Mechanical pencil with automatic and manual lead advance

A mechanical pencil, comprising a longitudinally elongated at least partially hollow pencil body having a forward tip and provided internally with a seat having a seat surface spaced longitudinally backwardly from said tip;

• a lead-protecting sleeve longitudinally displaceable in said body between a front position relatively far from said seat and a back position relatively close to said seat, said sleeve having a longitudinally throughgoing passage dimensioned to receive a pencil lead;
• means for urging said sleeve forwardly into said front position with a relatively strong force;
• means in said sleeve frictionally engaging a lead therein for joint longitudinal displacement of said sleeve and a lead therein;
• at least two longitudinally displaceable jaws having outer surfaces at said seat and inner lead-gripping faces transversely and frictionally engageable with a lead projecting from said sleeve, at least one of said surfaces being so inclined that the two surfaces together converge in the backward direction toward said seat, whereby the transverse clamping force exerted by said jaws on a lead gripped between said faces increases as said jaws are moved backwardly towards said seat and decreases as said jaws are moved forwardly from said seat;
• and means urging said jaws backwardly in said seat with a relatively weak force, whereby when a lead is frictionally engaged in said sleeve and between said faces and said sleeve is in said back position said strong force can overcome said weak force and forwardly displace said sleeve, the lead engaged therein, and said jaws.