An added feature for the unique Twin Steer system available for JCB Fastrac 4000 Series tractors enables the front and rear axles to be offset to spread the load over a greater surface area.

The concept mirrors specialist four-wheel drive vehicles with this capability used for applying slurry, manure, AD plant digestate and similar materials.

Offsetting the rear wheels spreads their considerable weight over a larger surface area rather than concentrating it along two wheelings.

JCB Twin Steer uses separate A-B guidance lines to achieve this effect, which can be used for top work cultivations such as harrowing and rolling, or for grassland applications.

In standard form, Twin Steer exploits the unique four-wheel steering system of the JCB Fastrac 4000 Series tractor to control the front and rear axles separately while following a single A-B line.

Growers of organic field crops reliant on mechanical weed control and of high-value vegetable and salad crops grown in beds are using the system to avoid crop damage and the impact on yield of tractors and implements straying off course, especially across side slopes, when sowing, weeding and carrying out other operations.

They are using it alone or in conjunction with an implement guidance system.

“With JCB Twin Steer and camera guidance we’re down to millimetre accuracy levels and customers are seeing significant increases in crop quality and yield,” says Tom Mowforth, JCB Fastrac product specialist.

“In carrots, for example, by ensuring every plant has optimum room to grow and with no disturbance from weeds, implements or tractor tyres.”

The system can also have a role in grain and oilseed cropping by keeping a Fastrac on track when operating a heavy implement – such as a power harrow-seed drill combination – across steep ground.

JCB Twin Steer GPS Ready is available as an £844 factory option on the latest Stage V versions of the Fastrac 4000 Series tractors, which have uprated axles, increased payload capacity and higher performance tyre options.

The system developed in conjunction with Trimble then requires a precision farming display sourced from a Trimble reseller, along with additional function unlock codes, a second antenna mounted above the rear axle, and a second receiver and steering control package.

Unlike a conventional tractor, which makes steering corrections only through the front wheels, the Fastrac 4000 Series has multi-mode co-ordinated four-wheel steering for maximum manoeuvrability in different situations – a unique feature for a tractor of this size and power.

Twin Steer enables individual control of the front and rear axles to make small adjustments that keep the tractor and implement on course without passing yaw movements to rear-mounted equipment.

“Correcting sideslip with conventional front axle steering causes the tractor to turn towards, then slightly beyond and back to the guidance line,” points out Tom Mowforth. “That results in several yaw movements at the implement, which can only be countered by an active offset mechanism.

“With JCB Twin Steer, the Fastrac uses variable crab-steer mode with the front and rear axles controlled individually so that it gets back on to the A-B guidance line quicker and in a way that minimises any yaw effect at the implement.”

The latest concept for arable and grassland applications requires two precision farming displays in the cab so that the front and rear axles can be allocated their own A-B line to follow, the line for the rear axle being offset slightly to create the crab-steering effect.

For example, with one of the new high-performance tyre options available – VF 600/70 R30 – fitted all round, the rear axle can be offset by about half a tyre’s width to spread the surface load.