CDL General Knowledge TestTransporting Cargo SafelyHard
A driver is transporting a load of metal products that have a high potential for rolling, such as pipes or coils, but are individually secured. Which type of tiedown is generally most effective for preventing rolling movement?
- AOverhead tiedowns that pass over the top of the cargo.
- BSide tiedowns that secure the cargo to the side railings.
- CChain tiedowns with a low Working Load Limit (WLL).
- DDirect tiedowns that pull the cargo horizontally.
Show answer & explanationAnswer & explanation
Correct answer: A. Overhead tiedowns that pass over the top of the cargo.
Overhead tiedowns (or 'top over' tiedowns) are generally most effective for preventing rolling movement of cylindrical or roll-prone cargo. They exert a downward force that increases friction and presses the object against the trailer deck or blocking, effectively counteracting its tendency to roll. Direct tiedowns (A) primarily prevent horizontal sliding, while side tiedowns (C) are usually supplemental. Low WLL chains (D) are always inappropriate for heavy cargo.
Why the other options are wrong
- B. Side tiedowns help with lateral movement, but don't directly counteract the rotational force of rolling as effectively as overhead.
- C. Low WLL chains are unsafe and inadequate for heavy cargo, regardless of the type of movement being prevented.
- D. Direct tiedowns prevent sliding, but are less effective on their own against rolling without downward force.
Tiedown Types for Rolling Cargo
Different tiedown configurations are more effective for specific types of cargo movement, especially for cargo prone to rolling.
- Overhead tiedowns apply downward force.
- Downward force increases friction, preventing rolling.
- Direct tiedowns primarily prevent sliding.
- Blocking/chocks are also crucial for rolling prevention.
Memory trick: To stop the roll, put a strap over the whole!