Home › CDL Practice Tests › Air Brakes Questions › Question 236
What commonly identifies the emergency and service glad hands on a combination vehicle?
- A.The emergency line is commonly associated with red markings and the service line with blue markings, and the couplings must match their proper lines
- B.Both lines always use plain unmarked couplings
- C.Red always means service and blue always means supply
- D.Color never appears on air line couplings
Correct answer
A. The emergency line is commonly associated with red markings and the service line with blue markings, and the couplings must match their proper lines
Why
Color coding and keyed trailer connections help prevent crossed lines during coupling. Crossed or mismatched connections can leave the trailer without proper charging or service brake control.
Manual topic: Air Brakes - Trailer Air Brakes · From the Air Brakes practice bank (AB-236).