Now, with either one or two crawler gears, conventional I-shift trucks can tackle the specialised field of heavy haulage. Picture: Pontus Johansson / Volvo Trucks

Johannesburg - Volvo Trucks’ I-shift with crawler gears is now available in South Africa for the company’s FM FMX and DFH series trucks.

Volvo’s I-shift is an automated manual gearbox with pneumatically operated clutch and gearshifts; what makes it special is that its sophisticated electronic control unit monitors vehicle speed, acceleration, weight, road gradient and torque demand, and is also linked to the engine’s ECU, which adjusts revs revs and engine braking for fast, smooth shifting.

Internal energy losses are lower than on conventional gearboxes, thanks to precisely timed gear changes that not even the best of drivers can match, ensuring that the engine is always working at its most efficient revs. And when you’re going down hill, I-Roll declutches the engine, saving up to an additional two percent of diesel.

Now, with the addition of either one or two crawler gears and the option of extra, ultra-low reverse gears, I-shift trucks can tackle the specialised field of heavy haulage - and still do their usual long-haul runs at highway speeds.

Conventional manual-transmission trucks are adapted for heavy haulage - that means abnormal loads of more than 50 tons - by fitting them with a radically shortened final drive ratio, enabling them overcome the static inertia of gigantic loads and move them relatively short distances at very, very low speeds, typically less than 4km/h.

The problem is that the top speed of a heavy haulage truck is not much more than 20km/h, even with regular load of up to 40 tons, and at that speed it will also be uneconomical to run. Heavy haulage trucks are suitable for nothing else and, let’s face it, how often do you get to move something that weighs more than a Jumbo Jet?

But with the new I-shift the ultra-low ratios are in the gearbox, not the final drive, and the truck is also capable of cruising economically at highway speeds with a normal load. Unlike conventional heavy haulers, it doesn’t have to stand idle while waiting for the occasional big job.

Volvo Trucks Southern Africa sales director Malcolm Gush explained: “It’s like having two trucks in one, with enormous performance at normal engine speed because the I-shift crawler gears produce maximum torque while the truck crawls slowly.”

“Low-speed manoeuvring is one of the most challenging aspects of heavy haulage - a combination of precision and control. With its transmission ratio of up to 32:1 (and 37:1 in reverse), I-Shift with crawler gears lets you drive at speeds as low as 0.7km/h at plenty of torque, making it easy to park with precision to load or unload your enormous load.”

“The two crawler gears of the I-Shift gearbox allow you to pull away from a standstill with a load of up to 325 tons on an uphill gradient of three percent - and then you can hitch the same truck to a standard 40-foot container and haul it across the country at highways speeds.”

IOL Motoring