H8 Transit Bus — PM Inspection — practice test

High-yield H8 topics

The material that shows up year after year. If you're short on time, start here.

• Pushrod stroke and brake adjustment limits. The readjustment limit is chamber-specific - a long-stroke Type 30 is 2 in, a standard-stroke Type 30 is 1.75 in - and any brake at or past its limit is an out-of-service item. Know the method: system fully charged at 90-100 psi, brakes released, mark the rod, full application, measure travel. An automatic slack adjuster found out of adjustment does NOT get manually cranked back and sent out - that is a defective ASA.
• Air system leakage and buildup, by the numbers. Static leakage engine off, brakes released: 2 psi per minute on a single vehicle, 3 psi per minute applied. Low-air warning must be on by 60 psi. Spring brakes apply automatically somewhere in the 20-45 psi range. Governor cut-out roughly 120-135 psi, cut-in about 20-25 psi below that. Compressor buildup 85 to 100 psi in 45 seconds or less. These get asked as scenario values you have to judge, not recite.
• Lining, drum, and tire limits as pass/fail calls. Riveted lining condemned around 1/4 in at the rivet, bonded around 1/16 in; drum discard diameter is stamped on the drum; cracks reaching the friction edge are a fail. Tires: 4/32 minimum on the steer axle, 2/32 everywhere else, no regrooved or recap rubber on the steer axle, no cord-exposing cuts, no mismatched duals with a large diameter delta. Cracked rims and mismatched lug torque are automatic fails.
• Wheelchair lift, ramp, and kneeling inspection. This is the transit-specific section that separates transit techs from truck techs. Know the interlock chain - the bus must not move with the lift deployed or the door open, and a failed interlock is out of service. Know manual backup operation (hand pump or manual release), that the outer barrier must raise and hold before the platform leaves floor level, plus handrails, anti-skid surface, cylinder and hose leaks, and securement webbing. Cut or frayed webbing gets replaced, never repaired.
• Suspension, air ride, and steering play. Ride height is the master spec - wrong ride height throws off the height control valve, geometry, and door and kneeling function, so measure it before condemning anything else. Look for chafed bags, cracked or shifted torque rods, shocks running wet down the tube (a light film is not a leak), and broken leaves. Steering free play is checked engine running, wheels straight - about 30 degrees at a 22-inch wheel is the DOT threshold. Kingpin and wheel bearing play get a dial indicator, not a feel and a guess.
• Batteries, charging, and lighting on a multiplexed coach. Load test at half the CCA for 15 seconds at 70F and it must hold above 9.6 V - and the battery must be near full state of charge first or you will condemn a good one. Check voltage drop across cables and the ground path before you blame the alternator. Know required lamps and reflectors, and know that a weak battery on a multiplexed bus throws a fistful of false module codes.

Where techs lose points on H8

Good technicians miss these — not from lack of skill, but because the question is built to catch them.

• Confusing the inspection standard with the repair procedure. The question asks whether the bus passes, not how you would fix it. Out-of-adjustment ASA means defective ASA, replace or repair - not adjust it and go. Out-of-service brakes mean remove from service, not band-aid and dispatch.
• Applying the wrong stroke limit. Test writers hand you a chamber type and a stroke number on purpose. Long-stroke and standard-stroke Type 30 differ (2 in vs 1.75 in), and Type 24 splits the same way. One memorized number for everything walks you right into the plausible wrong answer. Measuring at 60 psi instead of 90-100 psi also reads short and makes a bad brake look fine.
• Chasing an air leak or a ride complaint before checking ride height and the height control valve. Wrong ride height mimics a hard ride, door and kneeling misbehavior, odd tire wear, and a bag that looks collapsed. When two techs argue and one says replace the bag while the other says set ride height first, the answer is set ride height first.
• Treating the wheelchair lift like an optional accessory. Truck-side techs assume interlock and barrier faults are advisory. They are not. An interlock that lets the bus move with the lift out, or an outer barrier that will not stay up, takes the bus out of service. The comfortable answer of note it and keep running is wrong every time on H8.

A study plan that works for H8

Roughly two weeks of real preparation, in the order that actually builds on itself.

1. Days 1-5: Air brakes by the numbers. Drill leakage rates, warning at 60 psi, spring brake apply 20-45 psi, governor cut-in and cut-out, buildup time, and the full stroke-limit table by chamber type and size. Write the table from memory until it comes cold. Then pull a PM sheet at work and actually measure stroke on a bus - the muscle memory is what sticks.
2. Days 6-9: Everything you can condemn with a tape, a gauge, or a dial indicator. Lining and drum limits, rotor thickness, tread depth by axle, steer axle rules, kingpin and wheel bearing play, ride height, steering free play. For each one say it out loud: the spec, how you measure it, and whether out of spec means out of service or just a note.
3. Days 10-13: The transit-only material you never touch. Lift and ramp inspection and interlocks, kneeling, securement webbing and hardware, HVAC PM (belts, filters, condenser fins), doors and sensitive edges, body and interior - stanchions, flooring, emergency exits and buzzers, mirrors. It feels boring, and it is exactly where techs lose the test. Give it real hours.
4. Days 14-16: Mixed practice questions, then re-drill only what you missed. Roughly two minutes per question. When you miss one, name the task area it came from and state the standard - do not just read the answer. On test day, read every stem for pass/fail/defer intent before you look at the choices.

Sample H8 questions

Straight from the bank — answers highlighted, with the explanation underneath.