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Pneumatic Torque Wrenches

Pneumatic Torque Wrench

Most people are familiar with pneumatic impact or break wrenches (often mis-called "torque wrenches"), used in nearly every auto shop and by many home mechanics everywhere. These are the ones that give the familiar "Pwummmm" when removing or replacing a tire and wheel. A pneumatic torque wrench, however, sounds and operates differently.

Like the equally common electric torque wrench, the pneumatic torque wrench can be set to a specific torque value and then it will stop turning the fastener when that value is reached. They are equally accurate because both electric and pneumatic wrenches use the same technology to operate, they just have a different power source.

How the Pneumatic Torque Wrench Works

The gearbox or torque multiplier inside the wrench uses a set of gears to convert a relatively small amount of power (in this case from compressed air) and turn it into a large amount of power with the gearing.

The torque setting dictates when the gears will go into neutral or stop powering the piston that turns the fastener. Power through the gearing can be amplified in some wrench models up to 4,000 times.

Differences in Torque vs. Impact Wrenches

The main ergonomic difference between an air-powered torque wrench and an impact wrench is in the weight distribution and the lack of kick-back. A torque wrench has all of its weight forward, where the gearbox is located, while an impact wrench has its weight at center where the air motor is located.

An impact wrench jumps as the torque increases or decreases whereas a torque wrench has no kick at all since all torque is fully controlled via the gearing.

In general, the power of the torque is controlled through the air line settings in both types of pneumatic wrench, but the impact wrench will not likely have power settings indicating torque, only psi.

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