Simple lightbar guidance systems are great for those starting down the precision farming path. Equally, a fully integrated system is the best solution for neatness and ultimate levels of accuracy.

However, there is a middle path – assisted steering. This adapts an existing vehicle without having to permanently install any special valve blocks or electrical equipment. And it can do a pretty good job.

Performance may not always be quite up to the standard of an integrated set-up. But systems that are relatively easy to install (and therefore transferable from one vehicle to another) can spread investment across field operations.

WHAT CAN YOU USE IT FOR?

On an arable farm, start using the system on a tractor for cultivations, pre-emergence spraying and autumn fertiliser or lime spreading and then put it on the combine. On a livestock unit or mixed farm, use auto steering for herbicide spraying and fertiliser spreading on grass, mowing with a triple-deck outfit and also combining again.

INSTALLATION AND TRANSFER

Check how easy or otherwise it is to install and transfer – some systems require nothing more than a simple collar-mounted bracket being attached to a fully telescoped steering column. Others demand considerable digging and delving behind the instruments and surrounding panels – it depends on both the design of the assisted steering system and the tractor or other vehicle to which it is being fitted.

TYPES OF SYSTEM

Three different styles of retro-fit assisted steering systems are available:

Friction drive – this uses a soft spring-loaded roller to twirl the existing steering wheel

Positive drive – an electric motor and gear ring are attached to the steering column and/or steering wheel

Integral drive – this involves fitting a replacement steering wheel with a built-in electric drive motor

Operators who want to upgrade from visual guidance using their existing display unit need to be sure it is both suitable for and compatible with an assisted steer system.

COMPATIBILITY

Most manufacturers make assisted steering products that work only with their own visual display units.

Upgrading from visual guidance using a Trimble FM-750 display unit, for instance, can only be done by installing a Trimble EZ-Pilot steering device. That said, Leica Geosystems says its mojo console can operate John Deere AutoTrac Universal and Trimble EZ-Steer devices.

As for vehicle compatibility, manufacturers can produce long lists of the makes and models of tractors, combines and spreading/spraying vehicles on which their systems can be installed. Just check to be sure, especially if running older vehicles.

ACCURACY

As with integrated satellite-guided steering, different levels of pass-to-pass accuracy are available, depending on the capabilities of the guidance instrument and the definition of the positioning signal used.

Spreading fertiliser on grass clearly does not need a high degree of bout-matching accuracy because of the evening-out effect of the overlapped application. But higher definition is clearly more important when establishing tramlines while sowing wheat, barley and oilseed rape.

Either way, assisted steering systems can operate with basic guidance – using the free EGNOS signal offering +/-40cm accuracy up to subscription RTK giving +/-2cm repeatable accuracy.

Farm topography will be a factor in hilly areas; guidance instruments with comprehensive terrain compensation will allow for crests, hollows and banks in keeping the tractor on a true straight line.

Ag Leader OnTrac2

Description:Electric motor drive via gear ring clamped to an existing steering wheel; works with Ag Leader Versa and Integra displays.

Upgrade from visual guidance: £3195

Complete system: £5940

Distributed by: Precise Solutions

AutoTrac Universal

Description: Self-powered steering wheel for use with GreenStar 1800 and 2630 displays (as well as older 2100, 2600 and original units) and GreenStar 3 Command Center displays on tractors ordered GreenStar Ready.

Upgrade from visual guidance: £4394 (£1939 plus £2455 for recommended StarFire1 AutoTrac activation giving +/-30cm accuracy) or £7282 (£1939 plus £4028 for SF2 AutoTrac activation and £1315 for receiver SF2 Ready for +/-10cm accuracy).

Complete system: To fit 6030 Series tractor with StarFire 1 – GS1800 £7064, GS2630 £9962; StarFire 2 GS1800 £9647, GS2630 £12,454. Can be upgraded to Radio or Mobile RTK.

Distributed by: John Deere

Leica Quicksteer

Description: Column mounted electric motor and friction steering wheel drive; works with Leica mojo guidance displays.

Upgrade from visual guidance: mojo3D £3100 including universal tractor bracket and Tilt terrain compensator; mojoRTK, mojo3D with mojoXact RTK £2350.

Complete system: mojo3D £5390 plus £350 for GLONASS, £570 for DGPS; mojo3D with mojoXact RTK system £13,190.

Distributed by: Leica Geosystems Agriculture, Peacock & Binnington

Topcon AES-25

Description: Steering wheel with integral electric drive motor to work with System 110 and X30 consoles.

Upgrade from visual guidance: £8450 (including AGI-3 multi-constellation receiver/steering controller).

Complete system: from £10,500.

Distributed by: LH Agro, Precision Decisions

Trimble EZ-Steer

Description: Electric motor with friction drive to existing steering wheel; works with Trimble EZ-Guide 250, CFX-750 and FmX displays, and superseded EZ-Guide 500, FM-750 and FM-1000 units.

Upgrade from visual guidance: £2700 (plus fitting kit approximately £245)

Complete system: £4195 to £4395

Distributed by: AS Communications, Case IH, New Holland, Soil Eessentials (prices may vary)

Trimble EZ-Pilot

Description: Positive electric drive motor installed on steering column beneath existing steering wheel; works with Trimble CFX-750 and FmX displays, and superseded FM-750 and FM-1000 units.

Upgrade from visual guidance: £3395 (plus fitting kit £550-£625)

Complete system: £5790 to £6415

Distributed by: AS Communications, Case IH, New Holland, Soil Eessentials (prices may vary)