100+ Free ASE H4 Brakes (Transit Bus) Practice Questions

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The primary purpose of the check valve at each reservoir inlet is to:

Apply the spring brakes

Drain condensate automatically

Reduce delivery pressure to the chambers

Trap stored air in that reservoir if upstream pressure is lost

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Key Facts: ASE H4 Brakes (Transit Bus) Exam

50 scored

Scored Multiple-Choice Questions (60 total)

ASE Transit Bus test series

75 min

Testing Time

ASE Transit Bus test series

~$59

ASE Registration Cost

ASE registration

Criterion-referenced

Scoring Method (set by ASE)

ASE scoring policy

48 / 28 / 14 / 10

Official Content-Area Weighting

ASE H4 content outline

2 years

Required Work Experience

ASE certification requirements

Prometric

Test Delivery Provider

ASE test administration

ASE H4 (Transit Bus Brakes) is a computer-delivered Prometric test with 50 scored multiple-choice questions plus about 10 unscored research items (60 total) and a 75-minute time limit. Scoring is criterion-referenced and set by ASE rather than a fixed percentage. The official content weighting is Air Supply & Service Systems 48%, Mechanical/Foundation Brakes 28%, Parking Brakes 14%, and Wheel Bearings 10%, and ASE certification requires two years of relevant work experience (up to one year substitutable through training). This free practice bank contains 100 selected-response items distributed across those four areas.

Sample ASE H4 Brakes (Transit Bus) Practice Questions

Try these sample questions to test your ASE H4 Brakes (Transit Bus) exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1On a transit bus, what is the primary function of the air compressor governor?

A.Maintain reservoir pressure between cut-in and cut-out by loading and unloading the compressor

B.Reduce supply-line pressure for the secondary brake circuit

C.Open the spring-brake exhaust during a parking-brake application

D.Time the rate of brake-chamber pressure rise to meet FMVSS 121

Explanation: The governor senses system air pressure and cycles the compressor between cut-in (about 100 psi) and cut-out (about 125 psi) by loading or unloading it. This keeps reservoir pressure within a regulated band without running the compressor continuously.

2Typical air-brake governor cut-out pressure on a transit bus is approximately:

A.80 psi

B.125 psi

C.100 psi

D.150 psi

Explanation: Governor cut-out, where the compressor stops building air and unloads, is typically around 125 psi. Cut-in, where it resumes pumping, is usually about 100 psi, giving roughly a 25 psi operating band.

3The reservoir safety (pressure relief) valve in a bus air system is generally set to open at about:

A.100 psi

B.125 psi

C.150 psi

D.200 psi

Explanation: The safety relief valve is a mechanical backup that protects the system if the governor fails to unload the compressor. It is commonly set near 150 psi so it only opens when pressure rises well above normal cut-out.

4Technician A says the air dryer removes moisture and oil before air enters the supply reservoir. Technician B says the air dryer's purge cycle is triggered when the governor unloads the compressor. Who is correct?

A.Technician A only

B.Technician B only

C.Neither A nor B

D.Both A and B

Explanation: The air dryer's desiccant and oil-coalescing filter remove water and oil aerosol before air reaches the supply tank. Most dryers purge accumulated contaminants when the governor signal unloads the compressor at cut-out.

5Water and oil collecting in the supply reservoir of a transit bus most directly indicates a problem with the:

A.Air dryer

B.Treadle valve

C.Quick-release valve

D.Slack adjuster

Explanation: The air dryer is responsible for removing moisture and oil aerosol from compressed air before it reaches the reservoirs. Significant water or oil downstream points to a saturated desiccant cartridge, failed heater, or non-purging dryer.

6What is the purpose of the one-way check valve located between the supply (wet) reservoir and the primary/secondary reservoirs?

A.To reduce delivery pressure to the rear brake chambers

B.To prevent loss of stored air from the service reservoirs if a supply-side leak occurs

C.To exhaust the parking brake when air is lost

D.To purge the air dryer at cut-out

Explanation: The check valve allows air to flow from the supply tank into the service reservoirs but blocks reverse flow. If the supply side develops a leak, stored air in the primary and secondary tanks is protected so the bus retains braking capability.

7A transit bus uses a dual air-brake system. The PRIMARY circuit normally supplies the:

A.Front axle service brakes only

B.Parking brakes only

C.Rear axle service brakes

D.Air horn and accessories only

Explanation: In a typical dual-circuit layout, the primary circuit serves the rear (drive) axle service brakes and the secondary circuit serves the front axle. This split ensures partial braking remains if one circuit fails.

8The low-air-pressure warning device on a bus must activate at no less than approximately:

A.20 psi

B.45 psi

C.90 psi

D.60 psi

Explanation: Federal requirements call for the low-air warning to activate at no less than about 60 psi (or one half of cut-out, whichever is greater) so the driver is alerted well before braking ability is lost.

9A bus builds air from 0 to cut-out very slowly (over 6 minutes at high idle). The MOST likely cause is:

A.A worn or carbon-fouled compressor

B.An out-of-adjustment slack adjuster

C.A leaking quick-release valve

D.A failed stop-light switch

Explanation: Slow build-up time usually indicates the compressor cannot move enough air, often from worn rings, carbon-fouled valves, or a restricted inlet. Build-up tests isolate compressor and supply-side capacity problems.

10During a static air-leakage test with the engine off and brakes released, allowable pressure drop for a single vehicle is generally no more than:

A.Any amount under 10 psi

B.2 psi per minute

C.20 psi per minute

D.Equal to cut-in pressure

Explanation: With the engine off and service brakes released, leakage on a straight truck/bus should not exceed about 2 psi in one minute. With brakes applied, the allowable rate roughly doubles to 3 psi per minute.

About the ASE H4 Brakes (Transit Bus) Exam

ASE H4 is the Brakes test in the ASE Transit Bus (H-series) certification program for professional transit-bus technicians. The official test focuses on air supply and service systems, mechanical/foundation brakes, parking brakes, and wheel bearings, emphasizing diagnosis and repair of heavy-duty air-brake systems used on transit buses.

Assessment

50 scored multiple-choice (60 total incl. 10 unscored) (official ASE); this practice bank is 100 selected-response items

Time Limit

75 minutes

Passing Score

Criterion-referenced (set by ASE)

Exam Fee

~$59 (ASE registration) (ASE (National Institute for Automotive Service Excellence))

ASE H4 Brakes (Transit Bus) Exam Content Outline

48%

Air Supply & Service Systems Diagnosis & Repair

Air compressor and governor, air dryer, supply/primary/secondary reservoirs, check and pressure-protection valves, treadle/relay/quick-release valves, low-air warning, FMVSS 121 build-up and actuation/release timing, dual-circuit operation, and leak testing.

28%

Mechanical/Foundation Brakes Diagnosis & Repair

S-cam and air disc foundation brakes, brake chambers and pushrod stroke measurement, automatic slack adjusters, drums and rotors, linings/pads, brake balance and fade, and transit duty-cycle wear inspection.

14%

Parking Brakes Diagnosis & Repair

Spring (parking/emergency) brake chambers, park-control valve, caging/release bolt safety, anti-compounding circuits, automatic low-pressure application, and combination-chamber diagnosis.

10%

Wheel Bearings Diagnosis & Repair

Wheel-bearing adjustment, endplay and preload, repacking and lubrication, wheel/hub seals, bearing and race inspection, and overheating or contamination diagnosis.

How to Pass the ASE H4 Brakes (Transit Bus) Exam

What You Need to Know

Passing score: Criterion-referenced (set by ASE)
Assessment: 50 scored multiple-choice (60 total incl. 10 unscored) (official ASE); this practice bank is 100 selected-response items
Time limit: 75 minutes
Exam fee: ~$59 (ASE registration)

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

ASE H4 Brakes (Transit Bus) Study Tips from Top Performers

1Weight your study by the official blueprint: air supply and service systems is 48% of the test, so master compressor/governor, air dryer, reservoirs, and treadle/relay/quick-release valve operation first.

2Practice the diagnostic logic ASE favors: start at the symptom (slow build-up, slow release, pull, drag) and reason to the most likely cause before choosing a repair.

3Drill numbers transit techs must know: governor cut-in ~100 psi and cut-out ~125 psi, safety valve ~150 psi, low-air warning at no less than ~60 psi, and released vs applied leak-down limits of about 2 and 3 psi per minute.

4Treat Tech A/Tech B questions as two independent true/false statements; verify each one separately before selecting both, neither, or one.

5Review pushrod-stroke measurement, slack-adjuster setup, spring-brake caging-bolt safety, anti-compounding, and wheel-bearing endplay/preload because these recur across the foundation, parking, and wheel-bearing areas.

Frequently Asked Questions

How many questions are on the ASE H4 test?

The official ASE H4 (Transit Bus Brakes) test has 50 scored multiple-choice questions plus about 10 unscored research questions, for roughly 60 questions total. This free practice bank contains 100 selected-response questions so you can drill each content area more deeply than the live test.

How much time do I get and how is ASE H4 scored?

ASE allots 75 minutes for the H4 test, delivered by computer at a Prometric test center. Scoring is criterion-referenced, meaning ASE sets the passing standard based on the knowledge required for competent work rather than a fixed percentage of correct answers.

What content areas does ASE H4 cover and how are they weighted?

ASE H4 covers four areas: Air Supply & Service Systems Diagnosis & Repair (48%), Mechanical/Foundation Brakes Diagnosis & Repair (28%), Parking Brakes Diagnosis & Repair (14%), and Wheel Bearings Diagnosis & Repair (10%). Air supply and service systems is by far the largest area, so prioritize compressor/governor, air dryer, reservoirs, and the treadle/relay valve circuits.

What does ASE H4 cost and what experience do I need?

The ASE registration cost is approximately $59 for the H4 test. To earn certification you must pass the test and document about two years of relevant hands-on work experience, with up to one year substitutable through relevant formal training.

Is ASE H4 a professional certification?

Yes. ASE H4 is part of the ASE Transit Bus (H-series) program used by transit agencies and fleets to certify professional bus technicians. It is a work-credential exam, not an academic admission test, and certifications must be renewed through recertification testing.

100+ Free ASE H4 Brakes (Transit Bus) Practice Questions

ASE H4 Brakes (Transit Bus)

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