"Boltar" wrote in message
ups.com...
On 6 Jul, 09:56, Adrian wrote:
February 2006.http://www.tfl.gov.uk/corporate/medi...ntre/3680.aspx

From the article:

"The battery pack is kept at optimum power by a 1.9 litre diesel Euro
IV engine. In other words, an engine which would normally be found in
a family car keeps the battery"

1.9 sounds a bit too small. I'm sure in start and stop traffic it
might be ok but ultimately the energy all comes from that engine.
Seems to me the bus would be hopeless for any long or even middle
distance runs especially if any hills are involved, since once the
battery has been used up its relying on the engine only and a 10 ton
(probably more) bus won't be going anywhere fast with an engine that
size.


Do the buses have regenerative braking as well?

Paul

Boltar ) gurgled happily, sounding much like they
were saying :

"The battery pack is kept at optimum power by a 1.9 litre diesel Euro
IV engine. In other words, an engine which would normally be found in
a family car keeps the battery"

1.9 sounds a bit too small. I'm sure in start and stop traffic it
might be ok but ultimately the energy all comes from that engine.
Seems to me the bus would be hopeless for any long or even middle
distance runs especially if any hills are involved, since once the
battery has been used up its relying on the engine only and a 10 ton
(probably more) bus won't be going anywhere fast with an engine that
size.

Don't forget that the engine is basically just being used as a generator,
therefore can run at optimum revs for the specific output - there's no
requirement for any kind of useful rev range or torque curve.

On 6 Jul, 11:05, Adrian wrote:
Don't forget that the engine is basically just being used as a generator,
therefore can run at optimum revs for the specific output - there's no
requirement for any kind of useful rev range or torque curve.

True , and I suppose that will mitigate it somewhat. However
ultimately that engine will produce less power than a normal bus
engine so when relying on the engine alone its going to be slower
compared to the normal engine running at optimum gearing.

B2003

Boltar ) gurgled happily, sounding much like they
were saying :

Don't forget that the engine is basically just being used as a
generator, therefore can run at optimum revs for the specific output
- there's no requirement for any kind of useful rev range or torque
curve.

True , and I suppose that will mitigate it somewhat. However
ultimately that engine will produce less power than a normal bus
engine so when relying on the engine alone its going to be slower
compared to the normal engine running at optimum gearing.

shrug
How often do bus engines require full power? Not very.

Don't forget that one thing electric motors are very good at is producing
large amounts of torque from rest.

In article . com,
Boltar wrote:
On 6 Jul, 11:05, Adrian wrote:
Don't forget that the engine is basically just being used as a generator,
therefore can run at optimum revs for the specific output - there's no
requirement for any kind of useful rev range or torque curve.

True , and I suppose that will mitigate it somewhat. However
ultimately that engine will produce less power than a normal bus
engine so when relying on the engine alone its going to be slower
compared to the normal engine running at optimum gearing.

Yes, but busses (especially in London) are very stop-start; if the engine
is busy recharging the battery when at a bus stop and/or red lights, it will
mitigate that to some extent.

Plus the regenerative braking, of course.

Exactly how far those effects help is something they will find out
as part of the trial, I guess.

--
Shenanigans! Shenanigans! Best of 3!
-- Flash

On 6 Jul, 11:15, Boltar wrote:
On 6 Jul, 11:05, Adrian wrote:

Don't forget that the engine is basically just being used as a generator,
therefore can run at optimum revs for the specific output - there's no
requirement for any kind of useful rev range or torque curve.

True , and I suppose that will mitigate it somewhat. However
ultimately that engine will produce less power than a normal bus
engine so when relying on the engine alone its going to be slower
compared to the normal engine running at optimum gearing.

B2003

You might be right for an outer suburban bus route, or one going from
town to town. However, a bus in London will probably average about
15mph. Hypothesising a little, if a 6 litre engine can deliver 60mph,
a 1.5 litre engine should deliver 15mph. The battery is being used as
an accumulator so average speed determined average power requirement.

"Boltar" wrote in message
ups.com
On 6 Jul, 09:56, Adrian wrote:
February
2006.http://www.tfl.gov.uk/corporate/medi...ntre/3680.aspx

From the article:

"The battery pack is kept at optimum power by a 1.9 litre diesel Euro
IV engine. In other words, an engine which would normally be found in
a family car keeps the battery"

1.9 sounds a bit too small. I'm sure in start and stop traffic it
might be ok but ultimately the energy all comes from that engine.
Seems to me the bus would be hopeless for any long or even middle
distance runs especially if any hills are involved, since once the
battery has been used up its relying on the engine only and a 10 ton
(probably more) bus won't be going anywhere fast with an engine that
size.

I was in Seattle a couple of months ago and noticed that all their bendy
buses proudly claim to be hybrids. The buses certainly didn't look new,
so presumably have older technology than the London buses, and Seattle
is a lot more hilly than central London. They seemed to get up the hills
all right, though I've no idea what size diesel engines they have.

Seattle has another pro-public transport featu buses are free in the
central area, so encouraging people to park their cars and then move
around by bus (I doubt that many people get into town other than by
car).

In message , Recliner
writes

I was in Seattle a couple of months ago and noticed that all their bendy
buses proudly claim to be hybrids. The buses certainly didn't look new,
so presumably have older technology than the London buses, and Seattle
is a lot more hilly than central London. They seemed to get up the hills
all right, though I've no idea what size diesel engines they have.

Seattle's dual-mode Breda buses date back to 1989, but were not very
reliable and have been phased out to be replaced by a system developed
by General Motors, in which the diesel engine powers the wheels as well
as charging the battery. Unfortunately, they haven't delivered the
expected reductions in diesel usage:

http://seattlepi.nwsource.com/transp...9_metro13.html
--
Paul Terry

"Paul Terry" wrote in message

In message , Recliner
writes

I was in Seattle a couple of months ago and noticed that all their
bendy buses proudly claim to be hybrids. The buses certainly didn't
look new, so presumably have older technology than the London buses,
and Seattle is a lot more hilly than central London. They seemed to
get up the hills all right, though I've no idea what size diesel
engines they have.

Seattle's dual-mode Breda buses date back to 1989, but were not very
reliable and have been phased out to be replaced by a system developed
by General Motors, in which the diesel engine powers the wheels as
well as charging the battery. Unfortunately, they haven't delivered
the expected reductions in diesel usage:

http://seattlepi.nwsource.com/transp...9_metro13.html

Yes, they certainly have a lusty diesel roar as they climb the Seattle
hills. I wouldn't have guessed they were hybrids if the signs hadn't
said they were.

I suppose this is yet another episode of hybrid vehicles not achieving
the economy that they claim.