Rear-steering axles for rigids

Instances of rear-steering axles being specified on rigid 6x2s are becoming more common. Steve Banner finds out why

The number of rigid 6x2 DAFs fitted with a 7.5-tonne rear-steering axle has risen steadily in recent years. The company’s marketing manager, Phil Moon, explains the reasoning. “It makes the truck more manoeuvrable than it would otherwise be – and reduces rear tyre scrub.” As a consequence, the tyres last longer, which means reduced maintenance expenditure.

DAF isn’t alone in understanding the benefits of rear-steer axles. “They can also help cut fuel consumption,” says Ashlea Awbery, product manager, MAN. “The percentage reduction is small, but every bit helps.” Meanwhile, Mercedes-Benz Trucks’ David Simm, product manager for heavy-duty trucks, adds: “You’ll probably save around 0.5% [in fuel] and the driveability of your vehicle will be a lot better.”

Truck makers are invariably wary of quoting prices for public consumption; but specifying a rear-steer is likely to add at least £1,500 to the final invoice for the vehicle. DAF fits electro-hydraulic rear-steers. “They’re self-contained units and 30kg lighter than the ones we used to fit,” confirms Moon. Like its non-steering tag-axle, the rear-steers DAF fits are also lift-axles, while MAN’s rear-steers can typically be lifted, too. “Our rear-steers are offered with lifting capability as an option – and 99.9% of our customers take it. It might as well be standard,” says Steve Powell, country product manager and alternative propulsion lead at IVECO.

Such a set-up means there are spells of reduced tyre wear and better fuel consumption when the truck is empty, enabling the axle to be raised. When the vehicle is loaded, the axle lowers to ensure on-highway axle loading compliance. What this approach gives the operator, says Moon, is the same degree of manoeuvrability no matter whether the truck is laden or unladen.

At Renault Trucks, the rear-steer phenomenon has not gone unnoticed. “Steer-only is more common with low-chassis heights, where lift clearance is difficult, or on trucks that seldom run light; refuse collection vehicles with rear-end bin lifts, for example,” says Mike Stringer, product engineer at the French company.

MAN’s 26-tonne TGM comes with a rear-steer/lift as standard. “If you want a TGS at 26 tonnes, however, then you can have it with or without,” says Awbery. A TGS is likely to be used for single trips from A to B rather than on multi-drop work, he furthers, so the ability to manoeuvre into and out of difficult-to-access locations several times a day is not so important. Also, sticking with a non-steer tag means a lower front-end price.

The weight penalty imposed by a DAF rear-steer over a standard axle is zero, says Moon. “The single-tyred rear non-steered tag and the steered tag we fit weigh the same, which is perhaps more of a coincidence than anything else,” he observes. “The steered tag is essentially a front axle adopted for use at the rear, whereas the non-steered axle is a tube design with different suspension mounts.”

Awbery agrees that the payload penalty imposed by rear-steers is minimal. “We’re only talking about a few kilos – and it certainly doesn’t outweigh the benefits,” he reasons. However, that is not the case with all rear-steers, although Powell says he would be surprised if the extra burden was more than 50kg to 60kg.

Some manufacturers report that they can impose a weight penalty of from 100kg to 150kg. “A rear-steer typically adds around 80kg, a lifting system another 80kg,” says Stringer.


DAF’s Moon says that, when it comes to inspection, some components – such as the steering joints – need looking at from time to time but, otherwise, he maintains the DAF rear-steers are “maintenance-free”.

It’s a common trend among the manufacturers: “We use sealed king-pin bearings and they don’t need maintaining,” says Awbery, adding that none of the parts involved impose a additional servicing requirement. Simm agrees that no extra maintenance is needed, although the hydraulics may need checking from time to time.

Aside from reducing tyre wear, DAF’s rear-steers impose less strain on suspension components than a fixed axle does, which means they are less likely to require premature replacement; a service and repair saving. They communicate electronically with the steer angle sensor on the front axle – the steering input from the driver defining the amount of lock delivered. The maximum rear-steering angle is available at speeds of up to 25kph then progressively diminishes until the truck reaches 45kph. Above that speed it is zero – and the axle is locked in the straight-ahead position.

The rise of the 6x2 rear-steer/lift-axle truck has coincided with a decline in demand for 6x4 rigids, given the cost and weight penalties the latter incur. “These days, [6x4s] are only specified by customers who operate in hilly terrain and might encounter traction problems,” admits Moon. “In 2023, the FAN 6x2 rear-steer accounted for over 70% of three-axle rigid sales with more than 470 ordered. Non-rear-steer 6x2s were responsible for just over 25%, while the 6x4 made up less than 5% of orders taken.”

Meanwhile, Awbery believes there is still a market for 6x4s, but admits fewer and fewer customers are opting for them. The presence of an additional driven axle increases fuel usage, he points out, and while building sites used to resemble swamps, these days basic hardcore roads are laid down at an early stage. Therefore, the extra traction that a 6x4 delivers is seldom called on.


A 6x2 with a rear-steer/lift can be of more use than other configurations because it makes life easier for a driver delivering bricks and blocks to manoeuvre around the site and deliver them to exactly where they are needed. DAF – and others – offers rear-steers on eight-wheel rigids as well as on six-wheelers, which represents an interesting move. “They’re specified by operators who use 8x2s rather than 8x4s on brick-and-block or plant and machinery delivery work because they want greater manoeuvrability,” explains Moon. “Our FAX rear-steer 8x2 with twin steered axles up front – and a drive axle and steered rearmost axle making up a rear bogie – now makes up 25% of our four-axle rigid sales.

“The traditional 8x4 is still the most popular choice however, accounting for around 70%, or some 480 orders, so far as we were concerned in 2023,” he adds.

Meanwhile, a tridem configuration offers a potential alternative for eight-wheeler operators who want both manoeuvrability and traction. They typically come with a lifting rear-steer, which forms part of a three-axle rear bogie with two driven axles.

One example now in service is the Renault C440 P8x4*4 Tridem Off Road, operated by Oxford-based tipper operator Smiths Bletchington. “It provides the manoeuvrability of a six-wheeler combined with a load capacity that is closer to that of a traditional eight-wheeler, which helps with the profitability of our business,” says fleet manager, Paul Needle. “It allows us to confidently access narrow roads and entrances where a traditional eight-wheeler, with its conventional-length wheelbase, can struggle.”

An alternative tridem configuration, if the easiest possible access to awkward locations is vital, is an 8x2 with a triaxle rear bogie with a central driven axle sandwiched between two steerable lift-axles, says Awbery. While they are remarkably manoeuvrable for their size, tridems can pose challenges so far as axle loadings and weight distribution are concerned, which limits their appeal. “They’re more popular in mainland Europe, where they’re typically allowed up to 27 tonnes across a three-axle bogie,” he adds. “In the UK, we’re limited to 24 tonnes.”

Weight distribution is another inhibiting factor for DAF tridem sales, admits Moon. “Our two tridem configurations – FAW, which is an 8x4, and FAQ, which is an 8x2 – together make up no more than around 5% of our eight-wheeler sales,” he reveals. But an increase in permitted bogie weights could alter the percentage in tridem’s favour.

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