The following article is from Earthmovers UK Publication: and with special thanks to Stuart Plant Hire Group.
Stuart Piling, part of the Stuart Plant Hire Group, from Chorley in Lancashire, has taken the piling concept and combined it with their traditional earthmoving and civil engineering disciplines.
Established by Peter Stuart in 1987, the company is now run by the second generation of the family with son Sam at the controls. The firm has its roots in the deep drainage and civil engineering side of the industry and, while this work has tailed off somewhat over recent years, the company diversified into the more specialised sector of supplying and installing a wide variety of piles nationwide.
The firm is able to handle a wide variety of pile types including tubular, H Beam and the more commonplace sheet piles. Pile lengths of up to 16m can be handled with traditional leader rigs, but our visit was to a site that called for a smaller and more manageable solution.
The company operates a pair of Hitachi ZX350-6 excavators, which were among the first Dash 6 machines to enter service in the UK. Equipped with state-of-the -art Movax piling attachments, the two-man team are able to handle piles up to 14m in length.
The ZX350-6 excavators were the first choice for the Stuart team following excellent service and reliability from a pair of previous Dash 5 models. Powered by a six-cylinder Isuzu engine that delivers 210kW at 1900rpm, the Hitachi weighs a shade under 36 tonnes without its Movax piling attachment.
Where the Hitachi excels over many other excavators of this size is the addition of a third hydraulic pump. The three variable displacement pumps mean there is always sufficient flow to the attachment and boom and dipper to allow combined movement and operation of the attachment, something that is needed when handling and driving piles.
Despite being intensively used on piling operations, the company’s previous Hitachi excavators remained in excellent condition throughout their time on the fleet and it is hoped the latest arrivals will emulate them.
The Hitachis are essentially standard specification machines, apart from the installation of the added hydraulic and electrical lines re quired for the piling rig operation. There are a few subtler additions to the specification, including a Brigade 360-degree camera system and a Prolec height and slew limiter system.
Sam said, “We can work in some restrictive applications such as rail or marine work where these systems come into play. While they are not required by law, we take the safety of our teams and others working around us very importantly.
“We could have chosen a much cheaper alternative to the Hitachi, but it carries our name and therefore our reputation.”
We caught up with Sam and his team on a project on the outskirts of Derby. The huge industrial estate was once home to a large chemical works, now demolished, and to be re placed by storage and distribution warehouses. Stuart Piling is tasked with installing a waterproof continuous sheet-piled banier between the site and an adjoining watercourse.
The piled enclosure will allow works to progress without the opportunity for any contaminated water to leach into the site from the surrounding ground. This had been lightly contaminated from the previous industrial use and while it was not deemed a hazard to health, the sheet piles protected the site from any ingress of potential contamination.
The Hitachi is equipped with a Hill Tefra quick-hitch and comes with a range of buckets, as the firm is often called upon to undertake excavation work before and after their piling works.
Sam said, “We will undertake a reduced level dig should our clients ask us. We often have to level the areas before we pile them to provide a safe and stable base for the machine to work from. It also allows us to set up a laser line to get a perfect line on the piles as they are driven in.”
Another reason for choosing a Hitachi for this piling application is its cab, as the vibration levels felt by the operator from the Movax rig are negligible, thanks to the cab structure being fixed 011 four fluid- filled elastic mounts.
Sam is its regular operator and said, “It’s extremely comfortable and quite quiet considering the noise produced, especially when using the drop hammer.”
Staying with the cab for a moment, as well as the usual Hitachi refinements, there is a lot for the operator to focus on. Mounted above the machine’s standard control screen, conveniently anchored to the bars that run across the large side windscreen, is the Brigade camera system screen. This offers a clear bird’s-eye view around the machine at all times. Next to the camera screen is the Prolec control box.
Just below the two is the Movax Control System, which allows Sam to control all of the Movax operations and settings from one place. While the system settings are catered for within the control screen, the actuation of the Movax unit is controlled from the standard Hitachi joysticks, and the open, close and rotation functions are assigned to the auxiliary buttons and rollers.
The firm operates two Movax packages including the set-up on site with Sam ‘s machine. The project at Derby called for the installation of 8m-long sheet piles. In a traditional piling operation, the pile would be lifted up and into position with a hook mounted on the piling rig. The piling hammer would be slotted on to the pile, which would then be driven in.
With the Movax system the piling head, in this case an SG-75V, is used to pick the pile up from the ground and install it in a single action. Seen as safer and far more productive than traditional piling techniques, the side grip Movax system could allow this to be a one-man operation should the accuracy not be required.
Weighing 3.6 tonnes, the SG-75V unit is fitted with heavy-duty arms capable of handling a wide range of piles. The high frequency pile driver uses variable eccentric movement to install the piles. Operating at high frequencies mean s the surrounding ground around the pile is not disturbed during installation.
The speed and precision at which the piles were installed were testament to the experience Sam has. Quickly picking up a pile and aligning it with the next allowed his man on the ground to level and line up the pile with a laser se t-up at the far end of the site. In under a minute the pile was driven into the ground and the Movax SG-75V released.
Using this method, the piles can only be driven to approximately 2m above the existing ground level, but a rapid change of attachments saw the Hitachi furnished with another part of Sam ‘s Movax arsenal, the DH-20 drop hammer. Weighing a shade under five tonnes, it is used to knock the sheet piles further into the ground to create a level finish.
The 2t hammer situated inside the 1.3m-high leader drops from a maximum height of 1.2m and gives a variable blow rate of between 0 and 100bpm and a variable impact of O-22kNm. Extremely narrow with a tilt of +/-15 degrees and able to rotate either side up to 60 degrees allows the DH-20 to get into some extremely tight spaces.
The final piece of Movax equipment is a TAD auger kit. This allows the team to pre-auger for tubular piles and reduces the amount of reinstatement work required once the piles are installed.
Sam concluded by saying, “As we have mentioned with the Hitachi, the Movax rig is simply the best available. And while it may be a huge financial investment, the build quality and reliability are more important to our company.”