The clean side of waste collection

Gianenrico Griffini, from Italian publication Vie&Trasporti, drove the experimental Iveco Stralis 260S42 with hydraulic hybrid powertrain in real operating conditions. FOCUS gets the exclusive.

Today, a unique combination of innovative ideas, technological expertise, specialised construction skills and deep commitment to research and development are required to develop the transport solutions of tomorrow.

These are the features that characterise the two experimental trucks with low environmental impact for transport in urban areas – a parallel hybrid based on the Eurocargo, and a series hybrid based on the Stralis 6×2 chassis cab – both of which are products of the Vector 2015 research project.

Launched in 2009, this initiative was co-financed by the Italian Ministry of Economic Development and coordinated by Iveco. It focused on developing environmentally friendly, safe, interconnected vehicles with reduced fuel consumption and emissions – including carbon dioxide (CO2), which is responsible for the so-called greenhouse effect.

An advanced diesel-hydraulic hybrid powertrain with serial layout was developed for the experimental Stralis 6×2, equipped with a waste compactor.

This solution is “tailor-made” for waste collection in urban areas, characterised by low speed and frequent stop and go. The most interesting aspect of the hybridisation of the Stralis powertrain – a 313 kW (420 hp) Fiat Powertrain Technology (FPT)Cursor 10 internal combustion engine, which is coupled to a hydraulic system developed by the North American specialist Parker – is that the more frequent the stops and starts, the greater the reduction in consumption and emissions.

Over the course of a typical waste collection job in a city, says Marco Aimo Boot, alternative traction and electrification manager at Iveco, the fuel consumption of a diesel-hydraulic Stralis is on average 30 to 35 percent lower than conventional vehicles used for this purpose, with peaks of up to 45 percent. At the same time, trials show a drop in the amount of CO2 produced, directly proportional to fuel consumption.

“Among the additional benefits of this solution, it is worth mentioning the decreased brake wear due to energy recovery during deceleration, which allows drivers to use the auxiliary system only when needed, as well as an increase of up to 15 percent in vehicle productivity as a result of improved performance when stopping and restarting in terms of acceleration.”

The Vector 2015 project Stralis is an advanced serial-hybrid vehicle in which the internal combustion engine is directly connected, via a drive shaft, to a complex device consisting of several components; namely a transmission unit with three gear ratios (called the Power Drive Unit), a primary hydraulic pump, two secondary hydraulic motors with variable displacement axial pistons, high-pressure diaphragm accumulators, a low-pressure tank and an electronic control unit.

The Cursor 10 drives the primary pump directly, which sends oil to the accumulators, compressing the nitrogen (an inert gas contained inside) through an internal membrane. The energy (which is stored from this process) can then be used during start-up for the vehicle pick-up, by means of hydrostatic drive, which replaces the torque generated by a traditional internal combustion engine.

The hydrostatic transmission is backed up by two secondary variable displacement pumps that act, in this instance, as motors. There are two modes of traction available: low speed and high speed, to bring the vehicle from zero to around 50 or 60 km/h.

Beyond this speed, when the hydrostatic drive becomes inefficient from an energy perspective, a direct mechanical connection between the engine and the wheels is automatically made.

When slowing down, the two secondary pumps send the fluid to the two accumulators, re-charging these (regenerative braking). In this manner, up to 70 percent of the energy used during vehicle deceleration can be recovered; this would otherwise be dissipated as heat. Regenerative braking also serves to slow the truck, without the need for a traditional hydraulic retarder.

“There are several advantages of the serial-hybrid vehicle solution,” specifies Boot. “First and foremost, in a particularly demanding field of transport such as municipal waste collection, which is characterised by constant stops and starts, this technology allows for a reduction in the load on the thermal engine, allowing it to run at maximum energy efficiency, with positive effects on both consumption and pollutant emissions.”

Inside the driver’s cab, the experimental Stralis does not differ significantly from a conventional heavy-use road vehicle. The only difference lies in the colour display that shows the energy flow along the vehicle drivetrian and charge level in the accumulator tanks.

The three gearshift buttons remain unchanged. The latter, however, is not the standard Eurotronic 12-speed system; it is the Parker Power Drive Unit, which controls the two hydrostatic drive phases during pick-up and low speed and, beyond the 60 km/h threshold, the direct mechanical connection between the engine and the drive wheels.

The integration of the powertrain components allows the Stralis to achieve smooth, jerk-free, powerful acceleration. When slowing down, regenerative braking is especially effective when the vehicle is in hydrostatic mode; for example, at speeds below 50 km/h during typical waste collection in urban areas. This mode is activated by simply turning down the multistage-multifunction lever, located on the right side of the steering column.

In addition to the diesel hydraulic Stralis, the Vector 2015 project has led to the creation of a hybrid EuroCargo, with internal combustion engine and electric units arranged in parallel.

This solution also offers considerable advantages in terms of improved fuel economy and reduced CO2 emissions, with reductions of up to 25 percent compared to a conventional truck. These results have been obtained in typical urban distribution applications characterised by low speed and frequent stops and starts. An automatic engine switch-off and restart system has been adopted on the EuroCargo, for longer stops at traffic lights or in traffic jams.

Like the Stralis, the EuroCargo also features regenerative braking, with energy recovery to charge the on-board battery pack. Finally, the motor generator, positioned between the clutch and the automated transmission, allows the vehicle to start in electric-only mode from stationary.

As regular readers of FOCUS know, this magazine has been appointed an associate member of the International Truck of the Year (IToY)! FOCUS is the sole South African magazine to have joined this prestigious body. One of the advantages of this association is access to exclusive articles, specially written for FOCUS by ITOY jury members. This is one such article.