Mind the gap: next generation excavators

Manufacturers have continued to launch a number of next generation machines and model upgrades to complete their ranges following last year’s implementation of emission control legislation. Steve Skinner reports on the latest designs, advances and processes.
The legislative need to upgrade engines to stage IIIA compliance has acted as the catalyst for manufacturers to review not just their requirements, but their entire machines and even whole product lines. The result has seen continued brisk market activity during the past year as upgraded, redesigned and new machines have been launched in all classes - and without exception, each and every launch has featured far more than just emission compliant engines.
While compliance has necessarily been on the agenda, focus has also fallen on more traditional themes with productivity, comfort and cost-effectiveness all grabbing the headlines.
“The two things most important to our customers are reliability and what it costs to own and operate a machine from purchase price, through productivity and fuel efficiency all the way to resale value,” said Mike Rhoda, president and CEO of Volvo’s excavator business line.
“With operators running eight hours - and sometimes longer when they’re working to daylight hours in summertime - cabin comfort, good visibility, decreased whole body vibrations and noise levels, and then the creature comforts of seating and controls all add up to improved productivity,” continued Mr Rhoda, “and what is important to our customers is what we’re attentive to.”
Sentiments clearly matched across the industry as launches from all the key manufacturers have featured improved cab design and attention to noise and vibration levels.

Space

In May, Doosan Infracore launched two new flagship models to its range in the shape of the 14 tonne and 15,3 tonne DX140LC and DX160LC. “For users, the most remarkable change with the DX models concerns the cabin,” said a spokesperson. “Space has been increased extensively and its width now reaches 1,1 m, a gain of 150 mm on the previous models.”
Visibility in the DX range has been enhanced by the limitation of dead angles too in order to reduce blind spots. “This has been achieved through the use of wider window surfaces and a reduction in strut thickness,” continued the spokesperson. “Significantly, we have also managed to achieve a reduction in cab noise levels over the earlier solar models to 71 dB.”
Employing a four valve per cylinder common rail fuel injection system and electronic control unit on the 71 kW, 5,9 litre Doosan DL06 engine in both models means that the company has been able to achieve increased performance levels with reduced emissions. Furthermore, maximum power is attained at just 1750 rpm, giving the machines excellent torque at low revolutions.
In standard specification, both machines feature 4,6 m mono booms with 2,5 m arms, although front blade and articulated boom versions are available.
Liebherr used the Samoter show in March to debut models and launch upgrades on several machines, including its new 24 tonne R914C litronic crawler excavator.
Fitted with unit pump injection on the 115 kW Liebherr engine to meet Stage IIIA emission standards, the model also features a completely revised cab including new structural separation between the hydraulics, fuel tank and fuel cooling systems.
Furthermore, the cab offers +10% more space for operators over previous models, while a redesigned right-hand side window, without a centre spar, improves visibility. Standard air conditioning and optimised cab suspension both contribute to improved comfort.
Available with either a HDS (heavy duty narrow gauge) or HDSL (wide gauge) substructure, the R914C is equipped in standard format with a hydraulically adjustable 4 m long jib, a 2,4 m shovel arm, standard bucket capacity of 1 m3 and digging depth of 6,2 m.

Variation

Also in the Samoter line-up for Liebherr in its litronic range were the 32 tonne R934C crawler and 17 tonne A900C wheeled machines.
The R934C features Liebherr’s innovative ‘regeneration plus’ function, which enables the boom to be lowered without using any additional pump energy. The company claims that operators benefit from faster bucket movements as a result of this system because capacities in the hydraulic oil circuits can be exploited in alternative directions.
The cab of the R934C features a +10% increase in space over previous models and the machine has climate control as standard. Powered by Liebherr’s ‘optimal power density’ four cylinder engine, which produces 150 kW (203 bhp) at 1800 rpm, the litronic machine can operate a range of stick and boom variants.
Variation is a theme shared by the wheeled A900C, which can be fitted with either a 3,6 m hydraulically adjustable boom or a 5 m monoblock boom matched to stick lengths of 2,25 m, 2,45 m and 2,65 m.
The torsion resistant undercarriage on the upgraded A900C incorporates the travel drive unit. This sophisticated design arrangement makes for optimum ground clearance between the axles, thus improving off-road performance, while for on-road situations increased traction leads to better acceleration and rapid travel on slopes.
Optional four wheel steering is a feature that Mecalac has introduced as an option on its 13,5 tonne 714MW wheeled model. The super compact dimensions enable the 714MW to rotate through 3600 within 3,7 m, due in part to its 1,6 m tail radius, while the machine’s overall manoeuvrability makes it ideal for urban worksites.
With either Mecalac boom or excavator boom variants, the 714MW can be operated not only as an excavator but also as a wheeled loader.
The new Mecalac 11 tonne 712MC crawler excavator benefits from similar compact dimensions to its wheeled relative with a tail radius of just 1,5 m and a 3600 rotation within 3,6 m. In line with all Mecalac machines, the hydraulically coupled cylinders facilitate the operation of the articulated two piece boom so that it can be controlled exclusively with the joystick and no pedal input.

Representation

JCB used the first quarter of 2008 to unveil new crawler excavators in its JS range and also debut a working concept of its proposed new 52 tonne variant in the shape of the JS520. At 29 and 36 tonnes, the JS290 and JS360 models respectively were launched to meet customer demand for models in alternative weights to those already produced.
“The JS290 will bridge the gap between the JS260 and JS330 while the forthcoming JS360 gives us a more extensive range through to the JS460,” commented Ken Covell, excavator product manager. “The JS520 extends the range still further as this is the largest machine that we’ve ever previewed to the market.
“Still very much in the development stage, the 520 features three top rollers which is somewhat unusual,” continued Mr Covell. “I would estimate that the model shown at Conexpo was perhaps 80% of how we envisage the final production model to be. We may well need to modify cylinder diameters to give the exact lift and breakout capabilities that our customers require, but on the whole initial response has been extremely positive.”
The JS290, which sits in the 28 to 35 tonne market, is powered by a six cylinder Isuzu Stage IIIA compliant engine, and combines high productivity with excellent lift capacity and drawbar pull. Furthermore, close attention has been paid to operator environment and serviceability, with the company claiming that the model represents the best in class.
“The JS290 is set to raise the bar in the 29-tonne sector with its exceptional power and performance,” said group CEO, Matthew Taylor. “The introduction of this all new model will strengthen JCB’s position at the forefront of excavator design and spearheads our drive for a significantly increased share of the world market.”
Following Caterpillar’s spring 2007 launch of its 319DL, 319DLN and 321DLCR models in the 19,5 tonnes to 24 tonne sector, the company this year introduced the 13 and 16,7 tonne 312 and 315 models to its D series range.
In response to customer feedback and extensive market research, the 312D, 312DL and 315D were designed specifically to satisfy a demand for a comfortable operator station and high productivity.
“Special attention has been given to the ergonomic design and lay-out of the cab in the D series to enable operators to work in both comfortable and familiar surroundings,” said a company spokesperson. ”Furthermore, the cab has been pressurised to 0,5 bar to reduce the intrusion of dust particles.”
A full colour graphic display has been designed to simplify machine use by acting as a man-to-machine interface. The display includes an on-board servicing scheduler which provides proactive system diagnostics (PSD), continuously monitoring levels of engine oil, hydraulic oil and coolant.
The Acert engines in all D series models feature electronic control of both fuel injection and air management to provide more efficient combustion and enhanced fuel efficiency, and to satisfy Stage IIIA emission controls. Service intervals have also been extended in combination with the PSD.
A new compact design of the hydraulic functions, using shorter tubes and lines, means that friction and pressure drops are reduced, resulting in more efficient use of power. Additionally, hydraulic flow and engine rate are automatically cut to a minimum when the controls are in neutral to reduce fuel consumption and extend component life.

Efficiency

Fuel consumption is a factor that has traditionally featured at the top end on Volvo’s agenda. “Ever since Stage I our engines have offered superior fuel efficiency, and we’re now busy researching electro-hydraulic control systems that could dramatically improve that fuel efficiency even further,” Mike Rhoda, president and CEO of Volvo excavator business line told CE.
“The Volvo group is also pushing the limits on bio-fuels. I think that all the Volvo engines can now tolerate B30, which is 30% bio-diesel, and they’re looking at what it will take to increase that rate. Typically, the problem is with the non-metallic components in the engine and how they wear as a result of the different ph balance of bio-fuels. I think though, that Volvo’s clearly targeting higher levels for bio-fuels,” continued Mr. Rhoda.
Volvo launched two new short swing models earlier this year in the shape of the 15 tonne ECR145C and the 24 tonne ECR235C. The ECR145C boasts a bucket capacity of 0,8 m3, with a maximum digging reach of 8,4 m and a maximum digging depth of 5,5 m. The larger ECR235C is fitted with a 1,3 m3 bucket capacity and digging reach and depth of 9,9 m and 6,8 m respectively. Still to come later this year will be a short swing 30 tonne model in the shape of the ECR305C.
“Product development has seen some fairly dramatic developments for us,” said Mr. Rhoda. “The short swing involved a complete redesign. The driver for this entire product range is that we see an increase in need for machines in Europe and North America that can work in tight spaces or on one lane of a highway.”
Further releases from Volvo include the 45 tonne EC460CL and the 70 tonne EC700CKL tracked excavators and a 20 tonne wheeled EW210C.
Case used the Samoter show at the beginning of the year to present its 80 tonne CX800 demolition. Although the model has been specifically designed for demolition work, the quick coupling hydraulic system means that it can be converted back to excavation mode very quickly.
Built around a 6 cylinder Stage IIIA compliant Isuzu engine, producing 369 kW at 1800 rpm, the CX800 features long, wide undercarriage and 650 mm tracks to provide a stable base for heavy work. Robust side protections shield the turret from shock damage, while the cab suspension is made of viscous material to reduce noise and vibrations.
The upper part of the cab is constructed from five layer reinforced glass to give maximum visibility while roof protection ensures safety from falling objects.
Other launches from Case this year include the 34 tonne CX350B, which CE featured in the July/August edition.

Hybrid

In June, Komatsu announced the launch of its PC200-9 hybrid excavator boasting an average +25% and up to +41% improvement in fuel consumption while on test with customers. Initially, 30 machines are scheduled to be produced before March 2009 solely for the Japanese market, but Komatsu Europe is hopeful that it won’t be too long before the product is rolled-out across all regions.
“The Dash 8 series, complying with Stage IIIA legislation, was introduced in 2006 and the future development of machines such as the PC200-9 hybrid is really exciting for us and our customers,” said a spokesperson for Komatsu.
The Komatsu hybrid system uses a capacitor to store energy, which is then fed to the main drive unit when the engine accelerates. During idle, the capacitor enables the main diesel engine to run at supremely low revolutions, further enhancing fuel efficiency.
Hybrid technology is a feature being pursued by New Holland too. In association with excavator partner Kobelco the company previewed its prototype excavator at the 2006 Intermat show. “The goal of the hybrid project is to obtain a +40% reduction in fuel consumption and C02 emissions over our existing product line,” said a company spokesperson.
Prior to future production of any hybrid models however, New Holland launched two new models this year in the shape of the 50 tonne E485B and the E150B blade runner - a combined crawler excavator and dozer.
Further developments for the New Holland range include new hydraulic systems featuring next generation pumps with low friction and low noise combined with an electronic control system to constantly optimise the hydraulic capacity.
“A significant recent enhancement for our customers is the establishment of our customer services centre,” said a spokesperson. “It’s the biggest multilingual call service in the automotive industry, available seven days a week and offering product and company information, complaints management and break down assistance services.”

Stage IIIB

While manufacturers have all complied with Stage IIIA legislation, Stage IIIB compliance is already looming when one considers lead times, design processes and product development.
“I think most of the industry found Stage IIIA puzzling,” said Matthew Taylor, CEO of JCB. “It was focussed on NOX as its measurement criteria and as such the whole process worsened fuel economy and increased smoke… How can that be a sensible emissions strategy?
“Stage IIIB legislation is a more logical route and will require a considerable amount of design work throughout the vehicle to control both the flow of gases and accommodate the after-treatment.
“Indeed, after-treatment filters are going to present an interesting packaging issue because the necessary particulate filters will have to match engine size. A machine powered by an eight litre engine will need to accommodate an eight litre particulate filter.”
While JCB is confident that it will reach Stage IIIB compliance prior to legislative enforcement, clearly the industry as a whole faces big changes in the very near future as the tighter emission controls prompt design challenges across the board.