What is a torque adapter used for?

Torque adapter wrenches are used to apply the correct torque to a 'critical part'. Often we'd like to apply the correct torque in order to avoid over-tightening the parts.

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Torque is equivalent to radius x force. As long as A, the force is applied at the same distance from the nut/bolt that you're tightening, and B, it's applied in the same direction then you'll be applying the same torque.