Last year we rode a funicular railway with a single overhead wire and a large bank of resistors on the roof that got very hot when it was descending. I'm guessing that it was a DC motor/generator setup with the resistors absorbing the generators output on the way down.

Today we rode a train with two overhead wires but no resistor banks. This train apparently runs on a three phase supply. Presumably the rails supplied the third "leg" of the supply but how safe is this with AC? Wouldn't the rails be dangerously live relative to earth?

There were no warning signs and the track was unprotected so it must be safe but I don't understand how. Can anyone explain? Also, how did the braking work?

https://en.m.wikipedia.org/wiki/Petit_train_de_la_Rhune

Tim

On 06/07/2019 20:55, Tim+ wrote:
Last year we rode a funicular railway with a single overhead wire and
a large bank of resistors on the roof that got very hot when it was
descending. I'm guessing that it was a DC motor/generator setup with
the resistors absorbing the generators output on the way down.

Today we rode a train with two overhead wires but no resistor banks.
This train apparently runs on a three phase supply. Presumably the
rails supplied the third "leg" of the supply but how safe is this
with AC? Wouldn't the rails be dangerously live relative to earth?

Why would they be? If the rails were earthed...

a three phase supply doesnt have to have each limb symmetrical with
respect to earth.

Consider a star or delta transformer with one phase earthed.



There were no warning signs and the track was unprotected so it must
be safe but I don't understand how. Can anyone explain? Also, how
did the braking work?

Feeding overvoltage back into a low impedance supply.


https://en.m.wikipedia.org/wiki/Petit_train_de_la_Rhune

Tim



--
"A point of view can be a dangerous luxury when substituted for insight
and understanding".

Marshall McLuhan

On 06/07/2019 21:08, The Natural Philosopher wrote:
Why would they be? If the rails were earthed...

a three phase supply doesnt have to have each limb symmetrical with
respect to earth.

Consider a star or delta transformer with one phase earthed.

I just spent ten minutes trying to check you out - and failed. I can't
find anything saying that in either English or French.

One of the few other such systems is the Jungfraubahn, which I went on a
couple of years ago. I'm damn sure there isn't a live rail - I walked
across the track - so your guess must be correct.

Or you have a source I couldn't find!

Andy

You should be able to have anything earthed if you use a transformer for the
supply with a separate secondary.
Brian

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Tim+" wrote in message
...
Last year we rode a funicular railway with a single overhead wire and a
large bank of resistors on the roof that got very hot when it was
descending. I'm guessing that it was a DC motor/generator setup with the
resistors absorbing the generators output on the way down.

Today we rode a train with two overhead wires but no resistor banks. This
train apparently runs on a three phase supply. Presumably the rails supplied
the third "leg" of the supply but how safe is this with AC? Wouldn't the
rails be dangerously live relative to earth?

There were no warning signs and the track was unprotected so it must be safe
but I don't understand how. Can anyone explain? Also, how did the braking
work?

https://en.m.wikipedia.org/wiki/Petit_train_de_la_Rhune

Tim

If you have ever played with slot racing cars the breaking when you bring up
the plunger is done by shorting out the track.
Brian

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"The Natural Philosopher" wrote in message
...
On 06/07/2019 20:55, Tim+ wrote:
Last year we rode a funicular railway with a single overhead wire and
a large bank of resistors on the roof that got very hot when it was
descending. I'm guessing that it was a DC motor/generator setup with
the resistors absorbing the generators output on the way down.

Today we rode a train with two overhead wires but no resistor banks.
This train apparently runs on a three phase supply. Presumably the
rails supplied the third "leg" of the supply but how safe is this
with AC? Wouldn't the rails be dangerously live relative to earth?

Why would they be? If the rails were earthed...

a three phase supply doesnt have to have each limb symmetrical with
respect to earth.

Consider a star or delta transformer with one phase earthed.



There were no warning signs and the track was unprotected so it must
be safe but I don't understand how. Can anyone explain? Also, how
did the braking work?

Feeding overvoltage back into a low impedance supply.


https://en.m.wikipedia.org/wiki/Petit_train_de_la_Rhune

Tim



--
"A point of view can be a dangerous luxury when substituted for insight
and understanding".

Marshall McLuhan

It was done on large three phase motors on radars which tended to have to be
tested with covers off, and it was most certainly earthed on one rail.
Brian

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Vir Campestris" wrote in message
...
On 06/07/2019 21:08, The Natural Philosopher wrote:
Why would they be? If the rails were earthed...

a three phase supply doesnt have to have each limb symmetrical with
respect to earth.

Consider a star or delta transformer with one phase earthed.

I just spent ten minutes trying to check you out - and failed. I can't
find anything saying that in either English or French.

One of the few other such systems is the Jungfraubahn, which I went on a
couple of years ago. I'm damn sure there isn't a live rail - I walked
across the track - so your guess must be correct.

Or you have a source I couldn't find!

Andy

Tim+ expressed precisely :
Today we rode a train with two overhead wires but no resistor banks. This
train apparently runs on a three phase supply. Presumably the rails supplied
the third "leg" of the supply but how safe is this with AC? Wouldn't the
rails be dangerously live relative to earth?

It could have been single phase and neutral on the wires, or two phases
and an earth via the earthed rail.

The motor would likely be synchronous, driving a worm gear. The drive
would only allow the car to decend limited by the motor's speed.

Tim+ wrote:
Last year we rode a funicular railway with a single overhead wire and a
large bank of resistors on the roof that got very hot when it was
descending. I'm guessing that it was a DC motor/generator setup with the
resistors absorbing the generators output on the way down.

Today we rode a train with two overhead wires but no resistor banks. This
train apparently runs on a three phase supply. Presumably the rails
supplied the third "leg" of the supply but how safe is this with AC?
Wouldn't the rails be dangerously live relative to earth?

There were no warning signs and the track was unprotected so it must be
safe but I don't understand how. Can anyone explain? Also, how did the braking work?

https://en.m.wikipedia.org/wiki/Petit_train_de_la_Rhune

Tim


I think you mean a rack Railway using cogs on a toothed Rail between the
running rails.

Funiculars are rope hauled and purists reckon there must be an up and down
cabin/carwith one counter balancing
the other either by using water filled at the top or a motor to overcome
any weight difference, even so the term as spread to other types but they
all have a rope permanently attached to the vehicle which differentiates
them from cable trams like in San Francisco where they can be released by
a grip mechanism.

As for the 3 phase electrification there are not many examples left of this
style which was a way of using AC
at the beginning of the 20th century when motor technology was in its in
infancy and speed control crudely done by pole changing, it also allowed
for easy regeneration by using the motors as generators and feeding back
into the supply.
Frequencies were low as again motor technology was not advanced enough at
the time for higher.
The biggest user of the system was Italy where the 3600volt 16.7 Hz system
remained in use on a good proportion of the network till the mid 1970s.
Junctions were very complicated as the two overhead wires had to have long
insulated sections over pointwork and to cope with that the locomotives had
a strange look due to the collector arms reaching out or extremities to
cope with crossing the neutral sections.

https://images.app.goo.gl/3BhWnAr9suGyEfvE6

In that photo there is a water supply as used to top up steam locos, except
here it was also used to top up the
electrics as to get additional speed control liquid rheostats were used
,the liquid solution in those got got hot so was cooled by a secondary
water circuit and radiators which had to be topped up at intervals.

At one time the system was almost adopted by the Metropolitan Railway in
London to replace the original steam traction as electrical expertise for
such things existed in Eastern Europe with the Ganz company of Budapest and
not here at that time and their tender had been accepted.
Only the arrival of American finance on other parts of what would become
the London Underground network and the board of trade arbitrating in favour
of the others whose American financier prefered the DC live rail system he
knew from Chicago stopped the contract.

GH

"Marland" wrote in message
...
Tim+ wrote:
Last year we rode a funicular railway with a single overhead wire and a
large bank of resistors on the roof that got very hot when it was
descending. I'm guessing that it was a DC motor/generator setup with the
resistors absorbing the generators output on the way down.

Today we rode a train with two overhead wires but no resistor banks. This
train apparently runs on a three phase supply. Presumably the rails
supplied the third "leg" of the supply but how safe is this with AC?
Wouldn't the rails be dangerously live relative to earth?

There were no warning signs and the track was unprotected so it must be
safe but I don't understand how. Can anyone explain? Also, how did the
braking work?

https://en.m.wikipedia.org/wiki/Petit_train_de_la_Rhune

Tim


I think you mean a rack Railway using cogs on a toothed Rail between the
running rails.

Funiculars are rope hauled

Counterbalanced cars connected by cables, actually.

and purists reckon there must be an up and down
cabin/carwith one counter balancing
the other either by using water filled at the top or a motor to overcome
any weight difference, even so the term as spread to other types but they
all have a rope permanently attached to the vehicle which differentiates
them from cable trams like in San Francisco where they can be released by
a grip mechanism.

As for the 3 phase electrification there are not many examples left of
this
style which was a way of using AC
at the beginning of the 20th century when motor technology was in its in
infancy and speed control crudely done by pole changing, it also allowed
for easy regeneration by using the motors as generators and feeding back
into the supply.
Frequencies were low as again motor technology was not advanced enough at
the time for higher.
The biggest user of the system was Italy where the 3600volt 16.7 Hz
system
remained in use on a good proportion of the network till the mid 1970s.
Junctions were very complicated as the two overhead wires had to have long
insulated sections over pointwork and to cope with that the locomotives
had
a strange look due to the collector arms reaching out or extremities to
cope with crossing the neutral sections.

https://images.app.goo.gl/3BhWnAr9suGyEfvE6

In that photo there is a water supply as used to top up steam locos,
except
here it was also used to top up the
electrics as to get additional speed control liquid rheostats were used
,the liquid solution in those got got hot so was cooled by a secondary
water circuit and radiators which had to be topped up at intervals.

At one time the system was almost adopted by the Metropolitan Railway in
London to replace the original steam traction as electrical expertise for
such things existed in Eastern Europe with the Ganz company of Budapest
and
not here at that time and their tender had been accepted.
Only the arrival of American finance on other parts of what would become
the London Underground network and the board of trade arbitrating in
favour
of the others whose American financier prefered the DC live rail system he
knew from Chicago stopped the contract.

GH

On Saturday, 6 July 2019 20:55:38 UTC+1, Tim+ wrote:
Last year we rode a funicular railway with a single overhead wire and a large bank of resistors on the roof that got very hot when it was descending.. I'm guessing that it was a DC motor/generator setup with the resistors absorbing the generators output on the way down.

Today we rode a train with two overhead wires but no resistor banks. This train apparently runs on a three phase supply. Presumably the rails supplied the third "leg" of the supply but how safe is this with AC? Wouldn't the rails be dangerously live relative to earth?

There were no warning signs and the track was unprotected so it must be safe but I don't understand how. Can anyone explain? Also, how did the braking work?

https://en.m.wikipedia.org/wiki/Petit_train_de_la_Rhune



There's a link you must have missed.
https://en.m.wikipedia.org/wiki/Thre...lectrification

On Sun, 7 Jul 2019 10:56:42 +1000, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:


I think you mean a rack Railway using cogs on a toothed Rail between the
running rails.

Funiculars are rope hauled

Counterbalanced cars connected by cables, actually.

Auto-contradicting senile IDIOT! LOL

--
Kerr-Mudd,John addressing senile Rot:
"Auto-contradictor Rod is back! (in the KF)"
MID:

On 06/07/2019 21:53, Vir Campestris wrote:
On 06/07/2019 21:08, The Natural Philosopher wrote:
Why would they be? If the rails were earthed...

a three phase supply doesnt have to have each limb symmetrical with
respect to earth.

Consider a star or delta transformer with one phase earthed.

I just spent ten minutes trying to check you out - and failed. I can't
find anything saying that in either English or French.


???

https://www.electronics-tutorials.ws...ansformer.html

One of the few other such systems is the Jungfraubahn, which I went on a
couple of years ago. I'm damn sure there isn't a live rail - I walked
across the track - so your guess must be correct.

Or you have a source I couldn't find!

Andy


--
"First, find out who are the people you can not criticise. They are your
oppressors."
- George Orwell

On 06/07/2019 23:24, Harry Bloomfield wrote:
Tim+ expressed precisely :
Today we rode a train with two overhead wires but no resistor banks.
This train apparently runs on a three phase supply. Presumably the
rails supplied the third "leg" of the supply but how safe is this with
AC? Wouldn't the rails be dangerously live relative to earth?

It could have been single phase and neutral on the wires, or two phases
and an earth via the earthed rail.

It is three phase and the rail is one phase and is earthed.

Phases are only phased with respect to each other, they dont care about
their relationship with 'earth'.

Voltage is not absolute, It is relative, as any bird sitting on a 132KV
line can tell you




The motor would likely be synchronous, driving a worm gear. The drive
would only allow the car to decend limited by the motor's speed.


--
"It is an established fact to 97% confidence limits that left wing
conspirators see right wing conspiracies everywhere"

On 6 Jul 2019 23:12:36 GMT, Marland wrote:

https://en.m.wikipedia.org/wiki/Petit_train_de_la_Rhune

I think you mean a rack Railway using cogs on a toothed Rail between
the running rails.

He does, you can see the rack very clearly in the pictures on
wonkypedia.

Had me confused as funiculars are passive not electrically powered.
Two cars llinked via a rope going round a wheel at the top. Make the
one at the top heavier than the one at the bottom (commonly done by
adding water to a tank in the top car and letting the water out of
the lower) and gravity does the rest.

There are rope hauled "inclined elevators / lifts" that are powered
but at a stationary winch not in the car.

With pure 3 phase (ie only the three phases no "neutral") the voltage
between the phases is relative to each phase. Bonding one (only one!)
to earth doesn't affect these relative voltages.

--
Cheers
Dave.

The Natural Philosopher has brought this to us :
It is three phase and the rail is one phase and is earthed.

Phases are only phased with respect to each other, they dont care about their
relationship with 'earth'.

I see how that would work now. I had in mind star, with the centre
point grounded - a delta output transformer with one point to ground
would do it.

Marland formulated the question :
cable trams like in San Francisco where they can be released by
a grip mechanism.

Thanks, I have always wondered how they worked!

Harry Bloomfield wrote:
Marland formulated the question :
cable trams like in San Francisco where they can be released by
a grip mechanism.

Thanks, I have always wondered how they worked!


Probably more than you really wanted to know at

http://www.cable-car-guy.com/html/cchow.html

There were examples in the UK , Edinburgh was the most extensive but
converted to electric in the 1920s.
The Glasgow Underground was also cable hauled till the mid 1930s.


GH

On 07/07/2019 11:27, Marland wrote:
Harry Bloomfield wrote:
Marland formulated the question :
cable trams like in San Francisco where they can be released by
a grip mechanism.

Thanks, I have always wondered how they worked!


Probably more than you really wanted to know at

http://www.cable-car-guy.com/html/cchow.html

There were examples in the UK , Edinburgh was the most extensive but
converted to electric in the 1920s.
The Glasgow Underground was also cable hauled till the mid 1930s.


GH

You really have to admire the ingenuity of people who managed to make
these work so well! It's (sort of) a logical successor to Brunel's
atmospheric railway.

Harry Bloomfield wrote:
The Natural Philosopher has brought this to us :
It is three phase and the rail is one phase and is earthed.

Phases are only phased with respect to each other, they dont care about their
relationship with 'earth'.

I see how that would work now. I had in mind star, with the centre
point grounded - a delta output transformer with one point to ground
would do it.


Oh well,Im glad someone does. ;-) Our physics classes never progressed to
three phase power when I was at school and Ive never had a need to
understand it in any depth (or at all really) since then.

Tim

--
Please don't feed the trolls

On 07/07/2019 15:46, Tim+ wrote:
Harry Bloomfield wrote:
The Natural Philosopher has brought this to us :
It is three phase and the rail is one phase and is earthed.

Phases are only phased with respect to each other, they dont care about their
relationship with 'earth'.

I see how that would work now. I had in mind star, with the centre
point grounded - a delta output transformer with one point to ground
would do it.


Oh well,Im glad someone does. ;-) Our physics classes never progressed to
three phase power when I was at school and Ive never had a need to
understand it in any depth (or at all really) since then.

Blimey.

I sort of thought that anyone in a DIY group would have basic electrical
knowledge


Tim



--
Labour - a bunch of rich people convincing poor people to vote for rich
people
by telling poor people that "other" rich people are the reason they are
poor.

Peter Thompson

On 07/07/2019 15:50, The Natural Philosopher wrote:
On 07/07/2019 15:46, Tim+ wrote:
Harry Bloomfield wrote:
The Natural Philosopher has brought this to us :
It is three phase and the rail is one phase and is earthed.

Phases are only phased with respect to each other, they dont care
about their
relationship with 'earth'.

I see how that would work now. I had in mind star, with the centre
point grounded - a delta output transformer with one point to ground
would do it.


Oh well,Im glad someone does. ;-) Our physics classes never
progressed to
three phase power when I was at school and Ive never had a need to
understand it in any depth (or at all really) since then.

Blimey.

I sort of thought that anyone in a DIY group would have basic electrical
knowledge


The only one I have ever actually worked on was at my mate's small
business. Unless you have three phase at home for a lathe I'd have
thought even fairly experienced DIY people wouldn't come across them.

The Natural Philosopher wrote:
On 07/07/2019 15:46, Tim+ wrote:
Harry Bloomfield wrote:
The Natural Philosopher has brought this to us :
It is three phase and the rail is one phase and is earthed.

Phases are only phased with respect to each other, they dont care about their
relationship with 'earth'.

I see how that would work now. I had in mind star, with the centre
point grounded - a delta output transformer with one point to ground
would do it.


Oh well,Im glad someone does. ;-) Our physics classes never progressed to
three phase power when I was at school and Ive never had a need to
understand it in any depth (or at all really) since then.

Blimey.

I sort of thought that anyone in a DIY group would have basic electrical
knowledge


You call it €œbasic€� but its knowledge needed by 0.01% of the population I
would hazard. I guess the education system I went though didnt see it as
important.

Of course I could spend time reading up on it but without any need to
understand it it any depth at all, I prefer to do other things with my
time.

Hands up every DIYer here who dabbles with three phase power?

Tim



--
Please don't feed the trolls

newshound wrote:
On 07/07/2019 15:50, The Natural Philosopher wrote:
On 07/07/2019 15:46, Tim+ wrote:
Harry Bloomfield wrote:
The Natural Philosopher has brought this to us :
It is three phase and the rail is one phase and is earthed.

Phases are only phased with respect to each other, they dont care
about their
relationship with 'earth'.

I see how that would work now. I had in mind star, with the centre
point grounded - a delta output transformer with one point to ground
would do it.


Oh well,Im glad someone does. ;-) Our physics classes never
progressed to
three phase power when I was at school and Ive never had a need to
understand it in any depth (or at all really) since then.

Blimey.

I sort of thought that anyone in a DIY group would have basic electrical
knowledge


The only one I have ever actually worked on was at my mate's small
business. Unless you have three phase at home for a lathe I'd have
thought even fairly experienced DIY people wouldn't come across them.


Yeah, but then youre forgetting that TNP has to throw out gratuitous
patronising comments regularly.

Tim

--
Please don't feed the trolls

On 07/07/2019 18:15, Tim+ wrote:
newshound wrote:
On 07/07/2019 15:50, The Natural Philosopher wrote:
On 07/07/2019 15:46, Tim+ wrote:
Harry Bloomfield wrote:
The Natural Philosopher has brought this to us :
It is three phase and the rail is one phase and is earthed.

Phases are only phased with respect to each other, they dont care
about their
relationship with 'earth'.

I see how that would work now. I had in mind star, with the centre
point grounded - a delta output transformer with one point to ground
would do it.


Oh well,Im glad someone does. ;-) Our physics classes never
progressed to
three phase power when I was at school and Ive never had a need to
understand it in any depth (or at all really) since then.

Blimey.

I sort of thought that anyone in a DIY group would have basic electrical
knowledge


The only one I have ever actually worked on was at my mate's small
business. Unless you have three phase at home for a lathe I'd have
thought even fairly experienced DIY people wouldn't come across them.


Yeah, but then youre forgetting that TNP has to throw out gratuitous
patronising comments regularly.

Three phase power is discussed here pretty often.

Indeed I believe you yourself brought it up in this thread

I told you how it probably was set up, you complained you didnt
understand, I pointed you to a web page that explained it.

Whatr is patronsioing about that?

It was only someome moaning that tehy couldnt ne expected to undersatdn
or summat that irritated me. I study **** I dont understand every day.
Do it yourself!

Tim



--
€œA leader is best When people barely know he exists. Of a good leader,
who talks little,When his work is done, his aim fulfilled,They will say,
€œWe did this ourselves.€�

ۥ Lao Tzu, Tao Te Ching

Tim+ wrote:

The Natural Philosopher wrote:
On 07/07/2019 15:46, Tim+ wrote:
Harry Bloomfield wrote:
The Natural Philosopher has brought this to us :
It is three phase and the rail is one phase and is earthed.

Phases are only phased with respect to each other, they dont care
about their relationship with 'earth'.

I see how that would work now. I had in mind star, with the centre
point grounded - a delta output transformer with one point to ground
would do it.


Oh well,I'm glad someone does. ;-) Our physics classes never progressed to
three phase power when I was at school and I've never had a need to
understand it in any depth (or at all really) since then.

Blimey.

I sort of thought that anyone in a DIY group would have basic electrical
knowledge


You call it "basic" but it's knowledge needed by 0.01% of the population I
would hazard. I guess the education system I went though didn't see it as
important.

Of course I could spend time reading up on it but without any need to
understand it it any depth at all, I prefer to do other things with my
time.

Hands up every DIYer here who dabbles with three phase power?

Tim
Please Sir, I've got a 1hp variable frequency three phase inverter for a
lathe motor. I had to think hard about the connections.

--

Roger Hayter

After serious thinking newshound wrote :
You really have to admire the ingenuity of people who managed to make these
work so well! It's (sort of) a logical successor to Brunel's atmospheric
railway.

+1

A very complex system to develop. I wonder why they developed it as a
below ground drive system, rather than on poles like a ski-lift?

Interesting stuff.

Its not that long ago that I heard about the extensive hydro power
(pressurised water) distribution systems they had in some large cities.

In message , Roger Hayter
writes
Tim+ wrote:
Snip

The Natural Philosopher wrote:
You call it "basic" but it's knowledge needed by 0.01% of the population I
would hazard. I guess the education system I went though didn't see it as
important.

Of course I could spend time reading up on it but without any need to
understand it it any depth at all, I prefer to do other things with my
time.

Hands up every DIYer here who dabbles with three phase power?

Tim
Please Sir, I've got a 1hp variable frequency three phase inverter for a
lathe motor. I had to think hard about the connections.

My house is supplied with 3 phase.

Outbuildings and workshop equipment mostly use 3 phase. One day I'll get
round to converting my centre lathe back to 3ph so I can use the
reversing switch!


--
Tim Lamb

On Mon, 08 Jul 2019 09:01:06 +0100, Harry Bloomfield wrote:

After serious thinking newshound wrote :
You really have to admire the ingenuity of people who managed to make
these work so well! It's (sort of) a logical successor to Brunel's
atmospheric railway.

+1

A very complex system to develop. I wonder why they developed it as a
below ground drive system, rather than on poles like a ski-lift?

Interesting stuff.

Its not that long ago that I heard about the extensive hydro power
(pressurised water) distribution systems they had in some large cities.

Including London, as late as about 1970. Pipes now used for telecoms.

The London Hydraulic Power Company, AFAIR.
--
My posts are my copyright and if @diy_forums or Home Owners' Hub
wish to copy them they can pay me £1 a message.
Use the BIG mirror service in the UK: http://www.mirrorservice.org
*lightning surge protection* - a w_tom conductor

On 08/07/2019 09:01, Harry Bloomfield wrote:
After serious thinking newshound wrote :
You really have to admire the ingenuity of people who managed to make
these work so well! It's (sort of) a logical successor to Brunel's
atmospheric railway.

+1

A very complex system to develop. I wonder why they developed it as a
below ground drive system, rather than on poles like a ski-lift?


2 issues with that a

a. what happens when the cable breaks - a heavy cable (over an inch
across in SF) moving fast (9.5 mph in SF) above busy city roads. I
wouldn't want to walking along the road unless the height of the poles
(H) minus the interval between poles (L) was around 2m. That's a lot of
tall poles! (And still leaves the risk of the cable moving sideways. And
buses etc)

b. transmitting the driving force from a cable several meters above the
car requires a /much/ more substantial structure than from a cable a few
inches below street level.

--
Robin
reply-to address is (intended to be) valid

Bob Eager wrote:
On Mon, 08 Jul 2019 09:01:06 +0100, Harry Bloomfield wrote:

After serious thinking newshound wrote :
You really have to admire the ingenuity of people who managed to make
these work so well! It's (sort of) a logical successor to Brunel's
atmospheric railway.

+1

A very complex system to develop. I wonder why they developed it as a
below ground drive system, rather than on poles like a ski-lift?

Interesting stuff.

Its not that long ago that I heard about the extensive hydro power
(pressurised water) distribution systems they had in some large cities.

Including London, as late as about 1970. Pipes now used for telecoms.

The London Hydraulic Power Company, AFAIR.

Which was bought by Mercury Communications ( remember them) in the mid
seventies who realised they could utilise the pipes as ducts and what was
probably more valuable acquire the legal rights the Hydraulic company held
in being able to dig up up public roads it had held since the 19th century
to install and maintain infrastructure.

Another asset in London reused in a similar manner were the ducts along
streets that once carried the power supply cables for Trams and
Trolleybuses , even now the odd feeder pillar which connected the ducted
cables to a section of tram or trolley bus wiring remains in place
undisturbed for decades.

https://www.flickr.com/photos/kk69521/10808318273

The odd one remains in place in other towns and cities as well.


GH

In article , news0073
@eager.cx says...

On Mon, 08 Jul 2019 09:01:06 +0100, Harry Bloomfield wrote:


Its not that long ago that I heard about the extensive hydro power
(pressurised water) distribution systems they had in some large cities.

Including London, as late as about 1970. Pipes now used for telecoms.

The London Hydraulic Power Company, AFAIR.

I think you'll find that the system had been defunct since
full telephone access had covered the City and they'd lain
empty ever since.

They were then bought by Mercury when they were first allowed
to compete with BT and saved them a fortune in the cost of
installing their cables.

--

Terry

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On Mon, 08 Jul 2019 11:30:02 +0100, Terry Casey wrote:

In article , news0073 @eager.cx
says...

On Mon, 08 Jul 2019 09:01:06 +0100, Harry Bloomfield wrote:


Its not that long ago that I heard about the extensive hydro power
(pressurised water) distribution systems they had in some large
cities.

Including London, as late as about 1970. Pipes now used for telecoms.

The London Hydraulic Power Company, AFAIR.

I think you'll find that the system had been defunct since full
telephone access had covered the City and they'd lain empty ever since.

"Two installations that survived into the 1970s were lifts. At Union Bank
Chambers, 61 Carey Street, WC2, the main passenger lift operated on a
hydraulic ram, with electric press-button control. With passengers aboard
the lift car traveled at normal speed but when called from rest, the ram
propelled the car at a truly unnerving rate of knots. The Grosvenor
Hotel, adjoining Victoria station, had a service lift of a very antique
character. It still used rope control (you pulled up or down on the rope
to start the lift and held it to stop). It operated at two speeds,
depending on your pull. There was no self-levelling at each floor but
auto-stop trips at the top and bottom of the shaft prevented over-run.
Electrical interlocks had been retro-fitted to the lift cars doors.
After the LHP Company went out of business, the system was converted to
oil, using an electrically driven compressor. Whether these two
installations survive is unclear."



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On 07/07/2019 08:31, The Natural Philosopher wrote:
On 06/07/2019 21:53, Vir Campestris wrote:
On 06/07/2019 21:08, The Natural Philosopher wrote:
Why would they be? If the rails were earthed...

a three phase supply doesnt have to have each limb symmetrical with
respect to earth.

Consider a star or delta transformer with one phase earthed.

I just spent ten minutes trying to check you out - and failed. I can't
find anything saying that in either English or French.


???

https://www.electronics-tutorials.ws...ansformer.html


One of the few other such systems is the Jungfraubahn, which I went on
a couple of years ago. I'm damn sure there isn't a live rail - I
walked across the track - so your guess must be correct.

Or you have a source I couldn't find!


You miss my point.

I have no trouble understanding how you could run a three phase system
with one pole earthed.

I could not find a reference saying that this is how they do it.

Andy

On 08/07/2019 11:30, Terry Casey wrote:
In article , news0073
@eager.cx says...

On Mon, 08 Jul 2019 09:01:06 +0100, Harry Bloomfield wrote:


Its not that long ago that I heard about the extensive hydro power
(pressurised water) distribution systems they had in some large cities.

Including London, as late as about 1970. Pipes now used for telecoms.

The London Hydraulic Power Company, AFAIR.

I think you'll find that the system had been defunct since
full telephone access had covered the City and they'd lain
empty ever since.

They were then bought by Mercury when they were first allowed
to compete with BT and saved them a fortune in the cost of
installing their cables.

Manchester's hydraulic system definitely ran from 1894 to 1972.

SteveW

On Mon, 8 Jul 2019 21:44:46 +0100, Steve Walker wrote:

Manchester's hydraulic system definitely ran from 1894 to 1972.

Wonder of the one in Bristol for the floating harbour and other dock
gates is still operational?

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Cheers
Dave.

On 08/07/2019 23:41, Dave Liquorice wrote:
On Mon, 8 Jul 2019 21:44:46 +0100, Steve Walker wrote:

Manchester's hydraulic system definitely ran from 1894 to 1972.

Wonder of the one in Bristol for the floating harbour and other dock
gates is still operational?

Probably not. Like other systems, the users probably switched to using
their own electrically powered hydraulic pumps in the short term and
where possible to purely electrical drives and many older systems
probably have gone out of use entirely since then.

SteveW

Steve Walker wrote:
On 08/07/2019 23:41, Dave Liquorice wrote:
On Mon, 8 Jul 2019 21:44:46 +0100, Steve Walker wrote:

Manchester's hydraulic system definitely ran from 1894 to 1972.

Wonder of the one in Bristol for the floating harbour and other dock
gates is still operational?

Probably not. Like other systems, the users probably switched to using
their own electrically powered hydraulic pumps in the short term and
where possible to purely electrical drives and many older systems
probably have gone out of use entirely since then.

SteveW




The Bristol Harbour system was for its own purposes rather than customers
elsewhere, like a power station the schemes that sold hydraulic power had
to run pumps to adequately supply a customer even though they may not
actually need any , at Bristol they would know when a crane was going to be
used a lock operated or a bridge swung.

I visited the International Festival of the Sea at Bristol in 1996 as a
crew member on a visiting vessel and the
Hydraulic system was still in use then, it finally ceased to be used in
2010 which was quite late compared to other installations and the pump
house is now a museum / visitor centre with some space used for small craft
businesses.

http://www.underfallyard.co.uk/about/our-story/

Dont know how the various items they still need to move have been
converted.

GH