Yukon Air Brake Practice Test 2

What this test covers

• The system fails safe: losing air pressure applies the spring brakes, it does not release them.
• The low-air warning must activate around 55 to 60 psi, before pressure gets dangerously low.
• Spring (parking) brakes apply automatically around 20 to 45 psi if air pressure keeps dropping.
• Governor cut-out is typically about 125 psi and cut-in about 100 psi.
• Know the daily leak-down test: check the allowable air-loss rate with the brakes released and then applied.
• Drain the air tanks daily, or rely on an automatic ejector, so moisture cannot damage valves or freeze.

This practice test draws on the official commercial driver's manual. The real Yukon commercial knowledge test requires an 80% score to pass.