I have recently been let loose on our firm’s new Actros 2546 wandering around for a week at a time hauling gear up country and returning with backloads. Well chuffed with the wagon after driving Atego wag & drags, but have encountered a small? problem that I hope some of you experienced guys may be able to help with.
When loaded heavy, the truck really struggles to get traction pulling from a stop up even a fairly slight incline. In the wet it is a real nightmare. The drive wheels slip very easily, causing the whole cab to shudder, and more often than not ending in a stall. I have tried all sorts of revs and gears, sometimes it works, sometimes not. With a light load I have found that lifting the tag axle helps a lot, but when loaded heavy I cannot get the axle up. (I think there must be a sensor keeping the axle down when the weight is above a certain amount). The truck is fitted with ASR which the handbook says controls slip on the drive wheels, but this is on all the time and it still slips. I work for a fairly small outfit so we do not have any really experienced drivers to pester, so if anyone out there can give some advice, it would be much appreciated.
I think all lift axles must drop when the drive axle reaches a certain load. At a guess your lift axle might be getting to much pressure and taking to much weight off the drive axle. I think it might be a dealer thing to check.
I would say the load sensor is set wrong or faulty 
this use to happen with the volvo units that we had,but to combat this we had a small button on the dash board that would transfer the weight from one axle to the other to prevent traction when pulling away from lights,roundabouts and junctions etc. what we done was quickly press the button once and the light would come on, (flashing )once we where moving we depressed the button and away we went.but the other main factor would be your weight over the front two axles,i think if i’m right in thinking its 2ton spread over the 1st and 2nd axles ( ie, the first 4 pallet spaces 2either side and double stacked if this adds up to 2ton then that is you,if more than that ,then it will give you problems.this just what we had problems with and this is how we had to combat the problem.it might not solve your problem, but you can try spreading the weight over the trailer more. 
Make sure the steering is straight ahead before moving off, that will help a little.
Also check the tyres, make sure they aint directional. (Little arrows on the tyrewall showing direction of rotation, should not really apply to rear tyres as they are normally chunky tread)
Brakes sticking on possibly?
Its one of my pet hates about the UK laws, having to use twin steer and pusher axles to carry the same weight as a European does on 5 axles.
The centre steer or pusher probably starts to work when there is around 5 tonne on it, so it takes weight off the drive, if the pressures are ok, make sure your not trying to drive like the shoemaker chap. ASR works like ABS in Reverse.
When a wheel starts to spin it applies the brake, then the other starts to spin and the brakes are applied again.
I had a twin steer 2800 Daf and I had some chains made up to keep the axle off the road in slippy conditions
on our actrosses if you push the axle lift button and the air dump button at the same time(normally next to each other or above each other on the dash) then this will raise the lift axle for about 1 minute when fully loaded .
but at a guess your lift axle needs recalibrating as it is pushing down to hard and taking some weight of the drive axle. a dealer will take less than ten minutes to do this on his laptop.
6 leggers - that’s the problem.
The Merc’s and Volvo’s are terrible for traction in the wet; the Axor especially.
Gimme a 4 legger any day.
Never had a problem with my 2553. There is a switch on the dash which lifts the centre axle for about 30 seconds to allow you to move off in poor conditions.
My problems have always been with 6x2 Scanias. You would think that they were fitted with slicks when lightly loaded. OK, lift the middle axle. Trouble is, it does not lift very far and scuffs any imperfection in road surface, flatspotting tyre and giving you a bill of £300.00/ tyre very quickly. Give me the Actros.
Many thanks folks. Plenty there for me to check and try. I’m out in it again next week, so I will print this page off and experiment, (and have a word with the TM)
Is the trailer as close as you can get it on the slider? Just a thought.