EcoLife: A breath of fresh air for buses

EcoLife, ZF’s fuel-saving automatic transmission for buses, was a big hit at the recent Southern African Bus Operators Association (Saboa) Conference and Exhibition. Popular in Europe as well as many African countries, the gearbox is said to offer substantial benefits in terms of economy and the environment

One of the biggest challenges associated with buses in congested urban areas is the fact that they have to make lots of short stops to allow passengers on or off. With engines idling, they pump out exhaust gases that, over time, help to rob cities of breathable air.

To combat the scourge, ZF developed its EcoLife transmission for city and intercity bus and coach applications. Introduced ten years ago in Europe as the successor to the popular EcoMat gearbox, the six-speed auto transmission incorporates a host of features designed to improve fuel consumption and reduce emissions, offering substantial environmental benefits.

Fully stop/start capable – which means no more engine idling at bus stops – and with TopoDyn Life shift software ensuring that the optimum gear is always selected, the transmission is said to offer significant economic advantages in terms of fuel-saving, service life, maintenance and comfort, while also contributing to lower air pollution and noise levels.

Suitable for use in all types of buses powered by engines conforming to Euro-3 specifications and up, the gearbox operates within a torque range of between 650 and 2 300 Nm, providing original equipment manufacturers (OEMs) and end customers with options regarding the types of application for which it can be used – midibus, city, intercity or coach.    

ZF’s representatives say the unit offers fuel savings of up to 20 percent compared with traditional manual gearboxes, and up to ten percent compared with other automatic transmissions.

A hydrodynamic torque converter with standard turbine torsional damper enables high input torque at low engine speeds. “This helps to cut fuel consumption by up to five percent compared with automatic transmissions with fewer than six gears. It also reduces the level of noise made by the transmission,” says a spokesman.

Top stopping power is guaranteed thanks to an integrated primary retarder that supports high braking capacity even at low engine speeds, reducing strain on the vehicle’s wheel brakes and prolonging their service life. Additionally, a dual cooling system, which includes a heat exchanger on the retarder, reliably protects against overheating and helps to extend oil-change intervals.

“The powershift transmission has an optimal gear-ratio spread combined with especially high mechanical efficiency. The torque converter lock-up clutch closes shortly after pull-off to use engine power effectively, with TopoDyn Life shift software optimising shift strategy, even taking into account the topography over which the bus is travelling to reduce fuel consumption,” says the spokesman. “As the nature of the road changes, the program always selects the right gear, while also taking into account all other driving resistance values.”

He adds that ZF sees big potential for the gearbox in buses built on truck chassis. “In this respect, we are involved in a homologation process with a number of OEMs in Europe. Also, Chinese manufacturers have begun to incorporate the EcoLife in a variety of buses built on truck chassis.”

In Africa, he says the gearbox is popular in countries to the north. Markets include Nigeria, Ethiopia, Ghana, Ivory Coast, Burkina Faso and Namibia. “The transmission is well-adapted for hot countries thanks to its dual cooling system. Transport operators in Africa have recognised this fact – some have coaches equipped with EcoLife gearboxes that have travelled more than 1,4-million kilometres and are still running trouble-free.”

With ZF having an established authorised service partner network across Africa – the southern African operation is headquartered in Johannesburg, with subsidiaries in Cape Town, Durban, Windhoek and Nelspruit – customer support is well taken care of, with mobile field service technicians available on call.

“ZF Services South Africa has a large stock holding of parts that cover all of our product ranges. In other African markets we also have good availability of spares,” the spokesman says.