ASE S4 Brakes (School Bus) case studies
ASE S4 Brakes (School Bus) · Put your knowledge to work in context.
The ASE S4 Brakes (School Bus) credential is one of the ASE certification tests offered through the National Institute for Automotive Service Excellence, the organization that certifies automotive service professionals across the country. The S4 test is aimed at technicians who service school buses, where brake work carries outsized safety responsibility because the vehicle transports students. The ASE S4 Brakes (School Bus) case studies are 5 cases and about 2,825 words.
1Governor Cut-Out and Slow Build on a Loaded Route Bus
A 2019 conventional school bus with a Bendix-style compressor and air dryer has a complaint of the low-pressure warning buzzer sounding intermittently on a hilly route. Static test: system builds from 85 to 100 psi in 95 seconds at high idle (spec is 85 to 100 in 45 seconds or less).
593 words, about 3 min2Hydraulic Pedal Fade After a Rear Drum Service
A Type A school bus with a hydraulic split-diagonal system and rear drum brakes had rear shoes and wheel cylinders replaced. The technician bench-bled the master cylinder, gravity-bled the rear circuit, and test drove.
521 words, about 3 min3Parking Brake Will Not Hold on a Grade
A rear-engine transit-style school bus with a spring-applied, air-released parking brake (maxi-can) on the rear axle fails a shop grade check. With the park brake applied and the transmission in neutral, the bus rolls slowly on a 20 percent grade with a full fuel load.
574 words, about 3 min4ABS Lamp and Intermittent Wheel Speed on a Wet Route
A 2020 conventional school bus with a 4-channel ABS (front axle individual, rear axle individual) has the amber ABS lamp on intermittently. It comes on after driving in rain and sometimes clears after a restart.
598 words, about 3 min5Hydro-Boost Assist Loss on a Diesel Bus
A diesel Type A school bus uses hydro-boost power assist (engine-driven power steering pump feeding the hydro-boost unit). The driver reports the brake pedal is hard and stopping distance is long, especially at low engine speed in the lot, and the steering feels heavy at idle too.
539 words, about 3 min