What system provides appropriate lubrication when a steam turbine's barring gear is engaged?

The auxiliary oil pump is specifically designed to ensure that lubrication is provided to the steam turbine's barring gear when it is engaged. This is particularly important because the barring gear allows for the slow rotation of the turbine, which requires adequate lubrication to prevent excessive wear and heat generation. The auxiliary oil pump can operate independently of the main oil system, ensuring that lubrication is maintained during instances when the main system might not be functioning or is undergoing maintenance.

In a typical steam turbine system, the main oil pump is responsible for circulating oil during normal operation, while an emergency oil reservoir may provide backup in certain situations. The gravity feed system relies on the force of gravity to deliver oil, which may not offer the consistent or high-pressure lubrication needed for the barring gear, especially under varying load conditions. Therefore, the auxiliary oil pump is the most suitable choice for providing appropriate lubrication during the engagement of the barring gear.