Guide-bar device for multi-spindle lathe

A guide bar device for a multi-spindle lathe with a rotatable barrel operable to be indexed by said multi-spindle lathe, said barrel comprising at least one shaft, at least one intermediate disk disposed on said shaft, a plurality of guiding tubes removably supported about said shaft by means of said disk for enclosing a bar stock to be machined, said bar stock being set into rotation by said multi-spindle lathe in a hydraulic fluid under pressure, each of said guiding tubes including a feeding iston for supporting a rear part of said bar stock and for advancing said bar stock in said guiding tube in response to said hydraulic fluid under pressure, said guide bar device further comprising a distributor with switching means and individual circuits of hydraulic fluid under pressure and vacuum for distributing said fluid or said vacuum to said guiding tubes, and means for detecting an advanced position of a feeding piston in a guiding tube enclosing a remnant of its bar stock, said switching means being controlled by said detectng means such that said guiding tube is set under vacuum for causing said feeding piston to retract toward the rear part of said guide bar device during said indexing of said brrel at the time of machining of a last piece from said remnant.