Liebherr’s New 6.6-Ton MK 73-3.1 Works In Tight Spaces In The Netherlands

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At its long maximum radius of 126 feet, the Liebherr MK 73-3.1 can lift loads of up to 4,400 pounds, or more with optional equipment. (Photo courtesy of Liebherr.)

Liebherr’s new MK 73-3.1 mobile tower crane, the smallest in the MK product line, provides quick setup, long reach, quiet operation, and a taxi crane’s ability to carry everything it needs to get to work. At just 45 feet (13.7 meters) long, 9 ft (2.7 m) wide, and 13 ft (4 m) in height, the single-engine crane is maneuverable enough to fit into small worksites.

A single operator can set up the MK 73-3.1 in 10 minutes, making it possible for the crane to work on multiple sites per day. The crane can lift up to 6.6 tons (6 metric tons) and features an infinitely adjustable elevating cab and smart assistance systems such as the Load Plus load curve and level luffing.

Day Jobs

One of the Liebherr MK 73-3.1’s first jobs took place in Haarlem, The Netherlands, not far from Amsterdam. Owned and operated by crane rental company Koninklijke Saan B.V., the crane lifted insulated roof sheeting for an historic former district court building being converted into 70 apartments. At its long maximum radius of 126 ft (38.5 m), the MK 73-3.1 can lift loads of up to 4,400 pounds (2,000 kilograms). This can be increased to 6,173 lbs (2,800 kg) with the luffing jib at 15 and 45 degrees using Liebherr’s optional Trolley-Plus reinforced trolley travel gear.

Crane company Nederhoff B.V. recently deployed another MK 73-3.1 in the Voorburg district of The Hague. The Liebherr crane moved 1,764-lb (800-kg) painting platforms on the roof of a residential building at a height of 66 ft (20 m). The platforms weren’t visible from the ground, but the MK 73-3.1’s elevated cab and camera systems carried the day. The crane’s assistance systems kept the load and undercarriage in view of the operator at all times.

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The MK 73-3.1’s elevated cab and advanced camera systems keep the crane’s load and undercarriage in view of the operator at all times. (Photo courtesy of Liebherr.)

Close Quarters

The three-axle MK 73-3.1 has a single 326-horsepower (243-kilowatt), six-cylinder Cummins diesel engine. Its quiet electric crane section gets its power from an onboard generator or emissions-free 63- or 32-ampere site power. Liebherr says the crane’s working speed remains the same at either amperage level.

The compact mobile construction unit has five steering modes and a turning radius of just 31.7 ft (9.67 m). It offers support widths of 18.9 and 23 ft (5.75 and 7 m), as well as a half-sided support option for confined spaces.

“The crane is really compact and I like the fact that I can also operate it using site power,” says Koninklijke Saan B.V. crane operator Tim Hoekstra. “For tight locations like here in Haarlem and Amsterdam, where I work a lot, the variable support widths are ideal for assembly.”

Another feature that helps the MK 73-3.1 fit into narrow spaces is its slewing radius of just 11 ft (3.35 m), or 11.5 ft (3.5 m) with additional ballast. Two ballast options increase the crane’s lifting capacity by up to 40%. Its maximum hook height of 87 ft (26.5 m) can be increased to a 167-ft (51-m) lift height in a 45-degree luffed jib position while supporting a 3.1-t (2.8-mt) load. The MK 73-3.1 has a top driving speed of 50 mph (80 km/h).

Source: Liebherr