- Location
- Scottish Borders
Will be because truck airbrakes don't come air/oil, suppose nothings fail safe if you look at it that way
Attaching trailer air brakes
- Thread starter Tarw Coch
- Start date
i agree in a way. Though a spring is more reliable than a hydraulic accumulator?
- Location
- Darlington
Mine has a dump/shunt valve. Releases the brakes and they won't come back on until you reconnect air lines.
- Location
- Darlington
DAF Merc etc put air through the yellow line to use trailer brakes when Handbrake is applied, Volvo and Scania don't. If you get stuck on an icy bank and try to apply your handbrake it can become somewhat interesting.
- Location
- Scottish Borders
Well this is it, why I originally thought all air brakes had the spring for max safety, but youd always need a vehicle on air to move it right enough
Captain Sensible
Member
- Location
- mid-Norfolk
Since 2018, all EU-approved ag. tractors with air (trailer) brakes must pressurise the Yellow ('Control') line when the tractor parking brake is applied ...... This then applies the trailer's Service brakes. All ag. trailers are still required to have a mechanically-applied Parking brake though .... but that could be a wire rope & ratchet or a spring brake actuator ... will do the same thing.
As for Emergency/Failsafe systems, all rely on there being some kind of 'stored energy' source on the trailer. That might be air pressure in a trailer-mounted reservoir, hydraulic pressure in an accumulator or mechanical energy in a spring. However, the rules surrounding use of Spring Brakes for this purpose are a bit more restrictive. You can only trigger a spring once: the other (hydraulic or pneumatic) systems must have enough spare capacity to be used a number of times without being re-filled.
Are Volvo & Scania running an EBS system (electronic braking control)? I'd have thought all trucks would have had to apply the trailer brakes when the tractor unit park brake is applied ....... But then I don't know much about trucks
- Location
- North West Wales
Since 2018, all EU-approved ag. tractors with air (trailer) brakes must pressurise the Yellow ('Control') line when the tractor parking brake is applied ...... This then applies the trailer's Service brakes. All ag. trailers are still required to have a mechanically-applied Parking brake though .... but that could be a wire rope & ratchet or a spring brake actuator ... will do the same thing.
As for Emergency/Failsafe systems, all rely on there being some kind of 'stored energy' source on the trailer. That might be air pressure in a trailer-mounted reservoir, hydraulic pressure in an accumulator or mechanical energy in a spring. However, the rules surrounding use of Spring Brakes for this purpose are a bit more restrictive. You can only trigger a spring once: the other (hydraulic or pneumatic) systems must have enough spare capacity to be used a number of times without being re-filled.
Are Volvo & Scania running an EBS system (electronic braking control)? I'd have thought all trucks would have had to apply the trailer brakes when the tractor unit park brake is applied ....... But then I don't know much about trucks
Ag system is silly really as if theiretically in the event a trailer came off brakes would come on, now on the road in traffic who would still be calm and collective enough to jump out and apply handbrake just in case the air leaked out!! Same as you can park a trailer with air in it only to return and find it eeeerrrrm, slightly more down the yard!!!
All tractor units not applying handbrake on trailer is another silly one, have you seen videos of trucks running away when plant are loaded onto low loaders and weight is inadvertently taken off drive axle as the machine goes up the ramp.
- Location
- Huntingdon, UK
Since 2018, all EU-approved ag. tractors with air (trailer) brakes must pressurise the Yellow ('Control') line when the tractor parking brake is applied ...... This then applies the trailer's Service brakes. All ag. trailers are still required to have a mechanically-applied Parking brake though .... but that could be a wire rope & ratchet or a spring brake actuator ... will do the same thing.
As for Emergency/Failsafe systems, all rely on there being some kind of 'stored energy' source on the trailer. That might be air pressure in a trailer-mounted reservoir, hydraulic pressure in an accumulator or mechanical energy in a spring. However, the rules surrounding use of Spring Brakes for this purpose are a bit more restrictive. You can only trigger a spring once: the other (hydraulic or pneumatic) systems must have enough spare capacity to be used a number of times without being re-filled.
Are Volvo & Scania running an EBS system (electronic braking control)? I'd have thought all trucks would have had to apply the trailer brakes when the tractor unit park brake is applied ....... But then I don't know much about trucks
Yes they have EBS, but Renaultman is right. Our Scania midlift, when you apply the handbrake in the cab, only brakes the 1st and 3rd axle. Not the trailer at all.
On the C&E driving test, they also don't give a fig which airline you disconnect or connect first, (in fact they now advise red first as the air builds up quicker) but you have to put the trailer handbrake on before you do anything and off just before you drive off.
- Location
- Darlington
Nearly everything is EBS now and spring actuators have been mandatory for a long time. This may be what gets them off not having to pressurise the yellow line when the park brake is applied. I've got a fairly new Richard Western high speed tipper. I really rate it, but tech wise it is 30 years behind a modern artic trailer (Which makes it easier for me to maintain)Since 2018, all EU-approved ag. tractors with air (trailer) brakes must pressurise the Yellow ('Control') line when the tractor parking brake is applied ...... This then applies the trailer's Service brakes. All ag. trailers are still required to have a mechanically-applied Parking brake though .... but that could be a wire rope & ratchet or a spring brake actuator ... will do the same thing.
As for Emergency/Failsafe systems, all rely on there being some kind of 'stored energy' source on the trailer. That might be air pressure in a trailer-mounted reservoir, hydraulic pressure in an accumulator or mechanical energy in a spring. However, the rules surrounding use of Spring Brakes for this purpose are a bit more restrictive. You can only trigger a spring once: the other (hydraulic or pneumatic) systems must have enough spare capacity to be used a number of times without being re-filled.
Are Volvo & Scania running an EBS system (electronic braking control)? I'd have thought all trucks would have had to apply the trailer brakes when the tractor unit park brake is applied ....... But then I don't know much about trucks
You can change the handbrake lever in a scania so that it will put trailer brakes on
- Location
- Darlington
I did that with my 113 years ago had to get a GV something or other construction and use thing to make it safer
- Location
- Huntingdon, UK
Yeah, just never bothered, got in the habit of pulling the trailer brake on by hand when needed and don’t go near proper hills now, especially in bad weather.
- Location
- Lincolnshire
We have a hire trailer on air, we have a problem whereby you can set off with the trailer ok but the first time you touch the brakes the trailer locks up and won’t release again till the shunt valve is pushed. None of us have ever used air brakes before so we’re a bit in the dark.
Do we have a problem with the tractor, or the trailer, or are we doing something wrong ?
Do we have a problem with the tractor, or the trailer, or are we doing something wrong ?
- Location
- Darlington
Probably the only way to find out is to try the trailer on another tractor or the tractor on another trailer with air brakes.
- Location
- Lincolnshire
The trailer today is regularly used on air without issue by our local contractor. We did have the same problem the last time we had an air brake trailer on the same tractor
- Location
- Huntingdon, UK
Start with the tractor. Press the probe in the middle of the fitting that the red line connects to. Air should rush out.
Now (with the wheels chocked and park brake released, no foot on the brake) press the probe in the middle of the yellow. No air should come out. Then get someone to press the brakes and release while holding probe in. Air should only come put while brake is pressed.
If these are reversed it could be your problem, someone has put the fittings on the wrong way round?
Now (with the wheels chocked and park brake released, no foot on the brake) press the probe in the middle of the yellow. No air should come out. Then get someone to press the brakes and release while holding probe in. Air should only come put while brake is pressed.
If these are reversed it could be your problem, someone has put the fittings on the wrong way round?