When holding a fastener in place during loosening, which wrench is used?

• A. Backup wrench
• B. Open-end wrench
• C. Box-end wrench
• D. Adjustable wrench

Answer: (A)

Hold a fastener in place by using a backup wrench. You put one wrench on the bolt head to apply the turning force, and you place a second wrench on the nut to keep it from turning. That backup wrench resists the rotation of the nut, preventing rounding or stripping of the nut threads and letting you apply torque to the bolt effectively to loosen it. Other wrenches are used for turning components, whereas the backup wrench’s role is to stabilize the nut during loosening.