The new kid on the block: Demag AC 450-7 all-terrain crane

Tadano Demag has introduced its new seven-axle model, the Demag AC 450-7 all-terrain crane. The unit has an 80-m main boom with a maximum lifting capacity of up to 195.5 t. If the main boom’s length is not sufficient, it can be extended with a luffing jib with a maximum length of 81 m.

The basic idea when developing the new AC 450-7 was both simple and demanding, said Tadano Demag. The company wanted to ‘give wheels’ to a more powerful alternative to its existing six-axle cranes, with the objective to keep it as compact as its counterparts despite the additional axle, all while combining that with significantly better performance.

In terms of its dimensions, the AC 450-7 meets the desired requirement, having a carrier length of only 15.99 m, an 8.45-m outrigger base, and a total length of 17.62 m. “In other words, it doesn’t need more space than a six-axle crane at a work site, and yet it offers significantly better lifting capacities,” said Michael Klein, product marketing manager at Tadano Demag.

But why seven axles to begin with? “Simple. The only way for the machine to be street-legal and meet our goals of having a longer boom and larger lifting capacities was for it to run on seven axles,” revealed Mr Klein.

The AC 450-7 features a maximum system length of 132 m. The luffing jib can be ‘divided up’ in 3-m segments from 24 to 81 m. For easy transport of the luffing jib, two system dimensions are used making it possible to slide the extension’s individual parts into each other.

The luffing jib rigging system allows for a fast, simple and safe setup – a design that the new AC 450-7 shares with the Demag AC 300-6, AC 350-6, and AC 1000-9 models. Furthermore, the AC 450-7 is extremely versatile when it comes to extension matters. Besides the luffing jib, there is also fixed jib configuration, even with an offset section, and also a runner.

New SSL Superlift design

Tadano Demag has adopted a new engineering design for the SSL Sideways Superlift system on the AC 450-7. This is a critical enhancement to the Demag SSL solution, said the company, with the Superlift arms now being mounted all the way in the front, on the head of the base section, meaning that they are ultimately longer and thus well-suited to larger lifting capacities.

With regard to lifting capacities, this also means that the Demag AC 450-7 is considerably superior to other seven-axle cranes or even some eight-axle units in a number of boom positions, according to Tadano Demag. More specifically, the AC 450-7 can lift 73.5 t at a radius of 9 m when equipped with a 60-m main boom with an SSL configuration, 37.9 t at  a 13 m radius when the boom is telescoped out completely to a length of  80 m, and 12.8 t at a radius of 50 m with this configuration.

However, the new Superlift design not only delivers more powerful performance, but also better functionality and handling. The new design only requires one single wire rope line for the connection between the main boom head and the SSL arm. In addition, the SSL arms are pinned hydraulically on the main boom, which reduces manual work for securing the arms and the associated work at height.

Improved counterweight design

The maximum counterweight for the AC 450-7 is 150 t. It consists of a 20-t base plate and redesigned counterweight plates that have been optimised in terms of swing radius, which is now only 5.60 m. The counterweight plates are available as 10-t plates, 5-t plates, or a combination of the two, with the goal being to enable customers to optimise their transportation logistics.

The base plate can be set up from the front – an advantage that is particularly beneficial at work sites where space is tight and the corresponding transportation truck can only be positioned in front of the crane. “This solution too was the result of us listening to our customers’ explicit requests,” said Mr Klein.

There is also an optional counterweight frame available for the AC 450-7 that can be used to increase the swing radius in order to further increase the lifting capacity – especially when using a SSL configuration. And last but not least, Tadano Demag offers various adapters that make it possible for customers to keep using existing counterweight slabs from other larger AC or CC models with their new AC 450-7.

Demag Surround View system

At 8.45 m, the outrigger base is at the level of a six-axle crane. The AC 450-7 has five different outrigger widths, so the crane can be used flexibly, particularly in confined construction site conditions.

The new optional ‘Demag Surround View’ makes it easier for the crane operator to position the AC 450-7 at the job site. This system uses the six crane cameras to display the possible outreach of the outriggers as well as the tail swing radius at the current position of the crane in a computer-aided display.

“Demag Surround View displays in the carrier cabin the different outrigger widths, so the crane operator can position the crane on the construction site in order to extend all outriggers sufficiently far and ensure the required slewing radius. This reduces time-consuming measuring and trial and error when looking for a location, so that the crane can be ready for operation more quickly," explained Mr Klein.

Demag Surround View also supports the driver on the way to the construction site. The cameras can deliver images of the crane side areas when turning, facilitating the crane driver to detect cyclists, pedestrians, or any obstacles. This function is activated automatically when the indicator is operated. “This new feature is a real highlight,” stated Mr Klein. “We discussed it with several customers and received enthusiastic feedback for it.”

Once the best location has been found, the IC-1 Plus control system provides maximum available lifting capacity, as it determines the crane’s lifting capacity for every boom position as a function of the superstructure’s slewing angle in real time. This means that the maximum available lifting capacity can be used with any outrigger configuration, including asymmetrical ones.

In addition to the IC-1 Plus control system, the crane is available with the IC-1 Remote straight from the factory, making it possible to remotely read and diagnose all important crane data.

Variable axle loads for flexible travelling

The AC 450-7 is available with two different carrier variants to satisfy axle load requirements all over the world. In the standard version, the crane can be configured to travel under a 12-t or 16.5-t axle load limit, in both cases with the main boom in place. If the main boom is removed, the maximum axle load is reduced to just a bit over 9 t with a gross vehicle weight below 48 t.

Tadano Demag now offers a special carrier version with removable rear outrigger box. “With this solution we provide our customers another possibility to reduce gross vehicle weight,” said Mr Klein. “The quick connections allow our customers to remove the outrigger box very quickly.”

The AC 450-7 excels in driving mode on the road as well as on the construction site. It is equipped with a Mercedes-Benz transmission with turbo retarder clutch for wear-less and powerful start-up, paired with an integrated high-performance primary retarder. Drivers benefit from sensitive starting and shunting and do not need to worry about temperature problems.

What’s more, all seven axles on the AC 450-7 are steered, while four of them are driven. This makes the crane so manoeuvrable that it can navigate tight work sites. The AC 450-7 is powered by a Mercedes-Benz engine with an output of 480 kW (625 hp). The diesel engine conforms to EU Stage V and Tier 4 Final emissions standards, but can also meet the Tier 3 requirement.