Abstract: To indicate externally of a printing machine the position of a turning bar, the turning bar (15) drive spindle (1) is coupled to a numerical indicator (11) by a worm gearing (8, 9). The numerical indicator, having a plurality of number wheels, is capable of indicating the position of the turning bar (15) on a traverse rod (14). Preferably, a stop wheel (6) having ball-loaded detents at its circumference provides for predetermined angular positions of fractional revolutions of the spindle.

Abstract: To permit adjustment of air flow through air exchange openings (7,8,9;25,29) of a hollow outer turning rod tube (11,23,30), a plurality of inner tube elements (12,24,32) are axially located within the outer tube, and formed with part-circumferentially extending slits (13) in alignment with the air exchange openings. The inner tube elements can be, slectively, rotated for alignment of the slit (13) with the air exchange openings, or blocking of the air exchange openings by solid portions of the tube elements. Rotation can be effected by adjustment knobs (FIGS. 1-3: 17) having an inner gearing (16) engaging a side gearing (15) on the tube elements; by finger adjustment (FIG. 4) or by positioning wheels (FIG. 5: 34) in engagement with a roughened, stippled, ribbed or corrugated surface portion or region of the inner tube elements.