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Test tractors If you're still not persuaded by the idea
Page 52
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of auto boxes, consider this: five of our six test tractors have dedicated auto boxes— there arc NO manual versions.They were designed from the outset as two-pedal autos, with electronics handling the gear synchronisation on the constant-mesh transmissions.
The odd one out is the Autotrans box on the Mercedes Actros. which is an automated version of the German manufacturer's standard 16-speed Tellige nt synchro manual. And even here there's a sting in the tail as an updated, lower-weight, dedicated constantmesh version of Au totrans with smarter electronics is hovering in the wings. According to our spies it will break cover within the next three months.
Three of our test sextet, namely the Stralis. TGA and XF95,sported ZF's 12-speed ASTronic box— albeit with their own 'engineunique' software control programs. Iveco and MAN also use their own marketing names (EuroTronic and TipMatic respectively). Daf commendably retains the AS-Tronic tag.
Last but not least, the Volvo FH12 and Renault Magnum also share the same basic 12-speed I-Shift auto, though Renault would no doubt vehemently claim that its Optidriver 2 auto originates from the Group Powcrtrain Division, Optidriver 2 does have different software from Volvo's 1-Shift. which comes with the choice of no less than five program options.
Finally, our test group featured something of a rarity (at least for the moment) in that the MAN TGA 26.430 boasted a Euro-4 engine complete with FOR.
Test procedure Our brief to the manufacturers was simple. Congregate at the Exel Mothercare site at DIDC1, Crick just off the AS, with an auto artic and fully laden trailer at either 40 or 44 tonnes.
Using the massive RDC as our base we drove each rig around a 45-minute/53km test route which included singleand dualcarriageway A-road running (with some nice little up and down sections along the way) before diving off into the narrow side streets of Hinckley with its mini roundabouts, road junctions and traffic-choked housing estates.
Having rejoined the AS at the M69 junction, we headed back to Crick and base. All in all, the ECU 'brains' in our auto warriors had plenty to think about.
Back at the Exel site we assessed their lowspeed controllability by reversing into narrow trailer bays.
Each box was subsequently marked out of 10 for driveability,control function and onroad 'intelligence'.
As in previous tests we kept all the boxes in full auto (even though they all feature manual overrides) and counted the number of changes made around out test circuit.
The drivers who turned up with 44-tonners did wonder if their lighter 40-tonne rivals would record fewer gear changes; in the event the difference between all the Imes was minimal. Fewer than 20 changes separated most of them, and even that had more to do with traffic flow than anything else.
The exceptions were the retarderequipped Dal: which didn't need to change down for engine braking,and the Mercedes. as explained earlier.
• Scania was invited to join the test but the newly launched Opticruise transmission wasn't available in the UK We look forward to putting Opticruise through its paces in a forthcoming issue.