Isuzu Giga CXZ Rigid Tipper

The world of the tipper and dog is beginning to change. There has been a long tradition in this industry of using older trucks with minimal gadgets and often compromised comfort. These trucks, working largely in the construction sector, had to get used to some rough treatment and operators have shied away from higher levels of technology in their equipment. 

There have been some notable exceptions in the past where forward thinking tipper operators have invested in the latest, most modern trucks. However, these operators have been the exception rather than the rule and many drivers working in the industry have had to put up with less than ideal working conditions.

The traditional suppliers to the tipper industry have been the US and Japanese manufacturers who have been able to supply a basic truck with the resilience to put up with the tough working conditions. These were no-frills trucks specified to take a hammering and earn a dollar. 

European truck manufacturers with their much more sophisticated specifications fitted as standard have made some inroads into the tipper and dog market but only in a number of specific fleets. The vast majority of trucks plying their trade hauling aggregates etc. up and down our highways have been sourced mainly from the US and Japan. 

This test drive by Prime Mover looks to be reporting on the beginning of a change in attitudes within the tipper industry with the introduction of the Isuzu Giga CXZ rigid tipper, powered with the 15.6 litre Isuzu engine at 453 hp (338 kW) and using a 12 speed automated manual transmission from Isuzu.

The gear changes are seamless and when the change is made the rpm levels are at exactly the right point to do the job required.

Isuzu has a long-standing reputation for producing trucks that have proved to be reliable in some of the toughest conditions the industry can throw at them. However, this latest generation of Giga models has seen the introduction of comfort and technology levels comparable with those pioneering European tipper trucks sold in the past.

One of the first impressions the driver gets after climbing up behind the wheel and setting off down the road is how different this truck sounds. Much of the work done in this type of truck will take place with the window wound down and many drivers would be used to a roaring upright exhaust noise in the right ear. 

Whether the window is up or down, noise levels emanating from this truck are minimised. Yes, it does have an upright exhaust, but it is mounted on the passenger side and a combination of this highly efficient ADR 80/03 compliant engine with considerable noise dampening equipment fitted under the cab makes for pretty quiet running. With the driver’s window open, the loudest sounds are wind noise and the occasional rattle of the tipper body. 

A driver used to the loud engine note in his right ear would also be used to working the left hand hard and fighting with an 18 speed gearbox while maneuvering in and out of traffic and getting the product where it needs to be on difficult construction sites. In his truck the transmission does not even have to be thought about to get the job done. 

Isuzu has done well with the specification of its own AMT gearbox. Because the engine and gearbox are both sourced from the same manufacturer, the level of electronic communication between the two is much higher than when a proprietary gearbox is brought in from a different manufacturer. The AMT has been designed to work with this particular engine. 

The result of this close matching within the driveline is a set and forget transmission. The gear changes are seamless and when the change is made the rpm levels are at exactly the right point to do the job required. When the truck is working hard on trying to climb a hill, the gearbox will put the revs right into the middle of the band where the torque is at its highest, around 1300 rpm. Out on the highway the gearbox is constantly looking to find the correct ratio to get the most power out of the engine between 1500 and 1700 rpm to maintain momentum without sacrificing fuel consumption.

Admittedly the technology involved and the computing power used does not match that used by the European truck manufacturers. Their systems are finely honed and use a large amount of available data to get the absolute best out of the engine and the truck itself. In the case of the Isuzu AMT that technology is good enough and the system is smart enough to get the job done without any fuss. So the driver can get on with doing everything else they are required to do as a busy tipper operator. 

The best way to assess the effectiveness of an automated manual transmission is to see how well it responds to movements of the right foot on the accelerator. If it is flexible and responsive, a small reduction in the throttle pressure can instigate an upward gear change, if possible. Similarly, when the truck is travelling along at a steady speed, extra pressure on the accelerator should instigate a change down by the AMT. 

Another aspect of this responsiveness is when the truck approaches a rise in the road and suddenly has to start working harder to maintain road speed. This is when an early down change is required to maintain momentum. In effect, an AMT needs to be able to demonstrate the same kind of anticipation and quick reaction to road conditions an experienced driver would be able to deliver.

Isuzu has a long-standing reputation for producing trucks that have proved to be reliable in some of the toughest conditions the industry can throw at them.

In terms of flexibility and responsiveness, this AMT from Isuzu does the job extremely well. The compatibility between the different elements of the driveline and their ability to communicate with each other makes this an effective gearbox. The traditional diehards in the tipper industry will take a lot of convincing to give up their US drive lines including the dependable 18 speed Roadranger. This AMT may be the gearbox to do it. It does not suffer from the perception of being overly complex that is often associated with European manufacturers.

If there is an issue with this transmission it is with the inclusion of a clutch pedal despite the fact it is not needed in just about every driving situation. It has been kept as an aid to slow maneuvering to enable the truck to inch either forward or backwards in and out of loading areas and in tight spaces. This is to compensate for the lack of sophistication in this AMT’s control system when compared to those European competitors. 

It is also possible to confuse this gearbox but there is a simple solution to hand. A good example of the problem the driver can create is when the truck and dog is approaching a roundabout. As the truck is slowing down, the AMT will go back down the gearbox to aid retardation but if there is a change in the road conditions and a driver decides to accelerate before coming to a halt at the roundabout it is possible to confuse the system and it is not quite sure which ratio to pick. 

If this happens, the solution is simple. The driver is immediately aware the AMT is not sure which ratio to use so they need to simply knock the gear control across into the neutral position and then bring it back into the drive position. This allows the computer-controlled gearbox to reassess the situation looking at pedal position, road speed and engine revs so it can choose the correct gear to continue on its way. 

Out on the road in this driving test around some of the construction sites of Brisbane and the Sunshine Coast this situation arose twice, once by chance and once deliberately. On both occasions hardly any momentum was lost and the quick flick to the left and back to the right again on the gear lever was a simple and easy move to make. 

Retardation is supplied by a two-stage engine brake when coupled to the AMT gearbox. This works much more effectively than the single stage exhaust brake on the CXZ with an 18 speed manual gearbox. This is another factor which may persuade truck operators to choose this AMT gearbox over the more familiar manual option. This two-stage engine brake is capable of reducing brake wear whereas the single stage brake is largely ineffective and the driver will resort to service brakes every time they want to slow down quickly.

At the end of an eventful day in the saddle of this tipper and dog, this driver felt relatively calm and relaxed. The AMT allows time and attention to be spent where it should be, on avoiding the worst of the city traffic and getting the combination in and out of some tricky loading and unloading areas safely. 

Compare this to the prospect of struggling all day in a very noisy environment with a constant mesh manual gearbox in something like an ageing Louisville and the choice is clear for the operator. Yes, it can be a challenge and good fun to work with some of the older, industry-standard equipment, but as the workforce gets older, they will start looking for some comfort and a little peace and quiet.


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