gurj254:
No I don’t yet…
But you are “quite new on artics” 
Daz1970:
norb:
Must congratulate bking on his postsHear Hear!!! Great explanation, well written & easy to understand. Well done Bking.
Indeed well done !! Bking.we all started green behind the lugs and asked questions,got to learn somewhere 
p.s it seems some on here were born with a 2 speed axle hanging out of their arse 
midlifetrucker:
Classic. Someone asks a question and gets ■■■■ taken.
Well said, we all learn over the years, I have been driving trucks for 38 years and still don’t know exactly how some things work, I learn new things every day.
On saying that … I do read some posts on here and wonder how the hell some people get through life with so little knowledge ? 
norb:
If your red (Emergency line ) fails then the air from the brakes is exhausted and the trailer brakes will come one.
Had it happen although I wasn’t driving at the time. On the M6 on the limiter too. Thankfully we only had a few cages on and were in a straight line. Even then, the trailer still lurched to the left forcing the truck we were overtaking across the hard shoulder and onto the grass.
Could’ve been a hell of a lot worse, makes you wonder about what could’ve happened 
From a regular driver’s point of view it’s best to treat as needed to supply continuous air to the trailer to feed the suspension and release the spring parking brakes.
From a technical side Bking’s explanation (unsurprisingly) isn’t correct although should perhaps be applauded for managing not to rant. The red line does not solely affect the parking/spring brake part of the trailer brakes. The emergency relay valve monitors the pressure coming down the red line if it drops below a set pressure it sends an air ‘signal’ down the service line and applies full service brake output using the air stored in the trailer tanks to the trailer wheels. The yellow line works, in basic terms, as an air signal and depending on how strong it is controls how much the taps are effectively opened on the tanks (kept topped up by the red line supply) air is stored in on the trailer is released to the brakes.
This is why if the red line pops off whilst you’re on the motorway the result is so incredibly violent it’s a safety feature in case the trailer breaks away. The effect is the same as if you’d just stamped on the foot brake as hard as possible, as this is what’s being applied, not the spring parking brakes.
On another point, on modern tractor units, when the parking brake is applied generally the pressure isn’t exhausted from the trailer spring brakes thus using the springs to hold the brakes on typically the unit supplies pressure down the yellow line so the trailer is held with the same effect as having your foot on the foot brake.
A related piece of information, which is useful but often not well known by newbies, is that the first portion of the throw on the lever of the parking brake in the cab is what’s known as the secondary brake and as you pull it on it has the same effect as gradually applying the footbrake effectively eventually getting to full foot brake application when its pulled all the way and clicks on. You can use this in an emergency if the foot brake pedal failed, got something stuck under it or any scenario really as it’s as safe as the pedal really if a little unusual.
Some Tilts used to have 2 red air line connections, but sometimes they were disguised
And another small snippet of info on DAF at least ,with the handbrake on lift the collar and pull the lever back ,it is a test point and should release the trailer brakes ,but leave the unit handbrake applied.So it lets you check if they combination remains stationary with just the unit handbrake applied
Just adopt my attitude, I know where they go and how to connect them and if they dont work, call the office and get the fitter out.
Job done 
Hiya. well done for asking…i’am sure i’ve read on TN in the old days you got to find your way by asking.
this chap has asked and some members have taken the p…
heres a good one, on my lorry when theres no air i can still drive it round, but god she don’t stop.
John
bald bloke:
Wheel Nut:
Anyone who remembers the third blue line would know that as the Auxiliary line and these had a larger coupling called a CA Type. We also had air taps tooAh yes i remember the taps and blue line.
I remember being shown by an ex Middle East driver in the 80s how to transfer diesel from one truck to another using a tapped red line, as far as I remember you put the red line and a syphon pipe in the donor tank and made it airtight with a rag and tape, you put the other end of syphon pipe in other tank, started the engine to keep the air supply going, and switched on the tap.
I learned a lot of good tips (and bad practices like blanking off brake chambers, chaining up axles to …get home , stuff you would be jailed for today ) from these guys as a young lad.
the fub:
Just out of curiosity but do you actually have a licence
If you don’t ask you will never learn.Do you remember
the old vacuam brakes I wonder? 
guesty,
robroy:
bald bloke:
Wheel Nut:
Anyone who remembers the third blue line would know that as the Auxiliary line and these had a larger coupling called a CA Type. We also had air taps tooAh yes i remember the taps and blue line.
I remember being shown by an ex Middle East driver in the 80s how to transfer diesel from one truck to another using a tapped red line, as far as I remember you put the red line and a syphon pipe in the donor tank and made it airtight with a rag and tape, you put the other end of syphon pipe in other tank, started the engine to keep the air supply going, and switched on the tap.
I learned a lot of good tips (and bad practices like blanking off brake chambers, chaining up axles to …get home
It is the same principle as an aerosol can, you force air onto the liquid and the liquid will take the easiest route, up the syphon pipe, it is the same as a road tanker and is much better than getting a gob full of diesel. It will work with a piece of tight fitting rag, wood or a gloved hand too