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plumbing diagram for pbr 4 trailer brake

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10 years 11 months ago #112217 by v8 inter nut
Thanks every one I think it's sorted I will hook it up to the trailer late this week and check it all out

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10 years 11 months ago #112218 by bigcam
Looking at the ports mate,

From the steering Colomn out-

1st one from the air pak
2nd one the red air line to the trailer
3rd one the blue air line to the trailer
4th plumb it out through the firewall for the exhaust
5th one air supply

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10 years 11 months ago #112219 by mammoth
The constant supply to the trailer (red line) will pull the maxis off but to use them as a park brake you will need a control valve to dump the air from the maxis. The other thing to be aware of is if you have a break in the control line you won't be aware of it, apart from getting no response from trailer brake.

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10 years 11 months ago #112220 by jimbo51
Mammoth, on the CA300F flicking the tractor protection lever to EMERGENCY dumps the air from the trailer supply line while protecting the prime mover supply. This would cause the trailer spring brakes to apply via a trailer spring brake valve such as a Bendix SR2.

Caveat - I'm talking older technology so current rego requirements may differ.

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10 years 11 months ago #112221 by bigcam
As Jimbo says the ADR's have changed over the years, but the Tractor Protection valve has always controlled the air supply to the trailer weather it is a CA 300 or plumbed with a different tractor protection valve set up.

On old trailers with out maxi brakes the trailer relay valve is set up so that the brakes come on if there is no air supply. (they only stay on until the trailer runs out of air)

On newer trailers with maxi brakes, the maxis come on when there is no air supply and stay on.

It has always been a requirement to have break away system in place which is why they work that way.

On older prime movers the tractor protection valve works independantly of the park brake valve.

On newer ones the trailer brakes must come on when the park brake is applied, so they cut the air supply off to the tractor protection valve when the truck maxis are on. There is a bit of an exception to that with tip over axle trailers.

You don't actually need a tractor protection valve, but on newer trucks the air supply to the trailer still needs to be cut off when the park brake is applied to meet the adr's. On trucks with a mechanical park brake they use a soliniod hooked up to the park brake light to achieve this, but that won't concern your old Inter as it is before the current adr.

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10 years 11 months ago #112222 by mammoth
So, on modern trucks is there a function to stop you heading down the Cunningham Gap, in the wet, unawares with a broken control line to the trailer? Apart from jacknifing into a rock wall that is.
Real question as last week my blue suzie was fully broken inside the springy part - nothing untoward to look at, but only with the hand piece full on a walk around found the air blowing out. I had earlier locked the drives at a zebra crossing in the dry on what should have been an easy stop but wasn't.

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10 years 11 months ago #112223 by bigcam
Erm Mammoth, there is a function that alerts you to the blue control line being broken or blocked..................

The trailer brakes won't work, unles of course you pull ot the tractor protection valve, in which case they will come straight on, maybe a bit of tyre smokin' action, but far superior to jack knifing into a wall.

Do Volvo's actually have tractor protection valves? Been that long since I've been in one I forget. The european's have some funny idea's, though I suppose the seppo's do too, like not having front brakes.

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10 years 11 months ago #112224 by paulc20
Drove a 3070 once, the air supply to the CA300 was supplied from the parking brake circuit of the truck. The maxi button in the 3070 would also apply trailer parking brakes.

Paul

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10 years 11 months ago - 10 years 11 months ago #112225 by mammoth
I am talking 1970's Volvo. It has a protection valve but you can't "pull it' like the yank design. The park brake is a proportional valve to drive axle only (plus the trailer hand piece can be used in the same way to trailer axles but is limited pressure and relies on having a working control line).
Ifn air pressure of park brake disappears the maxis come on.
The function you mention (to alert break or blockage) - how does it work?
Last edit: 10 years 11 months ago by mammoth.

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10 years 11 months ago - 10 years 11 months ago #112226 by bigcam
Mammoth, not sure of what you mean by the function, but if you are referring to Paul's post, all the newer trucks are plumbed up so that when the park brake is applied it shuts off the air supply to the trailer emergency circuit and the trailer brakes come on. It is an ADR now that the trailer park brake must come on when the truck park brake is applied.

The "function" I was referring to isn't really a function at all, more of a mal-function, if the blue line is disconnected or blocked the brakes don't work.

Last edit: 10 years 11 months ago by bigcam.

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