Caught one of the new emission free busses on the 25 today. I thought
they were electric, and expected them to sound the same as a trolleybus;
but they sound just like a very quiet diesel engine, with very definite
gear changes. Can anyone explain what technology is used?

Stephen Richards wrote:
Caught one of the new emission free busses on the 25 today. I thought
they were electric, and expected them to sound the same as a trolleybus;
but they sound just like a very quiet diesel engine, with very definite
gear changes. Can anyone explain what technology is used?

Hydrogen fuel cells. Although they're labelled emission free,
technically water is their sole emission.

http://www.tfl.gov.uk/buses/fuel-cell-buses.shtml

--
Dave Arquati
Imperial College, SW7
www.alwaystouchout.com - Transport projects in London

Dave Arquati wrote:


Hydrogen fuel cells. Although they're labelled emission free,
technically water is their sole emission.

http://www.tfl.gov.uk/buses/fuel-cell-buses.shtml

the pdf at the link above talks about an electric motor to drive the
bus, so what is with the gear changes? Or was I imagining them?
SR

On Wed, 01 Sep 2004 20:36:44 +0100, Stephen Richards
wrote:

the pdf at the link above talks about an electric motor to drive the
bus, so what is with the gear changes? Or was I imagining them?

If the electric motors are of the three-phase type often employed on
recent[1] rail stock, the "gear change" is actually a change in the AC
frequency being applied to the motors as they speed up. It (put
simply) has broadly the same effect as a gear change, but no physical
"gear" is being "changed" as such.

[1] While all EMUs built since the 1990s have this technology, it's
not always audible for various reasons. The Class 323 EMUs used in
the Manchester area seem the most obvious.

Neil

--
Neil Williams in Milton Keynes, UK
To e-mail use neil at the above domain

On Wed, 01 Sep 2004 20:25:29 +0100, Stephen Richards
wrote:

Caught one of the new emission free busses on the 25 today. I thought
they were electric, and expected them to sound the same as a trolleybus;
but they sound just like a very quiet diesel engine, with very definite
gear changes. Can anyone explain what technology is used?

Just for info, the Fuel Cell buses are due to transfer to route RV1
from Monday, 06/09/2004, as part of the normal schedule rather than as
extras. They will operate on Mondays - Fridays, between approx. 0700
and 1500.

The timetable for these trips should appear on
www.firstlondontimetables.co.uk
by the end of the week.

Click on Timetables, select Routes R21 - W19, then select Route RV1
Fuel Cell. (The link is already there, but currently generates a 404 -
page not found error).

--
Thomas Covenant
Please observe Reply-to address.

Stephen Richards schrieb:
but they sound just like a very quiet diesel engine, with very definite
gear changes. Can anyone explain what technology is used?

I might be able to explain the gear changes. I suppose these buses are
part of this special european fuel cell project. We have a few of them
here in Hamburg, too, and the bus company explained to me that it was a
standard diesel bus with only the diesel parts removed and an electric
motor dropped in, leaving the transmission and gearbox and everything
intact.
This was done to make the bus as compatible as possible to diesel buses
of their type, and, it was said the conversion was cheaper than a fully
electric bus (why they did not just take a trolleybus design is beyond me).

They said that when fuel cell buses would go into full use, the design
would be changed appropriately.

The current fuel cell buses even kept their standard brakes, dissipating
a lot of energy into heat when braking which could be turned back into
electricity instead of heat...

On Thu, 02 Sep 2004 00:40:22 +0200, =?ISO-8859-1?Q?Gunnar_Th=F6le?=
wrote:

I might be able to explain the gear changes. I suppose these buses are
part of this special european fuel cell project. We have a few of them
here in Hamburg, too, and the bus company explained to me that it was a
standard diesel bus with only the diesel parts removed and an electric
motor dropped in, leaving the transmission and gearbox and everything
intact.

This strikes me as a bit silly and inefficient, seeing as the reason
for having a "changing" gearbox and torque converter/clutch at all on
an internal-combustion engine is because such engines work efficiently
at a very narrow rev range, while electric motors do not suffer the
same restriction.

Neil

--
Neil Williams in Milton Keynes, UK
To e-mail use neil at the above domain

Neil Williams schrieb:
standard diesel bus with only the diesel parts removed and an electric
motor dropped in, leaving the transmission and gearbox and everything
intact.


This strikes me as a bit silly and inefficient, seeing as the reason
[clutch and gearbox on electric buses]
Yes, of course, from an engineering standpoint this is really very silly.
Its the economics that make sense, they say.

Transport problem: The Hamburg fuel cell buses are quite nice i think,
but they have one design flaw: Somebody mounted a video screen directly
in front of the "next stop" sign.
The video screen shows a film about how great fuel cell buses are. The
next stop sign shows the name of the next stop (!) but it can't be seen
by most bus users!

I pointed that out to the bus company and the response i got was like
"Yes, we know. We are planning to display the next stop on the video
screen like on the Underground". (On the underground you can watch an
information and commercials programme that is interrupted for a few
seconds to show the next stop name which i hate because you have to look
at the damned thing all the time if you want to catch the name of the
next stop)

On Wed, 01 Sep 2004 20:40:39 GMT, (Neil
Williams) wrote:

On Wed, 01 Sep 2004 20:36:44 +0100, Stephen Richards
wrote:

the pdf at the link above talks about an electric motor to drive the
bus, so what is with the gear changes? Or was I imagining them?

If the electric motors are of the three-phase type often employed on
recent[1] rail stock, the "gear change" is actually a change in the AC
frequency being applied to the motors as they speed up. It (put
simply) has broadly the same effect as a gear change, but no physical
"gear" is being "changed" as such.

[1] While all EMUs built since the 1990s have this technology, it's
not always audible for various reasons. The Class 323 EMUs used in
the Manchester area seem the most obvious.

Neil

Thanks Neil - that's answered a question I've often thought when on
those trains :-)
--

ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø
Please reply to the group
Replies to this address will bounce!
ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø

On Thu, 02 Sep 2004 10:14:49 +0200, =?ISO-8859-1?Q?Gunnar_Th=F6le?=
wrote:

I pointed that out to the bus company and the response i got was like
"Yes, we know. We are planning to display the next stop on the video
screen like on the Underground". (On the underground you can watch an
information and commercials programme that is interrupted for a few
seconds to show the next stop name which i hate because you have to look
at the damned thing all the time if you want to catch the name of the
next stop)

I always thought the U-Bahn screens were a nice touch, because when
the next stop is displayed, a picture of the station or its
surroundings are also displayed. Admittedly, however, it's not
visible all the time - but it's more than was provided on the older
U-Bahn stock (is any of that still in service?) and it's more than is
provided on most UK underground/metro stock.

Admittedly, with bus stops closer together[1], there'd be less time
for such things on a bus.

[1] That said, bus stops in Germany are typically *much* further apart
than they typically are in the UK - certainly in Hamburg.

Neil

--
Neil Williams in Milton Keynes, UK
To e-mail use neil at the above domain