Wreckers!!
- Thread starter Kevtherev
- Start date
- Location
- North West Wales
It shouldn’t effect it if everything behaves.
- Location
- North West Wales
But air and hydraulic agri setups aren’t quite the same. When you dump the air the chambers retract for you to use the hydraulic side!!
Say that again. Slowly.
- Location
- Moreton-in-Marsh, Glos
Really, are you sure?
Without enough air pressure, I cannot move my trailer. The wheels and jammed.
The pressure has to build up before the brakes unlock.
Isn’t that just the same as a lorry?
Lakesdigger
Member
Without enough air pressure there is what you could describe as an in-between point where the brakes are on and you need to wait for more air pressure to let them off BUT it's not the same as hgv system. Hgv brakes are spring applied and rely on air pressure in the brake chambers to push against the spring to let the brakes off a completely fail safe system. Ag trailer air brakes (more often than not paired with hyd brakes) rely on air pressure to apply the brakes, there are no springs in the system (other than ones to pull the brakes off). It's fail safe only as long as there is air in the system to hold the brakes on. I assume the reason when pressure is low the brakes come on is just how the brake valve on the trailer works when there isn't enough pressure on one side of it.
It's like @Lakesdigger has already explained, a small bit of air in the tank will put the brakes on.
Lorry trailers have springs to apply the brakes when there is no air
- Location
- Moreton-in-Marsh, Glos
Thanks, I didn’t know that.
But I suppose it explains how the Dump valve works and why if you complete drain the air tanks on an old artic trailer, it can be moved.
I’ve never really understood why an HGV trailer has 3 air lines, yet an agricultural trailer only 2.
If it’s a old artic trailer it might just have single brake chambers
newer spring brake chambers only way you can release them is by air or the bolt that comes with them it screws in and you wind the brakes off
Hgv only has two, red and yellow
- Location
- Moreton-in-Marsh, Glos
It’s been a long while since I drove one. Did they once also have a blue or maybe black line too?
ollandroverman
Member
- Location
- nr Kendal (The Lake District)
Not quite.
Hgv trailer brakes are air applied, not spring applied.
Hgv park brakes are spring applied, and require air to overcome the spring clamping pressure. The two are usually stacked in a single device, but are in operation separate. https://www.researchgate.net/profil...88@1509992357182/Figure-1-Brake-Chamber-5.png
Netherfield
Member
- Location
- West Yorkshire
The ERF in my avatar had 3 lines at the rear for a trailer, never drew a trailer so can't say why there were three although many years ago all tractor units had the three lines as pictured above.
Ok. I've read the posts since yours and understand better now. Apologies to @Mur Huwcun for the tone of my reply!
An "unscheduled disconnection" should engage the brakes if the air system was in use up to that point though.
- Location
- Moreton-in-Marsh, Glos
I have driven an ERF and a Foden with the wooden cab and split Windscreen (Gardner straight 8 engine IIRC) and they had 3 air lines.
I haven’t driven an Artic for a few years now. The last would have been a Merc with an EPS gearbox, which I loved.
Thanks for the info. Nice to get updated.
I’m certain that my HGV training and experience has stood me in great stead when using our Fastrac, pulling its air braked grain Trailer. I used to deliver a most of our grain with it. Getting the gears right, knowing which ones to mis out, whether or not to use engine breaking, staying in a gear or not approaching a roundabout as opposed to traffic lights and knowing where or not to deliberately straddle lanes to prevent other vehicles trying to come up the inside, makes the job a lot smother for me and other traffic.
Its an art that becomes 2nd nature to all good lorry drivers, who can make other traffic do what they want them to do, without them even realising it.
- Location
- Bury St Edmunds, Suffolk
All this chat about air brakes reminded me of a friend now gone.
Went to start his cattle lorry early one morning, would go. It's on a steep hill so he thought he'd run it off, no air so that didn't work. Went and got some jump leads got it started, put the jump leads back, comes back, no lorry it's now down the bottom of the field at the end of his drive......
Went to start his cattle lorry early one morning, would go. It's on a steep hill so he thought he'd run it off, no air so that didn't work. Went and got some jump leads got it started, put the jump leads back, comes back, no lorry it's now down the bottom of the field at the end of his drive......
- Location
- DD9.
Dad did that twice in two consecutive harvests on the old manual eurotech Ivecos.
Started lorry, released handbrake, tried to move, air not built up, no patience so got out to change drier instead, returned first year to find lorry and full load buried in the wall of the work shop. The second year another one made it all the way thru the open doors to the back wall of the work shop, pinning the mechanics van. Bloody liability.
Like the time he bollocked me for going to move a fallen tree on an endrig as there wasn’t time for that, then next morning the Amac self propelled harvester is on its ribs after he hit said tree with the offside wheel and tipped it over.
Started lorry, released handbrake, tried to move, air not built up, no patience so got out to change drier instead, returned first year to find lorry and full load buried in the wall of the work shop. The second year another one made it all the way thru the open doors to the back wall of the work shop, pinning the mechanics van. Bloody liability.
Like the time he bollocked me for going to move a fallen tree on an endrig as there wasn’t time for that, then next morning the Amac self propelled harvester is on its ribs after he hit said tree with the offside wheel and tipped it over.
smcapstick
Member
- Location
- Kirkby Lonsdale
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