Abstract: The ram of the press is accelerated to an acceleration-terminating point whereat it attains a speed providing for the required energy of impact upon the work. During the acceleration, the velocity of the ram is measured, as well as the deviation of the actual point of attaining the required speed relative to the preset acceleration-terminating point. Depending on the value of this deviation, either the extent of the acceleration path is varied, with the acceleration value maintained constant, or else the acceleration rate is varied, with the acceleration path length remaining permanent. To effect control by varying the acceleration path length, the control system is provided with specific electric circuitry controlling a transmitter generating a signal sent to a solenoid-operated valve, to vary the latter's position so as to vary accordingly the approach portion of the ram's stroke, and thus to vary the acceleration path.

Abstract: A hydraulic drive according to the invention comprises a gas hydraulic accumulator and a chamber whose volume is equal to at least the consumption of fluid by a User, e.g. a hydraulic cylinder of a press. This chamber is divided by a piston into two spaces. One of these communicates with the accumulator through a pipeline which is connected to a pump. The other space of the chamber communicates with the pump through a nonreturn valve, and with the User, through a closing device. This layout of the hydraulic drive steps up its reliability and ensures the possibility of controlling the pressure in the gas-hydraulic accumulator.