Bus Vehicle Inspection: Daily and En-Route Checks
Core concepts
A pre-trip inspection is a legal duty, not a formality. You must be able to describe what a defect looks like and what it means, because exam questions often present a symptom and ask whether the vehicle may be driven. Learn the major systems: brakes (air pressure build-up and loss rates, slack adjusters, low-pressure warning), steering (free play, binding), tires (tread depth, sidewall damage, matching sizes, proper inflation), lights and reflectors, mirrors, wipers, horn, emergency exits, fire extinguisher, first-aid kit, and the passenger compartment.
Air brake checks
Know the sequence: build pressure to governor cut-out, check that the low-pressure warning activates before pressure drops too far, check the compressor build rate, then test for leaks with the engine off and the brakes applied. A question that gives you a pressure-loss figure is testing whether you know the acceptable limit - memorize the standard rather than guessing.
Traps to expect
- A defect that seems minor (a cracked mirror, a burned-out clearance lamp) may still make the bus out of service; if a required lamp or mirror is defective, the vehicle should not carry passengers.
- Questions that confuse the pre-trip inspection with the en-route check. The pre-trip happens before the first passenger boards; en-route checks happen at stops and at the end of the run.
- Tire questions that mix tread depth with sidewall condition - both matter, and a bulging sidewall is a stop-driving defect regardless of tread.
Worked example
You build air pressure and it rises slowly from 80 to 100 psi over several minutes. The build rate is below the required minimum, which points to a compressor or governor problem. The correct action is to remove the bus from service and report the defect, not to "drive carefully" and monitor it.