Hydraulic axle lift

[Snagglefoot]

I never noticed this before but a gasoline carrier in my hood finished unloading fuel, then lifted two of the three axles and got the tires off the ground for the trip back to the terminal. I guess it saves on tire wear. Maybe the truckers out there can comment on it.

 

[supton]

I've seen it a time or two. Wild guess says it's to reduce tire wear and increase mpg. Less tire drag, and less tire scuffing when making turns. At least while unloaded--with no load I'm guessing even one axle is more than enough to carry the weight.

If anything, I'm surprised they don't pick the axles up while making tight turns, even when loaded up. The tires would be overloaded sure but at low speed in a parking lot would it be dangerous? I don't think so. Maybe under a full load one axle would be just too overloaded to do that, dunno.

 

[MNgopher]

Very common these days. Main focus is on reducing rolling resistance and increasing fuel mileage. Less rubber deforming on the road = less resistance. Same reason you see super singles, etc... Seeing more bulk and tanker carriers using these these days.

Some trucks do dump air from an axle to assist in tight maneuvering - often flatbedders with spread axles. Watch Supertruckerdan on youtube for an example - he has a buzzer that goes off when he dumps the air from one trailer axle...

 

[Motu]

In NZ it's for axle loadings, we run more axles for the same load than the US...less damage to our substandard roads. This is a typical truck and trailer unit (stock truck)