Light Equipment: Electric hammers and breakers

There are a lot of good ways to break up concrete and masonry. The most powerful breakers and hammers draw their strength from air compressors or hydraulic systems, but when these power sources are not available or pose problems you can still get a lot of bang for your buck out of hand-held electric hammers and breakers. Today’s biggest electric breakers can tackle concrete slabs in some cases up to 8 inches thick.

But where electric hand held breakers and hammers shine is doing smaller and more detailed work. They are used on everything from busting up small slabs to cutting openings in walls and removing tile. Armed with specialty tools they are also used to cut sections out of asphalt, dig in clay and hard soils, drive ground rods and compact soil and gravel.

Electric tools are also cost efficient. The biggest units – 60- to 70-pound concrete breakers – range in price from $1,200 to $1,500. You also save by not having to include the cost of a big air compressor or a hydraulic power source to your job costs or tool budget. The electric models can be used anywhere you have current, they don’t create fumes, they weigh less and they generate a lot less vibration to the operator.

About the only limitation on electric tools is the length of the extension cord, since these tools draw a lot of current. Rebekah Gallert, product manager for demolition at Wacker, recommends a 12-gauge extension cord at 20 feet. If you’re going longer than that you should step up to a 10-gauge cord to prevent voltage drop and possible damage to the motor.

Choosing the right size
The force generated by electric breakers and hammers is usually stated in either foot-pounds or joules. But since there is no industry standard on how this is measured, reviewing specs between different manufacturers may not yield an apples-to-apples comparison. Most contractors will talk about a demolition hammer in terms of how much it weighs in their hands, says Jon Goebel, product manager, DeWalt rotary hammers.

There are three basic weight categories. The lighter models comprise a 20- to 30-pound class and include hammer-rotary drill combos and chipping hammers. As a class they’re generally referred to as demolition hammers. The biggest models weigh 60 to 70 pounds and are generically referred to as pavement breakers. Between these is another weight class that runs about 35 to 40 pounds.

The size of the tool is dictated by the application. “If you’re going to be holding the tool waist high or higher, or overhead, something heavier than 25 pounds is going to be difficult,” says Rayhan Majid, product manager for Hilti. “For those wall or ceiling applications go for the smaller and lighter tools,” he says. “For the floor applications or waist down applications, the heavier tools will do more work.”

Despite being outgunned by their pneumatic and hydraulic siblings, electric pavement breakers can take apart slabs. “Say you have a slab about 10 foot by 10 foot and 4 or 5 inches thick,” Majid says. “That’s about the cutoff point for an electric breaker. If you get any bigger it’s obviously going to take a lot of time.” The age of the concrete (it gets harder as it gets older) and how much steel reinforcement it has will also affect the amount of time it takes to break it up.

A typical 90-pound air tool will hit with about double the impact energy of a 60-pound electric model, Gallert says. “If you’re just doing a small slab, a 60-pound electric breaker will do the job. But if you’re doing road or bridge work, those are typically air applications,” she says.

Nonetheless, electric pavement breakers often play a supporting role in big demo jobs when hydraulic and pneumatic equipment is being used. “Contractors can’t afford to have too many trucks tied up at one job,” says Mitch Burdick, manager of the hammer category for Bosch. “So they’ll have one compressor running two breakers and include one electric breaker that can float around the jobsite and take care of the smaller stuff.”

How they work
Most hammers and breakers use a gear that rotates at a right angle to an exciter piston to which it’s connected. As the gear rotates, the exciter piston moves back and forth in a cylinder. When the piston moves down it pushes a cushion of air that pushes on a flying piston that connects with the ram that strikes the tool. Hence these are sometimes referred to as electro-pneumatic breakers. Wacker is unique in that they use a metal-to-metal strike design rather than the pneumatic design. The smaller hammer drills use a spring-loaded ratcheting mechanism that creates the percussive energy as the shaft of the tool spins.

The designs of these tools have also been created with durability in mind. Many are used in the rental industry and many rental outlets will sell refurbished/rebuilt hammers and breakers to contractors looking for a bargain. The only maintenance you may be required to perform is to change the carbon brushes when these get worn (every 200 to 300 hours) and grease the tool according to manufacturer’s specifications. Changing brushes typically takes just a few minutes with a screwdriver. And Hilti and Wacker say they’re working on brushless models that will eliminate this maintenance chore. All the units shown here also have tool-less, quick-change chucks.

The business end
If you’re looking to just break concrete, the most commonly used tool is a 1-inch or 1.5-inch chisel. Moil points are also deployed to break concrete, but a lot of manufacturers are moving toward a more effective design for these. The traditional cone-shaped moil point can create a layer of dust underneath it, dampening the impact of the tool. The new designs are tapered on the sides and come down to a star-shaped point. This forces dust up out of the hole and more efficiently transfers energy from the tool to the concrete. You’re also less likely to get a tapered point tool stuck in the concrete, and many of them are also self-sharpening.

For removing tile, flex tip chisels give you a bit more pop per impact. Contractors frequently cut small sections out of asphalt pavement with a 3- or 4-inch chisel in a demolition hammer. Shovel tips enable a demolition hammer to dig through clay and hard soils. And you can also get specialty tools such as rod drivers, soil compactor plates and scarifiers that rough up concrete surfaces … and even tent peg drivers.

Vibration control
Manufacturers have placed a big emphasis on vibration dampening in the last few years. European health and safety regulations are driving some of these design changes, but reducing vibration also contributes to increased productivity. The impact energy generated by the hammer or breaker is absorbed either by the work surface or the user. The more that can be transferred to the work, the more efficient the work and the less fatigued the worker.

Not all tools have vibration reduction but most manufacturers offer at least one if not more models with it. “Until a contractor has tried a tool with a vibration reduction system, he really doesn’t know what he’s missing out on,” says Goebel.

DeWalt and Bosch use a vibration dampening system that isolates the handle from the body of the tool via springs and or rubber cushions. For its new “Jack” breaker Bosch also optimized the size and weight of the striking mechanism and other components to reduce the shock waves traveling through the tool. Wacker and Hilti isolate the interior components of the tool from the housing to dampen vibration.