A colleague of mine broke down last night, turned out to be the air compressor pipe leaking, he pulled up and it just died stuck in gear and being an automatic it would not start up. 
He was blocking the route into the depot so I attempted to help by hooking my airlines to his to try and fill his tanks up to knock it out of gear so he could startup, connected up and got 12bar on my truck, but only 3bar on his Stralis, which was not enough to knock it out of gear, unfortunatly had to give up as I was told to move out the way. 
Eventually the fitter turned up 2hours later and filled the tanks direct from his compressor and managed to start it, and kept enough air in it just to drop the trailer and move it about 10feet so I could take my mates trailer.
But was wondering if this was a method that would work to fill someones tanks ?
Or if I filled his trailer with air and then put his own lines back on would that work ?
I know when the fitter came out he ran a airline direct to the tanks, is there a reason for this ? 
Many thanks
Lycanthrope:
A colleague of mine broke down last night, turned out to be the air compressor pipe leaking, he pulled up and it just died stuck in gear and being an automatic it would not start up.
He was blocking the route into the depot so I attempted to help by hooking my airlines to his to try and fill his tanks up to knock it out of gear so he could startup, connected up and got 12bar on my truck, but only 3bar on his Stralis, which was not enough to knock it out of gear, unfortunatly had to give up as I was told to move out the way.
Eventually the fitter turned up 2hours later and filled the tanks direct from his compressor and managed to start it, and kept enough air in it just to drop the trailer and move it about 10feet so I could take my mates trailer.
But was wondering if this was a method that would work to fill someones tanks ?
Or if I filled his trailer with air and then put his own lines back on would that work ?
I know when the fitter came out he ran a airline direct to the tanks, is there a reason for this ? Many thanks
In the golden days of palm couplings and air taps, you could have just joined your red lines together. Some trucks have a schraeder valve under the dash to release the brakes and possibly the gearchange on modern trucks.
However it sounds like the mechanic has used the tank valve which is utilised to either blow tyres up or take air pressure from the tyre to release brakes.