Hydraulic transmiting system in projecting molding machine

A hydraulic actuation system for injection-moulding machines is proposed, having a hydraulic pump 14 and a plurality of hydraulic drives 1 to 6, which can be connected thereto in a selectable number and sequence via a hydraulic line network 13 and valves 7 to 12. For working with good efficiency and low operating costs, it is proposed - that the hydraulic pump 14 is designed as a constant feed pump having a volumetric delivery (displacement) and/or delivery pressure which corresponds at least to the maximum consumption (absorption) of all the hydraulic drives 1 to 6, - that the hydraulic pump 14 can be driven by an electric motor 15 which can be controlled in its speed infinitely variably (steplessly) - or else at least with many steps - over a predetermined speed range, - that the volumetric delivery (displacement) and/or the delivery pressure can be adapted by the maximum drive speed of the electric motor 15 to the maximum consumption and/or to the maximum consuming pressure of all the hydraulic drives 1 to 6, - and that the speed for the electric motor 15 can be controlled proportionally with respect to the consumption and/or the consuming pressure of the respectively actuated hydraulic drives 1 to 6.