Pneumatic Impact Wrench With Torque Adjustment

Tightening torque on the nutrunner. Tightening torque on the nutrunner. Sent to Tips in choosing: Here’s a problem-misfortune happened Dano: there is a need to tighten a lot of nuts on studs (from M18 to M24) or bolts into the sleeves but the diameter is the same, with a certain moment. This will happen at sites most often in the wilderness, where builders do not always promise a compressor, but do not always bring it. We are talking about bridges and we fasten the structures directly to the structure, so in theory, follow the recommendations for fastening must be followed. N.

The only option is to look for an adjustable torque wrench.


We recommend working with dry compressed air with an oil mist.

Proper lubrication of the nutrunner during operation is necessary in order to ensure its high survivability and reliability.

Given the intensive use of a pneumatic impact wrench, lubricating oil should have properties that prevent wear and excessive heating of rubbing elements, the formation of rust and other oxidation products.

Recommended spindle oils meeting the above requirements:

  • I-20 (cold season),
  • I-30 (warm season).

Important notes

The drip nipple of the air preparation unit must be set at 3-4 drops per 1 m³ at maximum air flow. The remoteness of the preparation unit from the wrench is no more than 7 meters. In exceptional cases, when the network does not have an oiler, it is imperative to pour 2-4 ml of the recommended oil into the tool through the compressed air supply air nozzle every day before starting work. This action must be repeated every 2 hours of device operation.

This instruction must be observed for a longer and better work. Any pneumatic tool.

Finding during the warranty repair that the wrench was operated without lubrication or that the wrench contains condensation (moisture) will be the basis for the loss of the warranty.

General instructions for pneumatic impact wrenches

pneumatic impact wrench with torque adjustment

This manual must be read by the operator before using the air impact wrench. Must be accessible and understandable to the personnel operating the tool, service personnel (service) and safety inspectors.


  • Before starting work, the air connection must be tightly connected to the compressed air supply hose and clamped with a clamp.
  • Before connecting the nutrunner to the compressed air network, it is recommended to blow through the hose to remove water and other impurities. Use hoses no longer than 10-15 m, because the longer length causes a pressure drop that lowers the impact energy.
  • If it is necessary to use longer hoses, use the larger diameter hose first and then the recommended diameter.
  • Connect the fitting to the hose and tighten thoroughly with a hose clamp.
  • Check that the starting lever is not locked in the run position and only then apply compressed air.

Pneumatic Impact Wrench (Air Tighten Fasteners)

Compact and lightweight compressed air tool. Has gained immense popularity in car services, industry and everyday life. Capable of delivering impressive torque compared to electric counterparts, while being less prone to breakage, thanks to a simple, monolithic mechanism. In this article, we will tell you how an air impact wrench works, what tightening adjustment is, and also tell you what to look for when choosing this tool.

How to choose a pneumatic impact wrench

  • Scope of application. Determine for yourself in what types of work the tool will be used. Whether you are looking for a pneumatic garage impact wrench, a compact vent mount or a large truck wheel loosener.
  • Nut dimensions. The more compact the fastener, the less tightening force it requires. If you have to turn nuts with a thread size from M6 to M10, a 1/2 landing square will do. The 3/4 square impact wrench is suitable for fasteners with M10 M18 threads. For larger nuts, a 1 inch square is optimal.
  • Torque. Based on a certain type of work, a tool is selected with a suitable torque indicator, which usually ranges from 300 Nm to 3000 Nm (excluding the giants of the industry). The wheels of a car can get off the ground at 300-400 Nm, Kamaz at 800-1000 Nm, and extremely loaded joints will yield only to a tool with an indicator of several thousand.
  • Tightening adjuster. An important factor that adds versatility to the tool. The adjustment expands the range of fasteners to be screwed in, but on pneumatic impact wrenches has an error of 10%.
  • Device weight. Long-term work with a heavy tool with vibration can make life difficult. If you choose a pneumatic impact wrench for the garage and small household chores for a few minutes a day, then a unit with an all-metal body will do. For longer use, it is better to take a lighter tool with a composite body.
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Pneumatic torque wrench

Most modern impact wrenches are equipped with a torque adjustment feature. The main purpose of this function is to prevent fasteners from overtightening, breaking the thread or head. The adjustment will be useful for tightening relatively small nuts and bolts with a high torque tool. The fastener on the M8 will most likely be damaged if it is tightened with a tool without a regulator, with a maximum torque of 1000 Nm.

The principle of operation of a pneumatic adjustable impact wrench is to restrict the air supply, thereby reducing the torque. For example: if on a Fubag pneumatic impact wrench to 900 Nm, set mode number 3, its torque will decrease to 450 Nm, which will allow you to confidently tighten the M14 fastener. The number of modes on different instruments may vary, but on average there are from 3 to 5 of them. Information on operating modes is indicated in the documentation attached to the tool. Each individual device has its own characteristics of regulated powers.

Pneumatic ratchet Gross 57446

Static and percussion.

Static angle pneumatic ratchets like Intertool PT-1111 do not have an impact function. The reactive moment that occurs when the bolt is unscrewed is transferred to the operator’s hands, therefore they are used for fastening up to M12 inclusive, followed by manual pulling.
Wheel nutrunners multipliers are distinguished by a large tightening torque, but they have a body stop that is installed in a nut adjacent to the unscrewed one.

Impact models are used to easily break off over-tightened, defective or rusted nuts without transferring shaft torque to the user’s hands.
In the electric Sthor 57092 or the Yato YT-09540 pneumatic car service wrench, the shaft rotates freely inside the hammers and holder. With increasing resistance from the side of the fastener, the hammers deflect, bypass the shaft with the fitted head and strike it, transferring their energy. A series of successive shock pulses help crank the stud or nut even inside a heavily oxidized, thick rusty joint. The final tightening torque is equal to the sum of the moments of individual impacts.

The reliability of the tool depends on the type of construction, quality of performance
shock-rotational mechanism and the number of twisted fasteners, the shock interaction with which took place at the limit of possibilities.
Professional wheeled pneumatic impact wrenches, such as Yato YT-09571, have impact group resistance to destruction from 15 to 25 thousand unscrewing / tightening cycles. Cordless garage and workshop models like the Makita 6918FDWDE have 5 to 15 thousand cycles.

Pneumatic impact wrench 1/2 Yato YT-09528

Caution pneumatic impact wrench!

Pneumatic guns (pneumatic wrenches), due to their low cost, in recent years have firmly entered the list of tools available in almost any tire workshop or service station. The pneumatic impact wrench really significantly speeds up the process of dismantling / mounting the wheel and greatly facilitates the work of the master. True, only not many motorists know that tightening and tightening wheel bolts (nuts) with an air wrench is strictly prohibited!

How do pneumatic impact wrenches work?

The design of pneumatic impact wrenches, which are used in tire fitting, is quite simple: a pneumatic gun is connected to the compressor hose and is driven by high pressure air. An important element of the design of the pneumatic gun is the ability to adjust the maximum force transmitted to the chuck of the pneumatic wrench, due to which, in particular, the tightening torque of bolts (nuts) can be adjusted. This is precisely the main argument of the tire fitters in favor of using a pneumatic wrench when tightening the bolts, the tightening torque is set to a minimum, which means that the bolts (nuts) will not be overtightened.

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In fact, pneumatic devices cannot be used when attaching a wheel to a hub not at all because of the tightening force, although, given the fact that in the overwhelming majority of cases pneumatic wrenches in tire centers are cheap Chinese products and adjusting the tightening torque is the first thing that breaks in them (if worked at all), there is absolutely no reason to trust these devices, and the situation when problems arise during the next dismantling of the wheel is more than likely and vital. But the point is not even that the bolts when mounting the wheel can be tightened too much (or too weakly) for you.

Why do the fastening bolts (nuts) have a tapered base?

You’ve probably noticed that the bolt holes on the discs have a much larger diameter than the threads of the bolts (studs) that attach the disc to the hub? And, accordingly, the bolts (nuts) themselves have a cap with a tapered base? Have you ever wondered why this is done? And this is done because the car manufacturer is forced to very accurately calculate the fit of the wheel disk on the hub so that the axis of rotation of the disk exactly coincides with the axis of rotation of the hub. If these axles do not match, the wheel will beat, literally destroying the wheel bearing and other supporting elements of the suspension. over, the task is not only to properly fit the wheel on the hub, but also to securely fix it in this position in all load axes. That is why there is a centering hole in the disc (for a correct fit) and rules for the alternate and phased tightening of the wheel bolts. For a secure fit in the correct position. about the purpose of the centering hole and tapers. For more information, see the article on centering rings.

Tightening bolts (nuts) according to the rules, i.E. Manually, using a professional tool, slowly, according to the sprocket principle and in several stages, you ensure the most accurate centering of the disc bolt holes on the tapered bases of the bolts (nuts), and, accordingly, the most reliable fastening of the disc to the car hub in the desired position. What happens when the bolts are tightened with a pneumatic wrench? Under high pressure and at high speed, one bolt (nut) is twisted (and tightened), and, regardless of whether it correctly sits in the bolt hole of the disc and whether other holes fit correctly in relation to the studs (threaded holes) of the hub. And after that, all the other bolts are already forced to tighten based on the position that the wheel took relative to the hub when tightening the first bolt.

For fun, try to put the wheel on the hub and tighten only one bolt (nut), but without tightening to the end, you will see that the wheel will have a rather serious backlash

What are the consequences of pneumatic tightening of bolts (nuts)?

If the wheel has seated on the hub incorrectly, it means that it is not properly seated in the holes on the disc and the tapered bases of the bolts or nuts. And this, in turn, means that two forces will collide in the movement of the car: either the beating wheel will break the bearing (this is important for cases when the diameter of the centering hole of the disc does not exactly coincide with the diameter of the landing cylinder of the hub), or the wheel will still shift (for example, when emergency braking) and snaps into place (depends on the actual tightening torque of the bolts). In the first case, the consequences are clear, and in the second, when the bolts fit into place, it turns out that they are not tight enough! Well, then the vibration of the wheel and centrifugal force will inevitably do their job, the bolts (nuts) will sooner or later unscrew. It’s good if you have time to notice it

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Of course, the likelihood that the wheel will immediately sit correctly on the hub, and the cones of the bolts (nuts) will sit correctly in their places, not only exists it is quite high (especially if the diameter of the centering hole of the disc exactly matches the cylinder of the hub), but there is also the possibility of an incorrect wheel installation, which most likely will not happen with correct manual tightening of the bolts. Therefore, always require the wheel to be turned and tightened by hand., moreover, by weight, the complete tightening of the bolts (nuts) after lowering the car from the jack can lead to the same consequences.


If the SCREWDRIVERS are positioned as the LITTLE SISTERS of the SCREWDRIVERS, then the NUTS with certainty can be called the BIG BROTHERS.
The main features of NUTS are the presence of a more powerful PLANETARY REDUCER. Accordingly, the TORQUE indicator is much higher. For ACCUMULATOR NUTS, it reaches 200-230Nm. (BOSCH GDS18V, HITACHI WR18DL, MAKITA BTW251RFE), which allows you to tighten and unscrew (thanks to REVERSE) bolts and nuts of sufficiently large sizes.
REGULATION OF SPEEDS from the degree of pressing the power button makes the initial stage of tightening more comfortable.
Since the tightening force is high enough, all NUTRUNNERS have a RELEASE COUPLING, which prevents the tool from being pulled out of the hands at the final stage of tightening.
The main part of all ACCUMULATOR NUTS are PROFESSIONAL class models. Therefore, they are equipped with LI-ION batteries with a capacity of 2.6-3.0 Ah for serious continuous operation in difficult conditions.

IN THE NETWORK (ELECTRIC) NUTS, the number of revolutions (2200 rpm) is not adjustable. But the maximum torque is much higher than that of the battery. The indicator reaches 1000Nm (MAKITA TW1000), which significantly expands the range of work, for example, the possibility of using it in the automotive industry and on large-scale construction sites.
Instead of the hex shank bits used by SCREWDRIVERS, ELECTRIC NUTS and CORDLESS NUTS work with heads that attach to a square spindle.

The size of the nuts to be tightened depends on the torque characteristics.
Most of the NUTS have the so-called PULSE MODE, that is, at the moment the resistance increases, the impact function is added to the rotation. With this option the maximum torque is achieved. Also, using REVERSE, you can easily unscrew stuck and rusty bolts and nuts.
THE REDUCER OF THE ACCUMULATOR AND ELECTRIC WRENCH is enclosed in a metal case, which provides high reliability and better heat transfer.
The ADDITIONAL HANDLE included in the kit allows for better control of the tool during tough and challenging jobs.
Many developers improve the design of their models every year; rubber pads are placed on the cases for comfortable work, ensuring proper vibration damping. HITACHI went the farthest and put rubber on not only the main handle, but almost the entire body of the NUTRUN. Thus, the impact resistance of the tool is significantly increased. This is especially true when carrying out work at height.