If the air filter is not blocked and excessive oil is still found, which component should be suspected next?

When determining the source of excessive oil in the compressed air system for a bus, if the air filter is confirmed to be clear, inspecting the compressor rings becomes crucial. Worn compressor rings can lead to a failure in properly sealing the compressor’s internal components. This failure allows oil from the compressor's lubrication system to be forced into the air supply, resulting in the presence of excessive oil downstream.

The compressor rings are designed to maintain pressure within the compressor while preventing oil from escaping into the air stream. When they wear out, they cannot perform this function effectively, leading to the contamination of the compressed air with oil. Therefore, if there is clear evidence of excessive oil and the filter is functioning well, it is logical to suspect the condition of the compressor rings next in the troubleshooting process. This understanding is critical in ensuring the overall efficiency and safety of the braking system.