Lusk:
OK, so a truck and trailer (atric) are going down the motorway at 56 mph when all of a sudden the red air line fails. What would you expect to happen?
(The truck is a couple of years old and I’m not sure whether the trailer has ABS or EBS)
Had it happen. Unsurprisingly, the trailer wheels locked on and drifted sideways almost forcing another driver off the road. The driver (I was passenger) managed to get the unit onto the hard shoulder and the trailer was blocking the inside lane off but initially it drifted into the hard shoulder as we were overtaking someone. He slammed the brakes and swerved across and had half his wheels on the grass but managed to miss us.
Absolute fluke no one was hurt or no damage was done.
Lusk:
I’m not sure although suspect possible damage prior which weakened it.
should have been spotted on pre use checks though
But you said it should of been found on pre trip checks, I’m saying not necessarily.
Are you saying you stretch the suzies out and examine them fully before use?
I’ll refrain from callin you a ■■■■. A quick check for kinks and nicks would do as would checking for leaks. Also if jacknifing a trailer its best to not over stretch much like having too many Gareth Hunts will cause friction and damage equipment my old son
There could still be previous weakening that you can’t see. It like saying checking a tyre will guarantee you won’t get a blowout whilst you are on the road. But if you say so I bow to your superior knowledge…
There’s always a risk. What I’m saying is as long as you check your equipment you reduce the likelihood of failure. Not like the previous post … by stretching out the air line… that’s just being dumb.
You said it should have been spotted in pre trip checks. I’m saying not necessarily.
Had this happen to me once south of Bristol ( A38 Redhill ) at about 40mph, surprisingley it was only the drive axle 4 tyres that got flat spots. Was empty at the time on a dry road surface about 6 am road nice and quiet so no problem.
Lusk:
OK, so a truck and trailer (atric) are going down the motorway at 56 mph when all of a sudden the red air line fails. What would you expect to happen?
(The truck is a couple of years old and I’m not sure whether the trailer has ABS or EBS)
Had it happen. Unsurprisingly, the trailer wheels locked on and drifted sideways almost forcing another driver off the road. The driver (I was passenger) managed to get the unit onto the hard shoulder and the trailer was blocking the inside lane off but initially it drifted into the hard shoulder as we were overtaking someone. He slammed the brakes and swerved across and had half his wheels on the grass but managed to miss us.
Absolute fluke no one was hurt or no damage was done.
I am not sure if that was a question you were asking, but yes, this did actually happen and I cant understand why it jacknifed because as you can see from most of the replies, everybody to whom this has happened to, they have simply been stopped by the trailer very quickly.
neilg14:
About 9 or 10 year ago, a few mile south of Markham Moor on the A1, a tipper overtook a Reed Boardall (IIRC) & after he had pulled back in, his red line parted.
Reed Boardall ploughed into the back of him & his reefer shot the pin & crushed his cab against the tipper.
The driver sadly died immediately.
I’ve been out and about today and the amount of artics who have overtaken me and then pulled immediately back in has been amazing. And on each time this happened, I’ve been thinking about that little old £20 piece of air line…frightening really!!
FarnboroughBoy11:
I had a dodgy valve in my red airline a couple of weeks back, when ever I dropped a trailer and was solo I had to kink it to stop the air ■■■■■■■ out…
… weakening the airline & increasing the risk of failure ■■
jackslad:
Has anyone had this happen with a loaded trailer,
Yes but it was with single acting chambers years ago,they applied full service brake pressure to the chambers and they locked out solid,now you just get spring pressure so shouldnt get full lock out just a hard brake on the trailer bogey as they are only rated at 16% GVW.
Hiya…from what i’am reading you new driver,s can tell by doing a before trip inspection if
a tyre is going to blow out sometime in the day before you start your trip. how do you know that■■?
you now say you can even tell if a airline is going to give way WOW.
I,ve picked up trailer,s in Dover that have travelled across europe on roads what was just stones.
some tyres have had wire showing(you don’t see that today)large chuncks missing from the tyre wall
plus been as much as 20 tons over loaded. yes all dangerious,but it happened years ago. can i say
i never had a blow out although the tyres was Knackered, where did you get a tyre. there was no tyrevans
like today. we did,nt have plastic like today(and who has money in their bank accout to buy SOME tyres)
we did carry a spare but what use was that when you maybe needed 4 or 5.you needed to risk the trip.
I,am not knocking you newer drivers. i would like to know by looking at a tyre if its giong to
blowout sometime in the day, or the trip. infact i know of a new tyre been fitted to a tubless rim,
a driver was sitting on it having a cup of tea one saturday mornig. the side wall blew out and put
the driver in hospital.the new tyre and wheel had not even been fitted on the lorry.
old John
3300 john you are the problem.
Everybody has to learn and if people like you just sit back and laugh at ■■■■ ups made by people new to the job with no experience then we really are going to progress arnt we!
The real answer is to pass on what you know not bloody sit there with a bloody smug smile on your face while you watch some “newbie” ■■■■■ it up.
WE all have to learn and if we have to learn then who better to learn from than the people who have done the job?
Bugger your “cpc” give me a week with a man who knows the job,who has done the job, who can ■■■■ the job and then a “newbie” will know more in that 7 days than all that cpc bollox will ever teach him.
jackslad:
Has anyone had this happen with a loaded trailer,
Yes but it was with single acting chambers years ago,they applied full service brake pressure to the chambers and they locked out solid,now you just get spring pressure so shouldnt get full lock out just a hard brake on the trailer bogey as they are only rated at 16% GVW.
No, the emergency relay valve (which is located on the yellow line circuit) operates on the service portion of the spring brake chamber, applying full tank pressure, it doesn’t exhaust the spring portion. This is why the lock-up is so violent, the system isn’t designed for a gentle slow down it works on the basis the trailer has become detached from the unit if the red line has snapped and applies maximum braking force.
Generally the only time the trailer is held by the spring portion of the chamber these days is if the trailer is separated from the unit and either all the air has seeped from the tanks or the parking brake knob on the trailer is pulled out.
On the EBS point newer generation ones where there’s no longer a separate emergency relay valve in the yellow line circuit and the emergency relay valve is actually contained within the EBS block itself can do cleverer things, I think, but may have to be enabled. I’m surprised they’re allowed to do this as I’m not sure how it functions if there’s no electrical supply, maybe a rechargeable back-up battery but would seem dangerous.
One day own own account driver we will sit down and I will explain to you how a semi trailer braking system works because to put it in a nut shell my bloody cat knows more than you do.
And a little knowledge is a very dangerous thing.
You couple the red line push the park valve and away you go(as most professional yard shunters do) so where the hell is this emergency relay valve at this point if not in circuit,on holiday in bloody cyprus.
FarnboroughBoy11:
I had a dodgy valve in my red airline a couple of weeks back, when ever I dropped a trailer and was solo I had to kink it to stop the air ■■■■■■■ out…
… weakening the airline & increasing the risk of failure ■■
Yes, until I got back to base to change it in our workshop… But I suppose in this day and age of health and safety and bone idle morons that can’t think for themselves, I should of just called a fitter out and cost the family run business £300+.
The red airline pops off the trailer locks up simple. And don’t have a go at john, the trouble is now a lot of drivers are just that and no more, have imagination and if something goes wrong they haven’t a clue and won’t dare do anything out of the ordinary.
Bking:
You couple the red line push the park valve and away you go(as most professional yard shunters do) so where the hell is this emergency relay valve at this point if not in circuit,on holiday in bloody cyprus.
The park brake hand valve either exhausts or supplies the the spring portion of the chamber with air. The trailer emergency relay valve is situated in both red and yellow supply lines but only really is doing much on the yellow where it boosts the air ‘signal’ down the trailer (hence relay) and monitors the red line pressure is high enough (hence emergency). The red line really just passes through on its way to filling the trailer tanks.
The red line severs, supply from the red line to the emergency relay valve is cut and full signal goes down the yellow line, there will be some load-sensing modulation probably to what is applied to the service portion of the chambers.
You can get EBS trailers where the modulator is of the type where the load-sensing and the emergency relay valve is effectively contained within in it and there are some makes that do exhaust the spring part of the chambers rather than apply full service effort but these aren’t really common or standard.
Setting aside the fact you post in the style of the world’s angriest bell end I think your problem is you are taking your limited experience with the very limited amount of kit that Tescos run and then posting it in a manner that implies this is common or standard and then there’s the stuff that is just outright incorrect.
Bking:
You couple the red line push the park valve and away you go(as most professional yard shunters do) so where the hell is this emergency relay valve at this point if not in circuit,on holiday in bloody cyprus.
The park brake hand valve either exhausts or supplies the the spring portion of the chamber with air. The trailer emergency relay valve is situated in both red and yellow supply lines but only really is doing much on the yellow where it boosts the air ‘signal’ down the trailer (hence relay) and monitors the red line pressure is high enough (hence emergency). The red line really just passes through on its way to filling the trailer tanks.
The red line severs, supply from the red line to the emergency relay valve is cut and full signal goes down the yellow line, there will be some load-sensing modulation probably to what is applied to the service portion of the chambers.
You can get EBS trailers where the modulator is of the type where the load-sensing and the emergency relay valve is effectively contained within in it and there are some makes that do exhaust the spring part of the chambers rather than apply full service effort but these aren’t really common or standard.
Setting aside the fact you post in the style of the world’s angriest bell end I think your problem is you are taking your limited experience with the very limited amount of kit that Tescos run and then posting it in a manner that implies this is common or standard and then there’s the stuff that is just outright incorrect.
So if you dont have the yellow line connected how does it supply full “signal” pressure to the brakes if the red splits ,You like a lot on here spout crap you know nothing about,And yes I work for tesco at the moment but I have been in this job 40 years.And as I say your knowledge of vehicle braking systems is to pay it a compliment at best a joke at worst crap.
OK monkey here we go.Red line yellow line got it.
Red feeds air tank on trailer tank then once it reaches 9 bar then feeds suspension tank then rear steer tank and bag if fitted.Main supply through ERV to tank.tank charges to tractor pressure.ERV supplies tank pressure to membrane in quick release valve closing exhaust port and supplying air to spring brake chamber to release brakes
With me so far?
Remove pressure to ERV(remove red line) and cuts off air supply to top of quick release valve membrane,membrane lift off exhaust seat and pressure in spring chambers can then exhaust to atmosphere allowing the springs to apply the brakes.
As for"amplification " of signal pressure its done by the simple application of Boyles law which as such an informed gent that you are no doubt fully aware of,where the surface area can make all the difference.eg Impose a load of 100 psi on 1 square millimeter then a load of 1 psi on an area on 101 square millimeters on the opposite side of the membrane face will have the higher loading.Would have thought this was simple to a man of your intellect.Now if you need to know how the yellow line or abs works please feel to get in touch
jackslad:
Has anyone had this happen with a loaded trailer,
Yes but it was with single acting chambers years ago,they applied full service brake pressure to the chambers and they locked out solid,now you just get spring pressure so shouldnt get full lock out just a hard brake on the trailer bogey as they are only rated at 16% GVW.
No, the emergency relay valve (which is located on the yellow line circuit) operates on the service portion of the spring brake chamber, applying full tank pressure, it doesn’t exhaust the spring portion. This is why the lock-up is so violent, the system isn’t designed for a gentle slow down it works on the basis the trailer has become detached from the unit if the red line has snapped and applies maximum braking force.
Generally the only time the trailer is held by the spring portion of the chamber these days is if the trailer is separated from the unit and either all the air has seeped from the tanks or the parking brake knob on the trailer is pulled out.
On the EBS point newer generation ones where there’s no longer a separate emergency relay valve in the yellow line circuit and the emergency relay valve is actually contained within the EBS block itself can do cleverer things, I think, but may have to be enabled. I’m surprised they’re allowed to do this as I’m not sure how it functions if there’s no electrical supply, maybe a rechargeable back-up battery but would seem dangerous.
This is exactly how it works Own Account Driver… as soon as the RE Valve senses a drop in pressure in the red air line (i.e through red air line supply pressure fault), it applies the service brake and NOT the handbrake.
Moving on to the trailers which are fitted with newer version EBS, I thought that if the trailer was , say, going down the motorway flat out and the red air line failed, assuming the ISO lead was still functional then the system would not go into emergency mode. Emergency mode would only happen when the system was going at a speed equal to that which puts the EBS warning light out.
Bking:
You couple the red line push the park valve and away you go(as most professional yard shunters do) so where the hell is this emergency relay valve at this point if not in circuit,on holiday in bloody cyprus.
The R.E valve is situated before the park shunt valve.
