With a wrench length of 12 inches and a 2-inch reverse-extension adapter, what is the required TW to reach TA of 35 in-lbs?

With a wrench length of 12 inches and a 2-inch reverse-extension adapter, what is the required TW to reach TA of 35 in-lbs?

• A. 42 in-lbs
• B. 35 in-lbs
• C. 48 in-lbs
• D. 60 in-lbs

Answer: (A)

When you apply torque with a wrench, the actual torque at the fastener depends on the lever arm length. A reverse-extension adapter shortens the effective lever arm by its extension length, so for the same wrench setting you deliver more handle torque but the fastener torque changes according to the shorter arm. Here, the wrench length is 12 inches and the reverse-extension adapter is 2 inches, so the effective lever arm becomes 12 − 2 = 10 inches. The relationship between the wrench reading (TW) and the actual torque at the fastener (TA) is TA = TW × (L_eff / L_wrench). Solve for TW: TW = TA × (L_wrench / L_eff) = 35 × (12 / 10) = 42 in-lbs. So the required torque setting on the wrench is 42 in-lbs. If you weren’t using a reverse extension, the calculation would yield a different value (about 30 in-lbs with a standard extension), but with the reverse adapter the correct setting is 42 in-lbs.

When you apply torque with a wrench, the actual torque at the fastener depends on the lever arm length. A reverse-extension adapter shortens the effective lever arm by its extension length, so for the same wrench setting you deliver more handle torque but the fastener torque changes according to the shorter arm.

Here, the wrench length is 12 inches and the reverse-extension adapter is 2 inches, so the effective lever arm becomes 12 − 2 = 10 inches. The relationship between the wrench reading (TW) and the actual torque at the fastener (TA) is TA = TW × (L_eff / L_wrench). Solve for TW: TW = TA × (L_wrench / L_eff) = 35 × (12 / 10) = 42 in-lbs.

So the required torque setting on the wrench is 42 in-lbs. If you weren’t using a reverse extension, the calculation would yield a different value (about 30 in-lbs with a standard extension), but with the reverse adapter the correct setting is 42 in-lbs.