Demolishing concrete is hard, time-consuming, potentially hazardous work, regardless of jobsite conditions. Selectively demolishing concrete elements within an existing structure, with a tight deadline, and no space to accommodate a skidsteer or excavator is an even more daunting job. Under such constraints, demolition robots can save the day.

These machines look like mini-excavators, but without cabs. They run on tracks and have hydraulically powered arms to which breakers, crushers, drills, or loader buckets can be attached. Many are small enough to fit onto passenger elevators, pass through standard doorways, and even travel up and down stairs. Under their hoods, though, they have electric motors driving their hydraulic systems. And they deliver an exceptional amount of breaking power for such modest-sized equipment.

Operators control the robots’ actions remotely, using conventional joystick consoles that they carry or strap to their bodies.

Designed for safety and maneuverability

Peter Bigwood, vice president of sales and marketing for Brokk Inc., Monroe, Wash., says that operator safety was the motivation for developing the first demolition robot almost 40 years ago. “In 1976, a contractor in Sweden was asked to break out a smelting furnace in a very hot lead smelting facility. He decided that neither he nor his workers should have to be directly in front of this potentially dangerous area as they were demolishing it.

“He invented a demolition machine that the operator could work without sitting on it, unlike a backhoe, a skid-steer, or an excavator. A lot of the design elements he came up with are still present today in the 11th generation designs. One feature in particular that distinguished the first remote-controlled machine is the arm, which is actually three arms, whereas if you look carefully at a backhoe or an excavator, it’s just two. This means that right from the get-go, the hydraulic breaker at the end of the arm could be maneuvered and moved into place from a much greater number of angles. It allows the operator to choose the best angles of approach, whether it’s concrete or rock or slag, to do the most effective breaking,” Bigwood says.

Products range widely

Brokk introduced its first demolition robot to North America in 1983, and now produces 12 models. The smallest, the Brokk 60, weighs about 1,100 pounds and measures less than 24 inches wide and just more than 34 inches high with outriggers retracted. Its vertical reach is just more than 10 feet and its horizontal reach is just more than 8 feet, including the breaker. The models increase in size and power from there, but six of them are less than 32 inches wide and able to fit through many standard doorways. Its largest machines, which are clearly not designed for confined spaces, weigh almost 25,000 pounds, are over 7 feet wide and 8 feet high. Brokk’s robot motors run on 480-volt, three-phase electric power.

Brokk also makes a large diesel-powered model, the 400D, for use where electric power is unavailable. Husqvarna introduced its demolition robots in 2009 with the DXR 310, and its line now includes five machines. All are on the smaller end of the range, just under 31 inches wide and about 41 inches high. Husqvarna’s electric motors are powered by high-capacity lithium-ion batteries.

The robots are not cheap. Prices start at more than $100,000 for the smallest machines and rise from there. The manufacturers say the cost is justified by the greatly increased efficiency and productivity the machines allow, especially for confined spaces, where hand breaking would be the only feasible alternative.

Lars Gustafsson, Husqvarna’s global product manager for the DXR machines, says, “Although the investment is higher with this type of machine [compared with] handheld breakers or other substitutes like larger excavators, in many [situations] the only way to demolish is to use a demolition robot, due to the space…or other critical restrictions.”

Bigwood agrees: “Yes, the machines are expensive, but in a job that needs the robot’s capabilities, there’s nothing else that can accomplish the goals in the same way. If you have a demolition job to do where you can access the site with your breaker-equipped skidsteer, you don’t mind the emissions, and you don’t mind the time it will take, then I’d be the first to say ‘Have at it.’ It would be a less expensive option, and most contractors already own skidsteers.”