PH Origins: Active four-wheel steering
How early electric and four-wheel-drive vehicle development prompted the adoption of active four-wheel steering
In the early 1900s, the situation in German South West Africa was degrading at a catastrophic rate of knots. The Germans had been plundering the colony for resources, confiscating land and treating the locals in an increasingly oppressive fashion - and, unsurprisingly, numerous violent uprisings were soon threatening the stability of the region.
The response from the colonial leaders was not subtle, culminating in German forces conducting what is considered to be the first genocide of the 20th century. When news of this reached the German media, along with details of the increasingly corrupt and brutal management of the colony, a major shakeup ensued.
Emperor Wilhelm II promptly tore apart the existing colonial departments and established a new overarching authority that would be managed by a secretary of state. Numerous personnel were also recalled and more suitable candidates sent out to take their place.
Politician Bernhard Dernburg, who was appointed secretary of state for the new Imperial Colonial Office, was among those dispatched to Africa in 1907. His mission was to patch up the relationship between the colony and the Empire, as well as improving coordination between the two.
Dernburg, who aimed to reform German colonial policy, faced many substantial challenges - among which were taxing logistical issues. Many of the settlements were some considerable distance apart and the infrastructure was limited at best. Roads, if present, were often rough and the routes could be challenging.
One report, to put things into perspective, stated that a common 370-mile circuit between several sites would take 12 days on horseback. This posed communication and control problems - and the process of simply travelling between locations would consume a tremendous amount of Dernburg's time.
In order to mitigate these issues, the government commissioned engineering company Daimler Motoren Gesellschaft to build a passenger vehicle capable of tackling long trips on unmade roads.
DMG, one of the formative elements of the later Daimler-Benz business, had already demonstrated its prowess in the new field of automotive production and set about producing a passenger vehicle that could endure operations in Africa. Beneficially, the company had prior experience with four-wheel-drive commercial trucks that could prove a good basis for a new heavy-duty vehicle.
Leading the way was engineer Paul Daimler, who among other achievements would design the company's first purpose-built supercharged engine. He took one of the existing commercial four-wheel-drive DMG chassis, had a touring car body fitted on top and equipped the 6.8-litre, four-cylinder engine with a staggering 140-litre cooling system - which would keep the engine cool when operating in the hot climate under extreme load.
None of this would prove any good, though, if Daimler could not keep sand out of key components. When sand worked its way into couplings and gears, it would function as a fine abrasive and cause excessive wear. This would, over time, cause the component in question to fail.
Normally, DMG would use telescopic shrouds on the steering axle to protect the vulnerable components. The shroud would shield the components between the output of the differential and the wheel, while its telescoping action would prevent it from binding when the wheels turned left or right.
This shroud could not endure the punishment of rough roads, alas, so Daimler was forced to use a strong cylindrical sleeve. The catch was that this limited the steering action of the front axle to just 23 degrees. The vehicle was hard to manoeuvre as a result, particularly in tight areas.
In order to circumvent this issue, Daimler replaced the chassis' standard rear axle with a duplicate of the front axle - including steering gear, differentials, wheels and brakes. This steerable rear axle, which turned in the opposite direction to the front axle, granted a reasonable turning circle and also greatly simplified the supply of spare parts.
The vehicle, when construction was completed in early 1908, was among the first petrol-powered vehicles to offer four-wheel drive; only the likes of the Spyker 60HP preceded it. More prominently, it was also one of the earliest documented passenger vehicles with four-wheel steering - and certainly one of the earliest, if not the first, to be used for more than display or prototyping purposes. This innovation did not come cheap; the DMG cost 34,750 Marks which, today, is the equivalent of a whopping £175,000.
A series of arduous trials were carried out before it was dispatched to Africa in May 1908 for Dernburg to use for travelling between settlements. The DMG, which would later be dubbed the 'Dernberg-Wagen' as a result of its usage, immediately set about impressing its operators. Despite clocking in at 3.6 tonnes, and its engine putting out just 35hp at 800rpm, on flat terrain it could achieve a heady 25mph.
Power was sent through a centrally sited four-speed manual transmission, the output from which was permanently split between front and rear axles. This, coupled with its four-wheel-steering system, allowed it to tackle rough routes with ease. When pressed into action, thanks to its capabilities, the car completed the aforementioned 12-day trip in just four days.
By 1910, the DMG had covered a total of 6,200 miles. The car continued to be used after Dernburg left Africa, too, and reputedly outperformed all the heavy-duty trucks available. Maintaining its four-wheel-drive system proved complicated, though, and it was soon converted to rear-wheel drive.
What happened to it during World War I is unknown and, following the collapse of German colonialism, the Dernburg-Wagen disappeared. The capabilities of the four-wheel steering system had not gone unnoticed, though, and many manufacturers would produce vehicles so equipped from that point on.
That said , there are earlier examples of other vehicles equipped with four-wheel steering - despite the Dernburg-Wagen appearing so advanced in such an early phase of the era of the motor car. In 1876, for example, a French engineer reputedly built a steam-powered prototype vehicle that featured four-wheel steering.
Then, in 1882, engineer Thomas Parker - who would later help electrify the London Underground - set up a new battery company with businessman Paul Elwell. The Elwell-Parker company then began prototyping electric vehicles, including small electric cars, as they were becoming increasingly popular and profitable.
Parker, trying to combat some of the issues encountered in other electric cars, wanted a steering system that would allow for a small turning circle to make the car far easier to manoeuvre in urban areas. Eventually, after what he described as a 'great deal of scheming', he designed a steering system that steered both axles in opposite directions at the same time. The system, according to Parker, 'worked splendidly' and allowed the car to be 'turned in its own length without turning the wheels under the body.'
Prototypes were demonstrated and Parker himself documented the concept in a report published in the March 1899 issue of 'The Automoter and Horseless Vehicle Journal'. Parker was a great fan of electric power, as he rightly thought fossil fuels were harmful to the environment; his focus would soon shift to the electrification of the railways, in an effort to drive down inner-city pollution.
Similar four-wheel-steered commercial vehicles soon began materialising, as the reduction in turning circle made them far easier to handle in tight areas. Patents for such vehicles were granted as early as 1904 and, by 1905, the likes of the Quadray Electric Truck were on sale. This truck, built by the Michigan-based Commercial Motor Vehicle Company, featured electrically assisted four-wheel steering and motors at each wheel - granting it all-wheel drive.
According to a trade journal at the time, the Quadray's steering system permitted 'the truck to be turned around almost within its own length, and gives very quick action; the full swing from left to right taking seven seconds.'
Industrial and commercial vehicles would continue to make use of four-wheel steering systems in the following decades but, in the mass-produced automotive domain, it would remain the subject of concept cars and prototypes. Mercedes-Benz was among those trialling the concept and introduced a prototype 'NAFA' short-distance vehicle in 1981 that featured four-wheel steering and sliding doors.
The lack of uptake of four-wheel steering was in part no doubt due to the additional cost and complexity. That said, what were probably perceived as comparatively limited real-world benefits no doubt also played into the matter.
In late 1985, though, a form of active four-wheel steering did finally arrive in the automotive market. Nissan unveiled HICAS - High Capacity Actively controlled Suspension - which was offered in the GTS version of the R31 generation of Nissan Skyline. It was designed to improve stability at higher speeds and did so by using hydraulic rams that would deflect the rear subframe on its bushes, altering the geometry and causing a steering motion.
This system was a development of the passive rear-wheel steering used by Porsche in the 1977 928; the company's 'Weissach Axle' featured special bushes that would deflect the rear wheels in certain conditions to reduce the car's tendency to suffer lift-off oversteer.
Not long after HICAS made its debut, Honda went one step further with its 4WS-equipped Prelude in 1987. This was the first mass-produced passenger car with a fully fledged active four-wheel steering system. The initial set-up was mechanical, with a shaft running from front to rear to a standalone rear steering box which acted on the track rods to steer the rear wheels.
Eventually, the Prelude itself would also adopt an electrically driven rear-steer set-up, like that found on many a modern vehicle. Similarly, Nissan would later use hydraulic actuation to actually steer the rear wheels, in a set-up called HICAS-II, which itself would be replaced by an electric set-up in Super HICAS. These companies were not alone in their efforts; mind; Mazda and Mitsubishi also offered four-wheel steering systems around the same time.
Again, however, in many cases customers struggled to perceive any real benefit - and, in some instances, they disliked the overly responsive nature of the set-ups. This, coupled with the extra cost, weight and complexity of the systems, led them to remain a niche feature.
Eventually, active four-wheel steering was only utilised by those looking to use technology to eke every ounce of performance out of a vehicle - as was the case with the fabled GT-Rs. Even today, four-wheel-steering systems consequently remain comparatively few and far between.
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