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Prime Mover Magazine


Mack Trident

Mack Trident

With the introduction of the M-drive, Mack now has a fast changing reliable and responsive automated manual transmission to take the brand into the future of trucking here in Australia. Tim Giles put the latest Mack Trident to the test.

Mack has consistently offered a driveline to its customers from its own stable. However, since the company was taken over by Volvo, the amount of state-of-the-art technology available under the Mack brand has increased considerably. The latest addition to the options catalogue on a Mack truck is the M-drive, Mack’s derivative of the very successful Volvo I-shift automated manual transmission (AMT).

AMTs have been available for some time in Mack trucks but came from Eaton in the form of Autoshift and this gearbox did not compare well with its European competitors. The inclusion of the M-drive in the new Mack range gives the Bulldog brand a double advantage, going forward. Not only does it now have an efficient and flexible AMT but it is also a proprietary product branded Mack.

This development follows the introduction of the MP8 engine a few years ago which was derived from the Volvo 13L, completing an integrated driveline developed together over many years within the global Volvo organisation. As with everything the global company does, the Mack version of the AMT is programmed to suit North American conditions, as well as Australian conditions, rather than the needs of the European market.

The MP8 uses different engine mapping solutions to its Swedish counterpart and, as a result, requires a different solution from any AMT with which it is integrated. Those used to handling North American drivelines expect different characteristics of torque rise from the engine. These differences mean the transmission has to react in a slightly different manner to the information it receives from the vehicle’s systems.

Prime Mover took the latest Mack Trident on a test drive from Brisbane to Rockhampton to get an idea of just how this new technology fits in with the other characteristics we expect to see from any Mack truck. Pulling a fully loaded B-double set, the truck was put through its paces tackling the improving (slowly) Bruce Highway.

The 12.8 L MP8 engine is rated at 500 and 535 hp (373kW and 399kW) on the Trident. The model tested was rated at 535hp putting out 1920 ft lb (2603Nm) of torque. This rating is as high as the MP8 will go but is more than adequate to haul a B-double all day. The engine brake has 495hp (315kW) of retardation available at 2100rpm. The transmission is the M-drive, a 12 speed direct drive automated manual transmission. The alternative, for the traditionalist, on a Trident is either the Mack or Eaton 18 speed manual overdrive box.

For 26m B-double operation the 6x4 Trident with the 40 inch Mid Rise Sleeper fits the bill. This is a prime mover with enough space to be reasonably comfortable for the driver while still getting within the tight 26m B-double envelope. At the same time there is enough room on the chassis to handle 1400L of diesel class and 200L of Adblue for the SCR system. The truck, as tested, had a 200mm leeway inside the 26m, giving an operator room for different bull bar options.

Visually, the Mack Trident looks the same from the outside as the previous model, all of the major changes are out of sight. Climbing into the truck, the first thing to note is the new controller for the M-drive gearbox. Gone is the redundant Cobra control fitted to a stalk on the floor where the manual gear stick used to be. Now there is a neat and tidy seven button control pad on the dashboard with a blue screen indicating what exactly is happening with the transmission and which gear is engaged.

The controls are simple with a button for reverse, one to toggle between economy and power modes in the AMT software and a larger button to put the transmission back to neutral. The other four buttons are simply the drive button for automatic changing, the manual button to give the driver total control on ratio changes and two buttons to shift up and down the gearbox. The new shape of the dashboard curving round to the driver’s left means this controller is within easy reach of the driver’s left hand and only requires them to release the steering wheel momentarily to effect changes.

To make sure the driver knows exactly where they are, in terms of gearbox mode, the gear number indicator will flash if manual is engaged, reminding the driver they need to make the changes themselves, if and when required. Out on the highway, this driver did not feel the need to engage power mode very often. The economy mode for the gearbox seems to cope quite well with many and varied road conditions experienced at full weight on the Bruce Highway.

The gearbox will not even consider changing down until rpm levels drop to 1100. This kind of gear changing is very practical most of the time. This engine has got a lot of torque low down and is perfectly capable of pulling up from below 1000rpm. However, at 60 tonnes and approaching a grade it is often a good idea to get the first down change in early to maintain momentum, trying to keep up road speed to the top of the grade. There are two ways to achieve this with the M-drive. Simply pressing the performance button will tell the system to change down when the revs drop to 1400. The same effect can be achieved by pushing the accelerator through the normal detent to the floor, giving the system the message the driver wants to get going.

As the truck crests the grade, the sophistication of the system means the point of gearchanging moves back down the rev range, as the inclinometer in the gearbox tells the system the truck is now on level ground. The driver then simply returns the M-drive mode to economy and continues on their way.

For any truck driver used to North American trucks this layout looks very familiar with the pushbutton control looking similar to that used by some truck manufacturers with the Eaton Autoshift. The button system used on the rest of the dashboard is little changed from that used over many years in Mack trucks. The only difference is the pleasant blue illumination behind the buttons. What is very different is the systems they control. A button may look very similar to that used to control the Jake Brake of the past but it is in fact controlling a sophisticated modern European style compression engine brake, quietly going about its work.

The driver information display screen is centrally located at the top of the dash, directly in front of the driver and clearly visible through the steering wheel. This system does have plenty of information available to the driver but the control stalk is probably a little too complicated to be used very much while driving. It is probably preferable to set the screen to show the current road speed in large numerals while driving and leave it until being parked up to look through the many options.

The engine brake control has three settings available. Latch gives the driver 100% engine braking when the accelerator is released, Auto commences engine braking at 70% when the driver activates the foot brake and Set was used, on this run, as the default position as it brings in the engine brake as soon as the truck’s road speed gets to 3km/h more than the cruise control setting. When cruise control is not engaged the Set position can be pressed to hold road speed down as the system tries to maintain the current speed, using both transmission and engine brake. Further pressing of the Set button will reduce road speed in 1km/h increments.

To all intents and purposes the 2011 Trident is very similar to its 2010 predecessor but the addition of the M-drive has given the truck just a bit more effectiveness. Over the past 10 years the experience of drivers in a Mack has consistently improved, both in terms of driver comfort and vehicle performance. Much of this has been due to technological developments by the Mack organisation itself but more recently it has been due to the introduction of Volvo developed technology being gradually integrated into the Mack platform.

The result is a truck which still feels and sounds, pretty much, like a Mack. The trucks do, however, do their job in a much more unfussy and smooth way than they did in the past.
Engine performance and responsiveness is excellent and with this engine married to a transmission designed to do the job, a high level of performance results. This is the point at which the two worlds meet. On one hand, North American iron, with much of the driver interface, has remained little changed in 20 years. On the other hand, sophisticated European developed high-technology has made high levels of power and torque available in a relatively light package and using an electronic control to protect the driveline.

With the introduction of the M-drive this is probably the culmination of the integration between what we, in Australia, like about Mack and what the trucking industry needs in terms of efficiency, reliability and effectiveness.

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