JCB DIESELMAX to the MAX with the Protection of E-T-A

Many of you will have been aware that the JCB DIESELMAX car became the world’s fastest diesel-powered automobile in August when Wing Commander Andy Green drove it to a new record of 350.092mph (563.418kph) after two passes in opposite directions, within one hour, on Bonneville Salt Flats in Utah. But how many of you knew that the electrical circuits were protected by E-T-A circuit breakers?!

Sir Anthony Bamford, Chairman of privately owned JCB, was very clear why he wanted to build a JCB record-breaker when the project was started: “I am passionate about the importance of engineering excellence to Britain and I see using the JCB engine for this record attempt as a fantastic way of showcasing what British engineers can do. The JCB444 has been acknowledged as a remarkable piece of engineering, and this programme to build the world’s fastest diesel-powered automobile is precisely the sort of technical challenge that we should rise to.”

Powering the stunning, nine metre long JCB DIESELMAX car were two JCB444 diesel engines, developed with the help of Ricardo engineers to produce 750bhp each, five times the power needed to drive a JCB backhoe loader, and now the world’s most powerful diesel engine per litre. The JCB444-LSR engine displaces 5-litres, weighs 382 kg (dry), and produces 750bhp at 3,800 rpm on a relatively low 10.5:1 compression ratio and in excess of 1500 Nm of torque at 2,500 rpm.

The distribution panel was designed and built by R&D Vehicle Systems, based in Banbury. Rob Millar,director of RDVS, explained: “R&D Vehicle Systems is a specialist designer and supplier of electrical systems for military and niche vehicle manufacturers. We were delighted to be involved in the JCB DIESELMAX project. The superior technology and reliability of E-T-A’s circuit breakers are well known to us. It was very important for this project that we could build a system using circuit breakers that were very resilient to shock and capable of resisting damaging ingress of salt and oil.  For this reason we chose E-T-A type 483s, which we know are highly ‘spec’ed’ and well proven in motor sport and the aerospace industry, and we fitted them with standard dust covers.

The E-T-A 483 Circuit Breaker for Equipment (CBE) is a single pole temperature compensated thermal circuit breaker. Believed to be the smallest package on the market offering protection up to 35A, the range extends from 1A up to 35A. It features a push/pull on/off actuator with a tease-free, trip-free snap action mechanism. A high tolerance to sudden current surges is in-built, reducing the risk of nuisance operation, and enabling close matching of cable size to CBE. This avoids the common practice of overspecifying the cable size and using a higher rated fuse.

“Although the distribution panel was located behind a closed panel,” Millar continued, “it, nevertheless, was subject to inevitable exposure from fine salt particles and oil spray. We never had a single issue with the circuit breakers. One tripped just the once during the Bonneville runs, and that meant that that section of electrical harness was safely protected against the overcurrent that caused the trip.”

Andy Green, the fastest man on Earth, set the first-ever supersonic world land speed record at 763.035 mph in ThrustSSC on the Black Rock Desert on 15 October 1997. As he was feted by his jubilant crew on 23 August, Green said: “I am so pleased that we have got the car to 350mph which was always our ultimate goal and that was with a slow start to the second run. Today’s record proves the potential we have always believed JCB DIESELMAX to possess. This is another great result for a wonderful team and a testament to British engineering.”

"350mph is a fantastic speed for a diesel-powered car. To have built the world's fastest diesel in such a short timescale is a wonderful achievement for the JCB DIESELMAX team,” added Dr Tim Leverton, JCB’s Group Engineering Director and Project Director for the land speed record project. “What is even more impressive is to set three records – 317.021mph, 328.767mph (526.027 kph) and 350.092mph (563.418kph) in only six days.”

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