I’ve seen plenty of wagons around with various configurations of lifting axles but I haven’t got a scooby as to how they are used. I may be using trucks equipped with these systems, can anyone enlighten me as to when and why they are used? Thanks, Gedi
They are normally operated by a switch & they are for use when you are unloaded / part loaded (but with very little weight over the 5th wheel) & due to the weight being low do not need 3 axles to stay below axle weights.
They also give you a more comfortable ride as by lifting one axle when unloaded it stops some of the bounce.
They mainly save tyre ware when your empty/got a light load on, that what I was told when I asked 
. If I’m wrong, someone will put me straight.
i have heard this too liberace. The DAF CF’s where i work have automatic lifting axles as soon as the truck detects extra weight it goes down. For example whilst loading a powder tanker with the axle lifted as soon as the weight gets upto about 35 tonne it drops the axle.
Bend your knees, keep your back straight and wear gloves. 
I’m probably teaching granny to ■■■■ eggs for most on this site, but a tip.
If your trying to maneuovre in a tight space and the drive wheels start to spin, get the lift axle up if you can, you will get more traction. I watched a guy trying to back a fully loaded box onto a tight bay a few weeks ago and every time he put full lock on his wheels started to spin, I shouted “lift the axle” a couple of times but it just didn’t click and eventually went over to help him, he soon realised what I meant when he flicked the switch…
On the volvo the lift axil drops but it doesnt take any weight, so if you are over 40 tonnes you need to put the lift switch into the middle posttion to take weight of the drive axil.
It is handy if you are short of grip to lift the axil putting weight on the drive, but remember to drop it again
Basically they lift to save ware on the tyre and fuel conservation.
I got an M.A.N I always leave switch for lift axle on,as axle will drop automatically if box over 17 tonne,and lift when under.
Leaving axle down when empty uses more fuel
When axle down it makes it harder to manouver in reverse,as the lift axle on my truck are fixed,and dont steer with the main steering wheels,like on some trucks.
I have switch even when fully freighted to lift up axle for a few seconds to make steering easier,as you will find if the road is wet that when cornering,unit tends to slide and wheelspin when axle down.
Hope this makes some sense 
