This will sound like a really stupid question to an experienced driver, but I’m not so here goes
I’ve seen rigid lorries with 3 axles but the wheels on one of the back axles are not actually touching the ground they’re raised off the floor, can anyone tell me what these are ?/used for ?
Thanks
louis89uk:
This will sound like a really stupid question to an experienced driver, but I’m not so here goesI’ve seen rigid lorries with 3 axles but the wheels on one of the back axles are not actually touching the ground they’re raised off the floor, can anyone tell me what these are ?/used for ?
Thanks
there spares
They’re for when the vehicle carries more weight. Onboard sensor senses the weight on the vehicle and lowers (or raises when lighter) the lift axle so weight is shared over another axle. Keeping axle weights correct.
Lol…you are a cruel man Nick.
The axle you refer to mate is called a lift axle amongst other names. When on rigids,they are usually 26 tonners and when running light or empty,you press a button and the axle will lift saving on fuel(reduced drag) and tyre wear.
TJ82:
They’re for when the vehicle carries more weight. Onboard sensor senses the weight on the vehicle and lowers (or raises when lighter) the lift axle so weight is shared over another axle. Keeping axle weights correct.
Spoil sport
eagerbeaver:
Lol…you are a cruel man Nick.The axle you refer to mate is called a lift axle amongst other names. When on rigids,they are usually 26 tonners and when running light or empty,you press a button and the axle will lift saving on fuel(reduced drag) and tyre wear.
I think the correct ruling is or it use to be, when loaded the additional axel should be lowered it was all to do with having reduced road tax as well spreading the load over additional axels…
chase me chase me catch me if you can 
Axel rose? Take me down to the paradise city…
Hahaha thanks guys and Nick
Haha–guys and “Nick”
Talk us through this blatant discrimination lol…
eagerbeaver:
Axel rose? Take me down to the paradise city…
Where the grass is green and the girls are pretty…
nick2008:
TJ82:
They’re for when the vehicle carries more weight. Onboard sensor senses the weight on the vehicle and lowers (or raises when lighter) the lift axle so weight is shared over another axle. Keeping axle weights correct.Spoil sport
I would’ve felt guilty with this one.
Have had some fun in the past on car forums with flux capacitors and opposite pedal configurations lol
Called lift axles. Used when running at weights near to plated max weight. Idea being that when at light weights you can raise them to park the axle/tyres and not wear out the tyres for no reason. Most systems now automatically lower when load sensing valve detects higher weight but you still have to raise manually on most systems.
James the cat:
Called lift axles. Used when running at weights near to plated max weight. Idea being that when at light weights you can raise them to park the axle/tyres and not wear out the tyres for no reason. Most systems now automatically lower when load sensing valve detects higher weight but you still have to raise manually on most systems.
Surely, you deploy the extra axle if it’s anywhere near the plated weight? Two axle trucks have a max weight of 18 tonnes, so if you’re carrying more than that your extra axle should be down.
Whereas if it’s a mid-lift axle (in front of the drive axle rather than behind), you need to lift it up if you’re travelling light, because it’ll stop the drive wheels touching the ground, resulting in loss of traction. Some do this automatically, some don’t. Most of these are on artic tractors.
As has already been said the idea of lift axles is to save on wear and tear mainly to tyres but also brake lining and other mechanical components as well as to save fuel (less drag). However when its lifted on a 3 axle rigid with rear lift for instance it affects the whole handling off the vehicle, stability, cornering, overhang, it also makes it a lot less stable in wind. It should be down if there’s any load on the vehicle even if its under the individual axle weights as depending on the suspension set up, some are individually mounted to the chassis while others are connected to the axle next to it (Scania tag axles with steel suspension for instance) also the vehicle is taxed as a 3 axle and not 2 axles. Most with air suspension will drop the axle automatically when x amount of load is put on, but the best way is manually put it on the ground before loading.
If it’s a tag axle it’s there to keep you on your toes with back swing! Lift it and ■■■ end doesn’t half wander out on turns !!
Every so often I actually remember to lift mine when empty, automatic up/down not on my beast
nick2008:
louis89uk:
This will sound like a really stupid question to an experienced driver, but I’m not so here goesI’ve seen rigid lorries with 3 axles but the wheels on one of the back axles are not actually touching the ground they’re raised off the floor, can anyone tell me what these are ?/used for ?
Thanks
there spares
As Nick said they are spares so if you get the other wheels dirty you can change them to shiny clean ones use full this time of year too
Gotta watch that tailswing.
Bit more than mine by about a buckle (mines Scania P280) but that’s a hell of a diesel tank !!