At the weekend driving through some heavy rain the artic seemed to pull sideways from the rear wheels. I guess it was aquaplaning. Is this common, as I have driven through lots of rain but this was something else? Thing is, this happened a couple more times this day. Apart from easing off the throttle, any other tips? Thanks.
Was it the unit wheels that skipped sideways, or the trailer? If you are familiar with the road, can you remember seeing “tramlines” - those trenches that can appear over a period where heavy stuff has worn a tyre-width groove in the Tarmac? It may have been that…
Unlikely to be aquaplaning, as lorries are limited to <56mph, which is really rather too slow for aquaplaning to occur (the weight and reduced speed is the main reason why the tyre tread depth limits for HGVs are so much lower than they are for cars). I suspect what you experienced was the asymmetric drag caused by varying depths of standing water, and/or the wear ruts in the nearside lanes.
Roymondo:
asymmetric drag
Word of the Day Award [emoji471] goes to Roymondo [emoji106]
Sounds like an out of breath cross dresser [emoji6]
Sumsmeister:
Was it the unit wheels that skipped sideways, or the trailer? If you are familiar with the road, can you remember seeing “tramlines” - those trenches that can appear over a period where heavy stuff has worn a tyre-width groove in the Tarmac? It may have been that…
It was on the M1 north after j20. It happened three times, each several miles apart. It was the unit wheels that pulled. It felt fairly dramatic when it did occur, and while it was raining hard, there was reasonable water around but not standing deep water with the usual traffic passing me. Due to the conditions I could not see any tram lines.
That whole section needs relaying, its like a bloody ploughed field in places, as is the A43 around Silverstone.
I agree that it was probably the tram lines, and due to the wet the pull in or out of them as you try to keep it straight was causing a slight slip.
Very unpleasant sensation, but its a handy reminder of just how poor grip can be in the wet.
Juddian:
Very unpleasant sensation, but its a handy reminder of just how poor grip can be in the wet.
I don’t think it’s poor grip that causes the unpleasantness - It is actually caused by the front wheels riding the sides of the ruts and being very slightly deflected from the straight-ahead position. It may well feel as if the drive axle is stepping out to the side, but I don’t think that’s what is actually happening.
Roymondo:
Juddian:
Very unpleasant sensation, but its a handy reminder of just how poor grip can be in the wet.I don’t think it’s poor grip that causes the unpleasantness - It is actually caused by the front wheels riding the sides of the ruts and being very slightly deflected from the straight-ahead position. It may well feel as if the drive axle is stepping out to the side, but I don’t think that’s what is actually happening.
It tends to put you on edge more and feels worse when empty on a wet road, so is that real side slip or is that a driver’s seat of pants ‘feel’ working overtime due to knowing how easy it is get the bloody things out of line?
To be fair it was worse with a modern car transporter where its a short prime mover (tractor unit basically) but not a semi trailer, too easy on one of those to get the tail wagging the dog, so you’re already keyed up when its slippy anyway.
FM Volvos were really bad for it, you could nearly change lanes at some sections where the road was really badly worn, where for examples motorways merge so you’re riding all sorts of grooves…thats one of many things about the job i don’t miss…
It amazes me how many folk I see that have done a drop, then leave empty, and more often than not, go in to pick up a backload of crisps in Park Royal, then head off, all the while with their midlift dropped. Tried telling them, I’d say I ought to learn it in Polish, but some of the home grown lads are just as bad.
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PaulNowak:
It amazes me how many folk I see that have done a drop, then leave empty, and more often than not, go in to pick up a backload of crisps in Park Royal, then head off, all the while with their midlift dropped. Tried telling them, I’d say I ought to learn it in Polish, but some of the home grown lads are just as bad.Sent from my iPhone using Tapatalk
This was my next question. The “midlift”, is the middle drive axel of the unit? What is the correct use of this axel as often it is raised. I see the button in the cab to lift and drop it, but what is the correct time to either lift or run with this axel down? Thanks
A midlift (the middle axle) or taglift axle (the rear axle) is there for weight distribution.
If you’ve got it down (touching the road) you’re spreading out the weight and taking weight i.e. grip away from the drive tyres.
If you’ve got it up (not touching the road) you’re concentrating the weight and adding weight i.e. grip to the drive tyres.
If you’re heavily loaded, you need to have the lift axle down so that you don’t breach your axle load ratings. With a heavy load, generally, the extra weight of the load will compensate for the extra spreading it out that you’re doing. If it’s wet and greasy and you’re trying to start off, if you raise the lift axle you’ll get extra grip for the drive axle then you can drop the lift axle again once you’re rolling.
If you’re light loaded, if you raise the lift axle you’re helping the drive tyres get more grip and you’re saving some rubber off the lifted tyres too.
If you have a taglift, you can make tighter turns by lifting it, as it makes your wheelbase a smidge shorter. If you have a midlift, raising it for tight turns doesn’t do much, maybe prevents a bit of wear.
That’s my understanding anyway!
slowlane:
If you have a midlift, raising it for tight turns doesn’t do much, maybe prevents a bit of wear.
If you’re screwing it into a tight spot fully laden, it could save you ripping the rubber off the rims, and or considerable tyre wear.
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PaulNowak:
slowlane:
If you have a midlift, raising it for tight turns doesn’t do much, maybe prevents a bit of wear.If you’re screwing it into a tight spot fully laden, it could save you ripping the rubber off the rims, and or considerable tyre wear.
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Ooh, didn’t know that, thank you!
And if you’re light loaded, it shouldn’t have been down in the first place.
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PaulNowak:
And if you’re light loaded, it shouldn’t have been down in the first place.Sent from my iPhone using Tapatalk
That you all for for your advice on this.
slowlane:
PaulNowak:
slowlane:
If you have a midlift, raising it for tight turns doesn’t do much, maybe prevents a bit of wear.If you’re screwing it into a tight spot fully laden, it could save you ripping the rubber off the rims, and or considerable tyre wear.
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Ooh, didn’t know that, thank you!
The Renault units we have at my firm have auto mid lift axel so you don’t even have to worry about your weights and have a “optimum traction” setting that transfers the weight for optimum traction and minimum wear.