Marine Loading Arm - Manual Hydraulic & Electric Hydraulic

Manual = Without PLC, Electric = With PLC.

Another definition would be:

Manual hydraulic = control valves operated by hand levers;

Electric hydraulic = control valves operated by solenoids, in turn controlled by, say, a bank of pushbuttons.

Manual has the advantage of opening/closing the valves gradually for smooth control.

Electric has the advantage that the operator can move so as to see the action. But this tends to be jerky in operation, unless you have some kind of proportional control.

PLC = Programmable Logic Controller. A set of sensors tells the PLC where the arm, how fast it's moving, etc. and the PLC adjusts the motion according to its programming. This allows deployment of the arm to be controlled with only a sincle pushbutton, but the arm can only move as it's programmed to.

Manual control allows the operator to replace the PLC. Since people can perform much more complex command/control decisions than PLC's can, this gives more versatility but requires a trained operator.

Thanks for your answer..

What if the Marine Loading Arm is controlled by using remote control (pendant remote control), and with no PLC. Can we call it as a manual hydraulic system?

I am very sorry Sir.. But i am still confused between manual hydraulic and electric hydraulic system in Marine Loading Arm (MLA).

Thanks..

A pendant station is a bank of pushbuttons on a cable, so the operator can move to a convenient location. It controls hydraulic solenoid valves, which open and close abruptly (unless it is some kind of fancy system). This is electric hydraulic.

In manual hydraulic, the valves are operated by hand levers. You can open and close them more gradually for smoother control.