Dropping air pressure

UK PROFESSIONAL DRIVERS FORUMS THE UK PROFESSIONAL DRIVERS FORUM (INTERACTIVE)
1

I drive a 58 plate FH, whilst returning to the yard last night I was in roll mode (M27 (W) down the hill towards rownhams) and I noticed that the air pressure was dropping out of the green band. I switched to the air pressure gauge on screen for a more accurate reading and it dropped to 9.5 before I thought, [zb] this and slipped it into neutral and built it up again. Got to the bottom of the hill and climbed up the next incline. After reaching the next peak by the exit slip for rownhams it went into roll mode again and it did the very same thing again, dropped to 9.5 and I reacted the same.

Is this normal in roll mode? I can’t say I’ve ever spotted it before, or is this a problem?

2

Sounds like a slight air leak somewhere and because the compressor isn’t working hard when rolling downhill it’s not compensating

3

Try dropping your airline, then reconnecting them. As said, could be slight leak and that could sort it.

4

Whoever came up with the idea of ‘roll mode’ and whoever decided that it is a fit and safe system to meet type approval for a heavy vehicle must have come from the planet Zog.

No different from ‘silent sixth’ - just as dangerous; as the OP illustrates.