Wrightbus: now the complete bus builder
The company that supplies the new-generation of London buses, Wrightbus, is now expanding its operation, reports FRANK BEETON.
The name Wrightbus should be familiar to regular readers. It usually appears in the role of a specialist supplier providing bodywork for fitment to chassis, sourced from one of the major original equipment manufacturers (OEMs). During 2011, this company, from Northern Ireland, garnered significant attention when it was awarded the tender for the New Bus for London (NBfL) project, with a design proposal that was developed in conjunction with Heatherwick Studio.
The resulting 11,2-metre, hybrid double-decker was equipped with no less than three separate entrances, including an open rear platform (deemed highly desirable by commuters in London), a seating capacity of 62 and provision for 25 standing passengers, plus one wheelchair bay. At the time of writing, one hundred of these vehicles have already entered service, with 500 more scheduled for delivery by mid 2016.
More recently, Wrightbus announced that it had evolved from being a bodybuilder into a complete vehicle supplier. This follows the opening of its chassis assembly division, EN-Drive in Antrim, during April 2013, where frames for various products – including the NBfL project – are assembled.
This operation receives fabricated and powder-coated frames (from the Metallix division located at the company’s headquarters in Ballymena) and is responsible for integration of modules, driveline electric and air system installation, testing and quality assurance. Future plans include chassis production for sale to customers (including bodybuilders) outside of the Wrights Group.
In addition to the London double-decker, Wrightbus currently offers a number of branded products to the market, including the Streetdeck fully integral double-decker bus, StreetLite single-deck integral midibus and the StreetCar BRT system.
The Streetdeck utilises an EN-Drive underframe and is powered by a 170 kW (230 hp) Euro-6 Daimler OM934 5,1-litre, four-cylinder diesel engine. It drives through a Voith D854.6 four-speed, or ZF 6AP1000B six-speed automatic transmission – both of which are equipped with integral retarders. The drivetrain is longitudinally mounted on a demountable skid for easy maintenance.
The StreetLite midibus can be supplied with a choice of 4,5-litre Cummins ISB or 5,1-litre Daimler OM934 engines, providing a power spectrum that extends from 120 kW to 155 kW (160 to 208 hp). Drive passes through a Voith 824.6 four-speed fully automatic transmission with integral hydrodynamic retarder.
Alternative drivelines are also available. These include mild hybrid, with a low-cost mechanical kinetic energy recovery system (KERS); full electric drive with wireless induction charging; or micro hybrid, which uses recovered braking energy stored in batteries to power the vehicle’s auxiliary systems.
Wrightbus will also be testing a prototype of its Flybrid KERS system on a StreetLite midibus at the Millbrook Proving Ground early this year. This flywheel-based system converts recovered kinetic braking energy into traction power. It is being developed by a consortium comprising: Wrightbus parent Wrights Group, KERS specialist Flybrid Automotive, German transmission manufacturer Voith Turbo, low-volume manufacturer Productiv Limited, and bus operator Arriva Plc.
The system utilises a carbon-fibre KERS flywheel spinning within an aluminium casing at 40 000 r/min in a vacuum, and operates completely independently of the vehicle’s engine and gearbox.