Red air line failure - at speed

UK PROFESSIONAL DRIVERS FORUMS THE UK PROFESSIONAL DRIVERS FORUM (INTERACTIVE)
61

Bking:

Own Account Driver:

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.

In this scenario if the yellow air line were not to be connected and if the red air line split, then the R.E valve (relay emergency) would sense this and send FULL trailer air tank system pressure to the SERVICE brake portion of the brake chambers.

62

Bking:
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?

What is an ERV? Not every trailer will have quick release valves for the hand brake section of the chamber as it is not necessary to remove air quickly from the chamber. This is distinct from the service side as it is imperative that air is removed immediately from the chamber when the driver releases his foot from the brake.

Bking:
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.

At no point when the red air line is disconnected in a properly functioning semi trailer air brake system is the air ever exhausted from the spring brake portion of the anchorlock chamber.

Bking:
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

63

Bking:
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” [zb] it up.
Hiya…sorry to upset you BKing…it was how the reading pointed that you could determine if a tyre would
have a blow out within the day. now i think that is fooling drivers as they and i cannot for see a blowout.
John

64

Bking:
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

Let’s be honest, you’ve been an apprentice fitter for closer to 4 months than 40 years. That doesn’t mean you might not have something worth posting but the problem is you post a lot of incorrect nonsense as gospel and someone finding it from google might take it on an unqualified basis. I can help you with the numbers though in February this year you had 35 years experience yet in a little over six months you’ve somehow managed to get another 5 years under your belt.

viewtopic.php?t=95976&p=1407451

by Bking » Sat Feb 09, 2013 3:44 am

Ever been under trailers No never(only 5 nights a week) but I have a very well informed friend that tells me i talk an absolute load of ■■■■■■■■.

because I know absolutely [zb] all bout the the trucks I repair.Even after 35 years some driver can diagnose the “problem” for me

Maybe thats something you should take up with your union.

Stop being some smart arse [zb] and leave it to to the people who know what the hell they are doing
thankyou

I know what I do so dont feed me amatuer crap.

This is all very familiar, from that thread. Here it is from the horse’s mouth (Knorr Bremse), because I can’t be bothered any more and much of your ■■■■■■■■ now is still the same ■■■■■■■■ I’ve corrected before.

The Relay Emergency Valve transmits the brake demand of the driver to
the trailer’s service brakes.
In the event of a loss of pressure in the trailer Supply (Red) line, for example
from an intentional or accidental uncoupling, the emergency feature of the
valve will automatically apply the trailer service brakes using the air stored in
the trailer reservoir. This function is also apparent when charging the trailer
from zero pressure; the trailer service brakes will be partially applied until the
charge pressure exceeds approximately 3.0 bar

Not sure why poor old Boyle and his law find themselves unwittingly dragged into this. It’s a ‘relay’ valve, you see an identical idea to the electrical relay that uses a small trigger current to switch a larger one. With the air one it uses a small air input from the yellow line to transmit a larger one down the trailer. You can think of the trailer air tanks as batteries, in this context.

As a point of interest, to anyone that might have ploughed through this thread, and followed it. This is all the actual mechanics behind how the shunt button works. By pushing the shunt valve in it allows air to flow to the emergency relay valve ‘tricking’ it into thinking the red line is attached and releasing (for the umpteenth time) the service brakes.

Also can you please give your one man crusade to introduce the word membrane into the truck repair lexicon a break, it’s diaphragm - also for the umpteenth time.

65

I’ve just read the topic which was mentioned in the post above…I need oxygen :grimacing: :grimacing: I can see that you two obviously have some sort of love / hate relationship going on there!! Have to say, I’ve had a real chuckle at some of the words mentioned in this topic…‘bell end’ for one!!

Anyway, moving on. Having gone back through this topic, it would appear that nobody (fortunately) has been in the situation where they have got into a jacknife which makes me wonder whether there is more to meets the eye with this incident than the driver alleges.

The one good thing I’ve learnt from this topic is being very wary of artics which just cut back in front of you when on the motorway. Even today, I’ve been poised just in case that little bit of plastic should give way.

66

Lusk:
Anyway, moving on. Having gone back through this topic, it would appear that nobody (fortunately) has been in the situation where they have got into a jacknife which makes me wonder whether there is more to meets the eye with this incident than the driver alleges.

I think so.

67

FarnboroughBoy11:

Lusk:
Anyway, moving on. Having gone back through this topic, it would appear that nobody (fortunately) has been in the situation where they have got into a jacknife which makes me wonder whether there is more to meets the eye with this incident than the driver alleges.

I think so.

I’m suprised no one has mentioned the foo foo valve?

68

I had the coupling fall off the front of the trailer (it had been cross threaded) at 60mph on a steel sprung spread axle tandem, it was empty and it locked the wheels instantly and slid straight down the camber into what would’ve been the hard shoulder, except there wasn’t one as I was in roadworks, I dragged about half a mile of orange plastic netting and little flares (it was in Italy) down the road with me :blush:

Eight tyres with big flat spots and a mile long set of skidmarks on the road (only a bit longer than the ones in my boxers) had to whip the outer tyres off and spin them half a turn to stop the flat spots on the tyres giving it a square wheeled effect.

Having experienced the phenomenon, I cannot see how it could cause a jack knife, as the trailer is trying to go slower than the unit, so will not have the momentum needed to push the unit around into a jack knife situation.

Although stranger things have happened :open_mouth:

69

Mike-C:

FarnboroughBoy11:

Lusk:
Anyway, moving on. Having gone back through this topic, it would appear that nobody (fortunately) has been in the situation where they have got into a jacknife which makes me wonder whether there is more to meets the eye with this incident than the driver alleges.

I think so.

I’m suprised no one has mentioned the foo foo valve?

and the giggle pin, if that fail’s at speed, it really will jack knife on you…

70

philgor:
I’m suprised no one has mentioned the foo foo valve?

not heard that one for a while

71

Mike-C:

FarnboroughBoy11:

Lusk:
Anyway, moving on. Having gone back through this topic, it would appear that nobody (fortunately) has been in the situation where they have got into a jacknife which makes me wonder whether there is more to meets the eye with this incident than the driver alleges.

I think so.

I’m suprised no one has mentioned the foo foo valve?

Am I going to regret asking what a foo foo valve and giggle pin is?? :slight_smile:

72

FarnboroughBoy11:

Mike-C:

FarnboroughBoy11:

Lusk:
Anyway, moving on. Having gone back through this topic, it would appear that nobody (fortunately) has been in the situation where they have got into a jacknife which makes me wonder whether there is more to meets the eye with this incident than the driver alleges.

I think so.

I’m suprised no one has mentioned the foo foo valve?

Am I going to regret asking what a foo foo valve and giggle pin is?? :slight_smile:

Not at all, they both are found under the double underhand crapshaft.

Hth. :wink:

73

One last question ,how does a trailer tank at “zero pressure” from your quote apply the trailer brakes?

A big chock sticks itself under the wheels or divine intervention?

Maybe it ■■■■■ em on like a train?
please do tell?

74

Bking:
One last question ,how does a trailer tank at “zero pressure” from your quote apply the trailer brakes?

A big chock sticks itself under the wheels or divine intervention?

Maybe it ■■■■■ em on like a train?
please do tell?

Email Knorr Bremse and ask them ,they wrote it, maybe they do some sort of training course you can go on. I suspect the reply you will get is an explanation of how the springs in spring brake chambers are applied - which is not when the emergency relay valve has no pressure from the red line.

I can tell you where you’ve gone wrong, and should have earlier but, it’s too tempting to extract more ■■■■■■■■ from you. Tescos will probably have kit with either, very modern, park and shunt valves with a built in emergency function or some sort of Pownall brake type affair retro-fitted safety kit. Which you’re barking up the sort of right tree in how they work BUT this is not how trailer emergency relay valves as most fitters would know them function and ones with 40 years experience are frankly highly unlikely to be mashing up the two. VOSA felt the need to say this to testers on introduction, by Knorr Bremse of these combined valves - I actually disagree with them I don’t think spring brakes are acceptable in a trailer breakaway scenario.

This manufacturer has the option of not fitting a Relay Emergency valve.
If not fitted the first thing you will notice about this system is when you disconnect the Red emergency
line to conduct the shunt test, the parking spring brakes are applied and not the service brake. This is
acceptable.

As I said previously you’ve taken your small amount of, sort of right-ish, knowledge of kit uniform across the Tesco fleet and generalised it across everything in the lorry world as fact.

75

I had a problem with the valve inside the red air line a few weeks back.

The trailer brakes started dragging, so i stopped and reconnected the ABS & air line, trailer brake on & off, etc, but the problem still persisted. Air pressure seemed ok, no kinks or damage to the air line and I’d had no problems earlier. Didn’t get much further though until the trailer brakes came on fully.

I was only going slow, I can imagine it’s a scary moment if it happens at speed :open_mouth:

76

Own Account Driver:

Bking:
One last question ,how does a trailer tank at “zero pressure” from your quote apply the trailer brakes?

A big chock sticks itself under the wheels or divine intervention?

Maybe it ■■■■■ em on like a train?
please do tell?

Email Knorr Bremse and ask them ,they wrote it, maybe they do some sort of training course you can go on. I suspect the reply you will get is an explanation of how the springs in spring brake chambers are applied - which is not when the emergency relay valve has no pressure from the red line.

I can tell you where you’ve gone wrong, and should have earlier but, it’s too tempting to extract more ■■■■■■■■ from you. Tescos will probably have kit with either, very modern, park and shunt valves with a built in emergency function or some sort of Pownall brake type affair retro-fitted safety kit. Which you’re barking up the sort of right tree in how they work BUT this is not how trailer emergency relay valves as most fitters would know them function and ones with 40 years experience are frankly highly unlikely to be mashing up the two. VOSA felt the need to say this to testers on introduction, by Knorr Bremse of these combined valves - I actually disagree with them I don’t think spring brakes are acceptable in a trailer breakaway scenario.

This manufacturer has the option of not fitting a Relay Emergency valve.
If not fitted the first thing you will notice about this system is when you disconnect the Red emergency
line to conduct the shunt test, the parking spring brakes are applied and not the service brake. This is
acceptable.

As I said previously you’ve taken your small amount of, sort of right-ish, knowledge of kit uniform across the Tesco fleet and generalised it across everything in the lorry world as fact.

And just when I thought this topic had rolled over and died :grimacing: :grimacing:

So here we go, round 44… :grimacing: :grimacing:

Bking:
One last question ,how does a trailer tank at “zero pressure” from your quote apply the trailer brakes?

The mechanical force exerted by the spring brake applies the brakes.

Own Account Driver:
I can tell you where you’ve gone wrong, and should have earlier but, it’s too tempting to extract more ■■■■■■■■ from you.

Go on Own Account Driver, I am enjoying this :grimacing:

Own Account Driver:
Tescos will probably have kit with either, very modern, park and shunt valves with a built in emergency function or some sort of Pownall brake type affair retro-fitted safety kit. Which you’re barking up the sort of right tree in how they work BUT this is not how trailer emergency relay valves as most fitters would know them function and ones with 40 years experience are frankly highly unlikely to be mashing up the two. VOSA felt the need to say this to testers on introduction, by Knorr Bremse of these combined valves - I actually disagree with them I don’t think spring brakes are acceptable in a trailer breakaway scenario.

I totally agree with you Own Account Driver. It seems wrong that in the event of a trailer (fitted with this Pownall system) becoming detached, that legislation has deemed the application of the handbrake (as distinct from the service brake) to be satisfactory. Correct me if I am wrong, but upon presenting a trailer for test, Isn’t the minimum effort in the service brake twice that of the hand brake - I think the hand brake is 16%. I may well be wrong again, but I have a feeling that Pownall have applied for, and have been awarded a patent for their innovative design. Once change in legislation could potentially see there business model wiped out…:open_mouth:

77

Tesco have the greatest braking system in the world.
They have “developed” a system far in advance of westinghouse,Ae,Haldex etc that work on a totally different concept to air putting the brakes on or pulling the brakes off.

They work on [zb].
As do a lot of contributers on here.

78

Lusk what the hell is a “handbrake” on a trailer?

When you take a trailer for test and they ask you to apply park brake what the hell do you think they are asking you to apply?

The bloody spring chambers as a secondary brake system doh!

all air is dumped from chambers and the trailer is on stand alone braking.

Know what your talking about before you spout crap,You might end up sounding like your mate OAD

79

Bking:
Tesco have the greatest braking system in the world.
They have “developed” a system far in advance of westinghouse,Ae,Haldex etc that work on a totally different concept to air putting the brakes on or pulling the brakes off.

They work on [zb].
As do a lot of contributers on here.

Here’s your esteemed employer’s advanced emergency trailer breakaway system in action:

What we can observe is one of their trailers, potentially maintained by someone with seemingly little or no understanding of how they work, in the emergency breakaway scenario. Immediately, we can also see, their sophisticated system of planting trees along the side of the road leaps into action to supplement the insufficient braking force of the springs to prevent further carnage.

In exhibit B we have what appears to be a trailer with a traditional emergency relay valve fitted apparently not requiring the sophisticated trees planted at the side of the road system at all.

Exhibit A - ('You shop, we drop - they aren’t kidding)

Exhibit B -

80

Bking:
Lusk what the hell is a “handbrake” on a trailer?

When you take a trailer for test and they ask you to apply park brake what the hell do you think they are asking you to apply?

The bloody spring chambers as a secondary brake system doh!

all air is dumped from chambers and the trailer is on stand alone braking.

Know what your talking about before you spout crap,You might end up sounding like your mate OAD

What’s this someone’s put ‘hand brake’ instead of ‘parking brake’?

It’s all become clear now you’ve highlighted this on a point of pedantry. Everything you’ve been saying is right all along, I take it all back.