Over-braking with a trailer can sometimes lead to
- jackknifing. ✓
- turbulence.
- slowing down.
- none of the above.
Answer: A. jackknifing.
Over-braking with a trailer can sometimes lead to jackknifing.
Why this is the answer
The handbook explains that trailer brakes can be applied with the foot valve, and pulling harder on the trailer hand valve can raise the pressure on the trailer brakes. It warns that on wet or slippery surfaces, or on a curve, over-braking can cause skidding or jackknifing. That directly supports jackknifing as the result listed here.
Why the other answers are wrong
- B. turbulence. — Turbulence is not mentioned in the handbook as a result of over-braking; the warning names skidding or jackknifing.
- C. slowing down. — Slowing down is what braking normally does, but the handbook's warning about over-braking in poor conditions points to skidding or jackknifing, not simply slowing.
- D. none of the above. — This is wrong because the handbook does name jackknifing as a possible result of over-braking in those conditions.
Remember it
Wet, slippery or curved road plus hard trailer braking is the setup to remember: too much trailer brake can start a jackknife.
Official handbook: Official MTO Truck Handbook, Use of brakes