Tadano Demag is officially launching the new seven axle 450 tonne class Demag AC 450-7 with the aim to set new standards for seven axle All Terrain cranes.
The basic idea was to design a seven axle unit that was no less compact than a six axle All Terrain, while greatly exceeding it in terms of performance. All seven axles steer while four are driven (axles two, three, six and seven).
The AC 450-7 has an overall carrier length of just under 16 metres, with an overall travel length of 17.62 metres and an outrigger spread of 8.45 metres. It is just 500mm longer than Liebherr's six axle carrier, with a similar overall length, while being considerably shorter than the seven axle Liebherr LTM 1400-7.1. Grove’s six axle 400 tonne GMK 6400 has a carrier length of 15.73 metres and an overall travel length of 17.53 metres.
When Liebherr conceived its new 450 tonne LTM 1450-8.1 it decided to go with an eight axles while Tadano Demag has decided to follow Grove’s seven axle 450 tonne GMK 7450 approach, which was originally conceived around 20 years ago.
Tadano Demag product manager Michael Klein said: "The new AC 450 does not take up more space on construction sites than a six axle crane. At the same time, however, it offers significantly higher capacities. But why a seven axle in the first place? The answer is simple - for road approval. The objectives of a longer boom and greater payload could only be achieved on seven axles.”
The Demag AC 450-7 has a seven section 80 metre main boom, to which a luffing jib can be added with lengths of between 24 and 81 metres, built up in three metre increments to provide a maximum system length of 132 metres. The jib adopts the same rigging concept as that used on the AC 300-6, AC 350-6 and AC 1000-9, with sections of two different dimensions allowing them to stow inside each other to reduce transport loads. A range of fixed lattice extensions are also available with a length of up to to 59 metres which can combined with a 64.8 metre boom, it is also possible to offset the top half by up to 40 degrees.
This a 450 tonne 'class' in other words it lifts like a 450 tonne through the chart, but cannot actually lift a 450 tonne load - theoretically it could handle 450 tonnes at 2.5 metres. The maximum actual capacity is 195.5 tonnes at up to five metres. The new crane will also feature a new Sideways Superlift design concept, developed from Demag’s existing SSL concept. The Superlift arms are now mounted to the front of the base section, allowing them to be significantly longer and capable of supporting higher capacities. With a 60 metre main boom and SSL configuration the crane can lift 73.5 tonnes at a radius of nine metres. With the full 80 metre boom it can handle 25 tonnes in standard configuration or, with the Superlift installed, 37.9 tonnes at a radius of 13 metres or 12.8 tonnes at 50 metres.
The maximum counterweight is 150 tonnes, made up of a 20 tonne base plate and five or 10 tonne slabs which offer a reduced tailswing radius of 5.6 metres thanks an optimised counterweight plate/slab design. An extended counterweight frame is also available, and adapter plates are available that allow the new crane can use counterweight sections from larger Demag models.
A new patented operator assistance system - Demag Surround View - uses the crane’s six cameras to display the possible outrigger beam configurations and performance for location, which also displays in the carrier cab. It is intended to reduce time consuming trial and error set up selection to achieve the desired lift. The IC-1 Plus control system is also available with the IC-1 Remote, telematics and remote diagnostics.
The AC 450-7 can be configured for 12 or 16.5 tonne axle loads complete with main boom. If the boom is removed, the travel weight is reduced to less than 48 tonnes for travel with few restrictions and in sensitive areas. Power comes from a Mercedes Stage V/Tier 4 diesel coupled with a Mercedes-Benz transmission with turbo retarder with wearless clutch and integrated high performance primary retarder.
The first units will ship in mid-2021, with the first unit destined for German rental company Wiesbauer. We will follow up with a full review in the next issue of Cranes & Access.