Abstract: A device for adjusting the height an armrest of a chair including a support disposed on a chair and a receiving/supporting cylinder movably engaged with a support. Extending longitudinally in a slit in the receiving/supporting cylinder is a stepped member. An engaging piece within the cylinder is adapted to be moved into and out of engagement with the stepped member. The engaging piece extends through a slit in the cylinder. Surrounding the receiving/supporting cylinder is an operating cylinder which has circumferentially spaced internal ridges. As the operating cylinder is rotated. the ridges engage the engaging piece and move it into and out of contact with the stepped member.A spiral circumferential groove is also provided in the receiving/supporting cylinder and a pin on the operating cylinder is engaged in the spiral groove whereby rotatable movement of the operating cylinder causes axial movement of the same.

Abstract: An attaching cylinder 6 is disposed on an armrest main body 5. A main shaft 3 is disposed uprightly on an upper end of a support 2 and rotatably combined with the attaching cylinder 6 inside the attaching cylinder 6. A guiding portion 8A is disposed on an upper end of the main shaft 3 which protrudes from an upper end of the attaching cylinder 6. A guiding surface 8a is disposed on the guiding portion 8A along a circle formed with the main shaft 3 as a center. A supporting piece rotation-urged toward the guiding surface at a distal end portion thereof and attached rotatably to the armrest main body around the longitudinal axis at a proximal end portion thereof. A roller 14 is disposed on a distal end portion of the supporting piece and rolls on the guiding surface 8a. Receiving recess portions 11A, 11B, 11C, 11D, 11E, 11F, disposed at suitable locations of the guiding surface 8, with which the roller 14 is engaged or disengaged.