My guess is no park brake on front steer driver loads something up the ramps but didn’t apply trailer brake and it picked up the unit & set off ?
Debris from the space station finally landed?
Schoolboy error.
Scanias don’t apply the trailer brakes when the park brake is applied, unlike proper lorry designs 
.
Best to apply the trailer brake as well during operations that could see the trailer subject to weight transfer or shifting.
Or, is the vehicle modern enough for that pointless piece of garbage the current fashion must have that no one asked for, the electric parking brake, possibly failed?
Juddian:
Schoolboy error.
Scanias don’t apply the trailer brakes when the park brake is applied, unlike proper lorry designs
Best to apply the trailer brake as well during operations that could see the trailer subject to weight transfer or shifting.Or, is the vehicle modern enough for that pointless piece of garbage the current fashion must have that no one asked for, the electric parking brake, possibly failed?
Sounds about right 
Does not look steep enough for a runaway? Is that the driver taking pics? Could he be disputing culpability?
Janos:
Does not look steep enough for a runaway? Is that the driver taking pics? Could he be disputing culpability?
Wouldnt have thought that is the driver as he is not wearing rigger boots.
Juddian:
Scanias don’t apply the trailer brakes when the park brake is applied
Do they not? 
[zb] me I never knew that… TIL!
Reef:
Juddian:
Scanias don’t apply the trailer brakes when the park brake is appliedDo they not?
Nope (but someone with the latest versions with EPB will have confirm if its still the case with those), and i’m none too sure about modern Volvos either, previous Volvos didn’t pressurise the trailer brakes with the park brake applied.
Easy enough to tell, when you connect up to a trailer is the yellow service line pressurised and as hard to fit as the red line? 
, you’ve done it hundreds if not thousands of times Reef, just it doesn’t register til you have a job that benefist from that additional braking **
I know MAN and Daf units apply the trailer brakes with the unit park brake, Scania at least pre EPB don’t.
Might be an idea to have a thread about this, i bet lots of drivers doing jobs that would be maybe safer with the trailer brakes applied as well could benefit.
** its something i had early warning about, in my early days on transporters i had a 9 car wag’n’drag carrier with an FL10 prime mover, literally never serviced at the cowboy outfit i worked at.
One day i’m loading the lorry and realised its moving slightly down the hill as i’m putting cars on…park brake only applied on the drive axle and the brake shoes were simply worn out, luckly on the Volvos you had the extra aitr operated switch you could pull out labelled Broms Brake, which once pressurised stayed out, this applied the trailer brakes, and wouldn’t release till you pushed it manually back in again.
That was an eye opening moment for me, for some reason since we’d lost the blue auxilliary brake line (operated by the secondary or dead man’s brake) i’d assumed the park brake on two line systems applied all, wrong.
Juddian:
Reef:
Juddian:
Scanias don’t apply the trailer brakes when the park brake is appliedDo they not?
Nope (but someone with the latest versions with EPB will have confirm if its still the case with those), and i’m none too sure about modern Volvos either, previous Volvos didn’t pressurise the trailer brakes with the park brake applied.
Easy enough to tell, when you connect up to a trailer is the yellow service line pressurised and as hard to fit as the red line?
I know MAN and Daf units apply the trailer brakes with the unit park brake, Scania at least pre EPB don’t.
Might be an idea to have a thread about this, i bet lots of drivers doing jobs that would be maybe safer with the trailer brakes applied as well could benefit.
** its something i had early warning about, in my early days on transporters i had a 9 car wag’n’drag carrier with an FL10 prime mover, literally never serviced at the cowboy outfit i worked at.
One day i’m loading the lorry and realised its moving slightly down the hill as i’m putting cars on…park brake only applied on the drive axle and the brake shoes were simply worn out, luckly on the Volvos you had the extra aitr operated switch you could pull out labelled Broms Brake, which once pressurised stayed out, this applied the trailer brakes, and wouldn’t release till you pushed it manually back in again.
That was an eye opening moment for me, for some reason since we’d lost the blue auxilliary brake line (operated by the secondary or dead man’s brake) i’d assumed the park brake on two line systems applied all, wrong.
This is the type of education we should be getting on our DCPC courses.
Something to keep the ‘already know it all’ types awake.
Looking at the…
Pic, the Skarneeea in question has a rear lift axle.
Of the few I’ve driven (way back when) I found them twitchy in the dry and bed wettingly nasty in the rain.
I have noticed the yellow line pressure doesn’t put the trailer brakes on as hard as when you drop the red line off.
ScaniaUltimate:
Juddian:
Reef:
Juddian:
Scanias don’t apply the trailer brakes when the park brake is appliedDo they not?
Nope (but someone with the latest versions with EPB will have confirm if its still the case with those), and i’m none too sure about modern Volvos either, previous Volvos didn’t pressurise the trailer brakes with the park brake applied.
Easy enough to tell, when you connect up to a trailer is the yellow service line pressurised and as hard to fit as the red line?
I know MAN and Daf units apply the trailer brakes with the unit park brake, Scania at least pre EPB don’t.
Might be an idea to have a thread about this, i bet lots of drivers doing jobs that would be maybe safer with the trailer brakes applied as well could benefit.
** its something i had early warning about, in my early days on transporters i had a 9 car wag’n’drag carrier with an FL10 prime mover, literally never serviced at the cowboy outfit i worked at.
One day i’m loading the lorry and realised its moving slightly down the hill as i’m putting cars on…park brake only applied on the drive axle and the brake shoes were simply worn out, luckly on the Volvos you had the extra aitr operated switch you could pull out labelled Broms Brake, which once pressurised stayed out, this applied the trailer brakes, and wouldn’t release till you pushed it manually back in again.
That was an eye opening moment for me, for some reason since we’d lost the blue auxilliary brake line (operated by the secondary or dead man’s brake) i’d assumed the park brake on two line systems applied all, wrong.This is the type of education we should be getting on our DCPC courses.
Something to keep the ‘already know it all’ types awake.
Agreed.
I learned about the trailer brakes being applied or not when parked, yonks ago, but, as with so many other things,it had found a quiet place in the dark reaches of my memory. Reading g Juddian’s explanation of the pressured yellow line brought it back. A timely reminder, as I now drive a Scania, and occasionally Volvo. Merc evidently pressurise the trailer brakes, as the yellow line is a fxxxxxxr to get on…
ScaniaUltimate
“This is the type of education we should be getting on our DCPC courses.
Something to keep the ‘already know it all’ types awake.”
Exactly what the DCPC is supposed to be about and would make it far more interesting. I was reading that in the US they have air brake instruction and tests for PSV’s so all these different configurations should be covered
Wermy:
ScaniaUltimate
“This is the type of education we should be getting on our DCPC courses.
Something to keep the ‘already know it all’ types awake.”Exactly what the DCPC is supposed to be about and would make it far more interesting. I was reading that in the US they have air brake instruction and tests for PSV’s so all these different configurations should be covered
I was just considering the same answer. CDL requires you to take an air brake test!
yourhavingalarf:
Looking at the…Pic, the Skarneeea in question has a rear lift axle.
Of the few I’ve driven (way back when) I found them twitchy in the dry and bed wettingly nasty in the rain.
You’d think that given the fifth wheel is behind the drive axle on a rear tag that the extra imposed weight on the drive axle (compared to a mid lift where its spread between the front and drive), that the rear lifter would have better drive axle grip…and this ceratinly applies when off road hence why almost all the artics which go off road are rear lifters.
But it doesn’t work like that in practice on the road, modern transporters are basically a tractor unit prime mover, and again the towing eye is behind the drive axle, most skittish wagon it’s been my misfortune etc.
Is it a case of the tail wagging the dog or what? undulations causing rebound at the front end causing the weight imposed on the steer axle to vary, ideal on wet bends , what is it that’s happening? the physics involved well above my pay grade.
Yes agree with the lads above, if such things were covered in the DCPC it would be far more worthwhile, however it would need people with the relevant practical knowledge to explain in laymans terms.
Punchy Dan:
I have noticed the yellow line pressure doesn’t put the trailer brakes on as hard as when you drop the red line off.
Be interesting to know the pressures involved, by nice if Norb or one of the other pro mechanics spotted this, they’d know the ins and outs.
There are some interesting videos that the US use for training their commercial drivers, a few words we probably don’t recognise.
One of these is “Compounding” when you put full pressure through the foot valve and activate the spring brakes simultaneously, this will bend the brackets and break the brakes apparently.
Looking at the big A in the circle, Seddon Atkinson have re-emerged and built a new prototype, which did indeed become a Sudden Accident.