A hinge is a mechanical bearing that connects two solid objects, typically allowing only a limited angle of rotation between them. Two objects connected by an ideal hinge rotate relative to each other about a fixed axis of rotation all other translations or rotations being prevented, and thus a hinge has one degree of freedom. Hinges may be made of flexible material or of moving components. In biology, many joints function as hinges like the elbow joint. A shim is a washer or thin strip of material used to align parts, make them fit, or reduce wear. Shims may also be used as spacers to fill gaps between parts subject to wear. On machinery installations pumps, motors, etc. the recommended practice requires new shims to be placed under every supporting foot. A spring is an elastic object that stores mechanical energy. Springs are typically made of spring steel. There are many spring designs. In everyday use, the term often refers to coil springs. When a conventional spring, without stiffness variability features, is compressed or stretched from its resting position, it exerts an opposing force approximately proportional to its change in length. Features. Bottom Center GDMF Hinge Kit for Torsion Spring with Shim. Made with high quality material