I’m becoming a bit paranoid about forgetting to put my gear selector into neutral, and then losing air so that the gearbox locks into gear and the truck won’t start. I’ve heard about a few people this has happened to and the remedy has been to call out a service van to pump up the air tanks with a compressor.
I’m wondering if, theoretically, you could connect the red airline of another truck to the trailer and pump up the trailer tanks, then reconnect the red airline to the original truck, if air from the trailer would then fill up the truck reservoir?
The only reason I could see that this wouldn’t work would be if there was a one-way valve in the system. So is there?
I don’t know the answer to your question about one way valves but here’s another couple of possible solutions to the problem.
Would there be enough air in your tyres to use an air line you usually used for tyre inflation to get enough air into the system to get it out of gear? Obviously you could then reinflate the tyre from the truck when the engine is running.
Alternatively how long would it take with a small electric air compressor to pump up the tanks using battery power?
To be honest I didn’t even realise that this problem could happen. Auto boxes have been around long enough now that you would think there would be some kind of automatic feature to put it into neutral when you turn the engine off and/or some kind of audible warning to you if you forgot.
repton:
Would there be enough air in your tyres to use an air line you usually used for tyre inflation to get enough air into the system to get it out of gear? Obviously you could then reinflate the tyre from the truck when the engine is running.
Yes, I believe that’s possible and I’m going to get such an air line made up when I get the time.
repton:
Alternatively how long would it take with a small electric air compressor to pump up the tanks using battery power?
I wondered that too, and I have a fairly good 12v compressor. At the moment I haven’t found out where to inject air into the system. Older Magnums have inlet valves in the offside quarter panels but they aren’t there on mine. Volvos, or at least the ones I have driven, often have a tyre type valve in the cab but if my truck has one then I haven’t found it yet.
Harry Monk:
I’m becoming a bit paranoid about forgetting to put my gear selector into neutral, and then losing air so that the gearbox locks into gear and the truck won’t start. I’ve heard about a few people this has happened to and the remedy has been to call out a service van to pump up the air tanks with a compressor.
I’m wondering if, theoretically, you could connect the red airline of another truck to the trailer and pump up the trailer tanks, then reconnect the red airline to the original truck, if air from the trailer would then fill up the truck reservoir?
The only reason I could see that this wouldn’t work would be if there was a one-way valve in the system. So is there?
The tyre pressure hose works both ways Harry, there is normally a Schrader valve in the cab somewhere, or you can use one of the test points to put some air back in from the tyre. You only need enough air to operate the gear actuator.
A friendly Magnum mechanic will point you to the correct valve.
Still got an air line that came with my then new FL10, very useful for delaying a slow puncture till convenient, simply a good long air line with standard Shrader connector on one end and air tank outlet connector on the other.
Never thought about this though, and i should do as i had a dickens of a job to get an auto Actros to raise enough pressure after i’d got it under a trailer and it was stuck in gear with low air…Sorry there are not enough foul words in the English language to describe me feelings towards trucks with auto boxes, IIRC it had happened with other drivers there and they ad to get fitters out to blow the thing up…junk.
Having read this preventative measure thought of yours Harry, might well make up an airtank connector to Shrader adaptor to make that air line versatile for all eventualities.
Don’t remember any of this carp when trucks were proper…
Yes, perhaps that would do although I already have one of these.
I just don’t know if there is a suitable air intake valve on the Magnum. On Volvos there always used to be one somewhere near the gear lever and I’m wondering if my truck has one hidden somewhere
get an air line made up with an interchangeable end that fits on the test point, then a small length with another test point end on it, then you can get another truck and fill it direct from test point to test point
Didn’t realise this could happen. But then thankfully I drive a Scania and that pops it into neutral when you stop the engine. I feel sorry for you poor peasants in your cheap nasty lorries…
switchlogic:
Didn’t realise this could happen. But then thankfully I drive a Scania and that pops it into neutral when you stop the engine. I feel sorry for you poor peasants in your cheap nasty lorries…
It’s those little touches that make scanias better than the rest.
switchlogic:
Didn’t realise this could happen. But then thankfully I drive a Scania and that pops it into neutral when you stop the engine. I feel sorry for you poor peasants in your cheap nasty lorries…
It’s those little touches that make scanias better than the rest.
Yeh…Like having a clutch that is completely pointless…if you have an auto box fitted that works properly…
H you’re overthinking it. They pop into neutral when you switch off. They won’t start if the selector is not in neutral. I often find my I shift in gear and air down at zero after the boss had been moving it around or washing it for me.
The gearbox should automaticly select nuteral when you switch the engine off to avoid this kind of problem. The only reason this would become an issue, is if the air pressure is very low when you switch the engine off while still in gear. You would now have a truck which is stuck in gear, and unable to start until the air system has been charged up.
There will be one way valves that prevent filling from the trailer.
Test point adapters and length of hose are the way to go, and you could use air from trailer tanks that way. I’ve made all the various air couplings to standard workshop air tool bayonet connectors so I can interchange and only keep one length of air hose that will reach right round the truck. I’m out at the moment but will try and remember to post pics of what you need when I get back to the workshop.
It should be a straightforward job to fit a new test point wherever it’s needed on the truck though anyway. Older trucks had C couplings somewhere on the front for towing but newer trucks seem to have far less connectors.
damoq:
The gearbox should automaticly select nuteral when you switch the engine off to avoid this kind of problem. The only reason this would become an issue, is if the air pressure is very low when you switch the engine off while still in gear. You would now have a truck which is stuck in gear, and unable to start until the air system has been charged up.
I can’t recall ever having the problem but do religiously put it in neutral when idling or stopping.
switchlogic:
Didn’t realise this could happen. But then thankfully I drive a Scania and that pops it into neutral when you stop the engine. I feel sorry for you poor peasants in your cheap nasty lorries…
It’s those little touches that make scanias better than the rest.
Yeh…Like having a clutch that is completely pointless…if you have an auto box fitted that works properly…
And switches in random places …
Good old Skoda…
Who’s got a clutch? I haven’t. I think we were pointing out that Scania autos do work properly
