WHEN the engineers designed Detroit Diesel's DD15 engine, the EGR system chosen to reduce diesel particulate matter (soot), meant that the engine would be running hotter than its SCR competitors during its working life.
This meant that the Argosy engineers who designed the latest version of Freightliner's popular cab-over model for Australia would have to take account of that in the cooling system.
And that's why the latest Argosy is structurally different in many ways to the truck it replaces. Sure, from the outside it looks like it just has a bigger grill, but in fact the entire front panel has been re-designed to allow a bigger radiator, the cab is set 50mm higher from the chassis (as per Coronado), and the cooling system itself completely upgraded.
The radiator reaches from just below the windscreen to the middle of the bumper bar. That's 1650sq/inches, 32 per cent larger than the previous model. There's a new charge air cooler for the turbo and the air-conditioning condenser is expanded as well. The 50mm lift for the cab reduces airflow obstructions in the engine tunnel and allows the engine compartment to stay out of the danger zone. It also allows for easy escape of heat soak when the truck is stationary.
The Argosy also has an 11-bladed 2-speed Horton engine fan for those times when it's grinding up a long hill with a full load behind.
The effect of these changes became clear during my drive. Near the top of a long steep crawl the engine temperature gauge crept up to 103 degrees, at which point the Horton kicked in, taking a few kilowatts of power and sounding like an over-revving Corolla. But the fan was on for just 30 seconds, by which time the temperature had eased back to 96 degrees as I rolled over the crest.
Of course all of this heat treatment happens out of sight and out of mind for the driver and passenger. The Argosy cab is very comfortable - quiet, spacious and free of rattles and buzzes. It's smaller than the Kenworth K200, but at least passengers can sit comfortably without having to disconnect their feet and stow them in the sleeper.
There's plenty of adjustment for the driver's seat and wheel, which means it'll fit all but the most dedicated Biggest Loser contestant behind the wheel.
The truck was optioned with the 15-litre Detroit Diesel DD15 6-cylinder producing 560hp and 2508Nm of torque. Because of turbo compounding, 510 of those horses come from fuel - the rest from the auxiliary power turbine. Eaton Auto-Shift 18-speed transmission, "Airliner" 110-inch (279cm) raised roof sleeper, drum brakes all round, steel front suspension and Freightliner airbags on the rear completes the working spec.
Getting on board is of course an Argosy specialty. The patented swing-out step remains the best in the business - all other axle-forward cab-overs take note.
My test drive was out through the South Gippsland Highway to Leongatha with a loaded B-double behind. There we turned left on the Strzelecki Highway and headed north-east through Mirboo North to the Princes Highway intersection at Morwell in the Latrobe Valley.
I found the DD15 to be a very willing engine and there were few hills that slowed the rig down below 85kmh. The Eaton Auto-shift (Ultra-Shift on the latest arrivals) made it easy of course and I only used the manual feature to bump up the engine braking at times.
The truck steered dead straight on the winding road sections and feels very stable no matter what the road surface.
I think fleets will like the latest version of the Argosy. It's not the most technically advanced of cab-overs - all the Europeans will out-feature it in that department. But it is specced for hard work, easy maintenance and low costs for spares. That's always a winner.
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