Power Ratchet Wrench Q&A

Power Ratchet Wrench 101


Power Ratchet wrenches are often used to replace manual ratchet wrenches by saving repeated arm movement and faster spin.  As the applications are to use in tight space and save repeated arm motion, the torque power is usually secondary to many skilled users because the ratchet mechanism in the tool allows users to manually tighten to snug condition or break loose a bolt **.

For heavy stubborn bolts, an impact wrench should be considered.


Power Ratchet Wrench vs Impact Wrench


Power Ratchet Wrench is a direct-drive tool, meaning the motor drives anvil directly through gears combination which usually delivers less torque power than impact mechanism.  The final torque generated on a bolt is instantaneous (torque will not accumulate for repeated/continuous hit), heavily rely on the continuous spinning momentum, and is subject to some other factors, like friction (or smoothness), temperature, and bolt/anvil alignment* of the ratchet and bolt.


Due to design and applications, the torque from a power ratchet wrench is greater when tightening than loosening.  Users should apply manual torque when breaking loose or securing snug conditions.


ratchet angle
Applying cordless ratchet wrench on bolt with good anvil-bolt alignment

Due to the 90 degree between the anvil and the ratchet body, the torque delivered to the bolts could be affected if the user not holding steadily and creating misalignment on the anvil and bolt.  The longer the “ratchet neck”, the harder it to hold steady with good anvil/bolt alignment.


Similar to hand ratchet wrench, Durofix, and ACDelco power ratchet specifies the max. manual torque user should apply on the tool.  Exceeding the limit could damage the internal and/or external structure.


Impact wrench, on the other hand, equips with an impact mechanism where the motor is pressing and releasing tension on a tough spring at high speed to create “Impact” on a bolt, the torque generated on the bolt would build up over time when the user keeps hitting the bolt.  This is useful for heavy-duty applications or rusted and stubborn bolts.

Remarks: All Torque specifications are stated as per lab test results based on ISO6789 standards.