Lead writing instrument with selective locking of chuck

摘要

A refill lead writing instrument for stepped advancement of a lead has a spring biased clamping device for holding a lead in direction of its longitudinal axis against a writing pressure. The clamping device includes a clamping chuck supported in a clamping sleeve under a spring action and a longitudinally displaceable lead pipe against which the clamping chuck can abut. A gripping part is form-lockingly connected with a shaft so that the shaft and the gripping part are rotatable relative to one another about a common longitudinal axis. The shaft and the gripping part have opening of same diameters and provided with grooves. A longitudinally displaceable supporting pipe has strips guiding in the grooves, one of the grooves having an extension extending in direction of the writing pipe and formed as a recess in which one of the strips is turnable.