Length variable and lockable positioning device

Abstract

According to an illustrative example of the invention a gas spring has adjacent one end thereof an axially extending control pin. This control pin is prestressed towards an outer position and can be pushed inwards for opening a valve, which valve is provided in the passage between two working chambers established by a piston, said piston being fixed to a piston rod. When the pin is in its outward position, the gas spring is locked in the respective axial length. When the control pin is moved inwards, the axial length of the gas spring can be varied. The gas spring is intended for combination with a chair or table column. In combining the gas spring with a chair, the upper end of the gas spring cylinder is fixed to the lower side of the seat plate. The lower side of the seat plate is provided with a manipulating level. The manipulating lever engages the outer end of the control pin through a telescopic arrangement of control members or adapter elements. These control members can be adjusted with respect to each other in axial direction by axial movement without relative rotation during the axial movement. After the correct length of the telescopic arrangement has been adjusted, the telescopic members are fixed with respect to each other.