Hydraulic drive system

A hydraulic drive system having a first hydraulic machine and a second hydraulic machine, which are mechanically connected to one another;

• wherein the first hydraulic machine and the second hydraulic machine are operated conjointly by a variable-speed drive;
• wherein the first hydraulic machine and the second hydraulic machine are hydraulically connected to at least a first hydraulic cylinder, comprising a first hydraulic cylinder side with a first hydraulic cylinder surface and a second hydraulic cylinder side with a second hydraulic cylinder surface;
• wherein the first hydraulic machine or the second hydraulic machine has an adjustable delivery volume, and wherein the first hydraulic machine and the second hydraulic machine are configured as fixed displacement pumps;
• wherein the first hydraulic machine is connected to a reservoir of the hydraulic drive system, and the reservoir is configured as a pre-stressed reservoir;
• wherein the second hydraulic machine is hydraulically connected to the first hydraulic cylinder surface and to the second hydraulic cylinder surface;
• and
• wherein, when the second hydraulic machine conveys a hydraulic fluid with a volume flow from the second hydraulic cylinder side to the first hydraulic cylinder side, then the second hydraulic machine conveys a full volume flow from the second hydraulic cylinder side to the first hydraulic cylinder side.