Air brakes

[snipe]

Just wanting to know if there are some standard air pressures for trailer air brakes. I’d like to know at what pressure i should see the trailers brake chambers start to move, and at what pressure I should have maximum braking.

thanks.

 

[njneer]

Basic system would be 8 to 10 bar.
Bare minimum would be 5 bar max 8 to 10 Bar.
Approx 0.5 Bar should start to move the actuators.
All depends on the trailer system though .
Not all 10stud axles are “commercial” axles
Does it have proper load sensing?
We had an old low loader with air brakes and load sensing we loaded it up with the digger and put a gauge on the line at the actuator and adjusted the load sensing valve with the. Rake pressed to provide the max 8 bar pressure at the actuator to ensure maximum braking when loaded.
It did however make the brakes snatch and lock when empty though but we felt better to have the max brakes withnload and cope with the snatchy brakes when empty.

 

[ollandroverman]

i believe the brake pressure curve has now changed with the introduction of the relatively recent"Mother Regs", and, if i am correct with this..., are now the same as HGVs brake pressure curves.
In other words, there is something of an incompatibility between older tractor and newer trailers.
Putting a pre-mother regs air-braked tractor onto a new HGV air-braked trailer can result in instantaneous full trailer lockup whilst running empty just from the brake pilot pressure.

 

[njneer]

i believe the brake pressure curve has now changed with the introduction of the relatively recent"Mother Regs", and, if i am correct with this..., are now the same as HGVs brake pressure curves.
In other words, there is something of an incompatibility between older tractor and newer trailers.
Putting a pre-mother regs air-braked tractor onto a new HGV air-braked trailer can result in instantaneous full trailer lockup whilst running empty just from the brake pilot pressure.

Correct and most if not all tractor manufacturers have customers complaining that the new curve is not as responsive at the trailer brakes as pre mother reg tractors which means the trailer brakes are less effective on newer tractors than the old tractors.
Complete madness forcing the tractor manufacturers to comply with the new regulations when the trailer manufacturers don’t have to comply till 2021 .it has created a complete incompatibility between the newest tractors and existing trailer brakes.

 

[Matt L]

It is however easily adjusted to enable new tractors to work with older trailers.

 

[snipe]

It is however easily adjusted to enable new tractors to work with older trailers.

By adjusting the tractor or trailer.

 

[njneer]

It is however easily adjusted to enable new tractors to work with older trailers.

Not so the mother reg ( truck based) system is non adjustable which forms part of the regulation and the biggest part of the problem.

point 2.1.1.4 is replaced by the following: ‘2.1.1.4. It is not permitted to fit any adjustable valves that would allow the performance of the braking system to be changed by the user of the vehicle such that, in service, it is not subject to the requirements of this Regulation. An adjustable valve that can only be operated by the manufacturer through the use of special tools or the provision of a tamper proof seal shall be permitted provided that the user of the vehicle is not able to adjust this valve or that any user adjustment is readily identifiable by enforcement authorities.’

 

[Matt L]

By adjusting the tractor or trailer.

By adjusting the tractor side of things

 

[Matt L]

Not so the mother reg ( truck based) system is non adjustable which forms part of the regulation and the biggest part of the problem.

point 2.1.1.4 is replaced by the following: ‘2.1.1.4. It is not permitted to fit any adjustable valves that would allow the performance of the braking system to be changed by the user of the vehicle such that, in service, it is not subject to the requirements of this Regulation. An adjustable valve that can only be operated by the manufacturer through the use of special tools or the provision of a tamper proof seal shall be permitted provided that the user of the vehicle is not able to adjust this valve or that any user adjustment is readily identifiable by enforcement authorities.’

The second part of 2.1.1.4. Can be operated by manufacturer.

 

[snipe]

By adjusting the tractor side of things

That would be ideal. How do I easily adjust them please. I can get to the valve which controls the air flow to the trailer but I can’t see any sort of adjustment.

 

[Matt L]

It’s dealer or manufacturer adjustment only for safety reasons I’m afraid