TECHNICAL: The VariQtire tyre pressure control system not only has internal mounted rotary unions, but a single-line system that offers the reliability of a two-line set-up. We chat to maker IWN to learn how it works.

Basically, there are two different ways of adjusting the pressure in central tyre inflation systems — single-line and dual-line — and the pros and cons
of both are outlined on the next page.

Now IWN says it has succeeded in combining the advantages of the dual-line system with those of a single-line approach. At the heart of the VariQtire development is a cunning valve unit that is fitted to each wheel. When air hose pressure is 3.0 bar or less, the valve opens and allows the air to escape from the tyre, getting it ready for field work.

Alternatively, when the pressure is increased to more than 5.0 bar, the piston in the valve switches so no air can escape from the wheel and the tyre starts to inflate. We can’t tell you any more about the inner workings of the valve for patent reasons.

Radio-controlled pressure monitoring
IWN has also opted for a neat idea to monitor the pressure in each tyre. This consists of a mechanical pressure relief valve and a radio sensor for pressure monitoring. These are fitted in an extra hole in the rim. The stainless steel relief valve is set to 2.7 bar to create a safety margin.