The design process in marine engineering

This actuator C is the one that controls the forming operation labeled as (1) in the diagram. In order to return the actuator C to its normal position, solenoid C- is operated through a Normally Opened Contact (R1). However, on its way back through the cylinder, actuator C comes into close proximity of sensor TC- which leads to the operation of actuator labeled D under the effect of solenoid D+. The actuator D is used to control forming operation (2). Another normally opened contact (R2) is then used to return actuator D back to its normal position under the effect of solenoid D-. Later on, when the sensor TD- has been activated, actuator B is returned to its original position by the effect of solenoid B-. Meanwhile, sensor TB- is activated by actuator B which leads to operation of actuator A, which returns to normal position, through the effect of solenoid A-. This effectively summarizes the working of the circuit.