Attaching trailer air brakes

There's a lot of sense been said on this thread, BUT there's also been a certain amount of inaccurate information (other descriptive terms may be used ;))

Because Ag. Tractor-Trailer air braking systems are quite a bit more complicated than the old hydraulic single-line trailer brakes, the following Guide was put together to help users understand how they work & how best to use them.

It's totally FREE ... You can either download it or request a Hardcopy from the following site:- https://aea.uk.com/look-behind-you/

Please get a copy & have a read ....... It might just prevent a nasty accident :rolleyes:
 

eulb

Member
There's a lot of sense been said on this thread, BUT there's also been a certain amount of inaccurate information (other descriptive terms may be used ;))

Because Ag. Tractor-Trailer air braking systems are quite a bit more complicated than the old hydraulic single-line trailer brakes, the following Guide was put together to help users understand how they work & how best to use them.

It's totally FREE ... You can either download it or request a Hardcopy from the following site:- https://aea.uk.com/look-behind-you/

Please get a copy & have a read ....... It might just prevent a nasty accident :rolleyes:
Lad was killed near here hitching up a trailer,as he walked round the back the air built up and released the brakes and it was game over.
 
Duo-matic, great bit of kit.
Get's my vote. When the (then new) European Union tractor-trailer braking regulations were being developed about 15 years ago, it was suggested we all standardise on the Duomatic coupler for dual-line air brakes - then mainly used in Italy ...... But regional politics & the Germans didn't want to move away from Palm-type couplers ....... So we carried on with an unregulated mix of everything ....... and continue to try & balance on oil-stained trailer drawbars whilst attempting to connect air lines :(
 
PLEASE DON'T CONNECT THE RED LINE LAST ....... When unhitching disconnect the Red line FIRST (applies trailer brakes straight away & so SAFER). When Hitching Up, Connect the Red line Last ...... that way trailer stays braked for longest. Connecting Red line has no effect upon the Yellow (Control) line ........ If a post-2017 tractor (and many earlier ones), if tractor handbrake is on, Yellow Line coupling will be pressurised.
You appear to have contradicted yourself here, first off saying please don’t connect the red line last then later saying connect the red line last.........that way the trailer stays braked for longest.
 
You appear to have contradicted yourself here, first off saying please don’t connect the red line last then later saying connect the red line last.........that way the trailer stays braked for longest.
Your completely right ...... and I'm completely WRONG ...... I should have read what I wrote more carefully :oops::oops::oops::oops:

What I meant to say was please Always REMOVE THE RED LINE 1ST ........ ALWAYS RECONNECT IT LAST ......... The Golden Rule is, whenever only one of the two Suzies is connected to the tractor, it should ALWAYS BE THE YELLOW LINE, never the Red Line.
 
Your completely right ...... and I'm completely WRONG ...... I should have read what I wrote more carefully :oops::oops::oops::oops:

What I meant to say was please Always REMOVE THE RED LINE 1ST ........ ALWAYS RECONNECT IT LAST ......... The Golden Rule is, whenever only one of the two Suzies is connected to the tractor, it should ALWAYS BE THE YELLOW LINE, never the Red Line.
I certainly can’t claim to be right because I don’t know, I assumed you had made an error so just wanted to bring it to your attention for clarification
 

killie_cowboy

Member
Livestock Farmer
Location
Scottish Borders
Yeah because the air will hold the brakes on when parked up so you need to empty the tanks to use oil
Unless theres something I've missed out some of you are missing how air brakes actually work. Theres a strong spring pressing the rod out the actuator onto the brake lever, the red line then pressurises one section of the brakes to compress this spring and let your trailer move, this is why your trailer doesnt move when parked and why you need to wait for air to build before you move so it doesnt matter if theres a leak, your trailer isnt going anywhere. There is then another section within the actuator which your yellow service hose feeds and this is your on demand braking. Something I have wondered though is how the push to shunt actually works. We dont have as of yet any air braked trailers on the farm though we have a Redrock tanker ordered with them so shall see how that goes and will possibly put a kit on the 12 ton Marshall silage cart if its worth it.
 

Lincsman

Member
Arable Farmer
Location
Lincolnshire
Unless theres something I've missed out some of you are missing how air brakes actually work. Theres a strong spring pressing the rod out the actuator onto the brake lever, the red line then pressurises one section of the brakes to compress this spring and let your trailer move, this is why your trailer doesnt move when parked and why you need to wait for air to build before you move so it doesnt matter if theres a leak, your trailer isnt going anywhere. There is then another section within the actuator which your yellow service hose feeds and this is your on demand braking. Something I have wondered though is how the push to shunt actually works. We dont have as of yet any air braked trailers on the farm though we have a Redrock tanker ordered with them so shall see how that goes and will possibly put a kit on the 12 ton Marshall silage cart if its worth it.
Not on a farm trailer... no air = no brakes... its so it can then be hydraulic on another tractor after draining air out.
 

killie_cowboy

Member
Livestock Farmer
Location
Scottish Borders
Not on a farm trailer... no air = no brakes... its so it can then be hydraulic on another tractor after draining air out
Right, so how does that work then with the two hoses? If theres no spring whats the point in the emergency line and how does that work the brakes lock when its out? Why does it need to build pressure to move off aswell? is there a sort of airbag in place of the spring or?
 

Andrew

Member
Location
Huntingdon, UK
On most ag and older hgv trailers the brake actuators are sprung OFF.
The red line fills the air tanks on the trailer. The yellow line acts as a signal to the RELAY valve that uses air pressure from the air tank to apply the brakes. The yellow line does not apply the brakes. The relay valve also senses any drop in pressure in the red line and applies the brake if so using the air pressure from the air tanks.
This is why when you disconnect the red line you have brakes on, but drain the air out and the brakes will release - which is why a mechanical handbrake is a legal requirement.
A shunt valve can also be fitted, which sends air from the trailers tanks into the red line port of the relay valve, fooling it into thinking the airlines have been connected and releasing the brakes.

More modern HGV trailers use spring ON brakes, which have an extra port. Air pressure is needed to release the brakes, but then the system generally works as above.
This negates the need for a separate mechanically appllied handbrake.
 

killie_cowboy

Member
Livestock Farmer
Location
Scottish Borders
On most ag and older hgv trailers the brake actuators are sprung OFF.
The red line fills the air tanks on the trailer. The yellow line acts as a signal to the RELAY valve that uses air pressure from the air tank to apply the brakes. The yellow line does not apply the brakes. The relay valve also senses any drop in pressure in the red line and applies the brake if so using the air pressure from the air tanks.
This is why when you disconnect the red line you have brakes on, but drain the air out and the brakes will release - which is why a mechanical handbrake is a legal requirement.
A shunt valve can also be fitted, which sends air from the trailers tanks into the red line port of the relay valve, fooling it into thinking the airlines have been connected and releasing the brakes.

More modern HGV trailers use spring ON brakes, which have an extra port. Air pressure is needed to release the brakes, but then the system generally works as above.
This negates the need for a separate mechanically appllied handbrake.
Ahhh, makes sense now, thanks for that.
 
Unless theres something I've missed out some of you are missing how air brakes actually work. Theres a strong spring pressing the rod out the actuator onto the brake lever, the red line then pressurises one section of the brakes to compress this spring and let your trailer move, this is why your trailer doesnt move when parked and why you need to wait for air to build before you move so it doesnt matter if theres a leak, your trailer isnt going anywhere. There is then another section within the actuator which your yellow service hose feeds and this is your on demand braking. Something I have wondered though is how the push to shunt actually works. We dont have as of yet any air braked trailers on the farm though we have a Redrock tanker ordered with them so shall see how that goes and will possibly put a kit on the 12 ton Marshall silage cart if its worth it.
Sorry, I'm afraid you're talking about 'dual' pneumatic brake chambers / brake actuators as fitted to Commercial vehicles. They do (as you describe) have one chamber responsible for spring-operation of the Parking Brake and a 2nd chamber which operates the Service Brakes, once the Parking brake has been 'pressurised-off'. That's these sort of things (see below - left).

However, at the moment these type of brake actuators are VERY RARELY used on agricultural trailers or trailed implements fitted with dual-line air braking system ... although they are becoming slightly more common on really big stuff. Instead most are fitted with what's known as 'Dual-Supply' brake actuators .... which is a single-acting air chamber with a hydraulic ram grafted onto the front (see below - right). This enables the trailer's brakes to be operated EITHER pneumatically or hydraulically ... NEVER both at same time!. Dual-line air brake systems on towed ag. vehicles still give an emergency/failsafe operation when the Red/Supply line is disconnected, BUT only as long as there is pressure in the trailer reservoir. Once this is depleted you've no brakes.

So here's the thing. People who know about air brakes on trucks think that air brakes on tractors & trailer work in exactly the same way. I'm afraid that's not the case. In many respects they do use similar components and the systems might appear to be the same, but THEY ARE NOT THE SAME. Please don't make assumptions ....... it could be dangerous.
 

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roscoe erf

Member
Livestock Farmer
Unless theres something I've missed out some of you are missing how air brakes actually work. Theres a strong spring pressing the rod out the actuator onto the brake lever, the red line then pressurises one section of the brakes to compress this spring and let your trailer move, this is why your trailer doesnt move when parked and why you need to wait for air to build before you move so it doesnt matter if theres a leak, your trailer isnt going anywhere. There is then another section within the actuator which your yellow service hose feeds and this is your on demand braking. Something I have wondered though is how the push to shunt actually works. We dont have as of yet any air braked trailers on the farm though we have a Redrock tanker ordered with them so shall see how that goes and will possibly put a kit on the 12 ton Marshall silage cart if its worth it.
oops :)
 

Bloders

Member
Location
Ruabon
Sorry, I'm afraid you're talking about 'dual' pneumatic brake chambers / brake actuators as fitted to Commercial vehicles. They do (as you describe) have one chamber responsible for spring-operation of the Parking Brake and a 2nd chamber which operates the Service Brakes, once the Parking brake has been 'pressurised-off'. That's these sort of things (see below - left).

However, at the moment these type of brake actuators are VERY RARELY used on agricultural trailers or trailed implements fitted with dual-line air braking system ... although they are becoming slightly more common on really big stuff. Instead most are fitted with what's known as 'Dual-Supply' brake actuators .... which is a single-acting air chamber with a hydraulic ram grafted onto the front (see below - right). This enables the trailer's brakes to be operated EITHER pneumatically or hydraulically ... NEVER both at same time!. Dual-line air brake systems on towed ag. vehicles still give an emergency/failsafe operation when the Red/Supply line is disconnected, BUT only as long as there is pressure in the trailer reservoir. Once this is depleted you've no brakes.

So here's the thing. People who know about air brakes on trucks think that air brakes on tractors & trailer work in exactly the same way. I'm afraid that's not the case. In many respects they do use similar components and the systems might appear to be the same, but THEY ARE NOT THE SAME. Please don't make assumptions ....... it could be dangerous.
why the difference between Ag and trucks?
(i guess cost or something)

what i dont understand is why they didnt introduce twin line hydraulics the same, rather than using the accuulator (so now, if accumulator fails, you dont have a "fail safe" system, whihc actually means IMO, they system is not fail safe at all?)
 

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Man fined £300 for bonfire-related waste offences

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Written by William Kellett from Agriland

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A man has pleaded guilty at Newtownards Magistrates’ Court to waste offences relating to a bonfire next to the electrical sub-station on the Circular Road in Newtownards, Co. Down.

Gareth Gill (51) of Abbot’s Walk, Newtownards pleaded guilty to two charges under the Waste and Contaminated Land (Northern Ireland) Order 1997, for which he was fined £150 each and ordered to pay a £15 offender’s levy

On June 25, 2018, PSNI officers went to Gill’s yard, where they found a large amount of waste consisting of scrap wood, pallets, carpet and underlay.

Discussion with Northern Ireland Environment Agency (NIEA) officers confirmed the site...
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