Bus KERS – Coming to a bus stop near you

Low Cost Mechanical Bus KERS en route to production in mid 2016


Torotrak Group and Wrightbus confirm the completion of the in-service trial of a Wrightbus StreetLite midi bus fitted with Torotrak’s Flybrid mechanical kinetic energy recovery system (KERS). The trial was made possible by and conducted with Arriva, one of the largest bus operators in the UK.

The trial was conducted on a standard bus route in Gillingham, Kent from March 2015.  It successfully demonstrated the performance of the Flybrid KERS under real-world operating conditions including the capture, storage and release of energy from the brakes and the drivability of the system. The learnings from the trial have already proven invaluable in selecting the operating strategy for the volume production system, which will be a second generation design.

Already undergoing detailed testing on rigs and in a new Euro VI StreetLite bus, this new KERS design is intended to further improve bus fuel efficiency and reduces the KERS weight and cost, helping to improve the bus operator payback. The new design has reduced parts count and system weight by 30% and 80kg respectively and incorporates a simpler 2x2x2 clutched flywheel transmission system reducing ‘coast down’ losses and improving efficiency during torque transfer.

In collaboration with its global Tier 1 manufacturing partner, Torotrak is on track to commence production of bus KERS systems from mid 2016 onwards. Tier 2 suppliers across the UK and other parts of the EU have been nominated and the manufacture of production tooling is currently underway.

Adam Robson, Torotrak Group CEO, said: “This is a very exciting time for the Group with the bus KERS project that started in 2012 going into commercial production from the middle of this year. I am delighted with the progress we have made and we look forward to delivering our first systems to Wrightbus during Q3 2016.”

The Flybrid KERS for buses is a highly efficient and robust hybrid technology, ideal for the long service life and repeated stop-start duty cycle of public service buses. Using common materials and manufacturing methods, and removing the requirement for replacement batteries during service life the flywheel-based technology can offer exceptional value and an opportunity for widespread hybridisation. The KERS captures the kinetic energy that is normally wasted when the bus is braking and stores it in a steel and carbon fibre flywheel weighing 8.5kg and spinning at up to 30,000 rpm. The energy stored in the flywheel is then delivered back to the wheels reducing the energy that is required from the engine to accelerate the bus and so reducing the fuel consumption of the vehicle. The process of capturing, storing and releasing energy back to the wheels is fully automated, giving a high quality driving experience. The Flybrid KERS technology was developed in Formula 1 and has been applied in a variety of vehicle applications including motorsport, passenger road cars and excavators.

Brian Maybin, Wrightbus Engineering Director, said: “After the invaluable in-service trials with Arriva, Wrights and Torotrak have confirmed that the next generation of flywheel is now under extensive durability testing, and after successful fuel trials, will be put into service trials from May 2016. Production vehicles will be able to be delivered into service late in 2016.”

Ian Tarran, Engineering Director at Arriva UK Bus commented: “As one of the largest bus operators in the UK with over 5,900 buses, improving the efficiency of our bus fleet and reducing emissions is important to us and our customers. Having collaborated with Torotrak and Wrightbus on the flywheel project since 2012 we are looking forward to installing Flybrid KERS across our bus fleet from Q3 2016 onwards.”



About Torotrak:

Torotrak (LSE: TRK) is an innovator and supplier of low carbon vehicle technologies, focussing on mechanical solutions that increase efficiency and reduce CO2 emissions in vehicles. These include the V-Charge variable-drive supercharger, a range of Torotrak gearless traction drive transmissions, and the Flybrid energy recovery system, which uses a mechanically-driven flywheel to capture kinetic energy during braking and efficiently return it to the wheels. The company’s engineering team works with proven, global tier one technology partners to provide a validated route from prototypes to production. Customers include major vehicle manufacturers and their suppliers in the light duty, heavy duty and off-highway sectors as well as leading motorsport teams.  www.torotrak.com

About Wrightbus:

Wright Group manufactures buses for many niche market segments including midi, middleweight, full size city bus, school bus, double deck, and Bus Rapid Transit vehicles utilising both diesel and hybrid electric drivelines. Notable milestones include the launch of the world’s first hybrid-electric double deck at London’s City Hall in 2006 and the development of the ground breaking StreetCar RTV, a unique combination of both Bus Rapid Transit and hybrid electric technologies; fifty of these vehicles now in operation in Las Vegas! Today, every fourth bus sold in the United Kingdom on a PSV chassis is made in Ballymena.

Wrights Group is still a family owned and managed business, with nearly 70 years’ experience in passenger transit solutions. While remaining a family company in every respect, and proudly independent, Wright buses blend traditional values with innovative designs and technological excellence. This winning combination has laid a foundation upon which the company has grown from strength to strength, to the extent that the Group now employs more than 2000 people.

About Arriva:

Arriva operates 19,500 buses across 14 European countries, covering everything from taking passengers to school and work, to the airport and even on sightseeing tours. Arriva’s low-floor, environmentally-friendly vehicles are making bus travel more accessible to more people every day. Arriva bus services span local and commercial routes, sightseeing tours, airports, schools and chartered journeys. Having started out in the UK back in 1980, Arriva began its journey in the mainland Europe bus market with the first acquisition in Denmark in 1997. Arriva’s largest bus market remains the UK, with a fleet of 5,900 vehicles providing services for customers in London, the rest of England and in Wales. In London, Arriva runs nearly 20 per cent of the bus services and covers over 60 million miles, providing 400 million passenger journeys in the capital every year.