What is the correct way to connect a pair of glad hands?
Combination Vehicles • Free CDL Practice Question
Regulation
AAMVA CDL Manual, Section 6.2.5, p. 6-5
Why This Matters
A glad hand that isn't fully turned and locked can work itself loose or leak air on the road, weakening trailer braking exactly when it's needed most. The 90-degree-then-turn method is the one the exam, and a real roadside inspection, expects you to know.