BR81 question

BR81 question

Postby Marquette » Wed Feb 03, 2010 8:46 pm

Wondering if someone could tell me the wheelbase, axlespacing and driver diameter of the BR81? What other x-8-x's are there around in TT? Looking for something for a base to build a USRA 0-8-0...
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Re: BR81 question

Postby ConducTTor » Wed Feb 03, 2010 9:13 pm

Dang it, I'm still not quite unpacked from moving. Bump this up to remind me if no one answers.
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Re: BR81 question

Postby CSD » Wed Feb 03, 2010 9:50 pm

I don't have my BR81 with me but the BR86 or BR56 could be converted. Loosing the pilot wheels are as easy as taking off the bottom plate and pulling them out. You can also chop down the length of the frame as the area around the pilots is plastic.

Wheel diameter is 11.47 mm and they are spaced 13.67 mm apart.

Pilot wheels are 7.00 mm and if you choose the BR56 the tender wheels are 7.97 mm. These might give you a few wheel sets for your project tender.
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Re: BR81 question

Postby AstroGoat760 » Wed Feb 03, 2010 10:02 pm

TTQuebec wrote:Wondering if someone could tell me the wheelbase, axlespacing and driver diameter of the BR81? What other x-8-x's are there around in TT? Looking for something for a base to build a USRA 0-8-0...


I take it that you want the dimensions of the model, not the prototype. The prototype had 1100mm drivers (43.307 inches). The wheelbase of one of my Class 81 models is 15 feet (1.5 inches).

There have been quite a few eight coupled TT scale engines.

HP Products made 0-8-0's, 2-8-0's, 2-8-2's, 4-8-2's, and 4-8-4's.
Examples of German eight coupled include the Class 92 (0-8-0), Class 06 (4-8-4), Class 56 (2-8-0), Class 86 (2-8-2). I do not know if any models of the Class 06 have been made, I have examples of the Class 92, Cass 56, and Class 86.

The USRA 0-8-0 had 51" drivers (1,295mm), and a wheelbase of 15 feet, 0 inches, a match for the BR81.

It looks like if you are not too picky about the wheel diameter, a BR81 chassis should work fine.
Besides, during the course of an engine's life, changing the size of drivers is not unheard of. Areas where there are a lot of steep hills often saw locomotives with smaller drivers than locomotives used on level terrain.

I hope that I have been of some help.
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Re: BR81 question

Postby CSD » Wed Feb 03, 2010 10:07 pm

Here are a few pictures of the BR86 with the shell, weight and wheels removed. The BR56 uses the exact same mechanism, but has a modified frame at the back to accommodate the tender.
P2030001.jpg
P2030002.jpg
P2030003.jpg


I have to say that the performance of these models is not stellar. All 3 of mine have a noticeable "chugging" at slow speeds. Hopefully, it will be corrected with a little fine tuning. The BR50 and BR52 use the exact same wheel size, but the mechanism is in the tender (and works a whole lot better). The BR92 uses the exact same wheel base and mechanism as the BR81. Please note that the older BTTB versions of the BR50, 52, 56 and 86 use slightly smaller wheels.
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Re: BR81 question

Postby Marquette » Wed Feb 03, 2010 10:14 pm

Ooh, Sailor, thanks - very helpful indeed!

The smaller wheel diameter shouldn't be an issue (though there aren't all that many steep hills in Pere Marquette country) - if anyone says something, I'll just (after slapping them - you count your own rivets, I'll count mine) say that the tires have just been ground down for the last time before they need changing. ;)

More important IMO is that the wheelbase is right!

@CSD: I wonder if perhaps a motor swap could be done (not something I've ever tried yet), for a switcher low speeds are essential. If you manage to make it run better without an motor swap, do post how?
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Re: BR81 question

Postby AstroGoat760 » Wed Feb 03, 2010 10:48 pm

Changing out gears is one way to reduce speed and improve pulling power without changing out the motor, although some skill is needed to do this.

One thing about the USRA locomotives: many of the "USRA copies" had been modified to an extent. Some used different cabs, driver sizes, feed-water heaters, and tenders than the USRA specs.

It's funny that you bring up the USRA locomotives, I recently read an article regarding the USRA and the locomotive classes thereof in an issue of Railfan and Railroader from 1991 that Nicholle found at the train show last weekend. I will look it over again and see if I can glean any information that may be of some use for you.

Using the BR81/92 chassis for a North American proto engine is not a new idea, but is an easy way to start, though. There is a nice photo of a 0-8-0 camelback that someone made on the TTscale.com photo section, under "collection three".

I have a basic BTTB 0-4-0 set engine that I plan on converting to an 0-6-0T, as the shell is pretty bad off, all that I need to do is find a replacement gear for the drive axle, but other projects are at the forefront of the Gus Harkness Memorial Locomotive Shops.

Good Luck, and take good photos!
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Re: BR81 question

Postby Marquette » Thu Feb 04, 2010 1:08 am

Thanks!

The PM had "actual" USRA 0-8-0s, though of course I've gathered photos up and will be scrutinising these for variations made later in life. I figure this will be a good first steam project, will let me focus on building the boiler etc well. Frame-up can come in the future.

This probably isn't a project I'll have started by the time of our planned meet-up in March, as I've got several freight car projects underway, structures being dimensioned out and decal artwork being drawn up. This in addition to regular work and uni classwork!
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Re: BR81 question

Postby AstroGoat760 » Thu Feb 04, 2010 2:05 am

How do you plan on making the shell?

I am planning on using sheet brass for the Camelback model that I will be making with the spare HP six coupled chassis. I am not sure if this will be a 2-6-0 or a 0-6-0. I am leaning towards 2-6-0, as I have 5 HP products 0-6-0's, or at least major parts thereof.

If I get started before you do with your project, I will be more than happy to share what I have learned from the experience.
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Re: BR81 question

Postby Marquette » Thu Feb 04, 2010 3:09 am

As far as the shell goes, I have no idea yet. I'll probably experiment a bit with various materials for the boiler. The tender and likely the cab will be of styrene, as that is my preferred material in general. But short form, we'll see when we get there. I'd love to hear of your experiences, though!
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