New Grove family

A pair of all terrains in a new family of six axle cranes from Manitowoc make their first appearance this month in Germany.

The 300 tonne capacity Grove GMK6300L (GMK6350L and 350 US ton capacity in the USA) is designed as a quick set up taxi crane for general rental. Its new larger sibling is the GMK6400 (GMK6450 in the USA), a 400 tonner for heavy duty applications.

"In recent years we've followed a careful strategy to offer an optimum product in each of the all terrain segments. Our philosophy with our six axle cranes is the same ─ we have focused on applications and supplying the right tool for the job, which meant developing two individual cranes and not a single model compromise solution.

"Our GMK6300L is a great 300 tonne crane with the added bonus of the longest boom in its category, meaning that in many cases a jib is not required, saving set-up time and increasing efficiency. The GMK6400 is a very powerful crane able to lift more than any other six axle crane on the market. There are no compromises with either of these cranes. Each is clear in its capabilities and I am confident that each will be a market leader," says Neil Hollingshead, Manitowoc global product manager.

Starting with the GMK6300L, it offers the best boom characteristics in its class and has more power when lifting at height, Grove says. It is up to 25% stronger at long boom lengths than its long boom competitors and 10% stronger overall across the chart, according to the manufacturer.

Manitowoc describes it as the most powerful 80 m boom crane on six axles. Target applications include city centre lifting at height, tower crane erection and placing air conditioning units on rooftops.

The "L"suffix in the name denotes long boom, in this case 80 m in seven sections including the base. Michael Preikschas, senior regional product manager for all terrain cranes in EMEA, said "We've designed it for impressive picks on its main boom, without the need to rig the jib. For example, with the boom extended to 74.8 m [preliminary charts show] it will lift 14.3 tonnes and, with the full boom of 80 m, it lifts 12 tonnes."

An hydraulically luffing 37 m (initially 29 m in early preliminary charts) jib consisting of a 21 m bi-fold swingaway plus two (initially one) 8 m intermediate sections gives a total system length of 117 m (initially 109 m). Up to 40% advantage over competitors is claimed for this by the manufacturer. A heavy duty 38 tonne capacity jib is another option. It can be offset to 30 degrees to give strength at short and long radii.

Powering the crane functions in the upper works is a 210 kW Mercedes OM 926 LA diesel. In the carrier is a 405 kW Euromot IIIB Mercedes OM 502 LA V8 diesel. Selective catalytic reduction (SCR) reduces emissions of oxides of nitrogen by 80%, Manitowoc claims.

In response to customer request, the transmission is a fully automatic six-speed Allison 4500 SP with an integrated retarder as an option. This is instead of an automated manual transmission either with or without torque converter that has become the norm on all terrains. Drive continues through a two-speed Kessler VG2600 transfer case.

Suspension is the Grove MegaTrak hydro strut system with a travel range of +170 mm and -130 mm. Standard drive/steer is 12 x 6 x 6 where axles one, four and five are driven. An option is 12 x 8 x 12 where the sixth axle is also driven. The steering uses steer by wire technology on axles five and six. To help meet road regulations the spacing between the first pair of axles is 3.2 m and 2.5 m between the second pair.

A choice of five outrigger position settings is more than any other crane in its class, Manitowoc says, which gives it superior flexibility on sites where space for set up is restricted. All new Grove cranes, including the GMK6400, will now have this feature.

For easier set up and manoeuvring on site the suspension can be controlled from the outrigger control boxes on each side of the carrier. Another advantage is a boom overhang over the front of the 15.4 m carrier of 1.73 m, which is less than its competitors, Grove says.

Counterweight slabs are 10 tonnes or less for easier transport. The maximum 92 tonnes is built up from a 7 tonne baseplate, two 10 tonne blocks, two 9 tonne blocks and five 9.5 tonne slabs. An auxiliary winch can be rigged on the back of the main hoist without an assist crane using a self rigging system. Where there is no counterweight apart from the base plate, a rigging frame is used.

400 on 6

Turning to the GMK6400, Manitowoc claims it as the world's most powerful six axle crane. "It is a 400 tonner that takes six axle cranes to a new level," says Neil Hollingshead. Target applications include heavy civils work, power stations, refineries and ports.

The 60 m five section boom can have a maximum luffing jib of 79 m. Preliminary main boom load charts show the GMK6400 up to 35% stronger than its nearest rivals, Manitowoc says.

An innovative self rigging Mega WingLift (MWL) capacity-enhancing attachment is an option that around 85% of customers are forecast will buy. It is similar to the one on the larger GMK7450 but with the inclusion of a patented self-rigging system. Transport weight is 12 tonnes. Load charts with MWL are up to 50% stronger than competitors, Manitowoc says, while a typical competitive advantage is given as being between 20 and 35%.

With the maximum luffing jib and MWL, Manitowoc claims up to a 100% and typically 50% capacity advantage over its closest rivals.

A big difference between the two new cranes is that the larger one is a single engine design with idle reduction package instead of the more conventional two engines in this class as used in the GMK6300L and competing models. Both use the carrier mounted 405 kW Mercedes OM 502 LA Euromot IIIB V8 diesel.

Advantages of the single engine concept include a lower centre of gravity and lower weight. Manitowoc has calculated that, in daily work, using the larger carrier engine to power crane operations instead of a smaller dedicated engine in the upper offers better fuel consumption. A comparison between the OM 502 carrier engine and the OM 906 for crane operation shows the larger engine consuming 28 litres an hour - one litre less than the smaller engine. It is only at low engine speed where the crane is running but no crane functions are operating and power is only needed to run air conditioning or heating. In this situation the main engine can shut down and a small auxiliary diesel generator can take over.

Another feature of the 400 tonner is also in the carrier. For pulling away from a standstill and for low speed manoeuvring on site there is a hybrid hydrostatic drive system called MegaDrive. It operates on axles four and five via an hydraulic motor in each wheel and engages and disengages automatically according to travel speed. A similar hydrodrive system used in trucks by German manufacturer MAN claims better traction on poor ground, longer life of mechanical components and better fuel consumption.

Making up the rest of the driven part of the 12 x 8 x 12 drive/steer combination is the main drive on axles one and two via a ZF AS-tronic 12 automated manual transmission with Kessler W 2500 drop box. A steer by wire system operates from axles three to six and is mechanically locked over 25 km/h on axles three and four.

A striking feature of both new cranes is the new carrier cab design. It has a more rounded shape overall with more space inside and room for three seats. Ergonomics are improved with, for example, better positioned instruments. Visibility, heating, air conditioning, aerodynamics and noise reduction are all improved.

As part of the requirements of the new EN 13000 standard both cranes will have the LMI status display of external "traffic light" or "Christmas Tree" type indicator system of red, amber and green lights for hook loading.

Look out for the Grove GMK6400L and its smaller sibling shown for the first time on the Manitowoc stand at the Bauma exhibition in Munich, Germany between 19 and 25 April.