My N&W class A 1239 (gauge 5", 1 in 10 scale)

Bill Shields · Post by **Bill Shields** » Sat Apr 30, 2022 6:34 am

That's a hot water faucet...

Asteamhead · Post by **Asteamhead** » Thu May 05, 2022 3:57 pm

Hello friends of the N&W,
Today was fine to me for I could assamble all the parts to built a complete tender truck for the first time

. Just the right wheel sets are still missing. Will be built soon, too.
The cross bars are bolted rather than welded in favour of better access (for adding in the brake rigging!).
The equilisation will allow the axles to move about a generous + / - 5 mm (1/5 of an "). Springs will ad about 2 mm at full load then.
The trucks are intended to turn around the outer cross bar (the big bore) rather than the center

. Thus the wide lateral travel of the long tender ends in curves will be reduced for better connection to locomotive and train. Vertical load will be transferred by means of a central cross bar and sliding plates as common, yet.
Best regards
Asteamhead

Andy R · Post by **Andy R** » Thu May 05, 2022 6:06 pm

Very, very nice.
I like the offset support too.
The equalization will be interesting when in service because of the eccentric vertical load on the truck.
It may behave more like a 4-wheel truck with an idler axle. Time and experience on the track will tell.

Dick_Morris · Post by **Dick_Morris** » Fri May 06, 2022 4:08 am

Nice!

JBodenmann · Post by **JBodenmann** » Fri May 06, 2022 4:36 pm

Hello My Friends
Very nice and ultra cool Asteamhead.
Jack

Asteamhead · Post by **Asteamhead** » Sun May 08, 2022 8:40 am

Andy, Dick and Jack,
Thank you all!
Andy, you are right, the equilization will be supportet by just 4 points to the truck frame. The total load will be distributed to all 6 wheels equaliy, yet.
The people from Roanoke found this construction superior to the standard Commonwealth design at higher speeds. Hope they were right

The center axle-boxes will get a bit more lateral play to improve running around sharp curves (of about 30 feet radius).
In the meantime I started milling the 12 axle boxes, more to come soon.

Best regards by
Asteamhead

Asteamhead · Post by **Asteamhead** » Fri May 13, 2022 4:28 pm

Hello friends,
Time to show some progress. First, all the 12 axle boxes were turned, milled and tested by use of some tools in several steps from raw rings of bronze. Starting with the fit for the ball bearings of 32 mm diameter and the front surface

, they were turned and centered again. Thus the rear (inside) fit for the sealing was turned as was the rear side.
Next I milled the two sliding plates in two steps, related to the finished bore and front surface

. The final precision cuts were milled after some testing and adjusting the position of the parts in the vice. Thus the gap between the truck insides and the axle boxes could be achieved precisely at 2 x 0.1 mm (1 / 256 ") to insure for a slight glide without sticking. (The prototype drawing asked for 2 x 1 / 16 ").
The fits for the pair of ball bearings to be pressed onto the axles are intended as very slight press fits

to insure easy assembly.
The next steps will be milling the bottom first and then the top head finally. For all other surfaces are finished and rectangular that will be a more easy job

. A lot of chips could be saved by means of a shovel

Not to damage the finished surfaces by the vice, very thin plates of aluminium (taken from Märklin metall)

worked best.
More to come soon.
Asteamhead