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Car Forum / Volvo Cars / May 2008

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Volvo B12BLEA Brake Blending Problem

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Brian Graham - 04 May 2008 03:06 GMT
I am looking for drivers who have experienced Braking problems with Volvo
computerised braking system, in either buses or trucks.

please contact me

My colleagues' and I are currently experiencing braking problems with
B12BLEA buses that VOLVO and our employer will not acknowledge, causeing
erratic braking performance.

bigbadbrian@optusnet.com.au
James Sweet - 04 May 2008 07:40 GMT
>I am looking for drivers who have experienced Braking problems with Volvo
>computerised braking system, in either buses or trucks.
[quoted text clipped - 6 lines]
>
> bigbadbrian@optusnet.com.au

I don't think you'll find much info on that here, this is the first I've
seen someone post regarding buses or trucks, most of us here drive cars.

Crossposting is very much frowned upon, there's separate newsgroups for a
reason.
Conor - 04 May 2008 11:44 GMT
> I am looking for drivers who have experienced Braking problems with Volvo
> computerised braking system, in either buses or trucks.
[quoted text clipped - 4 lines]
> B12BLEA buses that VOLVO and our employer will not acknowledge, causeing
> erratic braking performance.

Such as what?

Every one I've driven, including one that had over 1.1 million km on,
have worked fine. (Tractor units..FM10/12, FH10/12 both 4x2 and 6x2
with ABS and EBD) As an agency driver, that's a fair few units. Must be
at least 20 different ones in the last couple of years.

Signature

Conor

I only please one person per day. Today is not your day. Tomorrow isn't
looking good either. - Scott Adams

Me - 04 May 2008 18:35 GMT
> > I am looking for drivers who have experienced Braking problems with Volvo
> > computerised braking system, in either buses or trucks.
[quoted text clipped - 11 lines]
> with ABS and EBD) As an agency driver, that's a fair few units. Must be
> at least 20 different ones in the last couple of years.

1.1 million miles? Christ, where was that delivery? Mars?
Adrian - 04 May 2008 18:51 GMT
Me <noreply@tiscali.co.uk> gurgled happily, sounding much like they were
saying:

>>  Every one I've driven, including one that had over 1.1 million km on,

> 1.1 million miles?

No, 1.1m km. About 700,000 miles.
Conor - 04 May 2008 19:29 GMT
> Me <noreply@tiscali.co.uk> gurgled happily, sounding much like they were
> saying:
[quoted text clipped - 4 lines]
>
> No, 1.1m km. About 700,000 miles.

Indeed. However it was only 6 years old and although it ran 7 days a
week, it wasn't double shifted.

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Conor

I only please one person per day. Today is not your day. Tomorrow isn't
looking good either. - Scott Adams

Adrian - 04 May 2008 19:38 GMT
Conor <conor_turton@hotmail.com> gurgled happily, sounding much like they
were saying:

>> No, 1.1m km. About 700,000 miles.

> Indeed. However it was only 6 years old and although it ran 7 days a
> week, it wasn't double shifted.

So just over 300 miles per day average.
Conor - 04 May 2008 20:21 GMT
> Conor <conor_turton@hotmail.com> gurgled happily, sounding much like they
> were saying:
[quoted text clipped - 5 lines]
>
> So just over 300 miles per day average.

Yeah..sounds about right. Got used less as it was older as they rotated
the work amongst the fleet when it was quiet.
Signature

Conor

I only please one person per day. Today is not your day. Tomorrow isn't
looking good either. - Scott Adams

Tony Dragon - 04 May 2008 21:14 GMT
> Conor <conor_turton@hotmail.com> gurgled happily, sounding much like they
> were saying:
[quoted text clipped - 5 lines]
>
> So just over 300 miles per day average.

Hypermobility?

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Tony the Dragon

Conor - 05 May 2008 11:28 GMT
> > Conor <conor_turton@hotmail.com> gurgled happily, sounding much like they
> > were saying:
[quoted text clipped - 7 lines]
>
> Hypermobility?

Depends if you want to eat or not.

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Conor

I only please one person per day. Today is not your day. Tomorrow isn't
looking good either. - Scott Adams

Tony Dragon - 05 May 2008 11:38 GMT
>>> Conor <conor_turton@hotmail.com> gurgled happily, sounding much like they
>>> were saying:
[quoted text clipped - 6 lines]
>>
> Depends if you want to eat or not.

Yes but do you really need to do that mileage with the truck, could you
not cycle or use horse & cart or even handcarts?

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Tony the Dragon

Conor - 05 May 2008 14:44 GMT
> Yes but do you really need to do that mileage with the truck, could you
> not cycle or use horse & cart or even handcarts?

I suppose so but we'd have to bring over a few hundred boatloads of
"those nego folk" to do the work cos the locals won't want to.

;p

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Conor

I only please one person per day. Today is not your day. Tomorrow isn't
looking good either. - Scott Adams

Tony Dragon - 05 May 2008 15:04 GMT
>> Yes but do you really need to do that mileage with the truck, could you
>> not cycle or use horse & cart or even handcarts?
[quoted text clipped - 3 lines]
>
> ;p

I know of a bloke with a bike & cart who might help.

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Tony the Dragon

Conor - 05 May 2008 21:00 GMT
> I know of a bloke with a bike & cart who might help.

I doubt it..he'll claim the methane output he generates would
contribute towards GW.

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Conor

I only please one person per day. Today is not your day. Tomorrow isn't
looking good either. - Scott Adams

petert - 05 May 2008 08:26 GMT
>> > I am looking for drivers who have experienced Braking problems with Volvo
>> > computerised braking system, in either buses or trucks.
[quoted text clipped - 13 lines]
>>
>1.1 million miles? Christ, where was that delivery? Mars?

No, not 1.1 million miles - 1.1 million kilometres, 687,500 miles :-)
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Cheers

Peter

Me - 05 May 2008 13:09 GMT
> >> > I am looking for drivers who have experienced Braking problems with Volvo
> >> > computerised braking system, in either buses or trucks.
[quoted text clipped - 15 lines]
>
> No, not 1.1 million miles - 1.1 million kilometres, 687,500 miles :-)

Oh, just the moon then ;-)
Alek Smart. - 10 May 2008 14:36 GMT
Just to return to the OP`s original request.
I notice its a B12BLEA...Is this an artic ?

Suffice to say that there are indeed "issues" surrounding Volvo`s "brake
blending" setup on it`s later B7 and even the newer B9 chassis.

To my knowldege this has presented as a most disconcerting "Snatch" at just
about the worst possible point in a Bus journey.....just as the Bus is
approaching a Bus-Stop of in Low-Speed Traffic.

The speeds involved are all in the sub 10 Kph bracket and result in much
discomfort for passengers and allegations of poor driving being flung at the
Busdriver !

Essentially it appears as if the Retarder cuts OUT at too high a speed which
requires the Busdriver to compensate by last minute rapid application of the
service brake accompanied by a certain coarse graduation of the delivery
pressure from the footvalve.

Again,AFAIAA Volvo are aware of these issues and have in some cases referred
to a "Software Modification" to addres them.

In my experience this modification IS successful,but it raises serious
questions as to whether such a critical component as Braking/Rertarding
should be the subject of research and development whilst actually in revenue
service.

Do they not have Test Tracks for this type of safety-critical issue ?
John Williamson - 10 May 2008 15:12 GMT
> Just to return to the OP`s original request.
> I notice its a B12BLEA...Is this an artic ?
[quoted text clipped - 24 lines]
>
> Do they not have Test Tracks for this type of safety-critical issue ?

I get a version of this on a 2002 B12B automatic coach, when the gearbox
goes into neutral (Volvo call it Bus Stop Neutral or summat, & it's a
pollution control thing they blame on the EU) under ECU control at just
below walking pace. Drive stops, but the brakes are still on hard
countering the drive, so there's a jerk at about 5kph. It's a deliberate
design feature, & there's no way to turn it off easily.

The one that *really* annoys me is on the Scanias, when the automatic
retarder cuts out at about 20kph, & half your brake force disappears
just when you're committed to stop in a certain distance, say, the
distance to a bus stop or stop line.

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Tciao for Now!

John.

Conor - 10 May 2008 18:54 GMT
> The one that *really* annoys me is on the Scanias, when the automatic
> retarder cuts out at about 20kph, & half your brake force disappears
> just when you're committed to stop in a certain distance, say, the
> distance to a bus stop or stop line.

IUt would have disappeared anyway as it relies on high engine speeds to
work. Any engine speed below 1500RPM isn't going to supply much
retardation. On my lorry when I use it, the autobox drops a gear or two
and takes it up to within 500RPM of the redline.

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Conor

I only please one person per day. Today is not your day. Tomorrow isn't
looking good either. - Scott Adams

John Williamson - 10 May 2008 21:55 GMT
>> The one that *really* annoys me is on the Scanias, when the automatic
>> retarder cuts out at about 20kph, & half your brake force disappears
[quoted text clipped - 5 lines]
> retardation. On my lorry when I use it, the autobox drops a gear or two
> and takes it up to within 500RPM of the redline.

It disappears gradually with reducing input shaft speed, yes, much as
the effectiveness of an exhaust brake does. I can live with that, on our
Volvo autoboxes. On the Scanias, it's still quite noticeable in low
gears down to about 750rpm. That isn't too bad, but suddenly losing
*all* gearbox retardation from quite a high value isn't funny,it feels
to the passengers as if the vehicle is lurching forward just as things
are getting critical. Because of this, I disable the transmission
retarder function in town for more predictable braking. The normal
brakes run hotter & work harder, but the passengers get a much smoother
ride.

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Tciao for Now!

John

Conor - 11 May 2008 19:19 GMT
> It disappears gradually with reducing input shaft speed, yes, much as
> the effectiveness of an exhaust brake does. I can live with that, on our
> Volvo autoboxes. On the Scanias, it's still quite noticeable in low
> gears down to about 750rpm.

TBH on lorries, I found the Scania systems to be so effective as to not
be worth bothering with - you could turn it off and there was no
noticable difference apart from a reduction in noise. The Volvos OTOH
could hold a 44 tonne artic at a constant speed going down Windy Hill
on the M62.

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Conor

I only please one person per day. Today is not your day. Tomorrow isn't
looking good either. - Scott Adams

Ivor Jones - 11 May 2008 21:25 GMT
In news:68orkoF2r7v5bU11@mid.individual.net,
Conor <conor_turton@hotmail.com> typed, for some strange, unexplained
reason:

: > It disappears gradually with reducing input shaft speed, yes, much
: > as the effectiveness of an exhaust brake does. I can live with
[quoted text clipped - 6 lines]
: could hold a 44 tonne artic at a constant speed going down Windy Hill
: on the M62.

You can't turn it off on our Scanias, there isn't a switch (or if there
is, they've hidden it very well..!)  On the Mercedes O405N's there's a
switch but if you turn it off a horribly loud alarm buzzer goes off
continuously until you turn it back on again.

Ivor
John Williamson - 11 May 2008 22:24 GMT
> In news:68orkoF2r7v5bU11@mid.individual.net,
> Conor <conor_turton@hotmail.com> typed, for some strange, unexplained
[quoted text clipped - 15 lines]
> switch but if you turn it off a horribly loud alarm buzzer goes off
> continuously until you turn it back on again.

On our Scania coaches, it's hidden on the manual retarder stalk. I've
not looked at our buses lately.

As for effectiveness, there's a very noticeable lurch as it comes on
with brake application in town, & a very noticeable lurch as it cuts off
again at 20kph or so. It does very little in higher gears, in my
experience. Comparisons with chocolate teapots come to mind....

I'm told it can be reprogrammed by the agents, though.

A feature of the B12 auto I like is the full cruise control, which lets
you set a speed & if you start overspeeding for any reason,
automatically engages the retarder. Very handy on those long French
motorways. :-)

That's only holding 17 tonnes or so back, though.

Signature

Tciao for Now!

John.

 
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