1.1 Operation of fin stabilisers
• A Hydraulic Power Unit (HPU) powers the fin tilting and rigging motions. Built into the HPU is a high power electric motor driving a variable delivery piston pump with a tandem vane pump for control pressure. A second vane pump for fin rigging and pump replenishment is driven from the other end of the main motor
• A variable delivery piston pump controls fin tilting. The flow rate of this pump is controlled by a rotary valve that is positioned by the Stroke Control Unit
• The SCU consists of a servo motor and gears with an integral resolver, mounted within rectangular cast box. The LCU contains circuitry to provide microprocessor based control of the SCU, and hence the direction and rate of flow from the pump. The fin’s rotational velocity is proportional to the pump flow rate
Fin rigging is controlled by solenoid actuated valves. The HPU also provides the means for stowage of the fin under emergency power. A second electric motor (of lower power) is connected to a constant delivery gear pump. This pump is connected to an auxiliary set of solenoid controlled valves that can be used to tilt the fin to zero angles and rig it in.
• The operation can be controlled from bridge or ECR. A selector switch located on the MCU control panel allows the MCU to become the active control station if the BCP or communication to the BCP becomes defective
Before starting the Gyro fin Stabilizer System, the Engine Room should confirm:1. There are no obstructions to the moving parts of the Stabilizer Machinery.
2. Cooling water is flowing through the Hydraulic Power Unit heat exchanger.
3. All local power isolation switches to controls and pumps are turned ON.