Hydraulic control device

In a hydraulic control device (S) for moving either a solar panel (B) to track the varying position of the sun or for a tooling machine feed system, by controlling at least one hydraulic consumer (H) by pressurised hydraulic medium, the hydraulic control device being of the type having at least one pressure source (P), the hydraulic medium being supplied under pressure from the pressure source (P) into a working line (1, 14, 13) to the hydraulic consumer (H) or under pressure from the hydraulic consumer (H) into a return line or a bypass line (1′, 11) to a return system, the improvement being characterised in that a dosing device (D) is contained in at least one of the working line (1, 13, 14), a discharge line, and the bypass line (1′, 11), that the dosing device (D) comprises first and second blocking members (G1, G2) arranged in a series from upstream to downstream, and a dead space (T) having a determined hydraulic medium volume capacity in between the first and second blocking members (G1), that the dead space (T) is constituted by a hermetically tight inflexible container (6) and a section of a line (1′) extending between the blocking members (G1, G2) and/or partially in at least one of the blocking members (G1, G2), that each blocking member (G1, G2) is a seat valve (V1, V2) movable between a leakage-free blocking position and a through flow position, that in the dosing device (D) a respective hydraulic medium dose is measured by supplying hydraulic medium under high pressure upstream and expanding highly pressurised hydraulic medium to lower pressure downstream exclusively by using a given limited compressibility of the hydraulic medium by alternatingly switching the first and second blocking members (G1, G2), and that for controlling just a small adjustment step of the hydraulic consumer (H) the measured hydraulic medium dose either is supplied to the hydraulic consumer (H) by switching the second blocking member (G1) into the through flow position while the first blocking member (G) is maintained in the blocking position, or by taking the hydraulic medium dose from the hydraulic consumer (H) by switching the first blocking member (G1) into the through flow position while the second blocking member (G) is switched into the blocking position.