Impact wrench with compressed air

Impact wrench with compressed air: wrench

Impact wrenches achieve enormous torque and are therefore used in many workshops. If you are in an auto repair shop for only five minutes, you can almost always hear the familiar rattling of the screwdriver. Here are dismantled wheels, new attached or solved rusty and difficult-sitting screws.

But why is the impact wrench of the pneumatic impact driver so much in the foreground?

The reason is simple. impact wrench mainly used in professional workshops, because they are quite special and do not have a wide range of uses. Added to this is the fact that compressed air tools, especially in the professional sector, have their advantages and are increasingly being used there. Therefore, many connect the impact wrench with the compressed air.

On this page we want to introduce such a device in more detail and show what to look for when buying.

Impact wrenches and drills - The exact name is important!

Frequently, cordless screwdrivers, impact drills and impact wrenches lumped together and compared. While cordless screwdrivers and percussion drills are still very similar despite their very different designations and have the same basic structure, the impact screwdriver is completely out of line here and can hardly be compared with other drilling and screwdriving tools.

Typical drilling and screwing tools derive their torque (turning or screwing force) from the power of the motor. Although a transmission supports and increases the power of the engine, when the limit is reached, the engine stops or an overload clutch responds. An impact wrench has no direct connection between the motor and the screw drive and thus can not be blocked. A type of clutch (similar to the torque setting on cordless screwdrivers) ensures that when the engine reaches a specific torque, the engine only jerks and thus activates the impact function, which achieves the high torque and represents the actual function of the impact wrench.

How does an impact wrench work?

If a screw / nut is difficult to loosen, or if a particularly high torque is to be achieved when screwing, a longer lever is often used or a wrench attached and hammer-driven. Although this method achieves no fast rotary motion, but an enormous amount of torque. A similar principle uses the impact impact driver.

Two contour discs - similar to an overload clutch - lie positively against one another and pass on the rotary motion of the motor. If a certain torque is required, the pressed together by spring force discs are pressed apart and the engine continues to rotate, the screwdriver stops but temporarily. After a short rotation, the discs snap in again and the contours beat in the direction of rotation against each other. As a result, the impact energy is generated, which achieves a higher torque than the drive motor itself. This method is often implemented by balls or rollers that roll on the contour disc, encounter an obstacle and hit it. If the screw drive stops by the required torque, the balls or rollers roll over the obstacle, make their rotation and strike again against the obstacle. If the required torque is very high, the motor continues to rotate, while the screw drive stops almost and is only jerkily moved by the impact force. It creates the typical "rattle", as is often heard in car workshops.

Figuratively, that can be easy with a small round rod (or nail), which is pressed against the teeth of a saw blade. As long as the saw blade can be moved, the rod sticks in the toothing and gives the movement on. If the saw blade is difficult to move, the rod eventually slips out of the valley of teeth, continues to move and hits the next tooth. The movement is now only jerky, but transferred by the blows against the teeth but with more force.

Although impact wrenches can differ in their construction and the functional implementation, however, the basic principle is always similar. Due to the striking movement, impact wrenches can not be used for drilling, which makes them fundamentally different from other screwdrivers and screwdrivers.

Why a pneumatic impact driver and other pneumatic tools?

Almost every tool consists of two basic elements - the engine and the working unit with gearbox. The work unit converts the rotary motion of the motor into the required working movement and hardly differs in power tools, cordless tools and pneumatic tools. It is needed to use the turning energy in the desired shape. If the optimal mechanism is found here, they are similar to different manufacturers and different drives.

Impact wrench with compressed air: wrench

Pressure air tools have a very simple structure

However, the shape of the drive and thus of the motor can be very different. There are motors for direct current, for alternating current, motors with and without brushes, Petrol engines and also with compressed air driven engines. Which engine is the best, can hardly set, but why find so often compressed air tools their use?

Electric motors have a very complicated structure and are susceptible to dust and dirt. Oil, falling rust, moisture or many impurities can hardly be avoided in workshops so that the simple structure of a compressed air motor has a clear advantage. Similar to a windmill, the compressed air is converted into a rotary motion. Except for a housing, a trigger mechanism and a fan, nothing is needed in principle. Accumulating impurities are simply blown out of the housing and the air used ensures a very good cooling of the tool. Even short-term humidity barely impressed compressed air tools, they can even be used under water. Durable moisture should be avoided due to the risk of rust.

However, compressed air has an advantage that should not be underestimated compared to electricity. If many tools are needed at several workstations, will require a complicated electrical system and installation. Performance must be taken into account, cable cross-sections calculated, fuses adjusted and the maximum power requirement made available. The entire system must be installed and approved by specialists, which entails enormous costs. Compressed air, on the other hand, only requires a correspondingly large compressor and compressed air lines, which everyone can lay themselves. If multiple connections are required, distributors are used which, unlike power lines, can not be overloaded. If the available compressed air is insufficient, compressed air tools only work with reduced power. On the other hand, if power lines are overloaded, the result may be scorched pipes or even fires.

In the field of accident protection, compressed air tools also offer enormous advantages. If it is wet, electric tools are a particular source of accident. Water conducts electricity and in unfavorable circumstances can make contact with people, which can cause serious injury. Even a falling tool that falls on an electric line, this damage, lead to trigger the fuse or wet areas set under power. If a compressed air line is damaged, only the compressed air escapes, which can hardly lead to injuries. After disconnecting the damaged line, the compressed air system can still be used. As a result, hardly any work breaks.

Air impact wrenches require large amounts of air!

Impact wrench with compressed air: compressed

Einhell air compressor on

Pneumatic tools are cheap and available for many applications. But just a tool with the idea "I have a compressor." Buying can quickly turn out to be a big mistake. Just as power tools have different power inputs, air tools also require different amounts of air. Especially the pneumatic impact wrench is one of the most power hungry devices here.

Typical compressors that are often used in private workshops cost around 100 € and advertise with air flow rates of 100 to 200 L / min. What looks like a lot of power at first glance, however, quickly turns out to be purely suction power, which has nothing in common with the power output, ie the compressed air actually provided. This is, depending on the required pressure, sometimes not even half of the specified intake capacity.

Very few manufacturers or salespeople specify the actual air output. Here it is worthwhile to look more closely at the technical data. There are sometimes indicated the air delivery rates depending on the pressure preset. By way of example, an example of Einhell is mentioned here. With an intensive search, you can certainly find other compressors with comprehensive technical and thus helpful data.

Compressed air compressor with exemplary performance on

For the correct use of the compressed air impact wrench with the maximum torque specified in the technical data, the required air volume and the required pressure are required. However, if the existing compressor does not achieve this airflow, it is not equally inappropriate. Decisive here can be the compressed air supply and in this case the boiler contents. If this is large enough, the required amount of air can be provided for a short time. For example, if a pneumatic impact wrench requires 120 l / min, that's 2 l / s. Thus, a boiler with 24 liters of content can provide the required amount of air for about 12 seconds. This is sufficient to solve four wheel bolts. Afterwards, the compressor has to provide the required amount of air again. But even with a slightly lower performance of the compressor can be quite a pneumatic screwdriver use. Although this does not achieve the same speed or the specified torque, but in most applications, the performance is not to be underestimated. However, the difference between the required air volume of the compressed air impact wrench and the delivered power output of the compressor should not be too large.

Do not use standard peanuts for an impact wrench

Nut is not the same nut. Although almost everyone has a "nut box" and probably in the car a suitable socket for the wheel bolts, but these are not suitable for the use of a striking screwdriver.

Impact wrench with compressed air: wrench

Socket wrenches for impact wiper are matt black

Depending on the quality are "normal" sockets are very stable and withstand high forces. However, the impact load using impact wrenches is not only greater, it also occurs in a different form. While hand tools tend to be designed for a slow bending force and are hard, socket wrench inserts in impact wrenches must also withstand strong blows and be tough and hard. Simple socket wrenches are not designed for such a load.

Breaking and slipping sockets can cause injury, especially at times when high force is applied. Often underestimated, however, is in many cases a more "optical property". A socket set gleams in sometimes polished chrome and leaves a particularly valuable impression. However, the chrome coating does not make a secure connection with the tool steel, which is often evident in chipping off spots. If such a socket is loaded with a pneumatic impact wrench, the nut deforms, which the harder chromium coating is not able to do - it tears and splits off in smaller pieces. In unfavorable cases, such chrome pieces end up in the eye and injure it through small cuts.

Note: Hand tools are silvery shiny - Machine tools matt black without chrome coating.

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