A brake device that puts a brake on a hydraulic motor includes a disc plate configured to rotate with a cylinder block, a brake piston supported by a first case, and brake springs compressed and placed between the brake piston and a second case. The second case has a dent shaped or projection shaped holding portion into which one ends of the brake springs are inserted, and the brake springs are held by the holding portion even in a state where the other ends are away from the brake piston.

In an example, a flexible structure comprises a plurality of interlinked spring units. Each spring unit may comprise at least three coaxial coiled springs, and each spring of a spring unit may comprise a first end and second end. In some examples, an end of one spring adjoins an end of a spring of an adjacent spring unit.

A high tension coil spring structure for a bed mattress includes spring bodies and exposed wiring portions which absorb an external load. Diameter-increasing portions (A) are formed on at least one of upper and/or lower end wiring portions (14, 14) of body wiring portions (12), and provide spaces in which upper and/or lower exposure start wiring portions (16-5, 16-5) move upward and downward. Rigid support ends (18) are formed on at least one of the body wiring portions (12) and upper and lower exposed wiring portions (16, 16), and absorb a compressive load. The diameter-increasing portions and the rigid ends of the coil spring structure fundamentally prevent noise caused by friction between the exposed wiring portions and surrounding wiring portions when the exposed wiring portions are compressed and significantly increase the elasticity of the exposed wiring portions.

An advanced (or supercoil) spring is disclosed herein. While the advanced spring can include any suitable feature, in some cases, it includes a coil spring having multiple external coils that define a portion of an inner lumen of the coil spring. In some such case, the coil spring further includes a first internal coil that extends at least partially into the inner lumen of the coil spring. In some cases, the external coils and the first internal coil are each made of, and comprise part of, one single continuous spring wire. In some cases, the coil spring includes a tension spring such that surfaces of adjacent external coils contact each other, and such that the first internal coil is disposed within a portion of the inner lumen defined by the adjacent external coils, when the coil spring is at rest. Additional implementations are discussed herein.

An advanced (or supercoil) spring is disclosed herein. While the advanced spring can include any suitable feature, in some cases, it includes a coil spring having multiple external coils that define a portion of an inner lumen of the coil spring. In some such case, the coil spring further includes a first internal coil that extends at least partially into the inner lumen of the coil spring. In some cases, the external coils and the first internal coil are each made of, and comprise part of, one single continuous spring wire. In some cases, the coil spring includes a tension spring such that surfaces of adjacent external coils contact each other, and such that the first internal coil is disposed within a portion of the inner lumen defined by the adjacent external coils, when the coil spring is at rest. Additional implementations are discussed herein.