For farmers in a hurry, JCB’s Fastrac series agricultural tractors are capable of speeds up to 43 mph (69 km/h) in stock form. But the British company believes in challenging its engineers to improve the breed, and in doing so they’ve taken the concept of a high-speed ag tractor to new heights. In June 2019, a JCB-modified machine, called Fastrac One, set a new world (modified) tractor speed record, averaging more than 100 mph.
Then in November, the JCB engineers, working with counterparts at Ricardo, GKN Wheels & Structures, and Williams Advanced Engineering, raised the record by 32 mph to establish another Guinness World Record: 135.19 mph (217.57 km/h), averaged over two runs at Elvington Airfield in Britain. In one of its passes through the speed trap, the Fastrac Two tractor reached 153.77 mph (247.47 km/h). At least 50% of the record-setting machine’s bill of material is shared with JCB’s production Fastrac 8000.
“When we reached 103.6 mph with the Fastrac One in the summer, I was convinced we could go even faster,” said JCB chairman Lord Bamford (formerly Sir Anthony Bamford). So along came the Fastrac Two project, with goals to be 10% lighter, more powerful and more aerodynamically efficient. Guy Martin, a truck mechanic, Isle of Man motorcycle legend and motorsports personality was selected as driver.
Martin was supported by technology and advanced development tools including a Ricardo-created virtual wind tunnel. The use of virtual reality facilitated design reviews that enabled engineering teams across multiple sites to collaborate quickly in real time. Ricardo’s IGNITE optimization powertrain software and WAVE gas dynamics simulation package were used for air system development.
The 7.2-L 6-cylinder JCB Dieselmax turbocharged engine, developed for the record attempt by Ricardo, delivers 1006 hp (750 kW) at 3150 rpm and 2370 Nm (1748 lb-ft), driving through a 6-speed manual ZF transmission and JCB clutch. The engine has a Cummins Holset turbocharger and a Federal-Mogul (now Tenneco Powertrain) COBRA electric supercharger similar to those used by production cars to help eliminate turbo lag.
“For JCB, this was a project that excited and enthused both our customers and our engineers—an opportunity to showcase our engineering expertise,” said Alan Tolley, JCB’s group director of powertrain. “The production Fastrac was a good starting point as it’s already a high-speed tractor, with separate chassis and suspension. We also knew that we had to retain all the basic features and architecture of the production tractor so that the ‘world’s fastest tractor’ (WFT) was instantly recognized as a JCB Fastrac and as a ‘real’ tractor.”
The development team set about reducing weight, drag and rolling resistance, and increasing power, while modifying the driveline for high-speed tarmac running rather than lower-speed field work. “We used a lot of predictive analysis to determine the design and development path and assembled a team of young engineers, many still apprentices or undergraduates, to design, develop and deliver the machine,” Tolley said. “And we also enlisted the help of some of our key supplier partners.”
Ricardo had worked with JCB on previous projects including Fastrac One and the company’s 2006 Dieselmax Land Speed Record streamliner, still the world’s fastest diesel-powered vehicle at 350.097 mph (563.418 km/h); see feature October 2006, page 33. Of several Fastrac Two technology challenges, Tolley singled out how to control transient torque spikes upsetting the driveline, and development of the wet plate clutch hardware and software that had to lay down such high power and torque on to the track. Balancing the required running conditions at 1000 hp with those for start-up, and light load running, were other hurdles.
Ricardo’s Matt Beasley, director of application engineering and project director, said his company’s role in both Fastrac projects has been to tackle a high-pace, high-performance development program, covering simulation, design, analysis, supplier liaison, procurement and engine build, through testing, rapid modification and optimization. The process took nine months for Fastrac One and three months for Fastrac Two.
“We knew from JCB’s initial estimate what weight we could expect for the finished tractor, and JCB did some early coastdown testing of a production Fastrac so we had some idea of the resistance to motion of a tractor,” Beasley explained. “Later in the program, when we had a better idea of the likely torque curve and the transmission ratios, we switched to using Ricardo’s IGNITE simulation tool.”
Beasley noted the key factor is the length of the available track—“you can have all the power in the world but if the gear ratios don’t allow you to accelerate to record speed in a short enough distance, the record isn’t going to be broken.” To finalize the overall strategy, Ricardo modeled expected vehicle speeds with a matrix of different vehicle mass, aerodynamic drag coefficient, frontal area, track length, and engine power. This enabled JCB engineers to understand the trade-offs to achieve a target record speed. For example, with a relatively short track, mass becomes the key factor. Fastrac Two was slimmed down to a little under 5 tonnes (5.5 tons).
Looking to the future, the agricultural and construction sectors will see increasing levels of electrification, according to Beasley, but he believes internal-combustion engines (ICEs) will still play a significant role. For the WFT, Ricardo and JCB applied technologies that will be apposite for future ICEs in the tractor sector.
“Industry trends such as downsizing and hybridization, together with customer demands for good transient response, machine productivity and fuel consumption, push more advanced technology into the engine’s air system, fuel system and structure,” he said. Some components for the WFT project, such as high-flow piston cooling jets, were engineered using additive manufacturing. More exotic solutions such as water injection and ice charge cooling used for the Dieselmax Land Speed Record were also fitted to Fastrac Two.
Aero design, lightweight chassis
The Fastrac Two team wanted the front-end styling of the record-breaking tractor to remain faithful to the production Fastrac, while minimizing frontal area for aerodynamic efficiency. Use of one small and one larger turbocharger would have created packaging challenges resulting in the addition of aerodynamically inefficient bodywork bulges that would also change the tractor’s visual identity. Using a single large turbo (delivering a pressure ratio of ~5) was easier to package. Another reason to employ a single turbo was that peak torque of the WFT engine was ultimately limited by the transmission, axle capacity and traction—together with ultra-high boost pressure being unnecessary in the lower gears.
Aerodynamics also were helped by a lower ride height, and a 200-mm (7.9-in) lower and 300-mm (11.8-in) narrower cab than that of the Fastrac One. Record-run simulations were applied by Ricardo, JCB and Rob Smedley Vehicle Performance Consultancy using models developed for Formula One. Ricardo performed initial CFD simulations of the external skin of the tractor to indicate higher drag areas requiring aerodynamic tuning, said Beasley. “We used our virtual reality suite to enable Ricardo, JCB and Williams Advanced Engineering to collaborate remotely in a ‘virtual wind tunnel’ and to allow us to see regions where significant drag would be generated,” he noted.
Williams revealed that more than 65 individual CFD runs were used to help reduce drag by 25% compared to a stock Fastrac. An aerodynamic front splitter was designed, front overhang reduced, a flat underfloor fitted, exterior mirrors removed, and rear fairings adapted to close the wake behind the cab. “We’ve been able to bring learning from racecar design to an agricultural vehicle,” said Ian Turner, head of aerodynamics at Williams Advanced Engineering. Ricardo’s “virtual reality state” was used to visualize the airflow over the tractor and enabled collaboration with JCB and Williams.
GKN Wheels & Structures was involved in the development and manufacture of the WFT’s wheels and lightweight chassis. After evaluating several prototypes, the final wheel specification was 12 x 28 in (305 x 711 mm). The supplier then assembled the wheels and gave them an automotive-standard finish.
For the new lightweight chassis, JCB provided the initial design based on the standard Fastrac tractor chassis, which GKN Structures supplies. It was redesigned to provide a lower center of gravity. The result was a 25% weight savings. The chassis was manufactured in the company’s prototype facility, every part handset and tacked prior to welding by hand. Bamford summed up the project: “It was an amazing achievement delivered by a young and enthusiastic engineering team. Everyone involved should be very proud of the part they have played.”Continue reading »