Synchronized hybrid clamp force controller for lift truck attachment

A hydraulic control circuit comprising:

• an input port configured to receive pressurized fluid from a pump and return unpressurized fluid to a reservoir
• a first output port connectable to a first hydraulic actuator and a second output port connectable to second hydraulic actuator, each of the first output port and the second output port configured to simultaneously deliver pressurized fluid to its respectively connected hydraulic actuator and receiving fluid discharged therefrom;
• and
• a selector capable of selectively using fluid discharged from the first hydraulic actuator to pressurize fluid delivered into the second hydraulic actuator;
• where
• the control circuit is configured so that, during simultaneous operation of the first hydraulic actuator and operation of the second hydraulic actuator, when fluid is not discharged from the first hydraulic actuator to pressurize fluid delivered into the second hydraulic actuator, the first hydraulic actuator and the second hydraulic actuator expand and retract synchronously even when fluid supplied into the first hydraulic actuator is at a different pressure than fluid supplied into the second actuator.