Headquartered in Tiverton, Devon, The John Luffman Group undertakes a wide variety of services from recycling and crushing materials through to groundworks and civil engineering. Working predominately within the counties of Devon and Cornwall, the company occasionally ventures further afield for some of its regular repeat clients.
The wide range of services offered by the company dictates they require a diverse range of machinery to successfully deliver projects and over the past few years, much of that equipment has been sourced from Avonmouth based Molson Equipment. “We have a long relationship with the team at Molson and have been working with them in some way shape or form since I started the business.” John Luffman commented. “They have been an excellent company to deal with.”
Luffman operates a range of crawler and wheeled excavators from both Hyundai and Kobelco, both supplied by Molson. It was one of the Japanese made Kobelco excavators that was hard at work stripping a site on the edge of Exeter’s Science and Technology park.
The SK210-11 Kobelco excavator had been on the Luffman fleet for almost a year but thanks to regular operator Adrian Parr, the machine looked as if it had just been delivered. “I like to keep the machine clean and tidy.” Adrian commented. “Never to the detriment of getting the job done, but as I spend my entire working life inside the cab, it has to be a clean and tidy space.” The outside of his Kobelco excavator is also a credit to Adrian with the machine regularly cleaned and polished. “I know it’s not my machine, but it is a good reflection for the company having clean and well looked after kit and it is the least I can do for John when he regularly invests in keeping the fleet up to date.”
Adrian was working alongside one of the fleet’s dump trucks to relocate a soil pile on a site in readiness for a new eco hotel to be constructed. The team were contracted to undertake the site strip and installation of an engineered piling mat, but they were also hopeful of securing the groundworks portion of the project for the developer.
The second site in Exeter was a development of new apartment blocks. A typical city centre development meant only smaller machines could be used to undertake the earthworks project. With one of the company’s SK140SRLC Kobelco excavators handling the excavation and concreting of the footings, it was down to the latest arrival on the fleet to undertake the excavation for a large attenuation tank.
The tank will ultimately sit below a landscaped area, in between the 92 new homes being constructed, and will manage the surface water before it is fed gently into the surrounding sewer system. With minimal space surrounding the tank and the footing already being constructed to one side of it, the excavation of the tank had to be undertaken using smaller than usual machines. “We started the excavation using a larger machine but as the depth of the hole increased, we decided to swap it over for a new SK140SRLC Side Drain Kobelco excavator.” John commented. “Access around the tank’s position was almost impossible with Vaughan Road running within a couple of feet of the edge of the hole, footings being installed to another side and the access road through the centre of the development on the other side. This meant that placing a machine into the hole and loading on a ramp as the work progressed was the only viable option for us.”
The Side Drain, or Offset Boom concept has been around for many years and has been used by many manufacturers to varying success. Kobelco excavators have taken the concept and refined it into a very useable format currently available on their SK75 and SK140 machines. The concept involves the standard mono boom being removed and replaced with a boom foot which is connected to a centre section comprising of two outer steel sections and a central hydraulic ram. The ram is angled left to right inside the sections and when operated allows the boom to angle towards the machine’s cab. As this happens the casting holding the three sections together and on where the dipper and ram is situated remains parallel to the upper structure. Not only does this shorten the distance from the centre of the slew ring to the dipper pivot point, but it allows the machine to dig in line with the cab side track. Thanks to the compact tail swing upper structure, this can be replicated on the offside track with a minimal slew.
The operator entrusted with the new Kobelco excavator is Alan Slocombe, an 11-year veteran with Luffman. “It’s a very versatile machine and capable of getting into some tight spots.” He commented. “The only issue I found early on is the added weight of the boom. Thankfully Kobelco have put the shorter 2.5m dipper option on, but you still have to be careful cross carriage. It’s far from unstable, but if I’m greedy with the bigger buckets, it can lift a little! Having the blade on the undercarriage helps a little and adds a little bit more weight low down. Apart from that, this Kobelco excavator is an absolute pleasure to operate. It’s smooth on the hydraulics and a very powerful little digger. The cab is a great place too, comfortable, and well laid out.”
Alan was able to show off the Side Drain boom perfectly as he was nearing the completing of the far side of the attenuation tank’s excavation. Gradually moving the boom to the side and slewing the upper structure, Alan was able to keep the ditching bucket parallel to the vertical wall of the cut and trim the last bits of material away leaving a clean and vertical face. As he approached the corner of the cut, he was able to square off the angle of the cut ensuring the sections of the crate fitted in perfectly. “You don’t want to find out that the hole is too small as trying to get back in afterwards creates a real problem.” He commented. “It’s the same if you just go and dig wildly, there’s always a big cost in both time and materials when it comes to backfilling. It may look a slow process, but we know it’s going to be 100% right.”
With the edges trimmed and the excavated material thrown behind him, a quick change to the digging bucket on his Kobelco excavator allows Alan the chance to get rid of some of the material out of the hole and tipped a few metres away on a temporary stockpile. Using a veteran JCB 714 ADT to haul the material just a handful of metres has proved ideal as the truck’s large capacity and phenomenal hill climbing ability has proved its worth on the job.
Once the final trimming has been completed the hole will be filled with plastic drainage crates wrapped in a permeable membrane before backfilling and installing the incoming and outgoing drainage pipes and being backfilled. Thankfully for the team undertaking this work, the excavation was through sandstone which has stood up impeccably throughout the work requiring very little in the way of shoring or tiering of the sides of the opening. “We have battered the top of the excavation back to stabilise it and again, doing this would have meant a standard excavator would have struggled even more to get the entire hole dug out as easily as we have.” Alan commented.
“Having the Side Drain Kobelco excavator gives us another tool to undertake our operations.” John comments. “It’s not going to be for everyone, but we find that having the ability to put a larger machine into certain jobs allows us to undertake them quicker, easier and more importantly, safer.”
