It’s what lies between the engine and transmission that makes it a very interesting piece of machinery indeed
By Matt Wood | December 2, 2013
Mercedes Benz is set to push its heavy-duty credibility even more with the 250 tonne GCM Actros SLT.
The Actros SLT arrived on the world stage back in 2000, yet has only surfaced in Australia relatively recently.
It
uses Benz’s 15.9 litre V8 for power, which develops a respectable 480kW (653hp) and 3000Nm of torque.
The transmission is the heavy duty 16-speed version of the Powershift AMT, but it’s what lies between the engine and transmission of the SLT that makes it a very interesting piece of machinery indeed.
The SLT uses a standard dry friction plate clutch for lightweight duties and empty running.
But for gross weights over 70,000kg, the Actros uses a Voith developed VIAB turbo clutch.
This hydrodynamic clutch enables the driveline to utilise full torque from a standstill, as it acts as a fluid coupling between the engine and transmission.
The dry plate clutch locks out until the AMT changes into second gear, and this is when the VIAB clutch locks out.
As the initial take up of load on the driveline is via a hydraulic coupling, there is virtually no stress on the driveline components.
In addition to this, the turbo clutch can generate 3,500Nm of braking torque, again creating virtually wear free retardation.
We recently had a chance to play with the SLT in 8×8 guise at a gross weight of 80,000kg.
The counter-weighted Benz SLT had a dolly and rows-of-eight spread-deck-float attached as well as being loaded with a 35 tonne excavator.
The performance of the turbo clutch was astonishing, under full load it is possible to let the combination come to a stop on a grade and hold it stationary using only the throttle.
By varying pedal pressure it’s also possible to let the combination roll back down the hill and then bring it to a stop, again only using the accelerator pedal.
As the engine and transmission aren’t mechanically linked at this point, there’s no prospect of engine or transmission damage.
Overheating also isn’t an issue as the turbo clutch has its own independent cooling system mounted behind the SLT’s cab.
The system provides an incredible amount of control at speeds less than walking pace, making manoeuvrability in heavy haulage applications that much easier.
However, when empty, the Benz can operate at legal highway speeds, allowing for quick transit times between jobs.
While heavy haulage is an obvious application for the SLT, multi-trailer mining roles are also on the cards.
Benz already has one SLT demonstrator currently working with the McAleese Group in Kalgoorlie at a gross weight of 246 tonne.
Initial reports are already suggesting an improvement in fuel economy and a reduction in trip times.
Check out the January edition of ATN for the full story on the Mercedes-Benz Actros SLT test. Click here to secure your copy.