Xtrac presents new hybrid powertrain at Autosport International
As a prime example of how the motorsport industry can help manufacturers build more environmentally friendly road cars, Xtrac, the specialist transmission technology company, will showcase the world's first commercially viable diesel-electric powertrain developed for a small family car at the Autosport International Show being staged at the NEC this week. Xtrac’s experience of designing high-performance motorsport transmissions has resulted in a compact, mechanically efficient, fully integrated gearbox for the Zytek developed powertrain, which meets the programme’s low cost requirement for high volume series production.
The powertrain will form the centrepiece for a significant display of new transmission developments from Xtrac including its brand new 529 gearbox for sportscar racing, 516 gearbox for touring cars, and the transmission system developed for the JCB DIESELMAX land speed record. The show runs from 11-12 January at the NEC, where the company will be exhibiting in Hall 19 on stand number E351.
The Zytek Xtrac hybrid showpiece fully meets the requirements of the Ultra Low Carbon Car Challenge. This £10m UK government initiative is aimed at producing an energy-efficient small family car with exceptionally low CO2 emissions of under 100g/km, equivalent to a fuel consumption of at least 75mpg (3.8l/100km).
Zytek’s novel solution is a dual-mode system which combines the high efficiency of series hybrids at low vehicle speeds with the high efficiency of parallel hybrids at high vehicle speeds. It eliminates the compromises of other dual-mode hybrids by using sophisticated control strategies to replace clutches and complex epicyclic gearsets. The gearbox design and electronic controls allow the diesel engine and electric motors to be fully optimised for their function within the drivetrain.
Xtrac managing director Peter Digby commented: “This new and innovative hybrid driveline really does drive home the technological capabilities of the motorsport industry and its ability to deliver energy-efficient solutions to the mainstream automotive sector.”
Another highlight of the Xtrac display is the transmission system developed for the 350mph record breaking performance of the JCB DIESELMAX project, which smashed the diesel land speed record at Bonneville in August last year. Xtrac supplied both gearboxes and differentials specified for the vehicle, which features two complete powertrain systems, one driving the front wheels and another driving the rear wheels.
“Within the demanding timescale for this project we took a derivative of our existing 427 sportscar transmission, packaged the automated clutch system from the JCB Fastrac vehicle and designed a bespoke differential assembly,” said technical director Adrian Moore. “It was true concurrent engineering between Xtrac, Visioneering and JCB utilising our Unigraphics NX4 CAD system, without our motorsport approach I doubt the project could have been completed to schedule.
“As you can imagine, there was significant development work involved in synchronising the automated clutch and gear changes, which clearly had to occur simultaneously and with absolute precision,” said Moore. “Any error whatsoever could have resulted in the gearboxes being in different gears, with potentially catastrophic consequences. Our laboratory test rigs were fully deployed beforehand running both transmissions and control systems simultaneously to prove the system’s integrity before venturing onto the airfield and subsequently the salt flats, thereby ensuring the safest possible passage for driver Andy Green.”
Also on display is Xtrac’s new 529 series gearbox, which is suitable for LMP1, LMP2 and GT1 class vehicles, and recently entered production at the company’s UK facility at Thatcham in Berkshire in readiness for the 2007 race season.
“Our new gearbox for endurance sports car racing is based on our Le Mans winning 229 transverse design, which has been one of the most reliable and successful gearboxes to be produced by Xtrac,” said development director Cliff Hawkins. “In developing the new 529 gearbox, we deliberately specified a significant number of well proven carryover parts for optimum reliability, combined with technical improvements in a number of key areas.”
The 529 gearbox is 3.4kg (7.5lb) lighter than its predecessor and its development has led to a narrower lightweight cluster, a revised gear-change rack & pneumatic actuator, improved oil feed galleries and, for ease of maintenance, a side mounted alternator and rear mounted starter. The new gearbox can fit inside the minimum diffuser size permitted by the latest Le Mans Prototype regulations without any modifications, and the narrow viscous-coupling plate differential permits longer driveshafts. Options include a low loss bevel bearing for increased mechanical efficiency.
Another state-of-the-art racecar transmission being shown is Xtrac’s ‘516’ front wheel drive gearbox developed for the World Touring Car Championship and other worldwide touring car championships. Presented as a resin mock-up last year, the new transmission makes it to this year’s show as a fully finished production gearbox, which has already been delivered to the launch customer.
The new gearbox makes use of reduced centre distance F1 derived gear ratios to minimise its mass, size and inertia, and the complete transmission weighs just 30.5kg. The gear-change system incorporates the latest polynomial barrel track design and a low inertia rack to improve gear-change response and driver feel. The low positioning of the gear cluster lowers the centre of gravity and enables easy removal from the car under the chassis rail. The gear cluster is fully exposed when removed from the gearbox allowing quick inspection and ease of access for ratio changes.
Xtrac will also display its 6-speed synchromesh gearbox developed specifically for high performance supercars. Intended for road use, such vehicles demand high levels of refinement and shift quality, which can be difficult to achieve with a bespoke design that may lack adequate engineering development because of ultra low volume budgetary constraints. Xtrac’s solution is a highly refined ‘one size fits all’ transverse transaxle system, which can be specified for virtually any supercar, and is the result of a major engineering development programme. Its first application is the Brammo Rogue GT; the first 1,000 Nm V12 supercar designed and built in the USA.
Further demonstrating that the motorsport industry can work to very short timescales, Xtrac has already responded to feedback from customers attending the recent Professional Motorsport World exhibition in Cologne, with a new production ready endurance kit for its 406 gearbox. Designed primarily for use in front wheel drive touring car applications, this transverse six-speed sequential racing gearbox is being used increasingly for longer races such as the VLN series in Germany. The endurance kit upgrade helps preserve the 406 transmission’s renowned durability for these longer races, while maintaining its ease of servicing; ratio changes are accomplished on the bench after the ratio cluster has been removed as one unit on its cluster plate. Value engineered to meet strict cost constraints, this gearbox offers the highest quality at a cost effective price.
Xtrac has also introduced recently a new range of specially developed lubricants. Working closely with the Neo Synthetic Oil Company, Xtrac has helped develop specific oils and greases from this American supplier tailored to meet the requirements of Xtrac’s high performance transmissions, limited slip differentials, driveshaft assemblies and hypoid axles.
The new XL1 synthetic oil is rated SAE 75W-90 and includes a newly developed additive to extend gear life and improve gearbox efficiency by reducing sliding friction, oil temperature and the impact of shock loads. The oil’s characteristics include excellent low temperature viscosity and high temperature stability.
The new XG1 synthetic grease similarly minimises the impact of high shock loads typified by the high torque reversals and large speed variations generated by constant velocity and tripod joints in motorsport applications. The grease also has bearing applications and is specified for uses involving high rolling contact.
Other products on display at the show underscore the breadth and depth of Xtrac’s experience in designing axles, differentials, gearboxes, steering rack-and-pinion components and systems, as well as other driveline components not only for the motorsport industry but increasingly for high performance applications in the aerospace, automotive, defence and marine sectors.
