Taking Leave

[DanielParticipant @daniel]

That sounds like a better plan Andrew.

[garyParticipant @gary44937]

good on you andrew, i have been following your traction engine build for a while now

[MeunierParticipant @meunier]

Posted by Andrew Johnston on 21/09/2020 11:55:37:

……was smacked round the head and told to stop being an idiot. …..
Please convey my appreciation to your somewhat blunt anonymous correspondent

…like it or lump it, I'll be back….
good to hear, Arnie…

…..I'm not entirely abandoning the traction engines and other engineering…….
Sagas lose their impact if they peter out halfway

DaveD

[Anonymous]

The astute reader may have noticed that I've been posting again today. Like it or lump it I intend to continue.

Regarding the tasks mentioned above I now have the wheels for my traction engine complete with rubber tyres:

I'm very pleased with the rubber tyres, less so with the rust from the vulcanisation process. I've got rid of a lot of it with wire wheels and a drill. But I've also bought a cheap blast gun and some garnet grit to get rid of the rest.

The safety valve design is on hold.

I now understand the basics of spiral bevel gears and also the difference between involute and octoid tooth forms. So it's now a case of modelling something I can 3D print and then machine.

A further distraction has occurred. Following discussions on the MEM forum I have found some old notes on the internet on the design of skew bevel gears. Of course I am aware of the work by Kozo. But I think his designs are based on hypoid gearing and the tooth profiles are significantly asymmetric. If one looks are drawings, and photographs, of the logging locomotives that used skew bevel gears the tooth forms are symmetric and look like straight tooth bevel gears. The design notes I have found use symmetric tooth profiles as per the full size engines. So I plan to model same in CAD and 3D print them to see if they work.

Talking of work I am now working for the first time in ten months and have been dragged into the 21st century with Zoom meetings for the first time this week. Work has to take priority as the savings are depleted. And we have a reputation with the client for delivering late so we absolutely have to deliver what we say, when we say this time. I am now delving into electrochemical gas sensors, potentiostats and transimpedance amplfiers, although given the large effective series capacitance in the sensor the output amplifier is more like a differentiator, complete with all its noise problems.

Andrew

[Ady1Participant @ady1]

[SteviegtrParticipant @steviegtr]

I spent many years installing instruments in the Electro chemical industry. ICI . Lindsey oil & some chemical plant in Ince, Chester. No idea what they were, i just installed them.

Good to see you are still around. Chin up & get grafting.

Steve.

[garyParticipant @gary44937]

good to see you back, gary

[Thor 🇳🇴Participant @thor]

Andrew, I'm glad you are back and I am looking forward to reading your posts again.

Thor

[Brian HParticipant @brianh50089]

Glad that you're back Andrew.

Brian

[Bob LambParticipant @boblamb44747]

Andrew, I enjoy reading your posts and have learnt a lot from them. Present times are pretty crazy and may well get worse before Christmas – I think we may all be getting a bit fed up with things. I hope you will reconsider your decision – slow down a bit on the posts but don't leave us all without the benefit of your knowledge. Hope the work goes well and look forward to seeing some more posts at sometime in the future. All the best – Bob

[Chris Evans 6Participant @chrisevans6]

A very warm and sincere welcome back Andrew. I always valued your knowledge and enjoyed reading your posts. Chris.

[ChrisHParticipant @chrish]

Welcome back Andrew!

Chris

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Andrew, your rubber tyres look really good and the wheels are good also.

Regards Nick.

[Another JohnSParticipant @anotherjohns]

Andrew;

I seem to remember reading that the Climax gears were hand-made wood patterns, then cast. i.e. not machined.

Although having seen about 1/2 dozen of them, I can't say that I looked that closely! The other 2 (Shay, Heisler) are more interesting, IMHO.

Kozo gives us a way to machine gears good enough for his model Climax, machining on small machines in the average workshop, so I give him top marks.

Yes, it is good to see you back posting; hope the flying stuff is also going well. Cheers from Canada!

[Anonymous]

Thanks for the welcoming comments. Looks like I've made the right decision to return. As before I'll have a few informal rules about posting. Some electronics threads in the past got a bit heated, so I intend to generally stay clear of electronics. It's my profession, not my hobby, so I have an approach to design and debug which probably isn't appropriate here.

Inevitably in the current panic there have been a lot of posts recently about import machinery, the pros and cons and what are best buys. I've never used any import machines and know nothing about them, so I will be steering clear of such threads. That's not to say I won't comment on machining issues involving said machines; the cutting process is not machine dependent.

Andrew

[SteviegtrParticipant @steviegtr]

I am pretty much the same as you there Andrew. See lots of questions about eastern machines & never having owned or even used one, better just read the posts.

Steve.

[Anonymous]

Posted by John Alexander Stewart on 23/10/2020 18:30:47:

Kozo gives us a way to machine gears good enough for his model Climax, machining on small machines in the average workshop, so I give him top marks.

Quite so and very impressive work. I've recently been sent a copy of his article in Livesteam. The teeth are cut on the slant and the tooth profiles are clearly asymmetric. What interests me is that on some logging locos this is clearly not the case. The tooth profiles are symmetric and the teeth do not lean over. So while the gears by Kozo are a tour de force what really interests me is how were the gears as depicted on the full size engines designed?

The publication I have found starts by stating that the pinion can be a normal straight tooth bevel gear. The key seems to be that for the bevel gear the tooth profile at the outer edge needs to expand, in much the same way as normal and tranverse DP in helical gears.

There has been some discussion of skew bevel gears recently on MEM including some pictures of the gears in production at the Lima Locomotive Works. It's clear that the teeth need to slide as well as roll over each other. Consequently it seems that in real life the gears had poor reliabilty. Apparently after Lima switched to cut gears rather than cast they offered a two year guarantee on the gears.

Andrew

[Another JohnSParticipant @anotherjohns]

Hi Andrew;

Lima Locomotive works made the Shay – straight bevel gears – that is what you see in the MEM thread. Heisler also used straight bevel gears, it's only the Climax that has skew bevel gears. (and, I'm not sure about the Climax class "A" machines – never seen one in person)

Anyway, I'm sure, knowing your skills, you'll find/discover/develop about a half-dozen tooth profiles that'll work!

[Anonymous]

Posted by John Alexander Stewart on 24/10/2020 11:53:14:

……it's only the Climax that has skew bevel gears………..

I never twigged that, thanks for putting me straight! Sadly, as far as I'm aware, there are no full size logging locomotives of any type in the UK.

Looking at pictures of the Climax the tooth profiles all seem to be symmetric whereas the Kozo gears are definitely not. They're straight on one side and curved on the other. In one of the Climax pictures the teeth on the pinion are definitely straight exactly as per a normal bevel pinion. In another the pinion teeth are at a slight angle. Presumably the works made a design change at some point. Looking at the design parameters for skew bevel gears the teeth on the bevel gear are straight when pointing at the shaft intersection. So if the teeth on the pinion are at an angle my working assumption is that the pinion is not located at the theoretical shaft intersection.

Andrew

[Author]

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