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aostling
08-11-2007, 10:19 PM
I visited the Maritime Museum in Monterey. They have the Fresnel lens assembly for the decommissioned Pt. Sur lighthouse. This was built in France in 1887, and shipped around Cape Horn. There were no roads on the California coast in those days -- Hwy 1 was not completed until 1937 -- so this was a very remote post.

The lens assembly was mechanically driven by a 450 pound weight cranked up by the keeper. A flyball governor held the speed constant. The Fresnel lens elements weighed 4330 pounds. Here you can see the rollers used to support the structure. They are beautiful, in brass (or bronze?).

http://i168.photobucket.com/albums/u183/aostling/Fresnellens.jpg


http://i168.photobucket.com/albums/u183/aostling/governor.jpg


http://i168.photobucket.com/albums/u183/aostling/rollers.jpg

In 1974, when I worked for the New Zealand Ministry of Works, I saw a position advertised, for Lighthouse Engineer. I applied, and was given an interview, but I was not the man for this job. I thought it would take me to inaccessibly remote parts of the country. I wonder if New Zealand had old machinery like this in service.

TGTool
08-11-2007, 11:35 PM
Beautiful pieces. Built when simply functional wasn't the only criterion. Any idea what rpm that ran? Were the oil cups a daily or a weekly chore? I'm glad you're seeing those places (and telling us about them.)

Mcgyver
08-12-2007, 12:00 AM
I used crew on sailboats and once in Hopetown, Bahamas (the real Bahamas) we snuck in the lighthouse at 2 am, and by minor miracle, liquored to the gills, we managed to climb to the top. We found a door, like in a submarine , and went out onto a balcony, sat down and marveled at the night and view. Some time later we notice the light had stopped! #$%#$ we tore down the stairs banged on the keeper's cottage door and (omitting huge parts of the story) said we'd noticed the light was out.

Turns out the light was a kerosene flame (our leaving the door open created a draft and put it out) The keeper was great, gave us a full tour, showed us how to crank the weight etc. the lenses looked much like your pic, but it floated in a pool of mercury. Apparently given how heavy mercury is, that massive structure would buoyantly float in a ring shaped trough of mercury, such that there was very little friction in rotating it. still in use so far as i know, and it's an important one, 20 mile visibility, first land on an Atlantic crossing at that latitude

http://marinas.com/view/lighthouse/356

great pics, thanks for bringing back the memory

aostling
08-12-2007, 12:12 AM
Beautiful pieces. Built when simply functional wasn't the only criterion. Any idea what rpm that ran? Were the oil cups a daily or a weekly chore?

I don't know the RPM, or the oiling interval. Like McGyver's lighthouse in Hopetown it had a kerosene lamp, visible for 23 miles. That's impressive!

Northernsinger
08-12-2007, 12:47 PM
I don't write in very much but thought I'd mention, McGyver that I've been to the top of the Hopetown light house also. I could, perhaps, find a photograph of myself about ten years ago posed in front of the quiet place.

dp
08-12-2007, 01:06 PM
These old lenses are truly artwork - the North Head Lighthouse lens is on display near the mouth of the Columbia River on the Washington side:

http://www.funbeach.com/attractions/lighthouse.html

It is massive, and each piece of glass is unique. The Fort Canby park and museum is one of the coastal highlights for our state. Unlike Oregon our coastal highway is not real close to the coast for much of it's way so the raw beauty of the northwest coast is more difficult to find by vehicle. But it's there.

John Stevenson
08-12-2007, 02:44 PM
Note the split anti-backlash gear in the last photo.
The thick part would be fixed to the shaft and the thinner part spring loaded so that it took all backlash out and as it wore would continue to keep pressure on via the springs.

.

.

TGTool
08-12-2007, 02:52 PM
Note the split anti-backlash gear in the last photo.
The thick part would be fixed to the shaft and the thinner part spring loaded so that it took all backlash out and as it wore would continue to keep pressure on via the springs.


Now that's interesting! What's the special issue with anti-backlash in this installation? The thing would presumably always be rotating in the same direction. Would wind set up a vibration that caused fretting of the gears? It must have been based on experience, but really seems to indicate that there's a lot more to know about problems of lighthouse design and operation.

dp
08-12-2007, 03:06 PM
It appears to me the gear it twice as thick as needed and can be flipped over half way through it's lifetime.

Alistair Hosie
08-12-2007, 04:11 PM
And we think we are pretty sophisticated these days the old guys could have taught us so much. Beautiful design and build simply beautiful. Alistair

Asquith
08-12-2007, 05:25 PM
Excellent photos of superb machinery.

Iíve seen some beautiful Fresnel lanterns made by Chance Brothers of Birmingham, but Iíve never succeeded in taking a good photo of one. Incidentally, anyone travelling on the M5 through the industrial wasteland of the English West Midlands will pass a tall Georgian factory building, a survivor of the great Chance Bros factory in Smethwick. Hard to imagine that such unprepossessing surroundings would have given birth to the artistry that would grace lighthouses all over the world, as well as producing the glass for the 1851 Crystal Palace, and ornamental windows for the White House.

But back to the beautiful French machinery. I would hazard a guess about the anti-backlash gears:
The lens assembly has a lot of inertia, and revolves slowly (2 - 3 rpm?). Itís driven by a weight on a cord that falls slowly through the height of the lighthouse. In between thereís a load of gears whizzing round at a rate of knots, and a governor. The final reduction gears seen in the third photo are simple straight cut gears, and any slight discontinuity in transmission as teeth disengage and engage could cause quite a shock to the faster-running gears. Hence the anti-backlash gears. Thatís my guess.

Fascinating things, lighthouses, huge fog horns and all.
Some of the lighthouses in Britain and Ireland, such as Fastnet, were first built inland in Cornwall. Great dovetailed blocks carved from granite, trial assembled, and then shipped out. 2000 blocks, 4000 tons, assembled on the lonely Fastnet rock in 4 months. Some info here:-

http://www.mizenhead.net/fastnet-rock.html

Chance Bros. info here:-
http://www.search.revolutionaryplayers.org.uk/engine/resource/exhibition/standard/default.asp?resource=4439

aostling
08-12-2007, 05:40 PM
Fascinating things, lighthouses, huge fog horns and all.
Some of the lighthouses in Britain and Ireland, such as Fastnet, were first built inland in Cornwall. Great dovetailed blocks carved from granite, trial assembled, and then shipped out. 2000 blocks, 4000 tons, assembled on the lonely Fastnet rock in 4 months.


Asquith,

Though your link has photos of Fastnet, I cannot resist inserting one of my own. I visited this lonely rock in May, taking the once-a-week launch from the town of Schull. It was the highlight of my Ireland travels.

http://i168.photobucket.com/albums/u183/aostling/Fastnetlight.jpg

J Tiers
08-12-2007, 07:14 PM
As far as bearings and anti-backlash.......

Think about it from the point of view of a ship.

For one thing, some lighthouses had a 'flash pattern", i.e. a dash and dot type pattern so you knew which one it was.

For another, out many miles at the limit of visibility, a fairly small movement of the lens can move the beam quite a lot.

So, if the beam "shook" and especially if it shook rotationally, it could change the "pattern" and mess up the good folks on the ship. That particular light does not seem to have had a pattern, but some did.

Probably a standard mechanism was used, and the anti-backlash would tend to prevent any shaking and pattern distortion for those that DID have a flash pattern.

Edit... looking at the far side, it may have had a pattern, since the lenses on the back side do not look the same as those on the side toward the camera, unless I am seeing a reflection.

BigBoy1
08-13-2007, 10:12 AM
And we think we are pretty sophisticated these days the old guys could have taught us so much. Beautiful design and build simply beautiful. Alistair

It is such a sad fact of life that so much expertise is being lost with the passing of the "older" machinists. To bad that each one didn't write a book called, "Things I Learned".

I've tried to mentor youngsters but most have the attitude that you don't need "old stuff" as anything can be done with CAD and CNC.

I just wish that each new person had to learn how to do the things manually BEFORE the could even get close to CNC equipment!

Bill

Peter S
08-14-2007, 06:34 AM
[QUOTE=aostling] A flyball governor held the speed constant. [QUOTE]

Anyone know how the speed was kept constant, i.e. what did the governor work on? A brake maybe?

My favourite odd piece of clockwork was a weight driven spit I saw a few years ago. A weight drove a quite elaborate heavy-duty wall-mounted clockwork which drove a spit via a series of shafts and universal joints. Quite old, and not surprisingly, Swiss-made.

Alan Smith
08-14-2007, 07:24 AM
Peter S, on holiday in France earlier this summer we stayed at a Chateau where the owner had commisioned his local blacksmith to reproduce a copy of a weight driven clockworks to drive a spit. This was to compliment one of the most attractive stone fireplaces I'd ever seen. The arrangement was goverened by a combination fan/flybob which took it's drive off the train via a wormwheel. To reproduce the wormwheel the smith had wrapped some 1/8*1/8 bar around a spindle and welded it in place.

As a keen amateur blacksmith I requested permission to take photographs for the purposes of (one day) getting around to making my own copy for my own stone fireplace.

On clockworks such as this the flybobs don't actuate a lever system operating a throttle such as on a steam engine but work by physics. As speed rises centripetal force makes the bobs fly out but as the radius of the swept circle increases the moment ? (is this right? I'm no engineer) increases, more resistance is introduced into the system slowing the works. Fine tuning was achieved by tweaking fans which can produce more or less air resistance, much like Evans hot-dog roaster last month.

A.K. Boomer
08-14-2007, 07:47 AM
Note the split anti-backlash gear in the last photo.
The thick part would be fixed to the shaft and the thinner part spring loaded so that it took all backlash out and as it wore would continue to keep pressure on via the springs.

.

.


I dont believe thats how that one functions but its possible, I still think its an anti-backlash but I dont think its a spring loaded automatic style, I think its manually adjusted by that large cinchdown nut at the top of the gears, its a fixed ring and pinon, as they wear over the years you undo the tension of the large nut and counter rotate the two gears until clearence is taken up --- then cinch it back down, either way you can see the offset in the gear teeth,
Lighthouses are very cool and that one is in "ship shape and bristol fashion"

I seen an engineering show that showed how they had to move one back from a constant eroding shoreline, crazy...

A.K. Boomer
08-14-2007, 07:54 AM
but it floated in a pool of mercury. Apparently given how heavy mercury is, that massive structure would buoyantly float in a ring shaped trough of mercury, such that there was very little friction in rotating it. still in use so far as i know, and it's an important one, 20 mile visibility, first land on an Atlantic crossing at that latitude

http://marinas.com/view/lighthouse/356

great pics, thanks for bringing back the memory


That is amazing --- what an incredible amount of mercury, if that baby ever crumbles into the sea theres going to be hell to pay for century's with the local fish population:eek: