Forum Options

« Back to Engines and Rolling Stock Topics

Sign In above to begin adding replies.
 

Tinkerbell 2-4-4 derivative

Tracksmith

Joined: 16-01-19

Topics: 1

Replies: 1

Posted: Thu 17th Jan 2019, 12:57pm
Tinkerbell 2-4-4 derivative

Tinkerbell 2-4-4 derivative
I am trying to work up a design for a Tinkerbell derivative along the lines of Moors Valley's Hartfield or Pete Beevers' Siusaidh, but have a number of questions to try and get me heading in the right direction. (The attached image is the draft 3D model I am creating to trial size and fit component parts - fly cranks have not been sized for balancing as yet).

(1) Is 1 1/2" wheel width too wide?
(2) What main frame thickness and spacing would be recommended?
(3) What frame height above rail and frame height would you recommend?
(4) What would be the recommended minimum clearance between back of coupling rod and fly crank?
(5) Would you recommend Loctiting wheels, bearings and fly cranks to axles, and if so what clearance would you recommend between mating surfaces?
(6) Are there any drawings/cad models available for a Walschaerts valve gear arrangement for this type of locomotive (I am looking at 3 1/2" cylinder bore with 4 1/4" stroke)?
(7) What main frame and buffer beam thicknesses would be recommended?
(8) What would be the recommended cylinder cl to cylinder cl spacing across loco?
(9) What would be the recommended wheel spacing, I have started with 17" Tinkerbell driving to coupled wheel spacing.
(10) Are there any standard steel boiler designs for this type of loco (130psi) and what would be the recommended mounting arrangement and key dimensions for such a boiler?
(11) I want to have a bolted frame arrangement, what bolt sizes and types would you recommend?

I am sure I'll have many more questions as I go along, but the above will get me started. I do not profess to be a mechanical engineer so any advice or guidance on other key aspects that I have missed would be greatly appreciated.

All the very best

David
 

Replies To This Post

Peter Beevers

Joined: 9-10-01

Topics: 4

Replies: 154

Posted: Thu 17th Jan 2019, 3:30pm

1) No.
2) 12mm at 13" apart (inside) then can be regauged to 10.25" by simply dropping in new wheelsets
3) As big as you need!!
4) With the big locos, I use 15mm thick rods, and they are 3mm from the flycrank. Part of this is used up by the self aligning bearing at one end (18mm thick 2205-2RS).
5) That's a personal preference. Personally, I make them a press (10 ton) fit but also make 3 grooves for loctite and then pin them together too. None of mine have EVER come loose!!
6) Nah, it's easy to do it yourself using Charlie Dockstader's simulator.
7) 12mm. For a tink, I'd say make the front beam 25mm to help with the weight distribution, but for a bigger one it isn't strictly necessary.
8) I work on the cylinder centreline being 3" from the frame but there's no need to be accurate about it, just make sure the frames themselves are straight and that the cylinders are parallel to them
9) No more than 17" unless you really have to. The MVR x-6-x locos use 24" and that works as well, but no way would I go longer for a loco for general use.
10) No. But go for 12.75" diameter, about 36" long with a 14" long firebox (outside) and you can't go wrong
11) Don't really understand the question but I use M10 to bolt the angle to the ends and to the buffer beams.

Oh yes, and my name is Peter (with an r). People who assume they can call me by names that I have not personally given them permission to use get very short shrift.

Peter
 

Tracksmith

Joined: 16-01-19

Topics: 1

Replies: 1

Posted: Thu 17th Jan 2019, 10:13pm

Peter

I apologise profusely for my error. I had no intention whatsoever of causing any offence to you on this forum. My intentions were completely honest and I hope you can accept my sincere apology.

Your locomotives (and writings) have been one of the main sources of inspiration to me and I greatly appreciate you being the one to respond to my very amateur questions.

I will limit my future involvement in this forum to the occasional direct question as I know few people at present within 7 1/4 gauge circles and do not want to cause offence again.

Once again, very many thanks for your expert guidance.

Yours sincerely

David
 

Peter Beevers

Joined: 9-10-01

Topics: 4

Replies: 154

Posted: Fri 18th Jan 2019, 7:43am

David,

Accepted 100%.

Can I suggest that, regardless of distance, you visit either MVR or SNBR or somewhere similar to pore over a loco like this. You will answer all you questions, and, more importantly, see answers to questions you haven't even thought of yet: the time and effort spent will be amply repaid (Been there, got the T-shirt).

Also, visit other places and look at what they've done and how they do it. Even locos with old fashioned plain bearings can give you pointers, all of which will be useful in what you're planning.

Above all, don't forget: this is EASY. Anyone can do it.

Regards

Peter
 

Martyhuck

Joined: 9-10-17

Topics: 1

Replies: 14

Posted: Sat 20th Apr 2019, 3:03pm

Peter, how deep would you make the firebox?
 

Peter Beevers

Joined: 9-10-01

Topics: 4

Replies: 154

Posted: Sun 21st Apr 2019, 9:14am

The throat plate is 4-5" high, the bottom of the firebox opening (which is about 5" square, round fireholes are hopeless for getting a decent sized shovel in) is about 7" above the bottom of the foundation ring.
 
 
« Back to Engines and Rolling Stock Topics

Web design by Slingshot