Robinson Hot Air Engine.

[Stilldrillin]

This arrived the other day. I believe it's a Poly Models 1/3 scale......







Very nicely machined and first off assembled/ unfinished. .....*(Edit, mid November...... Ignore that last sentence!).*.....

Complete with broken foot, and slightly bent crank. Which I did know about. No problem!  

Guess it's been dropped.......  





Slipped a small piece of esbit under...... We have a runner!  





Do I fill the rusty hole with water, and keep it topped up?




Some form of instructions/ ideas would be appreciated. There's next to no mention of these engines on HMEM!  

[NickG]

Nice looking engine,

Same as any hot air engine it's got a hot end and cold end. Looks like the top of the displacement cylinder does have a water jacket so yeah fill it with water. Looks like there's a drain on rear.

I would apply light oil to all joints, a drop on the displacer rod and oil the piston too.

Nick

[madjackghengis]

Well Still, that is a nice looking engine, a little tlc, and a couple of toes and half a foot, a spot of paint, and you've got a nice running display.  Can't say's I've ever seen one of those before, but it is interesting looking in its intersecting linkages, you ought to post a video of it, so we can hear it, too.  Very nice if I say so myself mad jack

[Stilldrillin]

Nick, Jack,
Thanks for your comments. I've been into the shed, with camera...... But! 

With water, it's not as happy as was..........

Lurched to a standstill..... I had a closer look........ Water from shaft, and piston. 

I didn't intend running it as is. It was bought to set up properly as an autumn project.

I would like to see a pic of component pieces/ whats inside, if anyone can help. Before I start having to prise the Hylomar joints apart...... 

David D

[Stilldrillin]

Jack,
Here's a vid of the real thing, at Stew's favourite Museum......

I saw this engine, and thought, hmmm, maybe, I could..... 

Then a member of my other forum posted this, and I realised castings were available......

http://modelsteam.myfreeforum.org/about32786

Then, when this one showed up, on Ebay. I thought it would save on machining time. 

All within two weeks! 

David D

[Bluechip]

Hi Dave SD


Nice .... looks like it may have originated with ETW  ..

Although, if it had a commercial prototype, it would look like it .... appen ??

http://www.camdenmin.co.uk/hot-air-engines-c-329.html

EDIT ... might just be an illustration. Maybe the engine is not in the book ?? Dunno .. just ordered one anyway ...I will find out 

Dave BC

[Dean W]

Thanks for the pics and video, David.  You know I'm thinking about it!..

Dean

[NickG]

Dave,

Strange ... appologies for my suggestion! Was there a bung in the rusty hole or was it open - I assumed it was open?

The plug in the end could be where the port has been drilled - somewhere there must be a transfer port between the top of the displacement cylinder and the bottom end of the power cylinder.

You'll no doubt want to take it apart anyway, but inside the displacer cylinder (big bit that flame goes under) there should be a loose fitting piston - possibly hollow or made up of discs. As I said, there must be a port connecting the two cylinders somewhere. Then there'll be a very good fitting piston in the power cylinder.

With a quick search on google I found this which may clear a few things up anyway and be of use in your rebuild:

http://users.moscow.com/oiseming/lc_ant_p/pic_Prj4.htm

Not seen the videos but looks like a nice little project.

Nick

[Stilldrillin]

Thanks for that Nick!  

I had already found this one......

http://www.steves-workshop.co.uk/steammodels/robinson/robinsonindex.htm

The hole is left open.

The brass headed screw is an airway plug, I am sure. I think it's been fitted by a bad tempered gorilla, 'cos I can't shift it, yet.

I would like to know how the air is supposed to transfer from displacer to piston, without picking up water on the way.

A couple of other jobs to do next....... Then I might find out, around the weekend!

David D

[Stilldrillin]

Well, I managed to get it apart without causing any damage. Apart from sawing off the end of the bent shaft, to remove the flywheel......

Hmmmm........




Still not sure how the cooling water, and internal air, are intended to be kept separate. 

Plenty of de rusting to keep me quiet/ mucky. 

David D

[Bluechip]

Hi Dave

Looks like a suitable candidate for Darrens famous Battery Charger / Washing Soda trick  

Whats the top left doins made from .. looks a bit brassy? But maybe it's just the PC image.

A slosh of paint on the rusty bit might have been a good idea on first build.
It's the cold end, so it wouldn't need to be anything exotic. Says he, knowing little about it ..  

Looks strange, would make some sense if the slot in the ( top row, 3rd from left ) was not there.
Otherwise it looks as if there is nothig to stop the displacer chamber filling with water.

Maybe I'm not seeing it correctly ??

Dave BC

[Stilldrillin]

Dave,

Hmmmm...... Yeah....... I was wondering who had done magic with rusty gloop, some time ago...... Ta! 

The top left doins is the hot cap. Made of brass, as is the displacer piston, next to it.

David D

[Bluechip]

Dave

Ah !!

That slot is the feed to the power cylinder, through the rib cast in the other bit, front 2nd left.

Can't see any sort of seal there though ??

How is the end of that air gallery wotsit supposed to seal to the displacer cylinder ?
Doesn't look any effective way of achieving that?
Bit missing ? Dollop of blue aardvark snot maybe?

Dave BC

EDIT  Not supposed to be an O-Ring or the like in the end of the gallery doins ??

[Stilldrillin]

Dave,
There's a male threaded tubey bit, (middle of 2nd left, front row), passes through the joint between 2nd left & top row 3rd left.

And, that's where it is probably leaking......

Will investigate further, sometime.....

O ring, or summat, imminent.......

David D

[sbwhart]

Interesting job you've got on their Dave.

I watched that engine for ages at Manchester trying to understand how it worked and failed.

Stew

[Stilldrillin]

Hi Stew!

Yes, I didn't see any explanation either!  Though, I did know about them.....  


I really loved the vacuum/ ratchet engine, which is behind you as you watch the Robinson. I'll post a vid, when I've got the time......  

David D

[Dean W]

I see how it's supposed to seal, and it makes sense.  A gasket around the bolt hole pattern inside the large square/round/rusty casting.  Same gasket goes up, over, and back down on the spigot thing that goes in the slot in the cast part of the hot end.
Well, that's how I'd do it.  No water would get where it shouldn't. 

Thanks for the take-apart pic, David.  I needed to see that!  ; )

Dean

[NickG]

Yep,

Looking at the picture you need a gasket like that to make an effective seal between the transfer port and u semi circular cut out in top of displacer cylinder to stop air leaking into the jacket and vice versa. Bit like a sump gasket - they are usually rubber though.

Nick

[Stilldrillin]

Well,
I left a part in some vinegar overnight. Worked a treat. Rub with a toothbrush, rust gone!  




Today was shopping day. At 13p a bottle, I stocked up..... Other parts are pickling now.  





Dean, Nick. Not sure I understand your gasket theories. Sorry!  

The port tube (if it is a through tube), is threaded at 90*, through the joint, but offset by some 75%.....





Sorry, the female thread is out of focus!  





I  think this is the other end of the tube, and should have come out first. But, it won't unscrew, and the brass plug was a press (hammer?) fit.

Guess it will need drilling out.....





Things should be clearer tomorrow, when the vinegar has done it's job.

David D

[NickG]

On the otherside of the casting where the port is, there must be a cross hole that lines up with a hole in the base of the power cylinder?

[Stilldrillin]

On the otherside of the casting where the port is, there must be a cross hole that lines up with a hole in the base of the power cylinder?

S' right! 

Pics later...... Me fingers are filthy, and smell like a pickle factory. All the rust is (almost) gone though! 

David D

[NickG]

Haha, good work David 

[Stilldrillin]

Here's a pic of an 'ole, for  Nick......





The tube is in permanently, as far as I'm concerned.
Someone previously, has opened the engine without withdrawing the tube first. Hence the "threaded slot" in the displacer housing, where the tube should screw in place. 

A little cleaner than yesterday. Wonder why the bronze flange ring?





Here's how it fits.....





And here's the inside view......





I don't think I will have much bother sealing it. (Famous last words?)..... 

David D

[NickG]

Thanks David, I can sleep much easier now i've seen the 'ole!

Naa, should be an easy job to seal it you may find it'll run a lot better once that's done!

 

[Stilldrillin]

Thanks David, I can sleep much easier now i've seen the 'ole!

Naa, should be an easy job to seal it you may find it'll run a lot better once that's done!

 

Nick,

Internally, engine and water jacket were covered with wet claggy rust. None of the body screws were tight.

No seal around the 'ole. Stripped/ hammered in, tube plug.

Bent crank.

      But, it would still run!! 

I think performance will be improved, after I've finished.......    

David D