This may be a bit noob but…
When should you use the midlift and is there a way to avoid the Wheelspin that I always seem to get?
I put the axle down only when trailer is fully loaded and unit is struggling with the weight.
Whenever I do though, i just get massive Wheelspin when accelerating.
Am I doing something wrong?
Cheers
Wheel spin at max weight? I’d say its the 5th wheel in the wrong place.
What’s the weight distribution like?
Condition of drive axle tyres?
Are the tyres evenly worn? Had a mate at my depot got a spot rental with a well worn cut tyre and a brand new one on the same hub. The cut one didn’t even touch the ground when solo!
Try not to use as much power pulling away.
Don’t drive it like you stole it lol also it is quite easy to wheel spin, I prefer 2 axle units, I quite often dump the air from the mid lift when pulling away too
Also check the ride height is set correctly. Some are programmable and if some bored monkey has been fiddling without knowing what they’re doing then it could need re setting. Consult the book of destructions.
When solo, switch off traction control select auto with axle down nice cloud of blue smoke in the hands of a skilled driver.
idrive:
This may be a bit noob but…
When should you use the midlift and is there a way to avoid the Wheelspin that I always seem to get?
I put the axle down only when trailer is fully loaded and unit is struggling with the weight.
Whenever I do though, i just get massive Wheelspin when accelerating.
Am I doing something wrong?
Cheers
The lift axle should drop automatically when max legal weight is on drive axle, shouldnt it? It has on all trucks I`ve encountered over recent years.
If you can raise the lift axle then you should do so.
WhiteTruckMan:
What’s the weight distribution like?
Good point. If the trailer is loaded, but there isn`t enough weight to force the lift axle to drop, your weight distribution is suspect.
It may well be legal, but not “correct”.
mike68:
When solo, switch off traction control select auto with axle down nice cloud of blue smoke in the hands of a skilled driver.
And engage diff lock too. Both sides smoke evenly then.
Franglais:
The lift axle should drop automatically when max legal weight is on drive axle, shouldnt it? It has on all trucks I`ve encountered over recent years.
If you can raise the lift axle then you should do
Didn’t know this. Never had it lower automatically so guess I should just leave it alone?
Weight distribution will be this particular issue, sealed double deckers loaded by monkeys. Sometimes front heavy, sometimes all on the arse end…
There’s nothing to stop you pressing the weight transfer button (usually the one look like an umbrella over the axles) when you want to pull away from a junction you are likely to encounter wheelspin so making an exit more dangerous than it need be, this will take all weight off the mid lift axle and transfer most onto the drive axle, on some vehicles, mainly DAF and MAN the mid lift will raise completely after about 30 seconds, once you get up to if my memory serves 20mph the mid lift airbags will automatically re-inflate even if you forget to cancel the weight transfer once going.
As said before you can try pressing the axle lift button anyway as it’s almost impossible for the axle to lift unless the weights are within spec, the last vehicle i drove that the driver had 100% control of the mid lift where you could drive around with it completely off the ground even fully loaded was the square Axor, almost all modern lorries will either ignore your axle lift request or put a message say lift denied if the vehicle is too heavily loaded.
If you used an axle weigher you would probably find the weight imposed on the drive axle of 6 axle outfit, even fully loaded would be in the region of 8 to 9 tons, where possible you want to get some weight loaded further forward so increase that drive axle weight to around 10 tons, when empty even with the mid lift up chances are the weight imposed on the drive axle is only around 4 to 4.7 tons.
So loaded at 42 tons around 20% is often all that is imposed on the drive axle, empty at say 15 tons only just over 25% is imposed, little wonder how easy it is to get wheelspin…plus modern tyres are not primarily designed for grip, they are now designed to offer low rolling resistance (ie lack of grip) and last as long as possible.
idrive:
Franglais:
The lift axle should drop automatically when max legal weight is on drive axle, shouldnt it? It has on all trucks I`ve encountered over recent years.
If you can raise the lift axle then you should doDidn’t know this. Never had it lower automatically so guess I should just leave it alone?
Weight distribution will be this particular issue, sealed double deckers loaded by monkeys. Sometimes front heavy, sometimes all on the arse end…
Juddian seems to agree,
Juddian:
you can try pressing the axle lift button anyway as it’s almost impossible for the axle to lift unless the weights are within spec
And he has more experience of different 6 wheelers than I do.
As he says years back the driver could accidentally raise the lift axle and overload the drive, but now? I dont think its possible.
Sounds like trailers light loaded on the neck.
Dont worry if it snows at any time, you wont even get it out the yard!
Yeah my unit has a mid-lift that will drop and won’t let you lift it if it will exceed axle weights. Same with trailers too.
Thanks for the replies. I will leave it well alone and ease off
idrive:
Thanks for the replies. I will leave it well alone and ease off
TBH mate i wouldn’t leave it alone, i’d learn how it all works, the speeds involved and when the thing will or won’t allow use, because come the winter and slippery roads being able to dump that mid lift air at exactly the right moment, coupled with manual use of the gears, plus when to or when not to use the diff locks can make the difference between getting home and being stuck out miles from anywhere, just saying like 
I’m a great believer in learning the strengths and weakness of your particular vehicle and the time to learn your vehicle is when you don’t need such techniques, you don’t want to be learning this stuff when the smelly stuff hits the fan and you’re trying to keep the sodding going in serious conditions.
There’s other techniques for increasing weight on the drive axle too, which having air suspension has given us…i only learned this in the last few years from one of our posters here who does a lot of offroad work, we’d only guessed the increases in weights possible so i did some experimenting on weighbridges, the results were remarkable, but that’s a discussion for another time.
Juddian:
I’m a great believer in learning the strengths and weakness of your particular vehicle and the time to learn your vehicle is when you don’t need such techniques, you don’t want to be learning this stuff when the smelly stuff hits the fan and you’re trying to keep the sodding going in serious conditions.
100% agree.
You need to know where the light switch is, before it gets dark…
Juddian:
idrive:
Thanks for the replies. I will leave it well alone and ease offTBH mate i wouldn’t leave it alone, i’d learn how it all works, the speeds involved and when the thing will or won’t allow use, because come the winter and slippery roads being able to dump that mid lift air at exactly the right moment, coupled with manual use of the gears, plus when to or when not to use the diff locks can make the difference between getting home and being stuck out miles from anywhere, just saying like
I’m a great believer in learning the strengths and weakness of your particular vehicle and the time to learn your vehicle is when you don’t need such techniques, you don’t want to be learning this stuff when the smelly stuff hits the fan and you’re trying to keep the sodding going in serious conditions.
There’s other techniques for increasing weight on the drive axle too, which having air suspension has given us…i only learned this in the last few years from one of our posters here who does a lot of offroad work, we’d only guessed the increases in weights possible so i did some experimenting on weighbridges, the results were remarkable, but that’s a discussion for another time.
Quite right, I should say I will leave it well alone and stop pushing buttons until I know how it works…
It’s pretty rare that I’ve driven 6x2 and only twice used the axle.
Once on a Renault the axle was down already and I couldn’t get it to go up. It was wheelspinning everywhere and I thought it was me not doing something right. Was a fully loaded fridge and I now know (think?) from above that it was down for a reason and not up to me.
Second time was the other day in a MAN with the decker. I convinced myself that it needed the axle down as it felt so heavy and the ride was so terrible. I now know (think?) from above that if it needed to be down, it would be.
Still a lot to learn though obviously.
When you say “dump the midlift air”, what does that mean exactly?
idrive:
When you say “dump the midlift air”, what does that mean exactly?
So, as discussed you cant lift the mid axle if the load on the unit is too high. It wont lift and let you run illegally.
But if on a slippery patch, a short sharp slope, or similar the unit (all of `em or not?) will have an air dump or “Load Transfer Switch” or similar. This will dump or let the air out of the mid axle, but wont actually raise it. Dumping the air from the air bag, or air-spring, means no real load is pushing that axle onto the road, and more weight is transferred to the drive axle, giving more grip.
It will have a timer on it, so after maybe 30 seconds, air will reinflate the centre air -spring. It is there to get you out of the mire.
Franglais:
idrive:
When you say “dump the midlift air”, what does that mean exactly?So, as discussed you can
t lift the mid axle if the load on the unit is too high. It wont lift and let you run illegally.
But if on a slippery patch, a short sharp slope, or similar the unit (all of `em or not?) will have an air dump or “Load Transfer Switch” or similar. This will dump or let the air out of the mid axle, but wont actually raise it. Dumping the air from the air bag, or air-spring, means no real load is pushing that axle onto the road, and more weight is transferred to the drive axle, giving more grip.
It will have a timer on it, so after maybe 30 seconds, air will reinflate the centre air -spring. It is there to get you out of the mire.
Most of the weight transfer set ups are re-set once you go above a certain speed rather than a time limit, it is possible to get the lift axle configured so that it will lift regardless of the weight on it to enable better manoeuvring in tight situations as long asyou then remember to drop it before continuing on
I’d have to disagree with few of the above posts…
I drive a 68 plate R450, 6x2. Company policy we must drop midlift axle when coupling with a trailer. After I hooked up and was pulling away, I did as I always do, and press the button to lift the mid lift. Sometimes is says something like “Tag axle overload” and it won’t lift. This time the axle lifted.
However this particular time I had access to a weight bridge, so I thought I’ll weight the thing… steering axle is permitted at 8000kg, but was sitting around 8300kg, drive axle was permitted at 10000kg, was sitting about 10222kg. I put the axle down and went through again… all well with in the legal permitted weights.
Reasoning always lift the midlift, guy from Scania was out with me, told me always lift it if it will, reduces drag and makes for better fuel efficiency.
WhiteDog:
I’d have to disagree with few of the above posts…I drive a 68 plate R450, 6x2. Company policy we must drop midlift axle when coupling with a trailer. After I hooked up and was pulling away, I did as I always do, and press the button to lift the mid lift. Sometimes is says something like “Tag axle overload” and it won’t lift. This time the axle lifted.
However this particular time I had access to a weight bridge, so I thought I’ll weight the thing… steering axle is permitted at 8000kg, but was sitting around 8300kg, drive axle was permitted at 10000kg, was sitting about 10222kg. I put the axle down and went through again… all well with in the legal permitted weights.
Reasoning always lift the midlift, guy from Scania was out with me, told me always lift it if it will, reduces drag and makes for better fuel efficiency.
But if the lift axle had been configured to your vehicles axle weights then it would have dropped 10,000kg limit on a drive axle is not the normal setting usually it is 11500kg so for whatever reason your company have specced the vehicle to that weight and then not set up the lift axle to match. The irony being is that the company probably watch the fuel figures and are quick to blame the driver for not getting good results yet company policy increases drag, wear and fuel consumption.