Which of these can exert the greatest force?
- Hydraulic brakes
- Electromagnetic brakes
- Air brakes ✓
- Mechanical brakes
Answer: C. Air brakes
Air brakes can exert the greatest force of the choices listed.
Why this is the answer
The handbook's air brake chapter explains how compressed air turns pressure into mechanical force at the brake chamber. It works through a diaphragm with a set surface area, so pushrod force grows with air pressure and chamber size — a common Type 30 chamber at 100 p.s.i. develops 3,000 pounds of pushrod force, which the text calls very powerful. The same chapter states plainly that air brakes generate more braking force than hydraulic brakes, which is why air is the choice that produces the greatest force.
Why the other answers are wrong
- A. Hydraulic brakes — Hydraulic brakes are the system the handbook directly compares against air, and it says air brakes generate more braking force than hydraulic ones.
- B. Electromagnetic brakes — The passages never present electromagnetic brakes as a source of braking force, and nothing in them puts electromagnetic brakes above air.
- D. Mechanical brakes — Mechanical brakes are not described anywhere in these passages, so nothing there supports them as the strongest of the group.
Remember it
Picture the air chamber: pressure times diaphragm area equals push force, and that multiplication is what makes air the heavy-duty choice.
Official handbook: ICBC Driving Commercial Vehicles, 8 Air brakes – Why air brakes?, p. 145