27 which is axially movable within the valve and more particularly is pushed upwardly as seen in fig2 of the drawings by any suitable means and which shank 27 is returned to its original position by means of a suitable helical spring 31 also shown in fig2 of the drawings the shank 27 has a pair of plugs one of which namely plug 30 partially shown in fig2 of the drawings plugs an opening provided centrally of flange 18 and another plug between chambers 25 and 26 that is coincident with an opening provided centrally of the flange 19 the body of the cartridge valve has a plurality of radial openings 32 to communicate the interior of the valve with the chamber 25 and similarly the body 17 has a plurality of radial openings 33 communicating the inner portion of the valve with chamber 26 for a purpose which will be clearly seen hereinbelow the cartridge valve has an extereme plate 28 to which an end guiding shank 29 is attached said guiding shank being guided by means of a cylinder or tube 30 arranged collinearly of the cartridge valve and supported on the upper wall of the block 1 and said tube extending across the space provided by the operational air manifold 9 the other end of each cartridge valve as described above is provided with a pusher plate 35 which in turn is actuated by means of a.