Spray application manual
31 January 2025
Module 12: GPS systems
12.5: Steering options
Published 24 January 2025 | Last updated 20 January 2025
There are several ways to steer the spray rig, including fully integrated, partially integrated and steer assist, which are explained below.
Tyre tip - aligning tyre centres
15 January 2025Tyre tip - aligning tyre centres. Another video from GRDC's Spray Application GROWNOTES™ series.
Graham Betts: ""I know this is a header tyre, but it relates exactly the same to a sprayer tyre.
The tyre information is a VF 620/70 R26. The VF stands for 'very flexion,' which means the tyre can carry 40% greater load at the same pressure, or, with an increased tyre pressure, it can carry even more load.
The 620 refers to the width of the tread in millimetres. The 70 is the aspect ratio, meaning the tyre's sidewall height is 70% of the tread width. The R indicates it's a radial tyre, and 26 is the rim diameter in inches.
One more tip: with today's auto-steer systems being accurate to within 2 centimetres, it's a good idea to line up the centre of the tyres, not the outside. For instance, you might have 800mm tyres on the front and 620mm tyres on the back. In the past, aligning the outside edges was fine, but with the precision of modern auto-steer, it's critical to align the centre of the tyres for optimal performance.
Fully integrated steering
The guidance system is fully integrated with the machine and it comes complete from the factory ready to go. These systems are characterised by a single display across machines that can interface with your existing equipment.
Most new machines are coming equipped with a full CAN bus/ISO bus system and manufacturers can control the steering directly from this.
Partly integrated steering
Partly integrated is where the sprayer is not fitted with an auto-steering kit from the factory, but has one added after-market. In many cases this involves fitting a hydraulic value and wheel angle sensor, which communicate with the auto-steer system in the cab. On older sprayers you need to decide whether the additional cost of installing a partly integrated steering solution is justifiable given the expense.
Steer assist
You can retrofit GPS capability if you decide to add guidance to existing equipment instead of buying new. Easily installed, most of these devices fit the majority of sprayer models without having to remove the steering wheel. There are also options to replace the steering wheel with one that has an integrated electric motor system.
The EZ-Steer® system from Trimble is one example of a retrofitted system
