G. Waller Engine – Two valves???

[Bruce EdneyParticipant @bruceedney59949]

Hi

Yesterday I visited the Dunedin Gasworks Museum in New Zealand and saw some lovely G. Waller engines operating.

One of these engines seemed to have 2 valves (rods and eccentrics) – The volunteer at the centre explained a bit about the dial control that seemed to be connected somehow to the outer most one but not why there were 2 systems.

Can anyone shed any light on the theory and perhaps diagrams to explain how this valving works?

Thanks

Bruce

Edited By Bruce Edney on 06/04/2015 04:02:25

[Bruce EdneyParticipant @bruceedney59949]

[John OlsenParticipant @johnolsen79199]

This is a variable cutoff system. There were a number of systems for this. There is a Tangye compound pump engine at MOTAT in Auckland that has a variable cutoff. We did work out how it all worked when we were working on the engine, but now that they have sacked all the steam section volunteers I can't remember all the details of how it worked. But the effect is that you can change the cutoff so that the power is matched to the load, while running at full steam pressure for best efficiency. I think also the systems like the Dunedin engine has with two valves give a faster opening and closing of the ports, so less wiredrawing.

John

[JasonBModerator @jasonb]

Quite possibly Meyer valve gear to conserve steam. The easton & Anderson that I made a while ago had that arrangement.

J

[Oompa LumpaParticipant @oompalumpa34302]

Posted by John Olsen on 06/04/2015 04:27:25:

, but now that they have sacked all the steam section volunteers I can't remember

How the hell do you sack a volunteer, and why on earth would you. The last three words are the words of doom really. You can't remember and the people who, either collectively or individually, could remember are nowhere to be seen.

There is a great deal of parallel here to the Planet of the Apes, the Monkeys are taking over that's for sure.

graham.

[Bruce EdneyParticipant @bruceedney59949]

Thanks Jason

A quick search on Meyer valve gear return this image which explains it quite well

The Waller only has one cylinder so likely to just be the HP cylinder

[Ian S CParticipant @iansc]

Bruce, I agree the gas works is a great place to visit, last time I was there, I spent half an hour or so driving round on a traction engine. Used to live in Dunedin, but don't get down very often these days.

Ian S C ???? Sack volunteers????, mind you I think it has come close to that at a historic park not too far from here.

[John OlsenParticipant @johnolsen79199]

Well, the CEO was quoted in the newspaper as saying we had been fired, so it must be true. So far as any of us were officially informed, the section was suspended due to the fact that the section manager had resigned. He resigned largely over a safety issue. The boiler house had had a problem with excessive water bills and so the management had arranged for it to be replumbed without telling anyone with technical knowledge, like the boiler attendant or the steam section manager. The first the boiler attendant knew was that he had a boiler under steam and couldn't seem to get water into it fast enough…he had to shut down. The boiler house had been plumbed up with a piece of half inch water pipe. The boiler attendant was a full time employee and has since left…the above would have been a factor but there were probably others.

The CEO did meet with the volunteers to try to persuade one of us to take over as steam section manager, but stormed out in anger when nobody was prepared to take on the role. The fact that none of us were actually qualified to the sort of level required does not seem to have been a factor in his reasoning. This all happened over a year ago, more recently all of us have received an email making overtures about getting things going again. So far as I know, none of the volunteers has shown any interest in doing so, all are busy with other projects, for instance most of them have been working on a replica Newcomen engine. Personally I have a steam launch that needs to be finished so I can use it. So the volunteers are not missing out on any fun, but MOTAT is missing out on all the work they could have done. In connection with which it is worth noting that the restoration of the beam engine which we did a few years back has now earned three international awards.

There does seem to be a policy of discouraging volunteers at MOTAT under the current management, and the numbers in other sections have fallen.

So to get back on topic, I could go back and take a look at the Tangye to remind myself of the external arrangements, however I could not take off the cover and look inside as we did before. I should have taken a photo but that was before I had a digital camera.The essential details of that one were that the external control worked a screw with left and right threads to move two port blocks together or apart, changing the timing of the cutoff, but not the admission.

John

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