G 12 conversion to 7.5" gauge?

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Glenn Brooks
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G 12 conversion to 7.5" gauge?

Postby Glenn Brooks » Thu Apr 06, 2017 1:08 am

Hello all,

Has anyone converted an MTC G 12 train set to run on 7 1/2" track? It seems like this would be easy to do - make a set of 7.5" trucks to fit underneath a G12" loco and coaches.

I wonder if the existing body size would become unstable and liable to tip over or derail at 7.5" ga? How would one mitigate this, besides adding dead weight to the bottom of the coaches? Some sort of spring assembly or anti sway bar maybe??

Here is a photo of an original MTC G12 truck. Pretty basic. The loco is maybe around 2.5 to 3" scale- not quite 2x as large as most live steam club diesels.

IMG_1449.JPG
G 12 truck


IMG_1450.JPG


Thanks
Glenn
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Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

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ccvstmr
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Re: G 12 conversion to 7.5" gauge?

Postby ccvstmr » Thu Apr 06, 2017 8:30 am

Hello Glenn, believe there are (2) MTC G-12's in my club converted to 7.5" gauge. Since the trains are articulated, you have the weight of two cars on each truck. Don't think sway or other provisions are necessary. Here's some photos of the equipment...

The 1st example is a 6 unit CB&Q train. Equipped with a Honda engine and a hydrostatic transmission.
xIMG_5180.JPG

Trucks were made from side frame castings from Dennis Goodman. Bolsters added along with the "tubes" for mating pins on the ends of the cars.
xIMG_5030.JPG

A side view of the truck frame. Frames are plain looking, but when tucked under the ends of the cars, you don't see much of the side frames.
xIMG_5031.JPG

The 2nd example is a 4 unit Santa Fe train. This is equipped with a water cooled, 4 cylinder fork truck engine. Don't recall the type of transmission. Very quiet on the rails when running. The trucks are equipped with what looks like Backyard Rails Blomberg truck side frames. Side frames are non-functional....bolt on decorations. Don't know if the original truck frames were used or not.
xIMG_4614.JPG

So to answer your question...yes, G-12's have been converted successfully to 7.5" gauge. Don't think either train has ever experienced any kind of tip-over incidents. Hope that helps. Carl B.
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Glenn Brooks
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Re: G 12 conversion to 7.5" gauge?

Postby Glenn Brooks » Thu Apr 06, 2017 11:53 am

Thanks Carl. Very good to know. I appreciate the photos also!

Glenn
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....

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BigDumbDinosaur
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Re: G 12 conversion to 7.5" gauge?

Postby BigDumbDinosaur » Fri Apr 07, 2017 11:31 pm

ccvstmr wrote:The 1st example is a 6 unit CB&Q train. Equipped with a Honda engine and a hydrostatic transmission.

Actually, powered by a 20 HP Briggs & Stratton industrial V-twin.

The 2nd example is a 4 unit Santa Fe train. This is equipped with a water cooled, 4 cylinder fork truck engine. Don't recall the type of transmission.

This one also has a hydrostatic transmission using a variable displacement, reversible pump.

I've both ridden in and operated both of these trains and can report that they are very stable.
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Glenn Brooks
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Re: G 12 conversion to 7.5" gauge?

Postby Glenn Brooks » Mon Apr 17, 2017 1:40 am

Big dumb dinosaur,

Any idea who sells this style transmission these days, and what capacity it is that is installed in the 4 unit Santa Fe?

Thanks
Glenn
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Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....

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dnevil
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Re: G 12 conversion to 7.5" gauge?

Postby dnevil » Tue Apr 25, 2017 1:40 pm

Bob Gill owns the Santa Fe re-gauged train.

See http://discoverlivesteam.com/2017/01/26/illinois-live-steamers-turns-50/

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Erskine Tramway
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Re: G 12 conversion to 7.5" gauge?

Postby Erskine Tramway » Wed Apr 26, 2017 9:34 am

Glenn Brooks wrote:Big dumb dinosaur,

Any idea who sells this style transmission these days, and what capacity it is that is installed in the 4 unit Santa Fe?

Thanks
Glenn


Hi Glen......

The usual suspect is the EATON 7: http://www.associatedgroups.com/EATON-C ... t_duty.htm

BTW, my 7-1/2" gauge equipment is +/- 24" wide, and is stable, so I think a G-12 should do fine.

Mike
Former Locomotive Engineer and Designer, Sandley Light Railway Equipment Works, Inc. and Riverside & Great Northern Railway 1962-77
BN RR Locomotive Engineer 1977-2014, Retired

Pontiacguy1
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Re: G 12 conversion to 7.5" gauge?

Postby Pontiacguy1 » Thu Apr 27, 2017 9:40 am

The Eaton #6 or #7 hydrostatic transmission has limited torque input/output capability. It is a great transmission, don't get me wrong, but I think it would be a bit light-duty for such a large locomotive and train. Most of the larger 1 1/2" scale locomotives that are built this way use the Eaton #11 hydrostatic transmission, which is much larger and can handle a lot more power though it.

Or you could use a hydraulic pump and motors and power it that way. The hydraulic systems used in those locomotives are very robust and reliable and can transfer a lot of power if needed.

Glenn Brooks
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Re: G 12 conversion to 7.5" gauge?

Postby Glenn Brooks » Thu Apr 27, 2017 10:51 am

Good to know! Thanks
Glenn
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Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....

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BigDumbDinosaur
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Re: G 12 conversion to 7.5" gauge?

Postby BigDumbDinosaur » Wed May 24, 2017 1:14 am

Glenn Brooks wrote:Big dumb dinosaur,

Any idea who sells this style transmission these days, and what capacity it is that is installed in the 4 unit Santa Fe?

Thanks
Glenn

Sorry for the very delayed response. Health issues have been getting in the way.

Both of these MTC locomotives use an engine-mounted pump and hydraulic motors in each truck. In Bob Gill's Sante Fe unit, the prime mover is a water-cooled, four-cylinder forklift engine, to which is mated a swash plate style variable displacement pump of a type commonly used in industrial hydrostatic drives. The traction motors are linked to the drivers through the usual roller chain drive. The pump is reversible, so no separate reversing valve is needed.

The CB&Q unit has a 20 horsepower industrial Briggs V-twin driving a fixed displacement gear pump. The output of the pump is passed through a three-position, lever operated spool valve, which acts as the reverser. A separate drift valve is used to load and unload propulsion. Here again, the traction motors are linked to the drivers with roller chain.

In both units, all the propulsion system components are off-the-shelf items. I believe Bob Gill got his pump through a surplus distributor.
Science makes it known. Engineering makes it work.


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