Prime Mover Magazine

Off the road again

Off the road again

The combination of Isuzu’s innovative compartmentalised Servicepack bodies fitted on its 4x4 running gear with up to 7.5 tonne GVM has taken another significant step with the integration of a two pedal automated transmission and can now access work sites in much more demanding terrain while keeping its occupants comfortable and safe.

For the single cab application the powder coated steel service body has nine storage compartments with the automatic locks integrated into the cab’s central locking system.

Every compartment is equipped with its own LED lighting operated by sensor switches on each locker’s door and controlled by a master switch on the dash. The total storage volume of the lockers is four cubic metres.

Between the two banks of lockers is a central storage area that is 2.26metres long and 1.17 metres wide and has five tie-down anchors in its chequerplate floor.

A removable wooden transverse panel acts as a tailgate to retain items such as bags of cement. Crew cab models have seven compartments and a single barn door in place of the wooden panel.

The single cab model is supplied complete with a Palfinger PC1500 hydraulic crane, which has a maximum lifting capacity of 990kgs at its shortest extension and 270kgs when it is at its fully extended range of 4.2metres.

The Palfinger adds significantly to the versatility of the NPS and when being operated maintains the truck’s platform stability by the use of extendable stabiliser legs.

The provision of the AMT in the NPS range provides emergency services such as bush fire brigades, resource exploration operations and remote field service operators with a reliable and rugged on- and off-road vehicle with the advantage of two-pedal operation.

Regular off-roaders may not consider this a big deal but for categories such as volunteer fire fighters where the drivers may not have a wealth of experience in rough conditions this is a significant advantage.

And for those who regularly venture off sealed surfaces either for industrial or recreational purposes the two pedal operation adds another level of convenience and control.

Our assessment of the NPS 4x4 tales place over two phases – the first in an abandoned quarry in the Victorian countryside and alternating between crew and single cab versions, and a longer test drive in a single cab over several days spread across Sydney metropolitan traffic, the M1 freeway and the Central Coast hinterland where fortunately some rain has fallen overnight providing the opportunity to splash some mud onto the Isuzu.

The Isuzu’s climbing abilities are on par with 4WD SUVs, which can be quite surprising in a seven and a half tonne truck.

Fording water hazards is easy too due to the traction and ground clearance.

The suspended driver’s seat works well at providing long term comfort both on and off road although the same can’t be said about the solidly mounted passenger’s seat.

The canvas seat covers and the very heavy rubber floor mat are an indication that this truck has been designed to operate in rugged conditions.

The full sized mirrors are an asset on the road but can be somewhat vulnerable when off-road and are best folded in when tackling narrow tracks.

For safely backing up there is a reversing camera and a rear mounted microphone.

Front protection is in the form of a polished aluminium bullbar which provides good looks and does such a good job of shielding the vulnerable lights that the indicators are all but hidden which has required additional LED indicator lights to be incorporated in the bar itself.

Isuzu is the first OEM to offer a two pedal 4x4 in the Australian market and the engineers have learned from their experience over the past three years including with the two-wheel drive N series.

Recalibrations specifically to suit the dual range 4x4 application under conditions likely to be encountered in Australia have been developed as well as the installation of wet clutch fluid coupling in place of the torque convertor used to connect the 4x2 engines to the transmissions.

On the road the AMT in the 4x4 is well behaved and at no time did it seem to be confused as to which gear it should be selecting.

Upshifts are smooth and unhurried and the addition of a kick down switch operated via a detent under the accelerator pedal translates into swift downshifts, which are great for maintaining momentum.

The five speed gearbox doesn’t have synchromesh on first gear so steep take-offs in high range are best achieved by stopping and pressing the small ‘first gear start’ button on the stubby selector lever.

An ‘economy’ mode switch encourages the AMT to upshift at lower engine revs to save fuel.

To best suit Australia’s often high ambient temperatures the transmission is now fitted with its own fluid cooler and a warning system that indicates if too much heat is being generated when operating off road.

The Isuzu engineers tell us that if this is to happen it is most likely when a driver stays in too high a gear, requiring the fluid coupling to slip more than usual. 

An instructional sticker on windscreen provides the actions to be taken if the transmission light and buzzer are activated and this is as basic as selecting low range or even first gear for a short period of time.

Selecting low range using a dash mounted switch takes away the self-shifting attributes of the transmission and it essentially becomes a clutch-less manual with the driver required to select up and down gear changes via the lever.

In off-road situations this is a great feature and provides much better driver control. On descents the improved engine exhaust brake comes into its own and helps deliver an almost ‘no-pedal’ driving style.

The exhaust brake in conjunction with being able to regulate vehicle speed and engine RPM using the shifter provides excellent driver control.

Selecting low range disables the anti-lock braking system (ABS) to further enhance the driver’s control in situations of poor traction.

The rear axle features a limited slip centre and the front free-wheeling hubs are very easy to engage by hand.

The four-cylinder 4HK1 engine displaces 5.2 litres and uses a maintenance free diesel oxidation catalyst to meet the emission regulations.

The maximum power of 114 kW (153HP) is developed at 2,600rpm and the maximum torque of 419Nm is spread between 1,600 and 2,600rpm.

Achieving the broad torque band is assisted by use of the electronically controlled variable nozzle turbocharger and an air-to-air inter-cooler. Service intervals are now extended to 12 months of 20,000 kilometres.

Isuzu have switched to Bridgestone tyres on the 4x4 models and the new rubber offers an improved tread pattern much better suited to muddy and sandy conditions.

The L330 Bridgestone rubber also gives the NPS a 200kg higher load capacity and maximises the steer axle’s 3,100kg weight limit.

The more aggressive tread pattern doesn’t seem to increase road noise on sealed highways.

With its GVM of 7,500kgs and a towing capacity of 3,500kgs the NPS doesn’t fit into the ‘small’ truck category with its total gross concessional mass of 11,000kgs.

However, it can be specified with a 4,500kgs GVM to be legal for drivers with passenger car licences.

It’s a shame the three tonne reduction in payload in order to suit drivers who don’t have a Light Rigid licence as a minimum takes away much of the Isuzu’s capabilities.

In fire-fighting parlance that 3,000kgs translates to 3,000 litres of potentially property- and life-saving water.

As with the rest of the 2018 Isuzu N series range the NPS is equipped with a new audio-visual system featuring a 6.2-inch touchscreen that is much brighter and has better resolution than the previous DAVE unit.

This latest unit runs on the Android Automotive operating system and includes USB 3.0 connection, Bluetooth V4 and an AM/FM/Digital radio receiver.

As an indicator of progress there isn’t a CD player but there is an internet radio function that can be accessed using the Wi-Fi of a tethered smartphone.

The satellite navigation system has provision for the truck’s specifications to be entered with factors including height and weight to ensure correct access and to take into account any restrictions on a route.

The NPS 4x4 Servicepack combination is an example of Isuzu’s approach to building trucks with reliable technologies that work together to assist the operators to perform their own functions more effectively regardless of the road conditions, or even if there is no road at all.

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