7¼" gauge in the garden

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7¼" gauge in the garden

Workshop

 

On the workbench      On the drawing-board      Reference

On the workbench

POEM

  Purchased from Murray Lane of Auckland in June 2008, POEM is a semi-freelanced 2-8-0 based upon a WWI trench loco.

As of March 2009 POEM is back on rails and we are working out the final few teething-troubles.

CLICK HERE for more info on POEM.

My petrol hydraulic

  Since my petrol hydraulic transmission arrived from the UK I have been pondering what style of loco to build. I decided that I would not start until POEM was back and running so that I didn't get distracted.

I have always had a soft-spot for the armoured Simplex tractors supplied to the British army in World War I, but I also prefer sit-in locos. Though I had originally planned a replica of the loco shown to the left, I am now tending more to a sit-in design.

CLICK HERE for more information on my petrol hydraulic

Passenger carriages

  I need to design and build a short passenger carriage to sit cross-wise on the tow-bar of my trailer to take to tracks that have no spare rolling-stock. I'll use the bogies from my existing carriage for the time being and build another set of bogies later.

CLICK HERE for more information on my rolling stock

Freight wagons

 

I have always had a soft spot for the classic V-tippers that were built in the thousands for industrial use all over the world. They are also very practical for construction purposes on a railway.

I have been working on-and-off on some CAD drawings to build some from profile-cut steel and I got the steel for the prototypes back from the profile cutters just before Christmas. I now have the "fun" of welding up what is quite a complex shape for the chassis.

Neither John B. nor I can TIG weld, but a friend of mine can. TIG welding would make a much neater job of welding up the chassis than MIG would.

On the workbench      On the drawing-board      Reference

On the drawing-board (or at least ideas in my head)

  In November 2008 I picked up a complete set of drawings for an Orenstein & Koppel rack loco to the design by Ken Swan. Not sure if I want to undertake this as a "first build" so might look for something a bit simpler but it would make a fascinating model.

Plans are also available (I don't have them) for an adhesion-only 0-6-0 which uses a lot of the same parts.

I am trying to find out whether castings (or patterns for them) are still available.

There are apparently two Koppels in New Zealand. There is a rack loco based somewhere around Havelock North (it has been seen there on several occasions - see below) but I do not know where the adhesion-only 0-6-0 is. I am trying to track it down.

 
  A friend in Sweden is researching a Decauville Type 6 and will produce drawings for one for 7¼" gauge.

This would be a project I would really enjoy.

(Prototype photo taken on the Bredgar & Wormshill Light Railway, UK)

 

John Bremner and I are looking at the feasibility of building two Garratts as a joint-project.

We're looking for proven designs for the chassis and the boiler to avoid having to modify too much during the build stages.

At the moment, L'il Lima by Keith Watson is the front-runner for the chassis as we want Walschaerts valve gear (so Romulus and Tinkerbell are out of the equation - at least as designed). I have got a full set of drawings for a L'il Lima and will draw up the modified chassis, cylinders and valve gear in AutoCAD to see who it all looks.

We are still investigating options for a locomotive-type boiler (not Briggs or marine) that is capable of providing steam to four reasonably large cylinders.

The photo above is of a 2' 6" gauge Sierra Leone Government Railway 2-6-2 + 2-6-2. Though it gives you an idea, the final design is likely to vary in a lot of details; not least of which is we'd build it outside frame for stability.

I just spent a pleasant couple of hours with AutoCAD. Stefan Lipsey drew up the frames for L'il Lima as intended (he's building one), then I took all his work and played cut-and-paste seeing how the chassis would work as a Garratt.

I especially like the 2-8-2 + 2-8-2.

This 2-6-2 + 2-6-2 works out at 3.5m (11' 6") long (over the frames and excluding whatever pilot or couplers go on the ends).

The 2-8-2 + 2-8-2 works out at 3.73m (12' 3"). Not much longer and I think it looks more in proportion seeing as it needs a cab much larger than normal to sit inside.

If this project goes ahead, it'll not be until 2010 as I want to get my petrol-hydraulic working and John B. needs to finish his Romulus.

CLICK HERE for more information on the Garratt project.

On the workbench      On the drawing-board      Reference

Reference

 

7¼" Gauge Society approved track and wheel standards

FLANGEWAYS

  On diagram above Standard Gauge Narrow Gauge
Fractional " Decimal " Metric Fractional " Decimal " Metric
Flangeway "A" 9/32

-0 +1/32

0.281

-0 +.031

7.15

-0 +0.79

9/32

-0 +1/32

0.281

-0 +0.031

7.15

-0 +0.79

Maximum gauge widening on curves   1/8 0.125 3.18 1/8 0.125 3.18
Track gauge "B" 7 1/4

-0 +1/64

7.25

-0 +0.015

184

-0 +0.38

7 1/4

-0 +1/64

7.25

-0 +0.015

184

-0 +0.38

WHEEL STANDARDS

  On diagram above Standard Gauge Narrow Gauge
Fractional " Decimal " Metric Fractional " Decimal " Metric
Check gauge "C" 6 15/16

-0 +1/32

6.938

-0 +0.031

176.5

-0 +0.79

6 15/16

-0 +1/32

6.938

-0 +0.031

176.5

-0 +0.79

Diameter point "D" 17/64 0.265 6.73 5/16 0.313 7.94
Flange angle "E"   20o 20o   20o 20o
Flange depth "F" 3/16 0.188 4.76 1/4 0.250 6.35
Flange thickness "G" 9/64 0.140 3.55   0.190 4.82
Flange tip radius "H" 1/16 0.063 1.59   0.081 2.06
Minimum wheel width "J" 13/16 0.813 20.64 1 1/8 1.125 28.58
Root radius "K" 1/8 0.125 3.18 1/8 0.125 3.18
Tread coning angle (maximum) "L"   3o 3o   3o 3o
Wheel back-to-back "M" 6 13/16

-0 +1/64

6.813

-0 +0.015

173

-0 +0.38

6 3/4 6.750

-0 +0.015

171.5

-0 +.038

 
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