The 10 Best Impact Wrenches
This wiki has been updated 29 times since it was first published in June of 2015. Yes, these are probably too much gun for that IKEA bookshelf, but if you've got a tough job ahead, let one of these powerful impact wrenches do the twisting and turning for you. Our top picks encompass a variety of model types — mains electricity, battery, and pneumatic — that are equipped with enough power for many intense applications. As the saying goes, "Work smart, not hard." When users buy our independently chosen editorial recommendations, we may earn commissions to help fund the Wiki.
May 08, 2019:
As there were no apparent availability issues or quality concerns with any of the products on this list, this was a rare instance where no replacement items were necessary. It helps that the list contains a strong mix of pneumatic (Chicago Pneumatic CP7748, AirCat 1150 Killer, Ingersoll-Rand 231C, Ingersoll-Rand 2235TiMAX, and NitroCat 1200-K), battery-powered (DeWalt DCF813S2, Milwaukee M18, and Bosch IWH181-01), and corded models (Hammerhead HDIW075 and Porter-Cable PCE211), giving users plenty of variety to choose from.
The combination of affordability and consistent performance that comes with the Chicago Pneumatic CP7746 is impossible to ignore, which is why we increased its ranking several slots. Seasoned mechanics and automotive technicians vouch for its durability and comfortable build, while home users appreciate its quiet operation.
Added two Special Honors to this list, including one offering from Stanley. Available in four sizes, this tool can be used for anything from everyday car maintenance to heavy-duty construction applications.
Greenlee Wrench This offering from Greenlee is a technologically-advanced model that will consistently work for you, not against you. Its auto-regulating flow control is a nice touch, and its auxiliary handle can be modified to three different positions based on the type of work you're engaged in. greenlee.com
Stanley Infrastructure To maximize its practicality for a wide range of uses, this Stanley’s tool has clearly prioritized versatility. It offers adjustable impact intensity settings and a reversing valve, plus it can generate impressive power despite its lack of bulk and weight. stanleyinfrastructure.com
All About Impact Wrenches
It is designed so that once it hits, it releases and then hits again.
An impact wrench is a tool used to make tightening and loosening tough bolts or nuts easier and more efficient. They reduce the effort and exertion of a user, while delivering high torque output in way that won't damage bolts or nuts. An impact wrench can produce a much higher amount of force than a person can with their hands, without the need for additional leverage. This makes them ideal for hard to reach places or stubborn bolts.
Impact wrenches can be found in a variety of settings from auto shops to large construction projects and may sometimes be called air wrenches (as many of them are pneumatically powered), torque guns, or impactors. In addition to pneumatic power, they may also be powered via a direct electrical connection or a rechargeable battery.
During operation, an impact wrench stores energy in a rotating mass and then quickly delivers it in short bursts to the output shaft. Inside of an impact wrench their is a hammer mechanism that is responsible for delivering the impact. It is designed so that once it hits, it releases and then hits again. This hammer hitting, releasing, and then hitting again is what gives impact wrenches their telltale sound and also the reason why their operator feels minimal torque when holding the tool.
Impact wrenches were first patented in 1939 by Harold C. Reynolds and Francis A. Jimerson, who worked for Chicago Pneumatic. The company is still known for making great impact wrenches and a variety of other air-powered tools, such as air hammers and pneumatic drills.
Air Impact Wrench Versus Electric Impact Wrench
Until recently, air impact wrenches were the most commonly used, especially for commercial applications. This is beginning to change though as electric impact wrenches, more specifically the corded versions, are now being offered that can produce roughly the same amount of power as pneumatic models.
This makes them less effective for large or rusted on bolts, but better for getting into small spaces and on-site work.
Air impact wrenches, also known as pneumatic impact wrenches, need to be directly connected to an air compressor during the entire time they are in operation. They are best used with large air compressors as small ones may not be able to supply them with the adequate amount of air. If the user only needs to loosen a couple of bolts, then a small compressor can do the job, but if one plans on using an air impact wrench continuously for an period of time, only large compressors will suffice.
Due to their need for a large amount of air, pneumatic impact wrenches are best for shop work and aren't suitable for on the go repairs. Another downside for those not experienced at using air impact wrenches is that most lack a variable speed trigger. This can make it hard for beginners to control them.
Electric impact wrenches come in cordless and corded varieties, each with their own unique benefits and drawbacks. Corded impact wrenches are similar in size, power, and speed to air-powered models, making them a good alternative to those who don't want to buy a compressor, or don't have the space to store one. Having access to a power supply at all times and running a large extension cord, which must be maneuvered around a busy workshop, can be problematic for some though.
Battery powered impact wrenches are often smaller and less powerful than corded and pneumatically-powered models. This makes them less effective for large or rusted on bolts, but better for getting into small spaces and on-site work. Often a home DIYer will find a battery-powered impact wrench to be the most convenient as they usually don't have to deal with as large or as stubborn of bolts as commercial users do.
Common Mistakes People Make When Using Impact Wrenches
The number one mistake most users make their first few times using an impact wrench is to overtighten their nuts and bolts. This is because they usually underestimate how much force the impact wrench is actually applying since they don't feel it in their hands. This can cause them to strip threads or even break the bolt itself. Luckily there are ways to remove a stripped screw or bolt.
The best way to avoid this is by threading the fixing by hand a few times before using the wrench.
Ideally those new to impact wrenches should look for one that has a torque limiter, which prevent overtightening. Another good way to avoid this is be using an impact wrench solely for loosening items, and a torque wrench for tightening.
Another way inexperienced users damage threads is by not setting the bolt or nut perfectly before using the impact wrench. Cross-threading a fixing and then using an impact wrench will nearly always cause damage. The best way to avoid this is by threading the fixing by hand a few times before using the wrench.
Impact wrenches require special sockets as ordinary sockets are not designed to be used under a cyclic load, but many consumers don't know this. Impact wrenches may cause standard sockets to break, or at the very least wear quicker causing them to become oversized and slip. To avoid this, buy a set of sockets designed specifically for impact wrenches.