Pulls up to collect cherry picker
drops ramps
starts cherry picker
starts to load cherry picker
as weight shifts on to back of trailer weight comes off fifth wheel - back axle on unit looses grip and away we go
probably new to the job
if he / she has a job next week its one lesson they won’t forget ,
look for flat level ground to load/ unload , pull on your trailer brake / disconect red line use the yellow plastic wheel chocks
First thing a timber truck driver does if he’s got a front mounted crane when he jumps out of the cab is pull the trailer park brake(Scania). When you load the back bunk and push it away to continue loading the weight comes of the drive and away she’ll go. Strange feeling when your sitting up on the crane and that happens lol. That’s when you find out adrenaline is a brown liquid!
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Punchy Dan:
I have noticed the yellow line pressure doesn’t put the trailer brakes on as hard as when you drop the red line off.
When you drop the red line the emergency relay valve sends full air tank pressure directly to the service brake portion of the trailer spring brake chambers to give the absolute maximum braking possible as this assumes a breakaway scenario.
The braking pressure applied when an air signal sent down the yellow line (it’s only an air pressure signal that operates a relay it’s not the actual air that goes to the trailer brakes) the air that’s then sent to the trailer brakes is modulated according to load sensing. Even grossed out you still might not get full tank pressure that dropping the red line gives.
A flaw in safety systems that automatically pop out the trailer park brake, when the red line is dropped, is that the trailer relies on just the parking springs, not full tank pressure, to stop it in a breakaway scenario which for anything but a light trailer on a gentle slope would be inadequate.
beefy4605:
Pulls up to collect cherry picker
drops ramps
starts cherry picker
starts to load cherry picker
as weight shifts on to back of trailer weight comes off fifth wheel - back axle on unit looses grip and away we goprobably new to the job
if he / she has a job next week its one lesson they won’t forget ,look for flat level ground to load/ unload , pull on your trailer brake / disconect red line use the yellow plastic wheel chocks
Probably attacked the ramps at a more than slightly spirited speed particularly loading on a downhill.
Juddian:
Carryfast:
Assuming the type of runaway described by Juddian what are those yellow things stowed on the front bulkhead ?.Those plastic chocks are about as much use a chocolate teapot, more often than not they’ll bounce down the road in front of the wheel until such time as the vehicle has enough momentum, by which time IF the chock eventually digs in the wheel goes straight over (or through when loaded) it often smashing it to pieces…still they look the part
.
Metal ones aren’t much better they just get pushed along easily too.
Juddian:
Reef:
Juddian:
Scanias don’t apply the trailer brakes when the park brake is appliedDo they not?
[zb] me I never knew that… TIL!
Nope (but someone with the latest versions with EPB will have confirm if its still the case with those), and i’m none too sure about modern Volvos either, previous Volvos didn’t pressurise the trailer brakes with the park brake applied.
Easy enough to tell, when you connect up to a trailer is the yellow service line pressurised and as hard to fit as the red line?
, you’ve done it hundreds if not thousands of times Reef, just it doesn’t register til you have a job that benefist from that additional braking **
I know MAN and Daf units apply the trailer brakes with the unit park brake, Scania at least pre EPB don’t.
Might be an idea to have a thread about this, i bet lots of drivers doing jobs that would be maybe safer with the trailer brakes applied as well could benefit.
** its something i had early warning about, in my early days on transporters i had a 9 car wag’n’drag carrier with an FL10 prime mover, literally never serviced at the cowboy outfit i worked at.
One day i’m loading the lorry and realised its moving slightly down the hill as i’m putting cars on…park brake only applied on the drive axle and the brake shoes were simply worn out, luckly on the Volvos you had the extra aitr operated switch you could pull out labelled Broms Brake, which once pressurised stayed out, this applied the trailer brakes, and wouldn’t release till you pushed it manually back in again.
That was an eye opening moment for me, for some reason since we’d lost the blue auxilliary brake line (operated by the secondary or dead man’s brake) i’d assumed the park brake on two line systems applied all, wrong.
I’ve got a new Volvo on order, luckily the boss sent me the spec sheet Volvo sent him after the initial enquiry, one of the things I got added was to put the trailer brakes on with the handbrake, I do the same work as the dude in the pic.
And my understanding on the broms brake is its purpose was to come on if you released the handbrake if there wasn’t enough air pressure to take the brakes off, without the broms brake you could forget to put the handbrake on as the truck wouldn’t move, but if running the air would build up and potentially start to runaway
Some good recent replies here chaps, thanks for clearing a few things up, very useful info from OAD about the pressures applied to the trailer re normal braking spring braking and disconnected red air line.
Also it would appear Volvos don’t necessarily apply the trailer brake when parked unless specified, interesting comment about the Broms brake, sort of triggers memories of how it used to come on by itself but too long ago to make any sense from those memories, we just need to know now if Scanias fitted with EPB are the same as those with normal park brakes.
What an enlightened boss you have Stevieboy, not only letting you know whats coming but also sensible enough to allow input from the chap intended to use it.
Fortunately i was also consulted on my present steed before build and i added a couple of things to the order to help the specific work we do, quite why most who polish office chair seats never consider asking those doing the job if there’s anything missing or suggestions for additions/alterations needed before the things are built is a mystery.
Juddian:
quite why most who polish office chair seats never consider asking those doing the job if there’s anything missing or suggestions for additions/alterations needed before the things are built is a mystery.
Because…
The majority would specify flat screen tellies, coffee makers and half a dozen Hella’s on a Kelsa bar.
Juddian:
Some good recent replies here chaps, thanks for clearing a few things up, very useful info from OAD about the pressures applied to the trailer re normal braking spring braking and disconnected red air line.Also it would appear Volvos don’t necessarily apply the trailer brake when parked unless specified, interesting comment about the Broms brake, sort of triggers memories of how it used to come on by itself but too long ago to make any sense from those memories, we just need to know now if Scanias fitted with EPB are the same as those with normal park brakes.
What an enlightened boss you have Stevieboy, not only letting you know whats coming but also sensible enough to allow input from the chap intended to use it.
Fortunately i was also consulted on my present steed before build and i added a couple of things to the order to help the specific work we do, quite why most who polish office chair seats never consider asking those doing the job if there’s anything missing or suggestions for additions/alterations needed before the things are built is a mystery.
Yeah I’d only been there 2 or 3 months and he said what do you want, can’t fault them, loved my last job but this is next level!
And the reason tags are twitchy is because of the shorter wheelbase
On the Volvo to set trailer brakes on parking hold in the retarder stalk both notches up to the wheel when you set the park brake, should light up on dash to show its on also.
yourhavingalarf:
Juddian:
quite why most who polish office chair seats never consider asking those doing the job if there’s anything missing or suggestions for additions/alterations needed before the things are built is a mystery.Because…
The majority would specify flat screen tellies, coffee makers and half a dozen Hella’s on a Kelsa bar.
I’d like to argue with that, but you’re sadly right, now if the TM knew who to ask quietly for sensible input instead of regarding everyone as clueless bums on seats wouldn’t the industry be a better place all round.
Stevieboys situation proves it’s a better policy for everyone including the guvnor, his new wagon won’t do what the one in the pic has probably done, not suggesting Stevieboy would ever forget about the trailer brake but if he’s on holiday…
Own Account Driver:
Punchy Dan:
I have noticed the yellow line pressure doesn’t put the trailer brakes on as hard as when you drop the red line off.When you drop the red line the emergency relay valve sends full air tank pressure directly to the service brake portion of the trailer spring brake chambers to give the absolute maximum braking possible as this assumes a breakaway scenario.
The braking pressure applied when an air signal sent down the yellow line (it’s only an air pressure signal that operates a relay it’s not the actual air that goes to the trailer brakes) the air that’s then sent to the trailer brakes is modulated according to load sensing. Even grossed out you still might not get full tank pressure that dropping the red line gives.
A flaw in safety systems that automatically pop out the trailer park brake, when the red line is dropped, is that the trailer relies on just the parking springs, not full tank pressure, to stop it in a breakaway scenario which for anything but a light trailer on a gentle slope would be inadequate.
This is yet another argument against the ridiculous DVSA policy of allowing triaxle trailers to pass the roller brake test on unladen locks while insisting that a tandem axle trailer must be tested at 65% axle weights. Both should meet the 65% requirement.
Juddian:
.What an enlightened boss you have Stevieboy, not only letting you know whats coming but also sensible enough to allow input from the chap intended to use it.
Fortunately i was also consulted on my present steed before build and i added a couple of things to the order to help the specific work we do, quite why most who polish office chair seats never consider asking those doing the job if there’s anything missing or suggestions for additions/alterations needed before the things are built is a mystery.
I was in a 19 plate hire truck the other day. It didn’t come with central locking. We do 2 man multidrop, guess how many times the truck was properly locked up on each delivery? [emoji57]
cav551:
This is yet another argument against the ridiculous DVSA policy of allowing triaxle trailers to pass the roller brake test on unladen locks while insisting that a tandem axle trailer must be tested at 65% axle weights. Both should meet the 65% requirement.
A unladen tri axle trailer will fail if it locks up if I remember correctly at under 500kgs per wheel.
As someone has mentioned the Volvo BROMs brake was never intended as a braking device, it was fitted to stop drivers jumping out without putting the handbrake back on whilst waiting for the air to build up, could be wrong
but I don’t think you could actually pull it out with the air up.
dave docwra:
cav551:
This is yet another argument against the ridiculous DVSA policy of allowing triaxle trailers to pass the roller brake test on unladen locks while insisting that a tandem axle trailer must be tested at 65% axle weights. Both should meet the 65% requirement.but I don’t think you could actually pull it out with the air up.
You could, it was the only way to stop an FL10/12 transporter running away whilst loading up if the drive axle shoes were worn and/or you were on a slippery incline, couldn’t leave it in gear cos engine and PTO running for hydraulics.
Juddian:
dave docwra:
cav551:
This is yet another argument against the ridiculous DVSA policy of allowing triaxle trailers to pass the roller brake test on unladen locks while insisting that a tandem axle trailer must be tested at 65% axle weights. Both should meet the 65% requirement.but I don’t think you could actually pull it out with the air up.
You could, it was the only way to stop an FL10/12 transporter running away whilst loading up if the drive axle shoes were worn and/or you were on a slippery incline, couldn’t leave it in gear cos engine and PTO running for hydraulics.
Sorry that was not how it worked, it only stopped you from releasing the handbrake until the air was built up, would it have have been safer applying the handbrake and dropping the red line on the trailer, a lot of Volvo tractor units including the F86 had spring brake chambers on the front axle, as this was found out by one of the Dukes mechanic in Stranraer who decided to do a hand brake turn with the unit in the yard which did not end well for him or the vehicle.
The trailers in question were drags, not semi trailers, the air lines and connectors not only filthy and covered in grease but the chances of the connector coming undone without hammering the living daylights out of it almost impossible that wasn’t going to happen, in practice the prime mover was seldom if ever disconnected from the trailer except for servicing…which where i worked sadly at the time never happened.
As i recall you would apply the park brake as normal and then hold the Broms button out for about 5 seconds and it would pressurise enough to stay out.
but I don’t think you could actually pull it out with the air up.
[/quote]
Oh yes you can whilst driving along as well, take it from me as I’ve done it !!