USCG Exam PracticeDeck machinery and ground tackle
The theoretical mechanical advantage of a tackle is determined by which of the following?
- A. The total number of sheaves in both the standing and moving blocks combined
- ✓ The number of parts of the fall supporting the moving (load) blockCorrect
- C. The diameter of the sheaves in the moving block only
- D. The length of the fall between the standing and moving blocks
Why B is correct
Per NAVEDTRA 14343 §8-2, the theoretical mechanical advantage of a tackle equals the number of parts of the fall supporting the moving (load) block. In practice, friction reduces this ideal advantage by roughly ten percent per sheave.
Cited:NAVEDTRA 14343 §8-2