Abstract: Joint arrangement (10) has a hollow cylindrical receiving cylinder (20) that extends in a cylinder axis direction (Z) and receives one end of a chair column (30) of an active-dynamic wobble chair, the latter movably mounted in a substantially hollow cylindrical outer joint shell (40) composed of joint shell segments (45). Movable mounting of receiving cylinder (20) is achieved by deformable elastic elements (50) arranged to be variable in shape and position in a bearing gap (60) between an outer wall portion (21, 22) of the receiving cylinder (20) and an inner wall portion (41, 42) of the joint shell (40). Receiving cylinder (20) is actuated in a force-dependent manner, whereby shape and/or position of the elastic elements (50) change as viewed in a radial direction (Rs) from changing, preferably reducing, clearance of the bearing gap (60) when the receiving cylinder (20) is actuated in a cylinder axis direction (Z).

Abstract: The invention relates to a self-adjusting joint (11) which is designed to receive an end of a chair leg of an active dynamic chair, comprising a hollow inner cylinder (12) that comprises an upper and lower end-face edge (12o, 12u) and a hollow outer cylinder (13) that is arranged around the exterior of the inner cylinder (12) and has an upper and lower end-face edge (130, 13u), each of which is offset relative to the upper and lower end-face edge (12o, 12u) of the inner cylinder (12) in the axial direction (A), and a first compression spring section (11a) that consists of a plurality of cylinder bodies or cylinders (15a) which surround the inner cylinder (12) and between which a respective elastomer section (14a) is arranged so as to connect the cylinder bodies or cylinders, and a second compression spring section (11b) that is arranged at a distance from the first compression spring section in the axial direction (A) and consists of a plurality of cylinder bodies (15b) or cylinders which surround the inner c

Abstract: The invention relates to an active dynamic stool comprising the following: a seat part, a three-dimensional articulation system made up of at least three legs with foot parts at the lower end thereof, wherein the legs each have their upper end mounted on the seat part for movement on seat-part-mounted connecting articulations, such that the seat part can execute oscillating and circular movements in respect of its non-deflected rest position.

Abstract: The invention relates to an active dynamic stool comprising the following: a seat part, a three-dimensional articulation system made up of at least three legs with foot parts at the lower end thereof, wherein the legs each have their upper end mounted on the seat part for movement on seat-part-mounted connecting articulations, such that the seat part can execute oscillating and circular movements in respect of its non-deflected rest position.

Abstract: A simple, center-less universal joint of ultra tight tolerance comprising two yokes, each having two facing, distinctly round interface surface areas; both yokes being easily engaged (a self aligning process) and disengaged.

Abstract: A stringed instrument having a stationary support; one part of the instrument interfacing with the musician's sternum, another part pivotally interfacing with the support using two pivot axes mounted perpendicular to each other, first axis dependent on second axis. The longitudinal axis of the instrument is aligned with the musician's anatomical median plane; the support enabling congruent movement between the instrument and the musician's swaying torso while preventing rotation of the instrument around its longitudinal axis, thus improving ergonomic posture and technique. The instrument has an effective string length less than that of a cello and greater than that of a viola, for enabling such ergonomic positioning.

Abstract: An apparatus for straightening the end of an elongated workpiece which has a longitudinal axis and an elastic limit includes at least three rams arranged symmetrically around the workpiece and around a common axis and are moveable perpendicularly to the axis for deflecting the longitudinal axis of the workpiece into a path of revolution by deforming the workpiece beyond the elastic limit without rotating the workpiece around the axis. A piston cylinder unit is connected to each of the rams for performing a reciprocal stroke movement. The piston cylinder units are selectively controlled so that the piston cylinder units and associated rams perform a phase shifted sinusoidal stroke movement.