Sulzer RT-flex. Servo oil
Servo oil is used for exhaust valve actuation and control. It is supplied by a number of swashplate-type axial-piston hydraulic pumps mounted on the supply unit. The pumps are of standard proprietary design and are driven at a suitable speed through a step-up gear. The working pressure is controllable to allow the pump power consumption to be reduced. The nominal operating pressure is up to 200 bar. The number and size of servo oil pumps on the supply unit depend on the engine output or number of engine cylinders. There are between three and six servo oil pumps.
Fig 4. Various RT-flex equipment on the half-platform of a 12RT-flex96C engine. From left to right, these include (A) the local engine control panel, (B) the automatic fine filter for servo and control oil, (C) the two electrically-driven control oil pumps and (D) the supply unit.
The oil used in both the servo and control oil systems is standard engine system lubricating oil, and is simply taken from the delivery to the engine lubrication system. The oil is drawn through a six-micron automatic self-cleaning fine filter to minimise wear in the servo oil pumps and to prolong component life.
After the fine filter, the oil flow is divided, one branch to the servo oil pumps and the other to the control oil pumps.