One of the most recognizable tools in demolition, the jackhammer is a large, powerful device designed to break up hard materials such as concrete, asphalt, and the like. You have seen jackhammers mostly used for street repair work, although they originated in the mining industry. They bust up the old materials so that new concrete or asphalt can be put back in place. Jackhammers are also used to break up rock for mining or road construction purposes.
What is a Jackhammer?
As the name suggests, a jackhammer is a device that creates a hammering action to break up hard materials such as rock, concrete, asphalt, and the like. It can also be used on even harder materials such as metal or softer materials such as wood, but it is not recommended or nearly as effective. Depending on the design and size of the tool, the hammer mechanism inside the tool is driven either by compressed air (pneumatic), electro-mechanical force, or by hydraulics.
Above: Makita 70 Lb. Electric Jackhammer – Click to See Price
While rock is quite strong, it is also quite rigid which makes it well-suited to be broken up by a jackhammer. They are sometimes called demolition hammers, which is mostly a term used in the UK. However, a demolition hammer is a smaller variant of jack hammer. You can distinguish a jackhammer from a demolition hammer by looking at the shape of the handle. The jackhammers have a T –shaped handle whereas the smaller demolition hammers come with L-shaped or D-shaped handle.
There is also smaller variations of the jackhammer such as the rotary hammer drill and combination drill.
Rotary Hammer Drill & Combi Drill: These are handheld devices that is usually smaller than a jackhammer. In these tools, the drill bit rotates as well as moves back and forth to create a hammering action. However, instead of a special clutch that is used in jackhammers, it uses a unique piston system. This is different than a hammer drill and makes it useful for breaking up smaller items.
You can see the difference between demolition hammer and rotary/combination hammer here.
Is using a jackhammer bad for you?
Operating a full-size jackhammer can be dangerous due in large part to the noise that the device makes. Earmuffs or earplugs are required when using jackhammers to prevent hearing loss. There is also a condition known as Raynaud Syndrome which is associated with prolonged use of jackhammers. The syndrome leads to what is known as “vibration white finger” in which the mobility of the fingers is affected.
Prolonged use of a handheld jackhammer can lead to nerve damage in the fingers and hands along with the integrity of the blood vessels being affected. In rare cases, fingers have had to be amputated. In addition, many who have used jackhammers regularly have suffered from carpal tunnel syndrome.
Many handheld jackhammers today use dampening materials to reduce vibrations. There are also rules on construction or demolition sites on how long a handheld jackhammer can be used by a single person. This has helped to reduce unwanted side effects.
History of Jackhammers
The very first jackhammer was created by Samuel Miller. In 1806, Miller patented a steam-powered drill that uses the same principles as a modern jackhammer. However, the steam was only used to raise the drill and not for the pounding action. By 1844, C. Brunton proposed a pneumatic drill for mining purposes. And two years late Thomas Clarke, John Varley, and Mark Freeman created a jackhammer that used either steam or pressure from the atmosphere to work.
Over the next several years, the jackhammer was perfected thanks to the addition of a piston and compressed air to make it more efficient in operation. The obvious use for mining evolved into creating large tunnels for roads and train tracks. By the 20th century, jackhammers had evolved to become more efficient and used for road construction and repair work.
Today, the jackhammer is a powerful device that offers a variety of uses when it comes to destroying existing hard materials which are mostly made from rock.
How Does a Jackhammer Work?
The principle used for jackhammers is based on applying a percussive force in repeated actions on the material that needs to be broken up. Although how the percussive force is applied can be different depending on the power source of the jackhammer, the principle is the same.
A jackhammer bit, usually a large chisel, is attached to the end of the device which moves it back and forth to create a percussive impact. The repeated impacts over a short period helps to break up strong, yet rigid material such as stone. The material is broken into smaller pieces that can be removed later.
The limitation of the handheld jackhammer is based on the strength of the person who uses it. For example, trying to use a jackhammer on vertical surfaces such as walls or along steep slopes is not practical as the weight of the device makes it difficult to lift and control at the same time. This is where rig-mounted jackhammers come into play.
Types of Jackhammers
Jackhammers can be divided into two categories, handheld and rig mounted. As the name implies, the smaller jackhammers are held by hand, although they are still quite large and powerful. Rig mounted jackhammers are larger and more powerful, normally used where a handheld jackhammer would not practical.
Within the two categories, there are three types of jackhammers. All three types perform in essentially the same way. The difference is how they are powered.
The pneumatic jackhammer, also known as a pneumatic hammer or drill, uses compressed air as its power source. This type of jackhammer has an air compressor that is powered by an engine, usually diesel-fueled. The older versions used a reciprocating compressor that engaged a centrifugal clutch. This meant that when powered, the jackhammer was either idle or running at maximum speed.
Newer versions of the pneumatic design are powered by a rotary compressor. They are quite large and usually rig-mounted. It’s common to see newer designs using an electrical generator as part of the power function. While operating in the same basic manner as the old reciprocating compressor, the newer versions are longer-lasting thanks to the pneumatic lubricator that is attached to the air hose.
These are handheld jackhammers which generally are quite small compared to pneumatic versions. As the name indicates, it is powered by an electric motor that rotates the crank that moves the chisel part of the jackhammer. There are two pistons present, a drive, and free flight version.
The device operates with the crank moving the piston back and forth all within the same cylinder. However, the piston itself never touches the free-flight piston. Instead, the compressed air that comes from the drive piston is what drives the flight piston to hit the striker which in turn contracts with the bit.
Electric jackhammers are normally plugged into an outlet. They are generally small and may weigh as little as 12 pounds. They are small enough to be easily handled, so they are normally used for demolition work inside a structure. This type of jackhammer is quite versatile, although because of its small size it takes longer for it to break apart hard materials over a large space compared to other types of jackhammers.
This type is so large that it is normally rig mounted. You will often see them on backhoes or excavators. While sometimes used for street repair work, they are most often seen in large-scale mining, construction, and demolition operations. Although large and heavy, a hydraulic system is smaller and more efficient compared to pneumatic systems. It is also cheaper to build and more powerful as a result.
Because they are rig mounted, they can be used against both horizontal such as the ground or roads and vertical surfaces such as walls or the sides of a hill or mountain. They can even be used against ceilings depending on if the arm can be turned in such a direction. The power of the jackhammer comes in large part from the vehicle which carries it.
The device uses a hydraulic breaker which is attached to a hydraulic motor that is inside a hammer system that is sealed. This separation is important because the impact of the hammer may damage the pump system used to produce the hydraulic power if it were directly connected.
A hydraulic hose is attached which provides the fluid used in the hammering process. The power source itself is the engine of the vehicle carrying the hammer, which is normally diesel or gas.
What is a jackhammer used for?
The primary use of a jackhammer is to break up rock-like materials. They were first used to break apart rocks in mining operations. Then, they were used to help construct tunnels as they could break up the rocks that normal digging tools would have a difficult time removing.
Today, they are mostly used to break apart concrete and asphalt on roads. The hammering action creates percussion which vibrates the rigid rock material and causes them to be broken up into smaller pieces.
For road repair work, the pneumatic hammer is used to break apart old concrete or asphalt around a crack or pothole so that new material can be poured into place. This creates a cleaner, longer-lasting repair compared to simply filling in the hole as it existed. The jackhammer can easily break apart the old, compromised material so that it can be shaped to accept new material and patch the surface area.
Jackhammers are often used for demolition work as well, breaking up older rock-based materials on a large scale.
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