Changes to the architecture of hydraulic systems resulting from growing expectations for speed and accuracy of operation, reduction energy consumption, and limitation of their complexity, are currently being introduced by most manufacturers of working machines. In the area of self-propelled trucks adapted to demanding underground conditions dynamic development of hydraulic systems takes place in the design office of KGHM ZANAM. One of the directions of this development is using hydraulic systems with elements controlled by a pressure signal, the source of which is a signal generated on the drain line. As a result an electrohydraulic control system for the additional drive motors of CB4–20/24 TB type haul trucks was designed, tested, and implemented for operation with an architecture enabling the use of the drain line as an element of the control system. The article presents the initial assumptions, the structure of the new system and the results and analysis of the dynamic response of the system to external loads in transient states. This allowed to introduce changes in the hydraulic structure of the system and in the scope of electric signals controlling the valves, which made it possible to obtain the desired parameters of the system supporting the main drive of CB4–20/24 TB type haul trucks during its activation and deactivation. The presented design solution characterized by the use of the drain line to generate hydraulic control signals, together with the results of tests of the described solution, seems to be an interesting contribution to the development of modern electrohydraulic drive systems.