What is semi-air, air assist, load support and auxiliary air?

For motorhomes and vans the terms semi-air suspension, air assist, auxiliary air suspension or load support are all used, depending on the company or country, but they all actually mean the same thing (but what do they mean, we hear you cry…)

Well, air assist (as we’ll refer to it from now on) predominantly relates to vehicles with rear leaf springs, rather than coil springs. In an air assist system, an airbag is used in addition to the original suspension (hence ‘assisting’ it).

Volkswagen Crafter Semi-Air for front axle

An example of air assist on a Volkswagen Crafter

What kind of vehicle is air assist used on?

Many heavy motorhomes, commercial vehicles or WAVs (Wheelchair Access Vehicles), which are often nearly at their weight limit. These vehicles tend to ride quite poorly on the road, wallowing, crashing and banging, and grounding on ferries and in petrol stations.

Almost all motorhomes sit very close to their bump stops and a lot of new ones we have seen would not pass an MOT for this reason (this is why so many air kits are fitted to three-year-old motorhomes.)

How does air assist help?

Air assist lifts the suspension up, thus recovering the lost motion from the vehicle’s weight-induced sag and stabilising the vehicle due to the additional support. It also creates extra clearance at the rear to overcome grounding. Recovering this lost suspension range allows the suspension to function correctly and better irons out any bumps.

Another example of air assist at work…

What is the difference between air assist and full air suspension?

Full air suspension entirely replaces the vehicle spring; this type of conversion tends to be more expensive and involved. The leaf or coil spring is totally replaced with an airbag and, if necessary, some links.

This offers more control of the vehicle and means it can often be lowered to extremely low levels, which aids loading, and maintains the ride height at any load. Air assist can only lift the vehicle.

Full air suspension is far more versatile and generally has a far-better ride quality. This is the reason it is often used for WAVs and Delicate Load Solutions (DLS) (e.g. for museums, outside broadcast units and aviation transport vehicles, all of which we have converted for.) It is also a good solution for most commercial vehicles and will make motorcycle loading, for example, far easier. We supply both air assist and full air suspension.

In summary…

Air assist leaves the original suspension in place, while full air suspension does not, is more versatile, and can both lift and lower the vehicle. All air suspension conversions reduce driver fatigue and maintenance costs, and make the vehicle better to drive. To discuss your requirements in person please email enquiries@airride.uk.