Benchmark on Seven Axles: New Demag AC 450-7 All Terrain Crane
Tue November 17, 2020 - National Edition Tadano
Setting new standards on seven axles — certainly not a humble goal for the engineers at TadanoDemag when they started their work on the new AC 450-7 all terrain crane. And this work was richly rewarded, as their goal was fully met and the crane manufacturer from Zweibrücken, Germany now offers a new seven-axle machine.
The basic idea when developing the new AC 450-7 was both simple and demanding: Tadano Demag 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 this criterion, having a carrier length of just 52.5 ft., a 27.7 ft. outrigger base, and a total length of 57.8 ft.
"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 Demag Product Marketing Manager Michael Klein, confirming that one of the company's crucial goals was achieved.
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," Klein explained.
Despite mostly identical dimensions, the new AC 450-7 features considerably better performance characteristics when compared to cranes with six axles, according to the manufacturer. In fact, the "new kid on the block" features a 262.5 ft. main boom with a maximum lifting capacity of up to 212.8 tons.
If the main boom's length is not sufficient, it can be extended using a luffing jib with a maximum length of 265.7 ft. The crane's maximum system length is 433 ft. The luffing jib can be "divided up" in 9.8 ft. segments from 78.7 to 265.7 ft.
In order to make it easier to transport the luffing jib, two system dimensions are used, making it possible to slide the extension's individual parts into each other. Moreover, the luffing jib rigging system makes setup especially fast, simple, and safe — 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 versatile when it comes to extension matters — in addition to the luffing jib, Tadano Demag also offers fixed jib configuration, even with an offset section, as well as a runner.
New SSL Superlift Design
The SSL Sideways Superlift system not only makes the new AC 450-7 part of the large crane category at Tadano Demag, but also means that the latter will represent more than one debut: Tadano Demag is using its new engineering design for the Sideways Superlift system for the first time ever on the AC 450-7.
This new design is a critical enhancement to the Demag SSL solution, 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 accordingly well-suited to larger lifting capacities, according to the manufacturer.
This means that the AC 450-7 is superior to other seven-axle cranes or even some eight-axle units in a number of boom positions, the manufacturer added.
More specifically, the AC 450-7 can lift 80.6 tons at a radius of 30 ft. when equipped with a 196.2 ft. main boom with an SSL configuration, 39.7 ton at a 48 ft. radius when the boom is telescoped out completely to a length of 262.5 ft., and 14.5 ton at a radius of 160 ft. with this configuration.
However, the new Superlift design not only offers more powerful performance, but also better functionality and handling, the manufacturer said.
In fact, 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 165 tons. It consists of a 22 ton base plate and redesigned counterweight plates that have been optimized in terms of swing radius, which is now only 18.4 ft. The counterweight plates are available as 11 ton plates, 5.5 ton plates, or a combination of the two, with the goal being to enable customers to optimize their transportation logistics.
Also practical: 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," Klein said.
In addition, there is 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 an 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
At 27.7 ft., the outrigger base also is at the level of a 6-axle crane. The AC 450-7 has five different outrigger widths, which means the new Demag crane has greater site flexibility, 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 six 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 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," said 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," said Klein, adding, "We discussed it with several customers and received enthusiastic feedback for it."
Once the best location has been found, the well-established 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.
In addition to the IC-1 Plus control system, the crane is available with the IC-1 Remote, making it possible to remotely read and diagnose all important crane data.
Flexible Traveling Capabilities as a Result of Variable Axle Loads
The AC 450-7 is available with two different carrier variants to meet axle load requirements all over the world. In the standard version, the AC 450-7 can be configured to travel under a 13.2 ton or 18.2 ton axle load limit, in both cases with the main boom in place. Moreover, if the main boom is removed, the maximum axle load is reduced to just over 9.9 ton with a gross vehicle weight below 52.9 ton.
Tadano Demag again listened carefully to its customers and 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," Klein said. "The quick connections allow our customers to remove the outrigger box with ease."
Wear-less, Powerful Start-up, Safe Braking
The AC 450-7 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 have to worry about temperature problems.
All seven axles on the AC 450-7 are steered, while four of them are driven. This makes the AC 450-7 so maneuverable that it can navigate tight work sites at least as well as a six-axle unit, according to the manufacturer. This was one of the key goals behind the crane's development.
The AC 450-7 is driven by a Mercedes-Benz engine with an output of 625 hp (480 kW). The diesel engine conforms to EU Stage V and Tier IV Final emissions requirements, but is also compatible with Tier III.
The AC 450-7 will be available in the Americas in October 2021.
For more information, visit demagmobilecranes.com.
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