LRMTECHNICAL On-board air compressor What’s the pros and how to install one

Trevor Cuthbert explains the benefits of having an on-board air compressor and shows how to install one

THE most common reason for fitting a permanent air compressor system to a Land Rover is to provide an air supply to operate an air-locking differential on one or both of the axles. As the driving conditions become arduous, the driver can switch the compressor on by the main switch and then flick individual switches for each of the axle diff locks. Each switch causes a solenoid valve to open, admitting air pressure to the differential to instantly lock up the diff – offering full traction from both wheels on that axle.

Many owners have realised that in addition to air-powering their locking differentials, the on-board compressor can be used for tyre inflation as well. And, by the simple addition of a T-piece at the air compressor, an air hose coupling can be fitted, and an air hose and inflator carried as part of the tool kit for the Land Rover.

Why do off-road drivers need a facility for tyre inflation? Land Rover tyres have a relatively high recommended pressure for use on the road ranging from perhaps 30 psi to say 46 psi, depending on the load carried in the vehicle. When off-road, much

lower tyre pressures, such as 15 to 18 psi, provide better grip in muddy conditions. It is very easy to lower the tyre pressures by letting some air out, but the problem arises when you want to drive home safely on the road, unless you have an on-board air compressor.

I find my mobile compressor system useful around my two yards where there are numerous vehicles including Land Rovers, tractors, forklift trucks, trailers and cars, any of which might need a soft tyre re-inflating. Here, an on-board system is far more convenient than unpacking and connecting a portable compressor.

On-board compressed air has recreational uses, too. On a camping trip, air mattresses are quickly and easily inflated, and even inflatable boats. And there’s always the advantage of being able to use air-powered tools.

I was in touch with Gwyn Lewis about an ARB compressor for an off-roader project that I have been working on, and when I discovered that a good price was on offer, I decided to purchase a kit for my working Defender Td5 90 for tyre inflation duties at my workshop and yards.