Electric Traction Engine

[Ron LadenParticipant @ronladen17547]

Having decided to build an electric traction engine (my first) I thought I would start a thread. For anyone interested they can keep track of progress and I,m sure I will have a number of questions as I go along. I know I,m repeating myself from another thread but the engine will be non scale, a freelance (working) stand off model that I hope will turn out to be a reasonable representation of a TE.

Some of the engine may not follow the accepted method of build and it will be basic, a lot of the bells and whistles will be missing but I,m hoping there will be enough of what you would expect to see.

I have material on the way to make a start with the boiler/firebox and here is the first break from accepted methods and materials. The scale I am working with is 1.625 inches to the foot, unusual but it gives the size of engine I will be happy with. The boiler tube is 4 inch x 10 swg aluminium, the firebox is all aluminium made from wide flat bar. Why aluminium..? well firstly I dont need a working boiler or firebox but I do need the empty space inside them. The firebox will house the motor and depending on which power train I go with the boiler may hold lipo batteries.

Also I didnt want to get into soldering or welding which sort of led me away from copper and steel. Another thing I considered was the fact that on a finished engine very little of the firebox is visible. The top sits below shafts and gearing, and the sides are hidden by horn plates, the only part fully in view is from the foot plate and that I will make up from steel etc with the expected detail.

I have added a sketch below (sorry for the poor image) of how I am thinking of putting it all together. The boiler tube will fit into a 25mm deep throat plate and providing I get a reasonable fit apart from a top and bottom fixing I intend to secure and fix it with a full face to face band of Loctite 638. The top and bottom plates are 3/8 thick and the two side plates 1/4 thick. It may all seem too heavy but been aluminium I have gone with the thickness to add some weight to the build. The firebox is square topped not radiused but so little of it is seen I am ok with that and it made the build simpler. Hope the sketch makes sense, I am no technical draughtsman.

Any questions, problems you see, whatever, its all helpful.

Edited By Ron Laden on 25/10/2018 17:27:35

Edited By Ron Laden on 25/10/2018 17:28:09

[Ron LadenParticipant @ronladen17547]

[JasonBModerator @jasonb]

Ron you could actually do away with Hornplates as they are really only used on models for ease of constructing the boiler. On a full size engine the sides of the boiler carry on up above the top of the barrel and also rearwards of the backhead to take the bearings for the various shafts and rear axle.

[Ron LadenParticipant @ronladen17547]

Thanks Jason, thats good to know I have material arriving which covers the dimensions of the side panels as per my sketch but I could keep those for other jobs and get two new pieces to cover extending upwards and rearwards.

[Ron LadenParticipant @ronladen17547]

As Jason suggested that I dont need hornplates with my build method, I have extended the boiler side plates upwards and rearwards to accomodate the shafts and axle bearings. The sketch shows the new sizes, I am also going to reduce the side plates to 4mm, I can get a couple of 6082 blanks locally.

Although the engine is freelance I have to start somewhere and I have taken all the main dimensions from a highly detailed Henry Greenly,s (1933) 1 inch general arrangements drawing. The engine is very similar to a Minnie, I cant see that much difference. All the detail parts or at least most I will take from the Minnie plus there is hundreds of detailed photos on line which is useful. The two engines are close dimensionally, at my scale the Minnies,s rear wheels are 9.75 inches and the Greenly,s engine is within a 1/4 inch.

Should receive some material today so I can make a start.

[Ron LadenParticipant @ronladen17547]

I realise that I havnt started cutting metal yet but as you do a 1001 things are going through my head, I am quite relaxed with regard to making most of the parts, that is apart from the wheels. They fill me with some trepidation, are they as difficult as they look..? or is there a reasonably easy way of producing a good end result.

Ron

[JasonBModerator @jasonb]

Ron if you have a read of what I sent you the link to the other day that is a good method to use and 100s of Minnies have been done that way.

[Ron LadenParticipant @ronladen17547]

Thanks Jason, I havnt read it all as yet, I will look take a look in the morning.

Ron

[Ron LadenParticipant @ronladen17547]

The engines name is TREVOR

Our two great grand daughters visited yesterday and they always head straight to the workshop. After showing them a picture of a Minnie it turned into an official naming ceremony, they didnt hesitate "Trevor" so it was orange squash and chocolate biscuits all round. I suspect I know where that name came from…

 

Edited By Ron Laden on 27/10/2018 08:31:48

Edited By Ron Laden on 27/10/2018 08:35:26

Edited By Ron Laden on 27/10/2018 08:38:45

[Ron LadenParticipant @ronladen17547]

On the 1 inch Minnie could anyone be good enough to confirm or otherwise that the gear ratio in low gear from crankshaft to rear wheel is 16/1, if my sums are correct thats what I make it and I cant see the ratio mentioned in the build notes. As I am not driving from the piston/crank I may have to drive from shaft 3 to achieve suitable gearing between the motor and rear wheel.

Ron

[JasonBModerator @jasonb]

Yep 16:1 low and 10:1 high

[Ron LadenParticipant @ronladen17547]

That was quick Jason, you obviously have that fixed in your memory.

Thanks

Ron

[JasonBModerator @jasonb]

No, front of the Minnie book!

[Ron LadenParticipant @ronladen17547]

One thing that did surprise me on the 1 inch Minnie is the 20DP gears, they look a bit coarse but I guess it is just a visual thing. They look ok on the larger gears 80T and 50T but just appear coarse on the small gears 15T and 20T.

Eh but what do I know it obviously works very well just an observation.

[JasonBModerator @jasonb]

Actually they are a bit too fine for the larger gears. On full size you often find several tooth sizes with the smaller siz eon the crankshaft gears working up to the largest teeth on the final drive. My 2" Fowler uses 10, 8 and 6DP gears to give the same tooth numbers as full size and that would equate to 20DP on the 1" minnie crank, through 16DP and ending with 12DP on the final drive but with less teeth.

[Ron LadenParticipant @ronladen17547]

Thanks Jason, makes sense.

What are those bevel gears for on the final drive of your Fowler..?

[JasonBModerator @jasonb]

That's the Differential so it is easier to go round corners.

[Ron LadenParticipant @ronladen17547]

A traction engine with differential, I would never have imagined that. Looks like some lovely work there Jason, just one last question, how are those two small bevel gears fitted, almost looks like they are built in. Does half the gear shaft sit in the casting with the ring providing the other half and forming a bearing..?

[JasonBModerator @jasonb]

There is a 1/4" hole that runs from one edge of the gear to the other and a couple of 1/4" pins slide into that for the pinions to rotate on. click image to enlarge

[Ron LadenParticipant @ronladen17547]

I see, clever, thanks Jason

Ron

[Paul KempParticipant @paulkemp46892]

Ron,

You can do without a diff (sigh of relief?) if you leave one wheel free to rotate on the axle. Depending on how far you go you could always lock it with a longer drive pin if you get stuck in the mud!

Paul.

[Ron LadenParticipant @ronladen17547]

Thanks Paul, No I wont be having a diff and I am assuming that most model traction engines without diffs have both wheels fixed to the axle.

Ron

[JasonBModerator @jasonb]

Very few have the wheels fixed to the axle both model or full size. They are free to rotate but by the use of pins can be locked to the drive gear boss and the winding drum boss which in effect gives a solid axle. Non Diff engines such as plouging engines would have pulled out one of the pins if manovering in tight spaces and to use the winding drum (winch) both pins are removed so only the cable drum rotates.

Engines with diffs also had an extra long pin so that the diff could be locked solid if they got bogged or were on very loose ground

[Anonymous]

Posted by Paul Kemp on 28/10/2018 10:23:16:

Ron,

You can do without a diff (sigh of relief?) if you leave one wheel free to rotate on the axle.

Quite, but they're a fun thing to make:

Sorry about the crap picture!

My diff lock is operated from the drivers position. It's a ring with spigots that fit into the four curved slots on the part middle left.

Andrew

[Ron LadenParticipant @ronladen17547]

Thanks guys, I think I need to sit down and read all of the 1 inch Minnie build, I assumed that the wheels were fixed.

Probably better if I got the book.

Ron

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