Since it first saw service in Isuzu trucks back in 2005, the The N Series AMT is much improved. For many, the first generation AMT left a bit to be desired in terms of shift quality and smoothness and this issue was addressed with the release of the 2nd generation unit in 2007. This was achieved largely through the use of a new linear solenoid arrangement and more efficient transmission to engine communication. By this stage the AMT had been made available in most models across the N Series range.
Fast forward ten years and Isuzu has raised the bar again with the 3rd generation TC-AMT available across the N Series 4×2 range. According to Simon Humphries, the TC-AMT used in NLR and NNR models provides a torque multiplication factor of 1.55 times, providing improved response from a standing start and a smoother drive experience.
In essence, it combines the best features of both automatic and manual transmissions. The torque multiplication factor producing zippy acceleration from a standing start while also featuring a lock up function that provides direct coupling to the AMT for optimised fuel economy. Other technical changes that help in this respect include a reduction in the ratio gap between 2nd and 3rd and also 3rd and 4th gears.
Given a large proportion of N Series models are GVM rated at 4,500kg enabling them to be driven by car licenced drivers, Isuzu’s engineers have been at pains to make the driving experience as car-like as possible. Hence there is now a kick down detent on the accelerator pedal. This feature has been developed specifically for the Australian market where roundabouts are a regular occurrence and the need to accelerate swiftly to enter the traffic flow is paramount.
“Roundabouts are not a common feature of the Japanese road landscape,” explained Simon Humphries,Isuzu Chief Engineer. “So once again we have developed this with Isuzu Motors for Australia. The end result is a predictable response when the accelerator is depressed beyond the detent.”
Continuing the car-like theme, TC-AMT also includes a new shift lever with a Park position that engages a parking pawl on the transmission that is capable of holding a fully laden truck when parked on a slope. As with cars, the P position needs to be engaged to start the engine although there is a button on the shifter that enables engine starting in other positions as may be necessary in an emergency.
“The TC-AMT with P position combined with the economical 3 litre 4JJ1 engine offers a driveline that delivers outstanding performance and is suited to our local conditions,” adds Humphries. “Isuzu Australia is the first market outside Japan to get the new 3rd generation TC-AMT, which is an indication of the high standing and importance Isuzu Motors Japan places on our market.”
Other enhancements to the N Series include the introduction of Isuzu Electronic Stability Control (IESC) and rear disc brakes to the popular NQR model. This completes the roll-out of IESC to the 4×2 N Series range, ensuring maximum safety for operators and other road users. IESC uses data from a variety of sensors fed to an electronic hydraulic control unit that in turn effects changes to engine torque and individual wheel brake applications when abnormal circumstances such as wheel slip and unwanted directional changes are detected. It corrects these by reducing power to the drive wheels and applying strategic braking force to the appropriate wheel(s).
Six new variants have expanded the N Series’ already prolific range, including the NNR 65-150 MWB in both manual and AMT guises. Powered by the 3 litre 4JJ1 engine, these models are rated at 6,500kg GVM. According to Humphries, this is the first time Isuzu has used the small displacement engine in a 6,500kg GVM truck. He says it shows Isuzu’s confidence in the performance and durability of the power plant as well as a general trend towards employing smaller capacity high output engines in higher GVM vehicles. Also new are the smaller NNR 55- and 45-150 units, with respective GVMs of 5.5 and 4.5 tonnes, which boast larger rear disc brakes than lesser rated variants.