs, lower cross bars having first ends pivotally coupled to lower ends of the legs, and a hub pivotally coupled to second ends of the lower cross bars, the hub including a hub mechanical central tube, a column slidably disposed within the hub mechanical central tube, a hub mechanical spindle disposed within the column, and hub lock fingers pivotally coupled to a lower portion of the column and including lower feet portions, the hub mechanical spindle having an enlarged diameter lower end portion that engages lower inner sidewalls of the hub lock fingers and maintains the lower feet portions of the hub lock fingers outside a perimeter of a lower opening of the hub mechanical central tube when the hub is disposed in a lowermost position in the frame.

A child play yard includes a frame that includes legs, lower cross bars having first ends pivotally coupled to lower ends of the legs, and a hub pivotally coupled to second ends of the lower cross bars, the hub including a hub mechanical central tube, a column slidably disposed within the hub mechanical central tube, a hub mechanical spindle disposed within the column, and hub lock fingers pivotally coupled to a lower portion of the column and including lower feet portions, the hub mechanical spindle having an enlarged diameter lower end portion that engages lower inner sidewalls of the hub lock fingers and maintains the lower feet portions of the hub lock fingers outside a perimeter of a lower opening of the hub mechanical central tube when the hub is disposed in a lowermost position in the frame.

An electronic device includes a display, and a hinge assembly foldable together with the display and corresponding to a folding area of the display. The hinge assembly includes a hinge bracket defining first and second hinge axes, first and second rotators connected to the hinge bracket and respectively rotatable about the first and second hinge axes, first and second sliders connected to the hinge bracket, respectively slidable relative to the hinge bracket in a direction parallel with the hinge axes, and spaced apart from each other in the direction, and an elastic member between the first and second sliders and providing an elastic force in the direction. The first and second rotators respectively include first and second helical structures having a helical shape with the first and second hinge axes as a center, and are each connected to the first and second sliders through the first and second helical structures.

A pinned connection assembly includes a first rigging component, a second rigging component, a rigging pin, a locking pin, and a lock. The first rigging component has an end with at least one coupling aperture and at least one retention aperture that is transverse to the coupling aperture. The second rigging component has an end with at least one coupling aperture. The rigging pin has an end with a retention groove. The rigging pin is inserted through the coupling apertures of the first and second rigging components. The locking pin has an end with a locking groove. The locking pin is inserted through the retention aperture and the retention groove. The locking groove has guide, transitional, and locking portions for engaging a key of the lock.

A pinned connection assembly includes a first rigging component, a second rigging component, a rigging pin, a locking pin, and a lock. The first rigging component has an end with at least one coupling aperture and at least one retention aperture that is transverse to the coupling aperture. The second rigging component has an end with at least one coupling aperture. The rigging pin has an end with a retention groove. The rigging pin is inserted through the coupling apertures of the first and second rigging components. The locking pin has an end with a locking groove. The locking pin is inserted through the retention aperture and the retention groove. The locking groove has guide, transitional, and locking portions for engaging a key of the lock.

An instrument for establishing orientation of a pelvic prosthesis comprises a hub, a first arm attached to and extending from the hub, and a second arm attached to and extending from the hub. The first and second arms define a nominal plane of the apparatus, and may extend from the hub at an angle relative to each other. Distances between the first and second legs and between the first and third legs are adjustable. The first, second, and third legs have tips, and the tips of the first, second, and third legs define a plane having a predefined geometric relationship to the nominal plane of the apparatus.