Over the last year or so I’ve done a fair bit of class 2 work at brakes and noticed this one night in their yard but haven’t had chance to ask their drivers what it is;
On the front of their trailers is a green light which iirc comes on and an audible beep sounds when the coupling engages - I think…
Any idea what it is? I don’t think it was fridge related, it seemed to be to let you know when the fifth wheel’s got hold of the pin properly but I don’t know anything for sure. There’s a chance brakes will be one of my first jobs in an artic so obviously I’d like to know what it’s all about…
Green light is for ABS, usually lights up when you press the brake.
If the green light is on the drivers side of the trailer then it’s the ABS light, I’m not sure about the audible beep sound but it could be that the units are fitted with hydraulic adjustable 5th wheel couplings.
The hydraulic 5th wheel couplings can be pushed back for easy access between the unit and the trailer when coupled then put back into the normal running position when you’ve finished connecting the airlines ec’t, it’s a long time since I’ve used one but as far as I can remember they do make a buzzing or beeping noise until the coupling is returned to the forward position.
Pretty sure it was on the passenger side but abs sounds about right if the guy had split coupled (I didn’t see), Hydraulic sliding fifth wheel 
sounds like something to leave well alone unless there’s no other option 
The audible bleep is most likely a test for a warning system. If you have faulty lights or a faulty suzie on the trailer it ‘beeps’ continuously when you connect the suzies. We have them at work, all the lights (front, side and rear markers - everything) flash continuously too.
Bob
could it be coincendence that they test the abs light and reversing bleeper and knock it off with them being on nights. Maybe stupid answer.
could it be conected to the fridge to warn if the temp is out of range?? ie fridge breakdown?
honestly, I don’t know what it was. Could be any of the things suggested, I got the impression it was something more interesting but could easily be wrong.
If I ever get chance, I’ll find out and let you know.
I’ve never heard of a hydraulic coupling, well not on a 5th wheel anyway, maybe the poster is refering to a sliding 5th wheel, which can have air actuated locking pins, it does have a small ram, but it’s air not hydraulic 
As Brake Bros run temp controlled (fridges) the green light will probably be fridge related, if it’s running on cycle an audible warning will beep before the motor fires up so that you don’t get parts replacers (fitters) getting their little pinkies caught up when the engine starts up as they’re tinkering about with it
newmercman:
I’ve never heard of a hydraulic coupling, well not on a 5th wheel anyway, maybe the poster is refering to a sliding 5th wheel, which can have air actuated locking pins, it does have a small ram, but it’s air not hydraulic
You are of course right the ram engaged/disengaged the locking pins, the coupling was moved by engaging the trailer brake and moving the unit forwards/backwards
tachograph:
newmercman:
I’ve never heard of a hydraulic coupling, well not on a 5th wheel anyway, maybe the poster is refering to a sliding 5th wheel, which can have air actuated locking pins, it does have a small ram, but it’s air not hydraulic
You are of course right
I don’t always spout useless drivel you know 
Well, I’ve driven one of brakes’ artic’s now and I’m still none the wiser - even the green light didn’t work on this one, the abs light went out on the dash though which was good enough for me
darkseeker:
Well, I’ve driven one of brakes’ artic’s now and I’m still none the wiser - even the green light didn’t work on this one, the abs light went out on the dash though which was good enough for me
Unfortunately that may not be good enough for VOSA.