CDL General Knowledge TestCombination Vehicles (if applicable)Medium
During a pre-trip inspection, a driver notices that the service (blue) glad hand is leaking air. What is the immediate action the driver should take?
- AReplace the glad hand seal or the entire glad hand assembly before driving.
- BAttempt to tighten the glad hand connection with a wrench.
- CDisconnect the blue glad hand and drive with only the emergency brake line connected.
- DContinue the trip but monitor the air pressure closely.
Show answer & explanationAnswer & explanation
Correct answer: A. Replace the glad hand seal or the entire glad hand assembly before driving.
A leaking service glad hand means the service brakes on the trailer will not receive full air pressure, severely compromising braking ability. This is a critical safety defect that must be repaired by replacing the faulty seal or glad hand before the vehicle can be safely operated.
Why the other options are wrong
- B. Tightening may not fix a seal issue and could damage components if overtightened.
- C. Driving with only the emergency line is unsafe and would result in no service brakes for the trailer and potentially lock-up.
- D. Driving with a leaking service brake line is extremely dangerous and illegal.
Leaking Service Glad Hand
A leaking service glad hand indicates a critical air brake system defect that must be repaired before driving to ensure trailer braking capability.
- Affects trailer service brakes.
- Severe safety hazard.
- Repair required immediately.
Memory trick: Leaking blue means no go, fix it now, don't be slow.