Abstract: A tiltable chair includes a flexible seat body including an integrally formed seat back and seat surface supported on a seat frame disposed on upper parts of legs, and the seat back connected to a back frame allowing tilting rearwards, the position of the connection being in an area around the upper part of the pelvis of a person seated thereon. A guide rail having an arc-shaped groove is fixed to the seat frame, and guide members which engage and roll in the arc-shaped grooves are pivotably supported on a shaft bracket of the rear surface of the seat surface. The arc-shaped groove has a high center so that the seat surface undergoes curved motion forward and upward such that the ischium is positioned lower than the lower part of the knees when the seat back tilts rearwards.

Abstract: A tiltable stool includes a seat support, a seat, and a tilt mechanism. The seat is mounted to an upper end of the seat support. The tilt mechanism allows the seat to tilt in a desired direction. The tilt mechanism includes a coiled wave spring, an upper spring retainer and a lower spring retainer, a fastener bolt, and a tilt limiter. The upper spring retainer and the lower spring retainer are disposed opposite each other to sandwich the coiled wave spring therebetween. The fastener bolt pivotably holds the upper spring retainer in position. The tilt limiter is disposed inside the coiled wave spring and is secured to either one of the spring retainers. The tilt limiter includes a conical surface thereon which contacts a contact surface when the seat tilts to a predetermined tilt angle. The upper spring retainer is secured to a lower end of the seat support.

Abstract: A tiltable stool includes a seat support, a seat, and a tilt mechanism. The seat is mounted to an upper end of the seat support. The tilt mechanism allows the seat to tilt in a desired direction. The tilt mechanism includes a coiled wave spring, an upper spring retainer and a lower spring retainer, a fastener bolt, and a tilt limiter. The upper spring retainer and the lower spring retainer are disposed opposite each other to sandwich the coiled wave spring therebetween. The fastener bolt pivotably holds the upper spring retainer in position. The tilt limiter is disposed inside the coiled wave spring and is secured to either one of the spring retainers. The tilt limiter includes a conical surface thereon which contacts a contact surface when the seat tilts to a predetermined tilt angle. The upper spring retainer is secured to a lower end of the seat support.