New technology in the excavator industry
By Chris Sleight31 May 2012
Over the last 18 months there have been numerous new excavator launches in Europe and North America in response to Stage IIIB (Europe) and Interim Tier 4 (US) regulations on exhaust emissions. The laws now apply to diesel engines from 56 kW to 560 kW, which translates to excavators from 10 tonnes to over 100 tonnes.
Those weight classes of course cover the most popular sizes of excavator used in the construction industry, particularly earth moving, quarrying and civil engineering applications. Machines light than this fall into the compact excavator category, and tend to be used on smaller-scale urban projects. Machines over 100 tonnes tend to be used for mining.
So if you're a construction contractor or rental company looking to buy a new excavator in Europe or the US at the moment, no matter which brand you go for, the chances are it will be a Stage IIIB/Tier 4 Interim machine.
It is not a foregone conclusion though. Flexibility provisions in the laws, which are designed to ease the transition for manufacturers, mean there are still 'old stage' machines, with the previous Stage IIIA/Tier 3 engines in them being sold. But as time goes on these machines will work their way through the supply chain to be replaced by the newer models.
The major change in moving to Tier 4 Interim and Stage IIIB is that aftertreatment systems have been employed to cut down the amount of soot (particulate matter, or PM) coming out of the exhaust. The most common approach has been to combine the exhaust gas recirculation (EGR) systems used in previous years to cut nitrous oxide (NOx) emissions with diesel oxidation catalysts (DOCs) and/or diesel particulate filters (DPFs) in the exhaust system to deal with PM.
Although most manufacturers have gone down this route, some have chosen an alternative system called selective catalytic reduction (SCR). This involves running the engine at much higher temperatures than used with EGR systems, which means PM does not form in the first place. However, high engine temperatures mean lots of NOx, and this is dealt with in the exhaust system by SCR.
SCR involves adding a diesel exhaust fluid (DEF) containing urea to the machine, which is injected into the exhaust and converts the NOx to nitrogen and water.
The downside to SCR of course is that the DEF needs to be periodically refilled. Just like any other fluid on the excavator, it is something else to manage and is an on-going cost, just like fuel or oil.
In some areas, the relatively low freezing point of DEF
(-11° C) might also be a problem in winter months. In such cases, it would be wise to check the excavator has an SCR heating system to thaw the DEF quickly, and to make provisions for DEF to be stored on site so it does not freeze.
However, CNH and other manufacturers that have adopted SCR point to the greater simplicity of the system - there is no EGR on the engine, which reduces cost as well as complexity of the machine. They also claim the higher engine temperature means better fuel combustion characteristics and therefore greater efficiency, and that SCR-equipped engines require less cooling, which means less noise from the fan.
Whether excavators feature an SCR or EGR/DPF emission reduction package, most of the new machines on the market claim efficiency improvements over the models they replace. This may not necessarily mean they burn less fuel than their predecessors, the more common claim is that they get more work done per litre of diesel.
New this year
However, for some machines Case has opted for an EGR engine. The 47 tonne CX470C which was launched at Intermat for example uses a 270 kW diesel with this emission reduction technology on board. The company says that compared to the CX470B it replaces, the new model offers a 6% increase in lift capacity, greater digging efficiency, reduced emissions and up to 5% lower fuel consumption.
Other fuel saving systems include Case's Auto Economy Control system, which automatically lowers engine revs when the joysticks are inactive. The CX470C is available with a long undercarriage (LC) or a retractable undercarriage (RTC) and both can be specified on standard or mass excavation (ME) specification models.
Volvo was one of the first manufacturers to market last year, with the launch of some of the larger models in its range as Stage IIIB/Interim Tier 4-enigned machines. This year has seen the company follow up those launches, with several lighter machines, including the short tail swing ECR145D and ECR235D, the EC140D, EC160D, EC180D, EC220D and EC235D traditional overhanging counterweight tracked machines from 13 to 25 tonnes and the EW140D, EW160D, EW180D and EW210D wheeled excavators from 14 to 21 tonnes.
As well as having low emission engines, the machines are fitted with an auto-idling system, which reduces engine speed to tick-over when the controls are inactive for a specified time - the operator can set this to between 3 and 20 seconds.
Operating modes include 'Fine', 'Heavy' and 'Power' and there is also a new 'Eco' mode, which uses an electronic hydraulic pump control to help cut fuel consumption without compromising performance. In any case, hydraulic power is automatically matched to the available engine horsepower whatever the work conditions, which again helps to reduce fuel consumption.
Caterpillar is also rolling new additions to its Stage IIIB/Interim Tier 4 excavator line-up. Like Volvo, having brought out larger models last year, no it's the turn of smaller machines.
Among the new additions are the 13.6 tonne 312E, which replaces the 312D, while the 16.7 tonne 316E supersedes the 315D. Caterpillar says the new machines offer fuel savings of 8% and 9% respectively.
Power comes from a Cat C4.4 Stage IIIB/Interim Tier 4 engine, while new systems to manage the engine and hydraulic pump mean the engine always runs at the desired speed regardless of load. This automatically calculates pump pressure and torque to enable engine speed to remain low in light load operations. An engine idle shut-down system automatically turns the engine off if it has been idling for a specified time, which can be set by the operator.
Komatsu's new excavator launches this year have included mainstream machines such as the 26 tonne PC240LC/NLC-10, 30 tonne PC290LC/NLC-10, 35 tonne PC360LC/NLC-10 and 49 tonne PC490/LC-10 tracked excavators, all of which feature Stage IIIB/Interim Tier 4 engines. Also new in a heavier weight category is the 67 tonne PC700LC-8, which has a gross horsepower of 323 kW.
The smaller Stage IIIB machines all feature Komatsu's KOMTRAX telematics and remote diagnostics system, as well as a new high efficiency hydraulic system which helps cut fuel consumption.
Komatsu has also been at the forefront of introducing hybrid technology to the excavator segment. It first launched a hybrid model in its home market of Japan in 2008, and swiftly moved on to China, where the combination of high market growth (at the time), and long working hours were seen as a good platform to launch such machines. The fuel savings but additional purchase cost of a hybrid means the more hours it works, the faster the pay-back comes.
Having sold 900 hybrids to date in China, Japan and the US, Komatsu has now updated its original launch with the HB215LC-1, a 21 tonne machine that was shown at Intermat.
The hybrid system includes a new electric swing motor, power generator, capacitor and 104 kW diesel engine, and works by regenerating swing energy and storing it in capacitors, which allow for fast discharge when the energy is needed again. Needless to say, the system works best in applications where there is a lot of slewing motion, and Komatsu says that on average the system uses -25% less fuel than a comparable conventional machine.
The latest model from Link-Belt, a subsidiary of Sumitomo which is active in the Americas, is the 21.7 to 23.1 tonne 210 X3. The company says the Interim Tier 4 Isuzu engine offers 10% better fuel efficiency, +7% more lift capacity, +3% faster cycle times and improved serviceability. As with most other new machines this year, there is an auto idle function to cut fuel consumption at times of inactivity.
Improvements have also been made in operator comfort, with a +5% bigger cab and better visibility. The large, 7-inch (178 mm) colour display is the main tool for changing the machine's settings and this can also take a feed from the rear-view camera, which is a standard piece of equipment.
JCB meanwhile is making significant changes to its excavator range, which includes installing its own Dieselmax 444 engine to its 11 to 18 tonne machines. The company says one of the key advantages of its engine is that it delivers much more torque than its predecessor.
For larger machines in regulated markets, it is continuing to use the familiar Isuzu engines.
Another manufacturer to favour Isuzu is Hitachi, which used Intermat to launch five excavators from 25 to 70 tonnes. The ZX250LC-5, ZX290LC-5, ZX350LC-5, ZX470LCH-5 and ZX670LCH-5 all feature Stage IIIB engines, while the new TRIAS hydraulic system contributes to the increased productivity, faster operation with lower fuel consumption than on the previous Zaxis-3 range. Auto idle and auto shutdown functions help conserve fuel in periods of inactivity, and these systems also help to reduce noise.
Meanwhile, Liebherr's new additions at Intermat included the 24 tonne R 924 crawler excavator and the 50 tonne class R 956. The R 924 features redesigned upper structure, which has a new layout to make maintenance simpler. All the daily maintenance points have now been grouped together and can be reached via the gull-wing doors. New hydraulics are teamed with a low emission 115 kW engine and the machine comes with Liebherr's LiDAT telematics system as standard.
The R 956 also features a Stage IIB engine and is offered with an increased range of undercarriage options. This includes a mechanically retractable option, which keeps the width of the machine under the 3 m limit that is critical for transportation in some countries. There are also heavy duty undercarriage options available for harsh quarrying applications.
New from Liugong is the Stage IIIB/Tier 4 Interim 22 tonne class 922E excavator, which the company plans to start producing in Poland later this year. Liugong says fuel consumption is -8% lower than on the D-series machine it replaces. This follows the 18% improvement in fuel economy the D-series excavators made over the machines they replaced.
Other features include Liugong's Intelligent Power Control System (IPC), which has an automatic power boost mode to increase digging force by up to +10% for ten seconds. Power comes from a Cummins QSB6.7 diesel engine rated at 127 kW.
Hyundai has also launched its range of Stage IIIB/Tier 4 Interim excavators this year, machines that are designated by the -9A suffix. Like many others, Hyundai has gone the EGR and DPF route to achieve emissions compliance, but it says that by using a range of sensors and other monitor equipment on the machines it has been able to extend service intervals, and that a two-year warranty is standard.
A key requirement for Stage IIIB/Interim Tier 4 excavators is that they must be fuelled with ultra low sulphur diesel (ULSD) to work properly, which means fuel with around 15 parts per million (PPM) of sulphur. Higher than this and the aftertreatment systems will clog with soot and ash, the back pressure on the engine will rise and it will overheat and break down, perhaps causing permanent damage.
This means manufacturers are now making more and more machines designed specifically for lesser regulated markets, where this fuel is not available. This of course means a different engine - either a Tier 2 or Tier 3 equivalent, depending on the country. However, there are many more design considerations.
One generalisation is that applications may be harder. In a densely populated and well developed area like Western Europe, the ground may have been turned-over many times in its life, and so will be softer to dig. In contrast, there is likely to be harder virgin ground to dig in emerging countries. Add to this longer working hours, perhaps more extreme ambient temperatures and other factors, and the stresses of an excavator's working life start to look very different.
This needs to be reflected in the design of machines for lesser regulated markets, so features like strengthened booms and undercarriages, and good in-cab climate control start to be very important.
Look for example at the three new models Doosan has launched specifically for the Middle Eastern and African markets, the DX225LCA, DX300LCA and DX340LCA.
Doosan says the 22 to 35 tonne machines have been designed with very few electronics on board, for ease of maintenance, and that if there is an electronic fault, it will not affect performance. It also says materials and components have been chosen for reliability and robustness, but there is also a new spacious cab to keep the operator comfortable on long shifts.
There are three operating modes, power, standard and economy, which are selected via an in-cab LCD display. The cab also features upgraded seats and joysticks compared to the old Solar models and a more powerful automatic air conditioning system. Noise both inside and outside the cab has also been reduced.
JCB meanwhile is fitting a 4.8 litre version of its own Stage 2/Tier 2 Dieselmax engine to 20 to 24 tonne excavators that are sold in lesser regulated markets. Rated at 128 kW, the engine can be found in the 20 tonne JS200, 21 tonne JS210 and 22 tonne JS220.
JCB says its engine has improved fuel efficiency by a massive 24%. It says that for a Chinese customer working a JS200 for 3500 hours per year, for example, this translates to an annual fuel saving of UK£ 10000 (US$ 15650).
The decisive split between highly regulated markets and the rest of the world also calls into question whether used equipment from Europe, Japan and the US will be sell-able outside these regions.
Adapting the machines to run on dirtier, higher sulphur diesel would have a cost, but would be technically feasible with support from the manufacturer.
More complex are the regulatory issues. When engines are manufactured they are certified to have a particular emissions level, and if this was changed by altering the exhaust and other systems, there is a question of whether they could be legally used in any market that has emissions laws in place.
It will of course be a year or two before Stage IIIB/Interim Tier 4 machines come up for sale as used equipment, but it could be a significant issue. Among other things, the reduced market for used excavators could hit their residual prices.
This is not an area that any manufacturer has taken a strong stance on. None have yet said they will offer any sort of 'de-tiering' kit to adapt excavators for dirtier fuel, and it is an area of growing concern for those involved in the used equipment sector. It has often been the case in the past that machines from Europe or the US have found their way to lesser regulated markets when they are sold by their original owner.
But speaking at Intermat, Tom Cornell, managing director of heavy equipment internet auction company Iron Planet said, "It is going to be a challenge. The key for us is to communicate to buyers what the exhaust specification is - that will be clearly indicated on our site. But it is a big question in the industry as a whole."
The latest generation of Stage IIIB/Interim Tier 4 machines include a huge array of new features besides their low emission engines. Auto shut-down and auto-idle systems, telematics systems as standard, higher performance hydraulics, more comfortable cabs and of course better fuel efficiency in most cases.
As such, they should make tempting used equipment purchases for many potential owners outside Europe, Japan and the US.
It would be a shame if these regulatory and technical issues can't be resolved to allow contractors around the world to benefit from the strides that have been made.