ROCK SOLD Performance

The latest generation of Kobelco’s 50 tonne excavator has recently been launched with significant upgrades from the previous model. The first of the new SK520LC-11E excavators in the UK have been added to the extensive Ovenden Earthmoving fleet.

Based in Kent, the company work across the UK on a range of contract crushing and heavy earthmoving projects, but it is the company’s work within the marine infrastructure industry for which they are best known.

Already running an extensive fleet of Kobelco SK500LC models in the fleet on both standard and long reach specification, the arrival of three new models as part of the regular fleet updates has seen them benefit immediately from the upgraded model’s arrival.

The three machines have been extensively worked on at supplying dealer Molson’s Avonmouth depot prior to delivery. ‘We have undertaken several adaptations to the machines before they left Molson.’ Director Jack Barwick commented. ‘This has included the machines being sprayed with a waterproof coating to help protect them from the marine environments where they work in on a day-to-day basis. We have also fitted our Leica MC1 machine control systems to the machine and with lessons learnt from prior installations, we have placed all of the control boxes inside the cab to protect them and installed marine grade sensors and wiring to add longevity and reliability to the system.’

Two of the first machines have been delivered to the Wyre coastline in the North West where they will spend the following months working on a long-term project the company is undertaking with Balfour Beatty on behalf of Wyre Council.

“The new Kobelco SK520’s are living up to our expectations...

The project involves the installation of over 200,000 tonnes of rock armour to protect the existing sea wall, build new groynes and add to existing structures to protect new cross over points which have been constructed to allow safe access for emergency vehicles to cross over the rock structures.

The new SK520LC-11e excavators have taken on a more aggressive appearance over their outgoing sibling. The gently curving upper structure has been replaced with straighter lines and a slightly bulkier outline more in keeping with the larger SK850LC model.

From the ground up, the SK520 has been designed for heavy operations. The excavator sits on a 4.65m long undercarriage with standard 800mm triple grouser pads giving an overall width of just over 3.3m. For transportation, the step on the cab side of the excavator can be folded up to reduce the overall width of the machine.

Underneath the bodywork sits a 6-cylinder, 15.6 litre Isuzu engine which at 384Kw at 1800rpm, delivers over 15% more power than the outgoing model. Renowned for their robust build and reliability, the Isuzu delivers its maximum torque output of 2050Nm at just 1300rpm ensuring the machine delivers production with power whilst also keeping fuel consumption to a minimum.

‘We have found the SK500 excavators in the fleet to be a very reliable product over the years we have been operating them.’ Jack commented. ‘If we have had any issues Molson have always been very quick to respond, or as the machines have come out of the warranty period, our own engineers have been equally at ease in dealing with any problems.’

With the nature of the work the fleet undertakes, the machines all run on bio-oils to ensure that any leak, no matter how small, plays no part in damaging the environment.

The two arrivals at Wyre have been supplied with standard reach equipment comprising of a 7m boom and 3.45m stick. Both sticks have also been fitted with a heavy-duty bracket to allow the use of the five-finger fixed leg grapples the company use on rock placing projects. The lifting capacity on the new model has also been increased to over 21 tonnes. ‘We have had a mass excavation SK500 before and that was great for heavy lift work.’ Senior Works Manager Marc Haughin commented. ‘Whilst the lifting capacity was great, it hindered the reach slightly. This configuration seems to be even better for lifting thanks to a heavy counterweight and with the longer boom and stick, we have the increased reach which is a major benefit for us on rock placing works. To increase the machine’s durability, bucket and tipping link pin sizes have been increased up to 110mm

The Dash 11E model benefits from the Japanese manufacturer’s stylish and operator friendly cab interior. Built around a heated suspension seat with integrated consoles, the cab interior has a luxurious feel with backlit switches and dials allowing easy use on darker shifts. The operator is well catered for with charging points, Bluetooth and a smartphone holder and with the new touchscreen providing a wealth of machine information, they are able to dial in any changes to flows or pressures for attachments within seconds. Externally, the cabs on the Ovenden machines have been fitted with a robust top guard and front bars with additional LED lighting built in.

“We have found the 50-tonne Kobelco excavators to be very reliable over the years...

The ongoing project in the north west sees the excavators and the ground team work together to excavate the sand between the newly installed reinforced concrete crossover points and the existing rock groynes. One of the excavators sits with a bucket to excavate the sand whilst the second machine with a five-finger fixed leg grapple picks and sorts the incoming rocks delivered by an ADT. Incoming rock is weighed and graded in the yard prior to delivery to the beach to make sure it is the right specification for the project.

The space left between the structure and the existing groyne, around 10m, is dug out by one of the Kobelco’s before it is lined with a heavy geotextile. A bespoke spreader beam has been manufactured to hold a roll of the geotextile allowing it to be safely handled and in the excavation. Following the placement of each pass of geotextile, the other Kobelco picks and places the rocks to build up the protection. As the rock nears the concrete structure, the first Kobelco then uses the bespoke frame to hang steel plates between the structure and the rock to keep a clear gap between the material. Part of the specification calls for interlocking on the rocks to avoid movement. Placing each rock isn’t a straightforward job as it may need moving several times to allow them to sit correctly, stay in place and achieve a tight tolerance which is monitored through the marine MC1 system.

As the rock is built up, Marc pushes the sand back over the open excavation, allowing the Kobelco to reach the far side of the cut. Depending on the tides and weather the team can easily complete each section in a shift.

‘The new Kobelco SK520’s are living up to our expectations.’ Marc explains. They are proving to be an excellent all-rounder, working to suit our required compliance and clients’ expectations the operators like them, and they are delivering the performance we need to continue delivering projects on time and budget.