Troubleshooter
About Twin
I’ll open a new chapter and talk about twin cranes. I worked on deck cranes and I am familiar with this function mode.
The purpose of twin function of the crane is synchronizing the rotary motions of the hydraulic motors in order to maintain:
- The same speed of both motors,
- The same angular position of both motors,
to be able to lift heavy load in case need it.
Synchro Unit
The two cranes install on the platform can function independently – as single crane – or combine as a twin crane by interlocking the two units mechanically. All winches in both cranes are install with synchro units. The units is connect to an electronic panel which controls their operation through of electrically control valves.
Accumulators are devices which can collect pressurized liquid and released when needed it.
The synchronizing unit provides pulsed signal, at power line frequency, which control the hydraulic motor speed by controlling the feed currents of the servo valve. A position signal error of the hydraulic motors can occur and is handle by the synchro unit which continually register the movement of hosting and luffing winches. If the error angle exceeds a limit value and adjustable is out of range the electrically operated servo valves is interrupted, and the hydraulic motor ceased.
Therefore the operating principle of the synchronising system is to maintain the slower motor at its chosen speed while slowing down the faster running motor to the same speed.
- The purpose of twin function is to hoist heavy loads
- The two cranes install on the twin platform can function independently;
- All winches in both cranes are fitted with synchro units;
- Synchro unit control the speed of hydraulic motors by adjusting the current to the servo valve.
