3-11. Because of the size of the air piston  in  an  air-over–hydraulic brake system, the air pressure is a much greater pressure than the hydraulic  pressure  that  is  admitted to the air cylinder. 1. True 2. False 3-12. In a vacuum brake system, what force acts on the rear side of the piston to exert a powerful pull on the rod attached to the piston? 1. Compressed  air 2. Mechanical  pressure 3. Vacuum 4. Atmospheric   pressure 3-13. What type of vacuum braking system contains within one unit, a hydraulically  actuated  control valve,   a vacuum power cylinder, and  a  hydraulic  slave  cylinder? 1. Hydrovac 2. air-hydraulic  unit 3. electric  vacuum  unit 4. air pack Learning  Objective: Recognize the  principles  and  components of  electrical  systems  used  in automotive  and  construction equipment. 3-14. Which  of  the  following  components is NOT a basic component of an automotive  and  construction equipment  electrical  system? 1. A storage battery 2. A  charging  system 3. A  starting  circuit 4. An  electrostat 3-15. Which  of  the  following  components is the heart of the charging circuit? 3–16. Battery  current  is  produced  by a  chemical  reaction  between  the active  materials  of  the  plates and what type of acid? 1. Bromic 2. Floric 3. Sulfuric 4. Phosphoric 3-17. You  can  thoroughly  clean  a  battery by using a stiff brush and what kind  of  solution? 1. Water and baking soda 2. Water  and  soap 3. Water and detergent 4. Water  and  vinegar 3-18. The cell elements of a battery contain two types of lead plates, known as positive and negative. 1. True 2. False 3–19. In what units is the capacity of  a  battery  measured? 1. Cold  current  amps 2. Circuit  cranking  voltage 3. Cold  cranking  amps 4. Continuous  cranking  voltage 3–20. The  charging  system  recharges  the battery  and  performs  what  other function? 1. Stores  charged  amps 2. Generates  current  during operation 3. Stores  charged  voltage 4. All of the above 3-21. Dc and ac are the two types of charging  systems  used  on  automotive and  construction  equipment. 1. True 2. False 1. The  storage  battery 2. The  starting  circuit 3. The  lighting  system 4. The gauges 18