I possibly owe Captain Caveman an apology, i believe it was he who warned about the pick up ramps getting closer to the trailer chassis and to be careful when the trailer lowered and unit raised.
Have edited the OP to credit CC accordingly, sorry about that CC.
Cheers juddian!
When I did it I got 2t of weight transfer, that was with a fully loaded bulker, but I can’t remember what it was loaded with, ie, if it was full by volume too, so evenly loaded or something more dense, so might not have been evenly loaded and I can’t remember if I measured the 2t onto the unit or onto the drive axle!!
Spot on Franglais
Yep it works by moving the pivot from the middle axle to the rear one, the only weight on the front and middle axle is the weight of the axles themselves, this gives the other big plus, when turning with tri-axle trailer there’s a lot of scrub to overcome, this pretty much eliminates the scrub, so reducing the amount of traction needed for the given manoeuvre whilst making more traction available. Yep you need to keep a check on the chassis rails and the skids, but you only need the unit up enough to lift the middle and front axles off their bump stops.
Another that has got me out of the ■■■■! If you’ve sunk a little and the tyres are sat in little divots
I’ve had about 50:50 success with this one.
Raise the trailer suspension to the top, put the trailer brake on, take the unit brake off, lower the trailer suspension, put the unit brake on, take the trailer brake off, the raise the trailer suspension again and repeat if needed and it’s a working. We’ve all seen when a dropped trailer loses it’s air, it walks forward on the legs, it’s using the angular rotation on the suspension arms and the brake to basically copy the action of a ratchet turning a socket
And to reduce the chances of needing the above, when you stop on snow / ice, keep going forwards and backwards for a couple of foot or so for a minute or 2, to take the heat out of the tyres so they don’t melt into their own little mold!!
Fairly easy to understand.
Assuming the trailer was a tri-axle, by dumping the air out you have moved the fulcrum from the center axle to the rear and by raising the unit to full height will increase the leverage.
Give me a fulcrum and a lever long enough, and I will move the world. -Archimedes.
stevieboy308:
Cheers juddian!When I did it I got 2t of weight transfer, that was with a fully loaded bulker, but I can’t remember what it was loaded with, ie, if it was full by volume too, so evenly loaded or something more dense, so might not have been evenly loaded and I can’t remember if I measured the 2t onto the unit or onto the drive axle!!
Spot on Franglais
Yep it works by moving the pivot from the middle axle to the rear one, the only weight on the front and middle axle is the weight of the axles themselves, this gives the other big plus, when turning with tri-axle trailer there’s a lot of scrub to overcome, this pretty much eliminates the scrub, so reducing the amount of traction needed for the given manoeuvre whilst making more traction available. Yep you need to keep a check on the chassis rails and the skids, but you only need the unit up enough to lift the middle and front axles off their bump stops.
Another that has got me out of the [zb]! If you’ve sunk a little and the tyres are sat in little divots
I’ve had about 50:50 success with this one.
Raise the trailer suspension to the top, put the trailer brake on, take the unit brake off, lower the trailer suspension, put the unit brake on, take the trailer brake off, the raise the trailer suspension again and repeat if needed and it’s a working. We’ve all seen when a dropped trailer loses it’s air, it walks forward on the legs, it’s using the angular rotation on the suspension arms and the brake to basically copy the action of a ratchet turning a socket
And to reduce the chances of needing the above, when you stop on snow / ice, keep going forwards and backwards for a couple of foot or so for a minute or 2, to take the heat out of the tyres so they don’t melt into their own little mold!!
Really interesting and useful stuff. Thanks. That suspension trick to shuffle the truck along is a bit like how some caterpillars walk I think? Arching up in the middle.
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Juddian:
Franglais:
Juddian, at play time today, … sorry, when you’re on duty at the TNUK Research Establishment, will you be able to do another weigh?
After loading put just the rear trailer axle on the bridge. Weigh that axle in normsl mode and then as before in air-dumped high unit mode.
I’ll predict that they’ll be a substantial change. Guessing 50% increase?Sent from my GT-S7275R using Tapatalk
Will do when i get the w’bridge to meself for a few minutes, which might not be this week.
I reckon 1500kg increase, however as i’m poor and you’re bleedin loaded i aint betting with real money, i can’t afford to lose any [emoji38]
Great if you get a chance without causing an angry queue. I can’t afford loads of dosh to bet with either. Just to Know rather than guess isn’t it? Cheers.
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That walking lorry method takes some thinking about 
Great idea and yes i can see the theory is sound, but if you have a tractor that applies the trailer brake when the parking then is on then boy oh boy does it get complicated, what with dropping the red line off/on using the shunt valve etc…it’s far too early for mind boggling stuff like this, but if one was to temporarily drop the yellow line off 
then that should make it happen…i’ll try to get me head round that when i wake up 
Juddian:
That walking lorry method takes some thinking aboutGreat idea and yes i can see the theory is sound, but if you have a tractor that applies the trailer brake when the parking then is on then boy oh boy does it get complicated, what with dropping the red line off/on using the shunt valve etc…it’s far too early for mind boggling stuff like this, but if one was to temporarily drop the yellow line off
Yeah to be fair I hadn’t thought of trucks that do that!
Gonna guess high teens or maybe just in the 20s on the back axle at full weight depending how the trailer is loaded
stevieboy308:
Juddian:
That walking lorry method takes some thinking aboutGreat idea and yes i can see the theory is sound, but if you have a tractor that applies the trailer brake when the parking then is on then boy oh boy does it get complicated, what with dropping the red line off/on using the shunt valve etc…it’s far too early for mind boggling stuff like this, but if one was to temporarily drop the yellow line off
Yeah to be fair I hadn’t thought of trucks that do that!
Gonna guess high teens or maybe just in the 20s on the back axle at full weight depending how the trailer is loaded
At 20 tonne on a trailer axle the customer would have to buy the trailer off me first .
Punchy Dan:
stevieboy308:
Juddian:
That walking lorry method takes some thinking aboutGreat idea and yes i can see the theory is sound, but if you have a tractor that applies the trailer brake when the parking then is on then boy oh boy does it get complicated, what with dropping the red line off/on using the shunt valve etc…it’s far too early for mind boggling stuff like this, but if one was to temporarily drop the yellow line off
Yeah to be fair I hadn’t thought of trucks that do that!
Gonna guess high teens or maybe just in the 20s on the back axle at full weight depending how the trailer is loaded
At 20 tonne on a trailer axle the customer would have to buy the trailer off me first .
It’s what you do with a tanker if you need to get the back end lower, it’s what you do if you’re wheeling pallets / cages about in the trailer to make it downhill if parked uphill, it’s how the Dutch drop trailers, drop the air out, it’s what’ll happen to a loaded trailer if left long enough, it’s what I do with a bulker to get under a gantry, it’s what happens when going over steep ramps!!
I ain’t suggesting doing the shift like that! just the 10 / 100 yards needed to get going again!!
Juddians op refers to a tight turn and a sharp slope ,I knows plenty about tipping scrap and dropping the air out .
Talking of just getting going again you’d have more luck with an axle that won’t lift loaded by blowing up the unit and put 2 bits of wood on the drive axle under the bump stops then drop the air out thus taking all weight off the lift or you could even trick it in to thinking its empty and get it to lift .
Punchy Dan:
Juddians op refers to a tight turn and a sharp slope ,I knows plenty about tipping scrap and dropping the air out .
You’ll more than likely put more weight through the back axle when dumping the air and tipping, unless it’s a free flowing and starts coming out straight away, than just dumping the air to get traction
To be fair 4 different make of truck I’ve drove in the last 10 year have all been able to completely lift the midlift when full, scania, Volvo, dad and man, before that I can only remember not being able to lift in in a premium, or at least not working out how too!!