Deleted
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Post by Deleted on Oct 30, 2014 9:09:27 GMT -5
In the recent thread "Bowser C636" author rmjmgo made a statement that got me curious.
rmjmgo mentioned that EMD introduced the 42" wheel on the SD45X HTC truck.
This got me wondering. Does this mean all the HTC trucks used the 42" wheel and not the 40" wheel? That would include all SD40-2 models? Or was this just an experimental wheel size used on the SD45X and the 40-2 got 40" wheels?
Brian
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Post by iomalley on Oct 30, 2014 12:39:16 GMT -5
CN started installing 'fat 40' wheels on their SD40s in the late 70's. Not sure if it was a bump up to a full 42" or something in between. As far as I can gather it was an option to go with 42" wheels since the dash 2s, but I'm not aware of anyone taking EMD up on it until the SD50/60 era. Maybe the Amtrak SDP40Fs scared them off? One thing I noticed with Kato SD40s, is that they arbitrarily seem to have changed the wheels closer to the larger 42" when they released the SD40s in the non cellophane boxes. Probably to limit stock. I always search for the old 37# stock number SDs so they come with the proper 40" wheels...they don't peek out beyond the ends of the sideframes like the newer releases do. Athearn seems to have been using an oversized 40" wheel on their BB trucks since inception, looking incorrect on everything but the Blombergs and HTCs. I've been swapping them out with NWSL 40s for years. They look especially big on BB switchers. I've never actually measured the BB Athearn wheel, but will definately do so now that you piqued my interest.  |
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Deleted
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Post by Deleted on Oct 30, 2014 12:50:00 GMT -5
Sean, your answer coincides with exactly what a friend of mine who owns a locomotive rebuilding business. He used that same term "fat 40". He stated that the 40" wheel was standard up through the SD40-2 and possibly the SD50.
I have been using the 40" wheel for some time now. But the post indicating that the SD45X had 42" wheels and had HT-C trucks got me worried for a moment. Thanks Sean for your reply.
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milw199
Superintendent
Beaded crossbucks FTW
Posts: 180
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Post by milw199 on Oct 30, 2014 15:45:50 GMT -5
Brand new nominal 40" wheels seem to measure out in the 40.75" size. This is the size usually installed at work, on various older EMDs.
The wheel size measurement is posted in the cab somewhere, and is used to make sure the counter is accurate. The counter can adjust from wheel sizes 36" to 45". As the wheels wear, get turned, etc., the size changes, and the counter gets adjusted.
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dtinut
Chairman
Modeling the DT&I of the 60's & 70's
Posts: 661
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Post by dtinut on Oct 30, 2014 16:12:19 GMT -5
Athearns std sintered wheels are scale 42" dia.
This makes NWSL a lot of dough cause using 40" wheels with mickle plating is better option.
Since Athearn started adding the grabs to the RTR line, they switched to a new wheel (non-sintered) that is better.
Size wise and comductively....
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Post by oldrail on Oct 31, 2014 3:09:48 GMT -5
Soo Line/CP first 42" wheels came with the SD60.
Dick Haave
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Post by CP_8530 on Oct 31, 2014 5:07:59 GMT -5
CN SD60F on the left has 42" wheels, CN SD40-2W on the right has 40" ones. That extra inch at the bottom between the rail and truck frames is quite noticeable: www.railpictures.ca/?attachment_id=8294Believe it or not that's not the most epic nose-to-nose shot I have - that would go to the shot of the CN SD60F and C40-8M cowl units nose-to-nose, with all those little differences between the GMD and GE wide-nose + cabs.  |
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cn2117
Probationary Member
Posts: 14
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Post by cn2117 on Oct 31, 2014 7:09:28 GMT -5
That is an awesome shot, you can definitely see the difference between the wheel sizes. The other thing that catches my eye is that the three holes in the sideframes are centered between the 1st and 2nd axles, but not between the 2nd and 3rd. I hadn't noticed this before.
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Post by iomalley on Oct 31, 2014 10:19:27 GMT -5
Good eye Ted, seems they are symetrical with the centre axle, including the yoke/bolster above it.
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spike
Chairman
They say I can't be Spike anymore, so Mr. Burns it is!
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Post by spike on Nov 1, 2014 22:36:07 GMT -5
I had a conductor who had worked in Central Vermont's St. Albans shop. When it was sold to New England Central, they had a fleet of GP38ACs. He said that they put on 42" wheels when the units were reconditioned for startup/takeover. It was something about having more meat. The wheels could wear longer, and have more trueings. They might be really your fat 40".
I'm not sure if 42" wheels have the same tread/rim thickness as a 40", only with a larger diameter, or if the 42" wheel has a thicker tread/rim. They might have thicker tread. I say this because I have seen some wheel gauges. They were stamped with 40/42". The reading is taken from the whiteness groove. The scale on the gauge was stamped like a ruler with the corresponding diameter. This way the speedometer, event recorder, LSL, and distance counters could all be calibrated.
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