TrailersQuestion 39 of 116
Why do you discharge air before you connect the glad hands?
- To raise the trailer pressure
- To test the governor
- To dry the seals
- To blow contamination out of the lines
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Correct answer: To blow contamination out of the lines
A quick discharge blows contamination out. It does not send the contamination into the trailer.
Questions last reviewed: 18 October 2026