Distance from trailer to tractor unit & allowed overhang?

Ok so this might be another set of dumb questions from me but what is a fool proof way to calculate the distance needed from the front of the trailer to the rear of the cab? We transport Ifor Williams horse boxes and after much head scratching I think I’ve figured out a way to carry x4 on a 13.6m artic trailer rather than x3 as we do at the minute. I’m planning move the fifth wheel back and then cut the head board off the artic trailer and over hang the trailers 60cm at the front & a 100 cm at the back. Obviously, I need to make sure that the front trailer doesn’t snag on the back of the tractor unit.

Also as far as permitted overhang is concerned? … my understanding is that if I don’t overhang more than a meter at the rear, then I can get away with some flashing beacons and I don’t need anything else … is that correct??

Diggerlot:
Ok so this might be another set of dumb questions from me but what is a fool proof way to calculate the distance needed from the front of the trailer to the rear of the cab? We transport Ifor Williams horse boxes and after much head scratching I think I’ve figured out a way to carry x4 on a 13.6m artic trailer rather than x3 as we do at the minute. I’m planning move the fifth wheel back and then cut the head board off the artic trailer and over hang the trailers 60cm at the front & a 100 cm at the back. Obviously, I need to make sure that the front trailer doesn’t snag on the back of the tractor unit.

Also as far as permitted overhang is concerned? … my understanding is that if I don’t overhang more than a meter at the rear, then I can get away with some flashing beacons and I don’t need anything else … is that correct??

Will moving the 5th wheel back put the overall vehicle length over 16.5metres?

Substitute your values with the forward projecting load. Measure first your true diagonal from pinto front trailer corner.

til.scania.com/groups/bwd/docum … 002_01.pdf

Hope this is not a stupid question, but when you say overhang the headboard with the first one by 60cm is that with the A frame of the horsebox ? If so, and it does not touch the cab when in a straight line then it never will. Sorry if I have misinterpreted, maybe you have to reverse them all on so that you can tow them off, rather than fork them on ?

manski:
Hope this is not a stupid question, but when you say overhang the headboard with the first one by 60cm is that with the A frame of the horsebox ? If so, and it does not touch the cab when in a straight line then it never will. Sorry if I have misinterpreted, maybe you have to reverse them all on so that you can tow them off, rather than fork them on ?

Yes they go on backwards with the a frame facing the rear. We can’t get them on forwards as they ground out when we winch them on.

Franglais:

Diggerlot:
Ok so this might be another set of dumb questions from me but what is a fool proof way to calculate the distance needed from the front of the trailer to the rear of the cab? We transport Ifor Williams horse boxes and after much head scratching I think I’ve figured out a way to carry x4 on a 13.6m artic trailer rather than x3 as we do at the minute. I’m planning move the fifth wheel back and then cut the head board off the artic trailer and over hang the trailers 60cm at the front & a 100 cm at the back. Obviously, I need to make sure that the front trailer doesn’t snag on the back of the tractor unit.

Also as far as permitted overhang is concerned? … my understanding is that if I don’t overhang more than a meter at the rear, then I can get away with some flashing beacons and I don’t need anything else … is that correct??

Will moving the 5th wheel back put the overall vehicle length over 16.5metres?

No … it’ll make it spot on 16.5m minus the rear overhang of the last trailer on the load.

cav551:
Substitute your values with the forward projecting load. Measure first your true diagonal from pinto front trailer corner.

til.scania.com/groups/bwd/docum … 002_01.pdf

That is great thanks!!

Diggerlot:

manski:
Hope this is not a stupid question, but when you say overhang the headboard with the first one by 60cm is that with the A frame of the horsebox ? If so, and it does not touch the cab when in a straight line then it never will. Sorry if I have misinterpreted, maybe you have to reverse them all on so that you can tow them off, rather than fork them on ?

Yes they go on backwards with the a frame facing the rear. We can’t get them on forwards as they ground out when we winch them on.

Be careful doing this if any place you go has a sudden change in gradient. A place I worked on fridges were obsessed with fuel economy and aerodynamics to the point where they wanted the trailer as close-coupled as possible without them fouling the cab. They achieved this to perfection with it all sat on level ground but completely forgot to consider the angle changes of the trailer on the fifth wheel. One of the deliveries we did had a steep concrete ‘ramp’ down into the yard and the sudden change in angle back onto the level ground at the bottom resulted in the fridge unit mashing into the back of the cab, destroying the fridge and putting a huge dent in the back of the cab which caused the interior storage cabinets and panels to be ripped off their mountings.

It doesn’t even have to a bad gradient at a customer site. Just think of some road junctions where you come down a hill and then the road you join or cross is a completely different level. I can see that blue air-deflector kit in your photo being on borrowed time :astonished: . You also want to consider the front underside of the trailer mashing into the catwalk and fuel tank in such situations as well, seeing as you’re on a low-ride set-up.

DCPCFML:
Be careful doing this if any place you go has a sudden change in gradient. A place I worked on fridges were obsessed with fuel economy and aerodynamics to the point where they wanted the trailer as close-coupled as possible without them fouling the cab. They achieved this to perfection with it all sat on level ground but completely forgot to consider the angle changes of the trailer on the fifth wheel. One of the deliveries we did had a steep concrete ‘ramp’ down into the yard and the sudden change in angle back onto the level ground at the bottom resulted in the fridge unit mashing into the back of the cab, destroying the fridge and putting a huge dent in the back of the cab which caused the interior storage cabinets and panels to be ripped off their mountings.

It doesn’t even have to a bad gradient at a customer site. Just think of some road junctions where you come down a hill and then the road you join or cross is a completely different level. I can see that blue air-deflector kit in your photo being on borrowed time :astonished: . You also want to consider the front underside of the trailer mashing into the catwalk and fuel tank in such situations as well, seeing as you’re on a low-ride set-up.

Good point thanks for the tip!

Diggerlot:
As far as permitted overhang is concerned? … my understanding is that if I don’t overhang more than a meter at the rear, then I can get away with some flashing beacons and I don’t need anything else … is that correct??

Sort of. Not exceeding 1.0m then no specific requirements other than to make it readily visible to other road users so read that as you will but remember that if things go wrong and you could have done better, then you are likely to be expected to have done so.

At 1.001m or 1001 millimetres rear overhang then you need need effectively light board and markers etc- have an enjoyable read of the Con&Use Regs '86, Reg 82 and then Schedule 4 & 12.

Acorn:

Diggerlot:
As far as permitted overhang is concerned? … my understanding is that if I don’t overhang more than a meter at the rear, then I can get away with some flashing beacons and I don’t need anything else … is that correct??

Sort of. Not exceeding 1.0m then no specific requirements other than to make it readily visible to other road users so read that as you will but remember that if things go wrong and you could have done better, then you are likely to be expected to have done so.

At 1.001m or 1001 millimetres rear overhang then you need need effectively light board and markers etc- have an enjoyable read of the Con&Use Regs '86, Reg 82 and then Schedule 4 & 12.

Great thanks !!

No flashing lights or beacons needed, if its under a metre dont worry about it, if its over a metre a hiviz tied on seems to be popular, if its over 2 metres then you need a proper triangle marker board, but “look at me” flashing beacons are definately not required