The initiative sees Cummins replacing the engine and exhaust after-treatment in older buses with a fully certified, Euro VI system – reducing particular matter (PM) emissions by almost 90% and NOx by 50%. The repower also extends the life of the bus by up to eight years, says Cummins, and delivers a performance upgrade with improved torque response.
The repower features an integral stop-start system which automatically switches the engine off when passengers are boarding or alighting. This can reduce the fuel consumption of a double-deck London bus by up to 8% on a duty cycle of up to 16 hours per day.
This, says Cummins, can cut operating costs per vehicle by up to £2,500 a year, so speeding payback of the repower price.
The announcement follows a previous successful trial, which saw a 1962 RouteMaster repowered to Euro VI (pictured). The vehicle was certified to the Low Carbon Bus standard and is achieving 9.5mpg.
One of the first repower projects is nearing completion at converter Millbrook Special Vehicles, with a 2009-built Euro V London double-deck receiving the latest Cummins B6.7 Euro VI system. This also incorporates a new ZF transmission, new cooling pack and replacement electric ancillaries such as fans and power steering.
Testing is underway at the Millbrook Proving Ground, with early results showing higher fuel efficiency with stop-start technology and improved drivability.
“Cummins is really pleased to be working closely with Millbrook Special Vehicles and their capability is invaluable for bus repower installations where powertrain replacement upgrades and vehicle refurbishment are needed to bring a vehicle up to today’s specifications,” says Ashley Watton, Cummins director for on-highway business Europe.
The Euro VI repower offer covers different models and emissions levels. Depending on the age and condition of the bus, each repower project will be individually evaluated: it could range from a simple engine after-treatment replacement, up to a complete powertrain refurbishment and fabrication work.
Cummins’ B6.7 system increases the top rating for bus applications to 296bhp and peak torque to 1200Nm. Engines intended for hybrid bus repowers have a specially adapted calibration and configuration.
The power step-up from B4.5 to B6.7 comes with exhaust after-treatment commonality, as both engines use the same integrated diesel particulate filter-selective catalytic reduction (DPF-SCR) switch-back system manufactured alongside the engines at the Cummins Darlington plant.