Oilers/Plant Tenders (HHC) Civil Service Practice Exam

What does a low viscosity oil lubricate in a steam turbine's governing mechanism?

1. The piston rings

2. The bearing surfaces

3. The spindle of the throttle valve and connecting levers

4. The steam inlet valves

The correct answer is: The spindle of the throttle valve and connecting levers

A low viscosity oil is designed to provide effective lubrication in areas where parts are in close operational proximity and require quick response to motion. In a steam turbine's governing mechanism, which involves components like the throttle valve and its connecting levers, low viscosity oil is essential to ensure smooth and responsive movement. This fluid's lower viscosity allows it to flow easily and reach moving parts quickly, minimizing friction and wear. The throttle valve controls the flow of steam to the turbine, and a smooth operation is crucial for the turbine's efficiency and performance. The connecting levers also require consistent lubrication to operate effectively without delay. While bearing surfaces and other components like piston rings or steam inlet valves do require lubrication, they often operate with different requirements, where oils of varying viscosities may be suitable or necessary for those specific applications. Thus, the choice of low viscosity oil for the spindle of the throttle valve and connecting levers is particularly advantageous for maintaining optimal functioning within the governing mechanism of the steam turbine.