Does a tri-axle vehicle need a set of 4 or 6 mobile column lifts?

Why is there a need to use sets of 6 mobile column lifts when a set of 4 can lift a tri-axle vehicle?

Before positioning mobile vehicle lifts you must first consider the load distribution and axle loads of the vehicle, the load capacity of the tyres and where the lifts are being positioned to ensure the columns are not overloaded.

Although a set of four mobile column lifts may well be able to lift the vehicle, the key factors to consider are weight distribution and preventing damage to the vehicle. This is true when lifting any vehicle, but it can be more pertinent when lifting multi-axle vehicles.

Mobile vehicle lift columns all have an individual safe working load (SWL) capacity and this must never be exceeded. Before using any mobile vehicle lifts you should seek advice from the vehicle manufacturer to confirm the correct lifting positions for your truck, bus or coach.

When lifting vehicles the front and rear axles must be used to distribute the weight of the vehicle, this ensures that no side load is applied to any column. The best way to picture this is to imagine a seesaw. The centre of balance on a seesaw is located in the middle, if the centre of balance was to move, this would alter the force needed to balance the weight.

So why the need to use six mobile columns when lifting a tri-axle vehicle?

When a tri-axle vehicle is lifted by the front and rear axles, the middle axle is left unsupported. When the weight of the vehicle is only being spread between four columns rather than six, creating an increased side load on the rear axle which can then cause damage to the vehicle and the airbags underneath. In terms of the seesaw, the centre of balance has moved to the rear of the vehicle, resulting on a greater force on the rear axle.

Sets of six column lifts will distribute the load of the vehicle evenly, and protect the vehicle and the mobile column lifts from damage from the unsupported axle. In the long term, lifting with sets of six lifts can save the expense of costly repair bills and unnecessary health and safety risks.