Torque-controlled impact wrench

Electric nutrunner with torque adjustment function. characteristics and selection tips

The manual coupling of components in the bolt-nut threaded connection method is too time-consuming, particularly when there are a large number of components. And in some cases, work with a wrench (horn or any other) is simply impossible due to impossibility of access to the work area or intensive corrosion of metal, which causes “sticking” of fasteners.

Rational solution is to use such a device as a nutrunner with a convenient function of tightening torque adjustment. Let’s see what’s so special about its electric modification.

General information

Outwardly, this tool is much like the electric drill, familiar to everyone. And by design almost identical. same housing and motor with gearbox. The only difference is that if the drill chuck is clamped with a drill bit or a small drill bit, the wrench is equipped with a special working tip. And their functionality is somewhat different.

Unlike their pneumatic, mechanical or hydraulic counterparts, these devices are considered to be universal, since they are equally suitable for both tightening and loosening nuts. It is the electric nutrunner models that are recommended for domestic use. For example, to work with roofing material (the same profmetal).


So widely advertised pneumatics in terms of service “iron horse” has limited use. It is not suitable for changing wheels. The reason is that this type of impact wrench is good only for unscrewing fasteners. But the reverse process, tightening the nuts, is better “entrusted” to other tools. When working with a tensioner even an experienced master negligently tears the thread. And if not, it will inevitably happen when you re-tighten it. It is only a question of time and intensity of operation of the car.

How to choose a impact wrench? Useful tips and tips and tricks

For domestic use, cordless wrenches are the most suitable, as they are maneuverable, lightweight, ergonomic and easy to use.

Let’s look below at what to look for when choosing a good wrench.

  • Purpose. Before choosing such a wrench, you should decide what kind of tasks your tool will perform. Depending on this, the model will have to comply with basic parameters such as the type of impact wrench, maximum torque, power, speed, spindle type and tooling.
  • Impact or nonimpact?
  • A hammerless impact wrench is worth choosing when:
  • You plan to assemble / disassemble lightweight structures;
  • tightening and loosening small nuts;
  • You do not plan to use the tool for a long time and not very often;
  • You are not planning to buy a more expensive impact tool.
  • car maintenance;
  • Assembly / disassembly of heavy structural parts;
  • Unscrewing old, rusty/soldered nuts;
  • tightening/unscrewing threaded fasteners.
  • The maximum torque for a impact wrench is the most important factor for this tool. Depending on the power of the engine, it ranges from 100 to 900 Nm. Average for residential models is 400-500 N-m.

This parameter should be chosen very carefully, because low-power models are not able to untighten / tighten complex structural elements, and too powerful models can overtighten, damage threads and even break fasteners.

So, different maximum torques can be used for different jobs:

  • 160 N-m for tightening/unscrewing thin plastic structures;
  • 250 Nm. for tightening/unscrewing small nuts on thin metal, aluminum;
  • 440 Nm. for roofing and other repair work;
  • 810 Nm. for repairing cars and other equipment.

For example, for a car repair shop, most cordless wrenches will have insufficient torque (e.g. for nuts on a hub, on an alternator pulley), so that powerful pneumatic tools are more suitable for such work.

Note that as the power and torque of the spudger increases, so does the weight of the tool.

It’s worth knowing this rule: the tool’s power is less on tightening, more on unscrewing.

  • Wrench power and pulse frequency:
  • The power output of domestic and semi-professional impact wrenches is usually 500-600 W, and does not exceed 1.2 kW, and professional tools, on the contrary, over 1.2 kW.
  • The torque and pulse frequency described above are the parameters by which it is best to choose a wrench. The pulse rate of a good impact wrench should be about 3,000 strokes per minute.
  • Spindle type and features of the impact wrench:

Since the wrench is designed to handle different diameter fasteners, most often the spindle has a hexagonal section (“hex”), which is most convenient to use for installing various bits:

  • The clamping chuck can have the parameters: 1/2, 3/4, and 1 inch.
  • A good, powerful impact wrench has a 3/4 inch or 1 inch square.
  • Low power, for simple housework. 1/2 in.

Spiral cap spring wrenches are designed to fit a variety of attachments, adapters, such as 3/8. Thus, the tool’s equipment makes it possible to work with different nuts, bolts, screws, and with different head cuts.

To tighten the nuts enough one spring, and to unscrew threaded connections should be two.

Not every tool is power or design suitable for all fasteners, so when choosing a ratchet, look in the manual which accessories are suitable for the model.

Speed of the nutrunner and the presence of a torque regulator are important depending on the application.

  • Among the domestic models, there are wrenches with a speed of 40-100 revolutions per minute.
  • Semi-professional models have speeds over 2000 rpm.
  • This may be greater than 5000 rpm for professional models (pneumatic and hydraulic). With such a tool, a nut tightened to 30-40 kg can be unscrewed.

If a cordless ratchet manufacturer lists a speed greater than 3000 rpm in the manual, this is cause for concern: the figures may be exaggerated in order to attract customers.

The number and accuracy of gear adjustment significantly increases the spanners’ functionality. The ideal offer from the manufacturer would be a model that has 3 torque settings and 2 torque settings.

The electronic variable speed gearbox has a high precision torque control, so it is recommended to pay attention to this option.

  • The quality of the gearbox plays a major role as this part of the tool supplies the torque to the spindle / clamp. The gearbox itself should ideally have a cast aluminum housing that makes the weight of the tool lighter. Gear wheels should be made of steel.

In low-priced models, manufacturers sometimes focus the customer’s attention on the powerful motor, and skimp on the quality of the gearbox. Do not lose sight of this point.

  • Ergonomics, weight distribution and load on the user’s hand: the impact wrench works according to the angled impact principle. Its design allows it to dampen vibrations by directing the impact precisely at the nut. Nevertheless, the balanced weight and rubberized handle do much to reduce operator hand fatigue. Therefore when choosing an impact wrench look out for a tool with a comfortable handle, additional handle, rubber pads and anti-vibration protection.
  • Power type:
  • Electric impact wrenches are exclusively powered from the mains. Available in a wide range of power outputs. Small models can even weigh less than a cordless impact wrench. Depending on power rating, networked impact wrenches weigh between 1 and 9 kg.
  • Cordless impact wrenches can be more expensive than cordless models, but are excellent mobility and maneuverability. Cordless models are used during roofing work, as well as by motorists when they need to change a wheel or do minor repairs on the road.

Top 5 best cordless impact wrenches 2020

This is a budget model that does not have high power, but it will come in handy at home. This ratchet is easy to use, lightweight and convenient. The tool comes with tall heads 17-19-21. According to. one battery charge (1.5 Ah) is enough to unscrew 40 M12×1 nuts.5 and tightening 32. If the operating time needs to be increased, you can quickly change the battery, because the kit includes another, albeit similar capacity.

This impact wrench develops a maximum torque of up to 250 Nm in pulse-mode operation. The torque is approx. 130 Nm in standard operation.

With the purchase of a nozzle, the tool can screw self-tapping screws into wood and other soft material (1/2″ square to 1/4″ hexagon adapter).

Optimum control of the torque of your impact wrench

Pneumatic impact wrenches were originally designed to loosen tight nuts and bolts. Nowadays, however, mechanics are also using impact wrenches to tighten bolts, for example on wheels, as this allows them to work more efficiently, safely and quickly. Here are some recommendations for torque control and ensuring proper tool operation.

Good torque control is essential for perfect bolt tightening (Torque Measurement for Wheel Replacements is covered in our blog), so your tools are designed with a range of features that provide torque and torque control for specific applications.

So, for example, screws usually need more torque to undo because they may have rusted or become jammed. In contrast, less power is needed when tightening bolts. in which case more precise control and monitoring is needed to avoid overtightening, stretching or breaking the bolt.

Yann Pasco. Global Business Development Manager. Automotive Service

The capacity of an air tool depends on the air volume in the motor, and there are two ways to regulate capacity based on this. The first is air pressure regulation, the second is a direct influence on the air flow by choosing the right air compressor or using a hose of the right diameter.

Most air tools on the market are designed for optimum performance at 90 psi. inch / 6.3 bar When connecting a tool to a compressor, operators need to use an air regulator to measure pressure. FRL device (filter, regulator and lubricator in one) limits air pressure to the tool and allows you to regulate the pressure in the hose. This provides a more accurate power setting. so mechanics should use such a regulator to adjust the air pressure and achieve high accuracy. If the pressure on the tool is not the same as the recommended pressure, the tool will undoubtedly perform less well than expected.

Over the years, tool design has evolved to allow for more precise control of airflow. In the first half of the twentieth century, the early classic models were equipped with a special lever that, when depressed, reduced the airflow inside the tool. These primitive impact wrenches had simple technology and could be operated with one hand, but they were not very accurate.

In the last ten years the focus has been on tool ergonomics and controllability. Most tools were still designed for single-handed operation, and their clever design allowed the operator to change direction and adjust torque with one hand.Nowadays the highest level of precision and ergonomics are of paramount importance. Tools are designed with the ability to more accurately adjust airflow. and therefore torque. The innovative design of the latest impact wrenches increases the work efficiency of mechanics. for example, by no longer having to move the tool to control the working power, since the control panel is freely accessible at the back of the tool.

Furthermore, special tools have been developed to prevent over-torquing of bolts. such as the torque-limiting impact wrenches. Modern tools provide better control for mechanics and have special settings that allow them to choose the torque value they need.

There is no “one size fits all” solution for every application. Rather the opposite, the best tool for the job is one that meets the needs of the mechanic, his habits and provides comfort of operation. from the enormous range of impact wrenches available nowadays, you have to choose the most appropriate one considering several criteria, and one of the most important criteria is the degree of precision you need to control the power and torque.

Yann Pasco. Global Business Development Manager. Vehicle Services

One last thing to consider: the position of the tool on the air line (at a small or large distance from the compressor) also affects the pressure exerted on the tool. Accordingly, the tool needs more or less air depending on the application, and this can easily be adjusted thanks to the possibilities of today’s precision tools.

Pneumatic wrenches (bolting machines)

HYTORC’s JGun DIGITAL is the world’s first pneumatic tool with torque control and digital readout. Allows you to work without using C. Unlike other systems that require a separate filter and regulating and lubricating system between the air duct and the tool itself, the patented design of the jGun DIGITAL avoids these elements for maximum mobility and handling.

Tightening torque: 81. 10,705 Nm Weight: 3.8. 17.5 kg

JGun DIGITAL is the world’s first pneumatic tool with torque control and digital display. Allows you to work without using C. Unlike other systems that require a separate filter and control and lubrication between the air duct and the tool itself, the patented design of the jGun DIGITAL avoids these elements for maximum mobility and comfort.

The JGun DIGITAL is one of its kind with an integrated air-flow regulator, which enables torque adjustment simply by turning the connector on the underside of the handle. The mechanism is particularly handy when switching between tightening and loosening so that you quickly reach full torque for unscrewing.

The new jGun DIGITAL is a workhorse for intensive industrial use. Thanks to its optimized power-to-weight ratio and its rugged, corrosion-resistant design the engine eliminates the need for separate air filters and lubrication systems. making the jGun DIGITAL the most mobile air torque wrench on the market.

Pneumatic wrench with torque adjustment

Most modern impact wrenches are equipped with a torque control. The main purpose of this function is to prevent fasteners from being overtightened, threaded or flat. The adjustment will be useful for tightening relatively small nuts and bolts, with a high torque tool. M8 fasteners are very likely to be damaged if they are tightened with a tool without adjustment, with a maximum torque of 1000 Nm.

The principle of operation of an adjustable pneumatic impact wrench is to limit the air supply, thereby reducing the torque. For example: If you set the Fubag 900 Nm impact wrench to number. its torque will be reduced to 450 Nm which allows you to tighten M14 fasteners with confidence. The number of modes on different tools may vary, but on average there are from 3 to 5. Please refer to documentation provided with your tool for information about modes of operation. Each tool has its own characteristics of adjustable powers.

How to choose a pneumatic impact wrench

Before you go to the store to buy a tensioning screwdriver, you need to ask yourself a few important questions, the answers to which will help you make a successful purchase. The tool has a lot of features and applications, so the performance of different models can vary significantly. One particular nutrunner, can be used successfully for one type of work, but is completely unsuitable for another. What you need to consider when choosing:

  • Scope of application. Decide for yourself what kind of jobs you want to use the tool for. Whether you need a pneumatic impact wrench for the garage, a compact impact wrench for installing air vents, or a larger unit for loosening truck wheels.
  • Nut size. The more compact the fastener, the less torque it requires. If you will be turning nuts with thread sizes from M6 to M10, the 1/2 inch square is the right size. A 3/4 square socket wrench is good for fasteners with M10 to M18 threads. For large nuts, a 1 in. square is best.
  • Torque. Based on the specific type of work, you should choose the tool with the appropriate torque, which is usually in the range from 300 Nm to 3000 Nm (not considering the giants of the industry). Wheels of a passenger car can come off at 300-400 Nm, a Kamaz truck at 800-1000 Nm, and extremely loaded connections can yield only to a tool with a few thousand Nm.
  • Tightening control. An important factor that adds to the tool’s versatility. The tightening control extends the range of fasteners that can be tightened, but on pneumatic wrenches has a 10% error.
  • The weight of the tool. Prolonged use of a heavy tool with vibration can make life quite difficult. If you choose a pneumatic wrench for the garage and small domestic work for a few minutes a day, the unit with all-metal body is suitable. For a longer application it is better to take a lighter tool with a body made of composite materials.


if wrenches are positioned as the “younger sisters” of shrewd wrenches. then it is safe to call the wrenches the “Elder Brothers”. The main feature of the Wrenches is the use of a more powerful PLANETAR ADJUSTMENT. This makes the torque level much higher. the battery-powered wrenches have a max. torque of 200-230Nm.( Bosch GDS18V, HITACHI WR18DL, Makita BTW251RFE ), that enables to tighten and unscrew (thanks to REVERS) bolts and nuts of big enough sizes. the RPM control by the degree of depressing the trigger makes the initial torque stage more comfortable. Since the tightening torque is relatively high, all Wrenches are fitted with an EXTENSION clutch. to prevent the tool from jerking out of the hand during the final tightening stage. the majority of all cordless torque wrenches are professional models. That’s why they are equipped with LI-ION batteries with a capacity of 2.6-3.0 Ah batteries for serious continuous operation in harsh conditions.

THE NETWORK (ELECTRIC WIDTH) HANDLING Wrenches have a rotational speed of 2200 rpm and a power output of 700 rpm./min.) is not adjustable. But the maximum torque is much higher than in cordless machines. up to 1000 Nm (Makita TW1000), which considerably increases the range of applications, e.g. in the automotive industry and on large-scale construction sites. instead of the hexagonal shank bits used by the SHOPPING HANDS. ELECTRIC and ACCUMULATOR HEAD Wrenches “work” with heads attached to a square spindle.

the size of the screws to be driven in depends on the torque characteristics. Most wrenches are equipped with a so-called PULSE MODE. i.e. at the moment of increasing resistance, the impact function is added to the rotation. With this option, maximum torque is achieved. Also, using the REVERSE. it is possible to unscrew stuck and rusty bolts and nuts without any problems. the ACCUMULATOR and ELECTRIC HANDWATCH DRIVE is encased in metal, for higher reliability and better heat dissipation. AUXILIARY HANDLE. included in the kit allows for better control of the tool during heavy and difficult work. Many developers improve the design of their models year by year; the body is covered with rubber pads for comfortable operation, providing proper vibration damping. HITACHI went one step further and put rubber on not only the main handle, but also on most of the body of the impact wrench. The impact resistance of the tool is thereby significantly improved. Especially important when working at height.

Electric nutrunner for cars

at home, the electric impact wrench is most often used for undoing wheel nuts on cars. This tool is more in demand during mass rubber replacement. The impact wrench makes the process of loosening and tightening wheels dozens of times faster than a conventional impact wrench. This device will come in handy for all those who do not want to go to the car service, as well as to spend time and energy on routine work.

The most practical companion on long trips can be a 12 volt car impact wrench. You can power it from the cigarette lighter socket or directly from your car battery. Has a good torque and no problem to cope with changing the wheel on the road.

The corded impact wrench is best suited for stationary work in the garage. Such a tool does not “loosen” at the most crucial moment and will work as long as there is voltage in the socket. Of corded tools, car repair shops often use a jackhammer electric impact wrench. This specialized device has a wheeled design and transmits almost no vibration, despite its high power.

Electric impact wrench with adjustable tightening torque

and more impact wrenches with adjustable tightening torque are showing up on the shelves. This function allows you to tighten fasteners of different sizes, eliminating the risk of tearing the thread or the bolt head. Will be very useful if the wrench is used when working with different types of alloys and sizes of nuts.

The principle of an electric nutrunner with adjustable tightening torque, is to limit the time. For example, if the setting is for M8, then after full tightening the device will hit the fastener for 1 second, for tightening M10 the time will increase to 2 seconds and cascading. Each device with the adjustment function must be supplied with special documentation from the manufacturer, where the dimensions of the fasteners and the time required for a firm tightening are indicated. These figures may differ for each device.

The best electric torque wrench

Zubr ZGUE-350 is a tool with an adjustable tightening torque. The gear housing is made of aluminum, equipped with external holes, which makes it easy to replace the brushes that are included in the delivery set. Two-step start button lets you change direction of spindle without taking your hand off the handle. Low power motor of 350 W allows for a maximum torque of 300 Nm and spindle speed of up to a traditional 2,000 rpm. rpm. Reliable impact mechanism generates 3,000 rpm. strokes per minute.

Equipped with ergonomic handle with rubber anti-slip pads and 5-meter long power cord eliminates the need for an extension cord. Storage and transport case needs to be purchased separately, because the tool is delivered in a cardboard box.


  • Type. straight, percussive, mains.
  • Power. 350 W.
  • Torque of 300 Nm.
  • RPMs are 2,000. rpm.
  • 3k Shock Frequency. rpm.
  • Chuck: type. ½”, diameter. 12,7 mm.
  • Reverse power available.
  • Speed adjustment is electronic.
  • Weight. 3.15 kg.


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Gasoline nylock wrenches

As mentioned before, these are fully autonomous and powerful wrenches with gasoline engines.

Guy-type wrench BG-1

It is a track tool used in laying and repairing of railroad tracks.

The unit has a torque of 1000 Nm; power of 2.3 l.с.Number of rpm min. 200; max. 500 rpm; weight 18 kg.

The disadvantages of this tool can include its weight, which creates a tangible load on the back and hands of the operator.

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