During a pre-trip inspection, a driver observes that the air compressor governor cuts out at 125 psi for the primary system, but the secondary system only reaches 110 psi before the compressor cuts out. What is the most likely issue?
- AA restriction or blockage in the air line leading to the secondary system's tank or gauge.
- BA leak in the secondary air tank.
- CA malfunctioning safety valve.
- DA faulty pressure regulator for the secondary system.
Show answer & explanationAnswer & explanation
Correct answer: A. A restriction or blockage in the air line leading to the secondary system's tank or gauge.
If the compressor cuts out at its normal range (125 psi for the primary system), but the secondary system doesn't reach that pressure, it suggests that air is not reaching or being registered by the secondary system effectively. A restriction or blockage in the air line or a faulty gauge for the secondary system would cause this discrepancy. A safety valve would open if pressure was too high. A leak would cause pressure to drop, not just fail to build to cut-out. A faulty pressure regulator would typically regulate pressure to a lower, specific set point, not just stop it from reaching cut-out.
Why the other options are wrong
- B. A leak would cause pressure to drop, not just fail to build to the cut-out point.
- C. A safety valve opens if pressure exceeds maximum, not if it fails to reach target.
- D. Pressure regulators are for specific pressure levels, not for the maximum system cut-out pressure.
Uneven Air Pressure Build
When one air tank in a dual system reaches the compressor cut-out pressure while the other remains significantly lower, indicating an issue with air delivery or measurement to the lower-pressure tank.
- Suggests a blockage or faulty gauge.
- Can indicate an issue with check valves.
- Requires immediate investigation for safe operation.
Memory trick: If air can't flow, the gauge won't show.