SECTOR Heavy-duty off-road ENGINE 5.1-litre Euro 6, 230hp, 900Nm GROSS WEIGHTS U4023 10.3t, U5023 14.5t
I’ve never heard anyone complain that their Unimog was struggling off the road. Despite that, Mercedes-Benz has gone back to the drawing board with its heavy-duty 4×4 to make it even more capable.
The firm’s off-road hauler is now split into two very distinct categories. There are the smaller U216-U530 implement carriers, which are designed for some off-highway use but mainly as attachment carriers to power a massive range of front, side and rear-mounted tools. The latest development here is the availability of four-wheel steering on some models.
Then there are the U4023 and U5023, built to conquer any terrain while carrying cranes and a range of bodies for fire fighting, agriculture, power generation and mining applications. It is these two heavyweight models, with maximum gross weights of 10.3 tonnes and 14.5 tonnes respectively, that have been updated, now running Euro 6 power with a revised tyre pressure control system, improved dash layout and more comfortable cab mounting system.
Mercedes has dropped the previous six-cylinder engine in favour of a powerful four-cylinder Euro 6 motor for both models. This generates 231hp and a massive 900Nm of torque from its 5.1 litres, using EGR, a DPF and SCR with an AdBlue additive to meet the emissions standards.
The big news, however, is the engine’s positioning, as the firm has moved the motor an incredible 100cm back in the chassis, to a point where it is almost sticking out from under the back of the cab, at least on single cab models. In the new seven-seat crew cab the engine hump does intrude slightly into the rear footwell, though it remains comfortable for booted workers.
The mid-engine concept helps with weight distribution and allows Mercedes to move the air conditioning system from the roof of the cab to in front of the engine. It also makes it possible to fit an engine power-take-off at the rear of the cab, to complement the transmission PTOs and allow attachments to be powered even when the vehicle is not being driven.
An uprated transmission with faster shift times offers eight forward gears and six reverse ratios. There is also the option of a low off-road gear set, in effect doubling the number of gears on offer.
The improved engine brake develops up to 180kW of brake force, with each cylinder now having its own brake unit for improved power. An off-road ABS system also comes as standard.
The trucks also feature a Tirecontrol plus tyre pressure control system, which allows the driver to individually inflate and deflate each tyre from the driver’s seat. The system has preset sand, rough terrain and road modes, but also allows more experienced drivers to set their own preferred pressures depending on load and terrain.
Unsurprisingly the Unimog is in a class of its own off-road, climbing the steepest hills and handling pretty much any terrain that you can throw at it. The truck’s fully welded chassis frame actually flexes to allow greater axle movement, with a three-point cab and body mounting system allowing that frame twist beneath the load-carrying platform.
What we think
The Unimog has been an off-road load-carrying icon since its launch in 1946. Thirty models and 400,000 sales later, quite incredibly, the best just got better.