Pneumatic Impact Wrenches: 1/2

1/2" models are the all-rounders for passenger cars and tyre service, 3/4" models suit vans and light trucks, and 1" models, often with an extended anvil, suit trucks and heavy equipment. For running small fasteners in tight spaces, a ratchet is more convenient. See how to choose a pneumatic ratchet wrench.

Manufacturers often quote maximum loosening torque, which is noticeably higher than working tightening torque: typically 600–1,600 N·m for 1/2" models, 1,000–2,500 N·m for 3/4" and 2,000–4,500 N·m or more for 1". Compare like with like, and remember that real torque depends on pressure and the hose. Read torque (N·m).

A Twin Hammer mechanism gives an even, powerful blow with less vibration, while Pin Clutch or Jumbo Hammer mechanisms stand up to heavy, continuous work. A composite housing makes the tool lighter, while an aluminium housing is more robust. Do final tightening with a torque wrench; see how to choose wrenches, sockets, ratchets and torque tools.

A reverse selector and a 3–4 step power regulator let you reduce force when tightening and use full torque when loosening. Free speed is usually 6,000–10,000 RPM for 1/2" models and 3,500–5,000 RPM for 1" models. See what is rotational speed (RPM).

Average air consumption of 1/2" impact wrenches is usually 120–250 l/min and of 1" models 300–600 l/min. The real delivery of the compressor should be about 30–50 % higher, and a tank of 50 l or more is advisable for tyre service. Read how to choose an air compressor and how to calculate compressor air delivery.

The rated working pressure is 6.2–6.3 bar; 1/2" models have a 1/4" inlet, while 3/4" and 1" models have a 3/8" or 1/2" inlet. Use a hose with an 8–10 mm inner diameter for a 1/2" wrench and 13 mm for heavy models, otherwise torque will drop. See how to choose compressor working pressure and how to choose an air hose and connectors.

Most impact wrenches are sold without sockets, and only impact-rated (black, Cr-Mo steel) sockets matching the drive size should be used. Ordinary chrome sockets can crack and are dangerous. Read how to choose an impact socket.

Condensate and dirt wear the air motor vanes and the hammer mechanism, so use a filter-water separator and a regulator. Put air tool oil into the inlet before work every day and grease the mechanism regularly. See how to prepare compressed air: condensate, filters, regulators, and lubricators.

1/2" models weigh 1.5–3 kg and 1" models 7–12 kg, so balance, a rubberised grip and exhaust through the bottom of the handle matter. Noise reaches 90–100 dB, and worn vanes, the hammer mechanism and the anvil can be replaced with spare parts. Read how to choose hearing protection and how to choose spare parts for pneumatic and hydraulic tools.