Ahydraulic circuit of an injection molding machine includesa 4-port servo valve having A, B, P, and T ports and adapted
to drive and control an injection cylinder. The A and B ports are connected respectively to the front and rear oil chambers of the injection cylinder. The P port is connected to a
hydraulic poWer unit. The T port is connected to an oil tankVia a shutoff Valve for Selecting a regular mode or adifferential mode. The T port is connected to the rear oilchamber via the logic valve. Alternatively, the rear oilchamber is connected to a hydraulic poWer unit side via theservo valve; the front oil chamber is connected to an oil tankvia the shutoff valve; and the front oil chamber is connectedto the P port of the servo valve via the logic valve. The abovecon?guration eliminates or simpli?es an additional braking
circuit. Also, proper and accurate braking control can beperformed