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Two of the trucks Prime Mover has driven during the first quarter of 2019 are from different manufacturers yet share a common major component of their drivelines with the ZF TraXon transmission.
It’s one of the most advanced heavy-duty transmissions to be developed in recent years and the ZF TraXon arrived on the Australian market in the MAN TGX D38 without a lot of fanfare at the end of 2016. It is now available in other MAN models and is the transmission of choice for IVECO’S Australian built Stralis X-way.
Of significance is the TraXon’s modular design, allowing different OEMs to incorporate, depending upon the intended application, a choice of dry clutch, dual clutch, hydraulic torque convertor, or even a 120kW/1,000Nm hybrid-electric motor drive. The basic architecture of the TraXon allows for torque ranges in direct drive up to 2,800Nm, and in overdrive models up to 3,500Nm. The mechanical efficiency of the twin countershaft TraXon transfers the power and torque produced by the engine to the driven axle(s) with virtually no loss and ZF are able to claim a 99.7 per cent mechanical efficiency from the direct drive versions.
For quite some time ZF has been collaborating with its engine manufacturer clients including Iveco, MAN and DAF in the development of the transmission to suit the different characteristics of Euro 6 engines.
IVECO refers to its version of the 12-speed direct drive TraXon as the ‘HiTroniX’ and its installation in the Stralis X-Way has only added to the ‘Aussie’ Stralis’s performance and appeal. Depending upon the weight and the incline it will start off in first, second or third gear, with a higher ratio being the default selection due to the contribution to fuel economy. Upshifts under power are very quick and smooth including the range change between sixth and seventh gears. Down changes under power are also lightning-quick with only infinitesimal disruption to the power delivery when climbing.
The MAN TGX we drive is specified to suit the requirements of the Penske Truck Rental fleet and consequently the transmission is configured to always start off in first gear regardless of load or incline. Here the philosophy suggests protection of the driveline provides better value than a slight improvement in fuel efficiency achieved by starting off in a higher gear. In practice the TraXon in the TGX usually starts upshifting almost immediately, often before the drive wheels have made a single rotation.
The sound reducing effects of the all new transmission housing combined with improved designs for the moving internal components contribute to a noise reduction of six decibels compared to the previous ZF Eurotronic. Driving the two examples of TraXons (MAN TGX 26.540 and IVECO Stralis X-Way C13 510) we have to focus to realise that the whining noise usually associated with truck transmissions is almost non evident.
Each manufacturer has taken a different approach to controls for the gearboxes with the X-Way using dash mounted push switches for forward, neutral and reverse, while the TGX uses a rotary switch located low on the centre of the dash to perform the same functions. Both use a steering column mounted stalk for manual over-riding of gear shifts. For fleet operators both manufacturers have an option that disables manual shifting.
The X-Way version of the Traxon has the ‘Ecoroll’ function which disconnects the driveline to allow coasting and is automatically activated a surprising amount of the time on our Sydney-Melbourne trip driving us along using ‘free’ kinetic energy while the engine idles. Ecoroll can be used with the cruise control either on or off and is operational between 50 and 92 km/h. The particular MAN we drive doesn’t have ‘EfficientRoll’ (MAN-speak for the drive disabling function) but it is available as an option.
Both versions have crawler ratios in forward and reverse which, when selected, also limit engine torque making slow speed manoeuvring and trailer hook ups safer and easier. The X-Way has a ‘Rocking’ mode which should appeal to trucks working in the construction industry. When rocking mode is selected the clutch is disengaged by simply releasing the accelerator pedal allowing the truck to roll back and re-engages when the accelerator is pressed again, in order to recover traction on slippery surfaces.
This ZF TraXon transmission complements the smooth overall performance of the MAN TGX. It also provides the IVECO X-Way with the transmission performance it deserves to be on an equal footing with other European truck manufacturers and their well-developed proprietary transmissions.
We look forward to driving a locally delivered truck fitted with the ZF ‘PreVision’ system which uses GPS to factor in uphill and downhill gradients in advance for the selection of the ideal shift points for the TraXon. The TraXon can also be equipped with ZF’s Intarder hydraulic retardation system which, depending upon the application, can exert up to a massive 4,000Nm of driveline braking force