You need to torque a nut to 35 in-lbs using an 8-inch torque wrench with a 2-inch reverse-extension adapter. What should the torque wrench indicate (TW) on the handle to achieve the target torque (TA)?

You need to torque a nut to 35 in-lbs using an 8-inch torque wrench with a 2-inch reverse-extension adapter. What should the torque wrench indicate (TW) on the handle to achieve the target torque (TA)?

• A. 46.7 in-lbs
• B. 35 in-lbs
• C. 28 in-lbs
• D. 43.75 in-lbs

Answer: (A)

Torque at the fastener depends on the lever arm from the handle to the fastener. A reverse-extension adapter reduces that lever arm, so the fastener sees less torque than the wrench indicates. With an 8-inch wrench and a 2-inch reverse extension, the effective lever length becomes 8 − 2 = 6 inches. The actual torque at the fastener is the indicated torque times the ratio of the effective length to the wrench length: TA = TW × (6/8) = 0.75 × TW. To achieve the target 35 in-lbs, the indicated torque must satisfy 0.75 × TW = 35, so TW = 35 / 0.75 ≈ 46.7 in-lbs. Therefore the torque wrench should indicate about 46.7 in-lbs. This matches the chosen answer because using the reverse-extension lowers the effective lever arm, requiring a higher indicated reading to reach the same actual torque.

Torque at the fastener depends on the lever arm from the handle to the fastener. A reverse-extension adapter reduces that lever arm, so the fastener sees less torque than the wrench indicates. With an 8-inch wrench and a 2-inch reverse extension, the effective lever length becomes 8 − 2 = 6 inches. The actual torque at the fastener is the indicated torque times the ratio of the effective length to the wrench length: TA = TW × (6/8) = 0.75 × TW.

To achieve the target 35 in-lbs, the indicated torque must satisfy 0.75 × TW = 35, so TW = 35 / 0.75 ≈ 46.7 in-lbs. Therefore the torque wrench should indicate about 46.7 in-lbs.

This matches the chosen answer because using the reverse-extension lowers the effective lever arm, requiring a higher indicated reading to reach the same actual torque.