Auto Shop

Auto & Shop Information: Technical Subtests The Auto Information (AI) and Shop Information (SI) subtests directly determine whether you qualify for mechanical and maintenance military jobs — so mastering these topics can open doors to high-demand MOS/ratings in the Army, Air Force, and beyond. --- ## Why This Matters on the Exam AI and SI scores feed into line score composites — specifically the Mechanical Maintenance (MM) and General Maintenance (GM) composites in the Army, and the M composite in the Air Force. Even if your AFQT is strong, a weak auto/shop score closes off entire career fields. Study this section *after* you've secured your AFQT foundation, but don't skip it if mechanical jobs are your goal. --- ## Part 1: Automotive Information (AI) ### The Four-Stroke Engine Cycle The heart of the AI subtest is understanding how a gasoline engine works. Every piston in a four-stroke engine completes exactly four strokes to produce one power cycle: | Stroke | What Happens | |--------|-------------| | 1. Intake | Piston moves down; air-fuel mixture drawn into cylinder | | 2. Compression | Piston moves up; mixture is compressed | | 3. Power | Spark plug fires; explosion forces piston down | | 4. Exhaust | Piston moves up; burned gases pushed out | Memory trick: *"Suck, Squeeze, Bang, Blow"* — one phrase, correct order, never forget it. ### Key Engine Components - Spark plug — ignites the air-fuel mixture during the Power stroke - Carburetor / Fuel injector — mixes or delivers fuel into the intake air stream - Camshaft — controls the opening and closing of intake and exhaust valves - Crankshaft — converts the up-and-down piston motion into…