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Cummins staging a comeback with structural engine

Armed with a new structural engine offering, Cummins is on a mission to get back into agriculture.


James Rickard finds out how it plans to do this and the effort gone into the new engine...


Famous for its diesel engines, it is fair to say the Cummins brand is highly regarded in the UK. And with about one million farm machines in the world equipped with the manufacturer’s engines, it appears to be a deserved reputation.


In the UK, the company reached its zenith in the 1980s and 1990s when it supplied engines to the likes of Case IH, JCB and Leyland trucks.


However, all good things must come to an end and the restructuring of companies such as Case IH which merged with New Holland in 1999, meant Cummins’ regional customer base in agriculture began to dwindle.


And although the use of its engines in agriculture around the world is still significant, it is now a minor share of the engine maker’s business.


Today, Cummins finds itself supplying smaller agricultural manufacturers, such as Versatile, or plugging engine gaps in manufacturers’ product ranges, such as John Deere’s larger tractors and self-propelled forage harvesters and in JCB’s large wheeled loaders.

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To address this diminished presence in the market, Cummins is undertaking a concerted effort to reassert itself back into agriculture with a product aimed at a mass volume market.


This comes in the form of a new 6.7-litre structural engine capable of producing up to 326hp.


Steven Nendick, Cummins marketing communications director, says: “With the new engine, which meets Stage 5 regulations without the use of exhaust gas recirculation, we think we have something attractive to offer tractor manufacturers.”


To learn more about this and the challenges of meeting Stage 5 rules, we take a look behind the scenes at its Darlington manufacturing facility.


Darlington: Mid-sized engines

Daventry: Large engines and generator sets

Huddersfield: Turbos

Cumbernauld: Engine remanufacturing

Stamford: Alternators

Number of UK employees: 5,000



Opened in 1965, Cummins’ Darlington plant, Co Durham, is responsible for producing engines from 3.9 to 8.9 litres, spanning 75-400hp.


Employing about 1,000 staff, it produces about 280 engines per day via three shifts, which can be ramped up to 380 units per day at peak times.


This equates to about 52,000 (80,000 maximum) engines per year at Darlington, 60 per cent of which are exported directly, with others finding themselves overseas having been installed in a machine and exported.


To date, the plant has produced about 1.5 million engines.


Its three core products today are the latest B4.5-litre, four-cylinder and B6.7- and L8.9-litre, six-cylinder engines, with the B3.9-litre, four-cylinder and the legendary B5.9-litre, six-cylinder engines still made for less markets with fewer emissions regulations.


For larger engines, Cummins’ US plants take care of 12-, 15- and 95-litre engines, while the 38- to 78-litre engines are made in Daventry, UK.


Employing lean manufacturing techniques, all engines are built to order with no batch building. At any one time, there can be up 2,000 different engine specifications in the system.




As an assembly plant, all components are shipped in from various Cummins facilities around the world.


The company has no foundries, with many of the castings coming from the US, Brazil, China and India.


Machining of these components is done in Cummins’ own facilities around the world including Daventry, UK.


As well as assembly, the Darlington plant also has testing and research and deveglopment facilities. In all, 12 test cells are used to test new engine designs and configurations. The new structural engine was also developed here and tested in tractor applications, into which the new engines could be used.


Unlike many other engine manufacturers, Cummins produces all its own engine technology, such as fuel systems, electronics, combustion, after treatment and turbos, including the well-known Holset brand, designed and supplied by Cummins Turbo Technologies.


This, says the firm, allows it to better integrate its engines into other manufacturers’ products. It also sells much of this technology to other engine makers such as Scania, Volvo and Daimler.


Similarly, Cummins engines feature in many machines around the world, but under a different name. These customers include Paccar, Hyundai and Komatsu.


For UK customers such as DAF, an engine could be fitted into a truck within 24 hours of leaving the production line.


Established: 1919

Headquarters: Columbia, Indiana, United States

Employees globally: 55,000

Manufacturing facilities: 18 in total spread across six continents, with plants in UK, Russia, China, Brazil, US, India, Japan and Mexico

Industry involvement: Agriculture, construction, mining, defence, rail and marine as well as on-highway applications such as trucks and buses

Number of engines built per year: About 1.1 million

Engine production: Everything from 2.8-litre, 55hp engines, to 95-litre, 4,400hp units



Having been without a structural engine in its portfolio for a while, Cummins hopes the new Stage 5-compliant B6.7 will attract potential tractor manufacturer customers.


It must be working too, with the firm set to unveil later this year which tractor maker will be using its new structural engines.


Much of the interest for the new engine has come from tractor manufacturers wanting more powerful and compact tractors, capable of being versatile enough to carry out powerful pto work, yet able to be ballasted up for heavy draft work.


The structural engine is based on the firm’s B6.7 block, with its new-found strength coming from a specially developed, two layer sump design.


This sees stresses and strains transferred through the cast iron sump, avoiding the need to completely redesign a new engine.


This modular design approach also means the ‘block’ can be used for a variety of applications.


Capable of producing 200-326hp (rated), features of the B6.7 are said to include quick torque rise and recovery as the engine revs die back, and 31 per cent higher peak torque compared to its Stage 4 predecessor.


A lot of bench marking took place in the early stages of development.


Mr Nendick says: “We needed to make sure it could potentially fit into all market-leading tractor models.


“One of the biggest challenges is to adapt the engine to different tractor manufacturer requirements via engine maps. CVT tractors also need very different tuning to powershift models, with CVTs able to handle higher torque curves.”




Throughout the four-year development process, a huge amount of emphasis was placed on structural testing which included impact, vertical bending, severe twisting and field and road simulations.


Additionally, high frequency/low magnitude vibration testing simulated farm tracks, while low frequency/high magnitude tests essentially simulated crashes.


In a short space of time, the engine is said to be taken through its full life cycle. Fitted in a tractor, the engine is undergoing extensive field testing.


Down the road, Cummins is looking to create structural versions of its larger and smaller engines, likely to be the 4.5- and nine-litre models.


Along with the new structural project, the company spends about £720 million on research and development per year. Other projects include alternative fuels, electrification of machines, and the complete integration of powertrains.



The sentiment from Cummins is enough is enough.


Mr Nendick says: “For all engine manufacturers, engines have become more complex as emission regulations tightened. So rather than keep adding technology to the engine to meet emissions regulations, for Stage 5 we have gone back to the drawing board.”


One of the key elements to be ditched on its 3.8- to 12-litre engines is the use of exhaust gas recirculation (EGR), leaving the engine to breathe fresh air rather than spend some of its energy trying to ‘burn’ off particles in the combustion process.




Still, a lot is done in the engine to tackle emissions regarding fuel pressure, timing, thermal management, the use of a variable geometry turbo and piston design.


Outside the engine, a new three-stage filter takes care of the exhaust emissions, which includes a diesel particulate filter, diesel oxidation catalyst and the selective catalytic reduction system.


If necessary, this module can be split in two, depending on how it needs to be packaged.


Overall, the bulk of the emissions treatment equipment has been reduced, making it much more compact, and it is a lot less complex making it more reliable, says the manufacturer.


As well as being easier to install, Cummins claims maintenance is also reduced for end-users.


From a manufacturing point of view, the Stage 5 solution makes the engine more attractive to the second-hand market, particularly if the machine is being exported to countries with fewer emissions regulations, as the engine can be more easily adapted.


However, the trade-off by taking this EGR-free route is an increased use of diesel exhaust fluid (AdBlue), but Cummins says this is offset by the overall improvement in engine efficiency, with overall fluid use reduced, depending on application.


Performance-wise, Stage 5 engines feature 20 per cent more torque and 10 per cent more power. This means a customer could then opt to downsize the engine and still retain the same performance, or stick with the same size engine and get more performance.


For engines above 173hp, Stage 5 emissions legislation comes into effect in January 2019. Engines below 173hp are exempt until January 2020.



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