Demag unveils narrow track chassis for CC2800-1
August 2, 2006 | Comments (0)
The narrow track chassis for its CC2800-1 crawler crane - shown to potential customers at its Zweibrucken factory last week - is one part of that policy.
With a chassis width of just five metres, it transforms the crane into a specialist unit for erecting turbines at wind farms and on any multiple large lift contract.
Its narrow chassis width can deal with the roads built specifically for transporting wind turbine components and the unit can travel with long booms and counterweights in place.
Demag says that its 600 tonne capacity CC2800 has been a great success, claiming that more than 250 units are currently at work. If initial orders for the narrow track version are anything to go by, Demag appears to have a winner on its hands.
At the customer day, eight orders were placed. The first machine to be delivered was already on the water to Finland and the second unit - the crane at the event - was due to leave immediately for Canada, purchased by Guay Inc of Quebec. Guay also ordered an AC500 at the same time.
"The narrow-track chassis enables the crane to be moved, fully rigged, from one windmill to the next along roads that are five metres wide. Due to the fact that dismantling, transportation and subsequent re-erection of the crane are done away with, the time saved means there are substantial, immediate gains in terms of productivity on site," said Klaus Meissner, Terex-Demag director of research and development.
With the wind power market currently experiencing a major upsurge, the Zweibrücken crane manufacturer has its sights on the onshore sector as a potential growth market.
It believes that around the world, facilities generating two to three MW have become the norm and are likely to dictate the shape of the wind power market in the years ahead.
In order to gain more efficiency from the turbines, engineers and designers are designing taller and taller masts and improved blade shape design. This, says Demag, is the primary reason for the demand for lattice boom equipment of between 400 and 600 tonnes.
These cranes are designed especially to hoist 75-100 tonne gondolas up to hub heights of between 90 and 130 metres above ground level.
The CC 2800-1 is already a very popular crane for the erection of two and three MW wind farms. When fitted with a 90-metre SH/LH SGL main boom plus special 12 metre, LF2 wind power jib, the crane can take loads weighing up to 125 tonnes to hub heights of 94 metres (hook height 102 m).
Using a 102-metre main boom of the same type, the unit will raise 109 tonnes up to a 106-metre hub height (hook height 114 metres). For the absolute top end its Superlift attachment will haul 97.5-tonne loads up to a hub height of 130 metres above ground level (hook height 138 m).
The CC 2800-1 can be converted from standard crane into one dedicated to wind power applications by means of the Narrow Track Kit and a few accessories and then be returned to its original status.
The Narrow Track Kit can be used either with 1.2 metre wide track shoes for the narrowest overall width, or 1.5 metre wide track shoes for lower ground pressures.
For transportation, the carbody is the largest single unit, measuring 3.5 metres wide, it weighs around 36 tonnes. Its "sideways outriggers" are three metres wide and can be transported with pads attached.
The counterweight is fitted a metre lower than on the standard crane to keep the centre of gravity as low as possible to help maxmise lateral stability.
The unit can travel with boom configurations of up to 114 metres, with up to 2.4 degrees of lateral tilt approved by the manufacturer.
A typical source of danger on any construction site is ground failure. To minimise potential risk in this respect the boom position can be adjusted via electronic indication of load gravities to ensure that weight is evenly distributed on all track shoes.
Liebherr was first with this narrow crawler concept for windfarms, when it designed the LR1400/2 in conjunction with Weldex, the Scotland based crawler crane hirer.
That crane while similar, in that it is designed to travel fully rigged on wind farm tracks, is dramatically different in execution. The Liebherr is a high machine which uses a double slew bearing system so that it can lift its tracks clear of the ground with its outriggers and then rotate them to face the desired direction of travel.
This elaborate device allows the crane to overcome the problem of trying to turn such a heavy crane on such a narrow base while fully rigged.
Terex while obviously having decided that the narrow concept has "legs", appears to have taken the view that by lowering the cranes centre of gravity, installing four motor "Quadro-Drive", allowing a greater degree of off level travel and introducing electroninc monitoring and balancing of the cranes centre of gravity, the Narrow Track will be able to cope with turning on wind farm roads in the normal way, even when fully rigged.
Time and real life experience will, of course tell.