9782075129435 - How does it work? - Engines and cars - Ages 7 to 12 A book specially designed for car enthusiasts and budding mechanics! By building nine mechanisms themselves, the reader will understand how the steering wheel, brakes, windshield wipers, engine or gearbox. With nine mechanisms to assemble on a perforated board and precise assembly instructions, clear explanations for each mechanism studied, 47 mechanical parts, 12 nuts and 12 bolts provided to make models.