Describe what the trailer air supply controls does
a) It is a device used to keep the trailer behind the tractor
b) It is used to supply the trailer with air, shut the air off, and apply the trailer emergency
c) It is a six-sided yellow knob used to control the tractor protection valve
Answer: b) It is used to supply the trailer with air, shut the air off, and apply the trailer emergency
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.