Why should you lock the tractor glad hands (or dummy couplers) to each other when you are not towing a trailer?
a) If you don't, you will never build system pressure
b) It will keep dirt and water out of the lines
c) The connected brake circuit becomes a backup air tank
Answer: b) It will keep dirt and water out of the lines
If the answers is incorrect or not given, you can answer the above question in the comment box. If the answers is incorrect or not given, you can answer the above question in the comment box.