What Is Air Impact Wrenches and How They Work
An air impact wrench is a pneumatic wrench that loosens and tightens fasteners with rapid hammer blows, and the gear below shows what each listing states.
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What is air impact wrenches? An air impact wrench is a pneumatic wrench that loosens and tightens fasteners with rapid hammer blows, powered by compressed air from a shop compressor. The tool spins a socket the way a ratchet does, but a hammer inside strikes the anvil in short bursts, so a stuck lug nut breaks loose with little of the twist traveling back into the hands holding the tool. Air impact wrenches live in tire shops and home garages for lug nuts, suspension bolts and stuck fasteners.
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FICHFOYE 1/2 in Air Impact Wrench, 1620 ft-lb
A 1/2 in air impact wrench with 1620 ft-lb of max torque, 8500 RPM free speed and a 4.4 lb composite body.
Pros
- 1620 ft-lb max torque, the highest figure in this set
- 8500 RPM free speed
- 4.4 lb composite body with a soft-grip handle
- 3 forward speeds, 1 reverse setting and a variable-speed trigger
Cons
- No socket set or case is included
- Needs 6.5 CFM at 90 to 120 PSI
- No warranty term is stated
- No lubrication adaptor is stated
XIIW 1/2 Inch Air Impact Wrench
A 1/2 in air impact wrench with 1560 ft-lbs of max torque, 8000 RPM free speed and an 11-piece CR-V socket set.
Pros
- 1560 ft-lbs max torque with a twin hammer mechanism
- 11-piece CR-V socket set with a 5 in extension bar
- 4.4 lb rubber housing with an ergonomic grip and muffled exhaust
- Lubrication adaptor included
Cons
- Title says 11 pieces while the spec table says 15 pieces
- No working pressure or air use stated
- No warranty term is stated
- No inlet size is stated
ROTAKE 1/2" Air Impact Wrench, 1400 ft-lbs
A 1/2 in air impact wrench with 1400 ft-lbs of max torque, 7200 RPM speed and a 5.14 lb composite body.
Pros
- 1400 ft-lbs max torque through a 1/2 in square drive
- Air supply stated: approximately 7 CFM at 90 PSI
- 3-speed forward control with full-power reverse
- 5.14 lb composite body with a TPE comfort grip
Cons
- No socket set or case is included
- No warranty term is stated
- 7200 RPM free speed, the lowest figure in this set
- 5.14 lb body, heavier than the 4.4 lb listings
AEROPRO TOOLS 1/2-Inch Aluminum Air Impact Wrench
A 1/2 in air impact wrench set with 1380 ft-lbs of max loosening torque, 7800 RPM speed and 5 impact sockets.
Pros
- Max loosening torque of 1380 ft-lbs with a twin hammer
- Working torque of 810 ft-lbs stated separately from loosening torque
- 5 impact sockets, 17 to 27 mm, with a carrying case
- Rear exhaust directs debris away
Cons
- 5.25 lb, the heaviest weight in this set
- No warranty term is stated
- Air compressor needed but not included
- No CFM figure is stated
What is air impact wrenches: how the hammer works
Inside the tool, compressed air spins a rotor, and the rotor drives a hammer that strikes the anvil in rapid bursts. Each blow turns the socket a small step, then the hammer resets and strikes again, so the fastener moves in sharp twists rather than a steady pull. The bursts break a corroded lug nut loose: the hammer stores energy between blows and delivers it in a sharp hit. A forward and reverse control sets the direction, and a speed control sets how hard the hammer hits. The twin hammer design in the listings below strikes from each side of the anvil, which keeps the blows balanced.
| Tool | Max torque | Free speed | Weight |
|---|---|---|---|
| FICHFOYE FLQ023 | 1620 ft-lb | 8500 RPM | 4.4 lb |
| XIIW 81704 | 1560 ft-lbs | 8000 RPM | 4.4 lb |
| ROTAKE RT-5276 | 1400 ft-lbs | 7200 RPM | 5.14 lb |
| AEROPRO A398 KIT | 1380 ft-lbs loosening | 7800 RPM | 5.25 lb |
Working torque and loosening torque are different figures. The AEROPRO listing states a max working torque of 810 ft-lbs and a max loosening torque of 1380 ft-lbs. The other listings state a max torque figure alone: FICHFOYE states 1620 ft-lb, XIIW states 1560 ft-lbs and ROTAKE states 1400 ft-lbs. Read the max figure as loosening power, not as the torque to fasten with.
Air supply: what the compressor must deliver
An air impact wrench is only as strong as the air behind it. The ROTAKE listing states approximately 7 CFM at 90 PSI, and the FICHFOYE listing states 6.5 CFM at 90 to 120 PSI, so the compressor must hold that airflow and pressure while the tool runs, not just at idle. The AEROPRO listing states a working pressure of 90 PSI. The AEROPRO, ROTAKE and FICHFOYE listings state a 1/4 in air inlet, and the ROTAKE and FICHFOYE listings call for a 3/8 in hose. Check the compressor output at 90 PSI, and use the hose size the listing states.
The gear
Loosening a stuck lug nut is the step that needs the hammer, and the wrenches below are the gear for it.
Wear eye protection and hearing protection. Use impact-rated sockets only, never chrome sockets, and keep hands clear of the socket while the tool runs. Disconnect the air line before changing sockets.
Wear eye protection with every air tool, use impact-rated sockets on impact wrenches, disconnect the air line before changing accessories, and finish lug nuts with a torque wrench to the vehicle's spec. See OSHA eye and face protection. Read our Safety Disclaimer.
Air impact wrench vs cordless
A cordless impact wrench runs on a battery and goes anywhere, while an air impact wrench needs a compressor and a hose but keeps hitting hard as long as the air holds. For work away from the compressor, see our picks for the best cordless impact wrench. For the air side, see our picks for the best impact wrench and the low cost air compressor guide.
FAQ: garage tools
What does an air impact wrench do?
It loosens and tightens fasteners with rapid hammer blows powered by compressed air. The hammer strikes the anvil in short bursts, so a stuck lug nut or suspension bolt breaks loose with little twist traveling back into the hands.
How much air does an air impact wrench need?
It depends on the wrench. The ROTAKE listing states approximately 7 CFM at 90 PSI, and the FICHFOYE listing states 6.5 CFM at 90 to 120 PSI.
Can I use regular sockets on an air impact wrench?
No. Use impact-rated sockets only: chrome sockets can split under hammer blows. The AEROPRO set holds 17, 19, 22, 24 and 27 mm sockets, and the XIIW set holds 10 sockets from 9 to 27 mm with a 5 in extension bar.
What size air impact wrench do I need for lug nuts?
A 1/2 in drive suits lug nuts and suspension work: every listing here uses a 1/2 in drive. Finish fasteners to the torque the manual lists rather than the wrench max figure.
Related: best impact wrench, best cordless impact wrench, lug nut size chart and our air tools hub.
