Steam & Excursion > Axle Loading on a Steam Locomotive.

See the attached Wabash RR diagram. How would I calculate maximum axle weight to compare, for example, with an E-60 bridge rating (60,000 pounds per axle).

Would I look at weight by total number of axles on the engine and tender separately or look at groups of axles by corresponding weight?


Victor A. Baird
http://www.erstwhilepublications.com



Edited 1 time(s). Last edit at 02/16/18 11:55 by wabash2800.

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I see the rear driver is 70" and the next is shown to be 62". That's an 8" difference Why it must be an error.

weight on drivers 270,000lbs divided by 4 driving axles = 67,500lbs and change, Hmmmmmm I admit that I'm not positive about how it plays with weight distribution on lead and trailing trucks.

No that's that not an error. They are two different measurements.

czuleget Wrote:
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> I see the rear driver is 70" and the next is shown
> to be 62". That's an 8" difference Why it must be
> an error.

I think I answered by own question. Axles weight numbers on the engine are right below the loco axles in the diagram. I can't find my source, but reference the line I'm studying, I was told it had an E-60 Cooper Bridge Rating. Perhaps it was more like an E-70 rating or my E-60 rating was-out-of-date?

Victor A. Baird
http://www.erstwhilepublications.com



Edited 2 time(s). Last edit at 02/16/18 12:02 by wabash2800.

czuleget Wrote:
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> I see the rear driver is 70" and the next is shown
> to be 62". That's an 8" difference Why it must be
> an error.

Look closer. The 70" diameter is for the wheel diameter WITH TIRES. The 62" diameter is for the wheel centers, i.e. without tires.

All the weight information is provided on that drawing:

1) Total weight on drivers = 270,400 lbs., divided by 4 gives 67,600 lbs per driver axle.

2) Total weight on engine truck = 72,100 lbs., divided by 2 gives 36,050 lbs. per axle within the engine truck.

3) Total weight on trailing truck = 63,900 lbs. which is a single axle trailing truck.

4) Total weight of tender, loaded = 291,000 lbs, divided by 6 gives 48,500 lbs per axle.

For what it's worth, Cooper Ratings are a VERY complicated mathematical process of; individual wheel weight, the spacing between those wheel weights at the point of rail contact, and the spacing of associated bridge stringers & cross braces within the bridge.

Have fun.

Thanks for the replies, particularly from Hotwater. As I wrote above, I noticed the axle weights after I did the original post.

Victor A. Baird
http://www.erstwhilepublications.com

If you had the engine in the shop, and picked it up with the overhead cranes, and left the drivers sitting on the rails, would the weight of the engine suspended be the weight ON the drivers, or would the weight of the axles and anything hanging off the axles, have to be added too? And, in the simplest example, if you had just a pair of drive wheels sitting on the track, wouldn't the axle be the only weight "ON" the drivers, or do they count the axle too ?

LocoPilot750 Wrote:
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> If you had the engine in the shop, and picked it
> up with the overhead cranes, and left the drivers
> sitting on the rails, would the weight of the
> engine suspended be the weight ON the drivers, or
> would the weight of the axles and anything hanging
> off the axles, have to be added too?


Yes, if I correctly understand your example/question. Although unsprung, the weight of the axle and wheels assemblies is STILL "weight on the rail head". Also, in your example of the engine picked up with the overhead cranes, remember that all the side rods and main rods might still be attached to the wheel sets.

And, in the
> simplest example, if you had just a pair of drive
> wheels sitting on the track, wouldn't the axle be
> the only weight "ON" the drivers, or do they count
> the axle too ?

Uh, no. Not only the weight of the axle, but also the weight of the entire wheel assembly (wheel center, tire, crankpin, and safety key), as it sits on the rail head.

For most of my career, we were still paid by "wt. on drivers". The timebook used to have weight on drivers for all diesel classes on our railroad. In the case of a six axle SD45, it might have showed 390,000lbs. Since there are no lead or trailing trucks, all it had was drive wheels, would "Weight on Drivers" be the same as total weight on the rail ?

LocoPilot750 Wrote:
-------------------------------------------------------
> For most of my career, we were still paid by "wt.
> on drivers". The timebook used to have weight on
> drivers for all diesel classes on our railroad. In
> the case of a six axle SD45, it might have showed
> 390,000lbs. Since there are no lead or trailing
> trucks, all it had was drive wheels, would "Weight
> on Drivers" be the same as total weight on the
> rail ?

With a diesel unit, yes. In fact, EMD actually weighed at least one unit out of every order, in order to insure that the engineer weight calculations were indeed correct. The EMD McCook plant, had a certified scale on the property.

HotWater Wrote:
-------------------------------------------------------
> For what it's worth, Cooper Ratings are a VERY
> complicated mathematical process of; individual
> wheel weight, the spacing between those wheel
> weights at the point of rail contact, and the
> spacing of associated bridge stringers & cross
> braces within the bridge.
>
> Have fun.

Absolutely correct! At work, I use a program called "Bridge1" to calculate actual Cooper's E ratings. It takes into account both axle loads and spacings and will calculate equivalent E ratings for various bridge span lengths. I use it mainly for special moves like heavy duty flat cars but it was necessary when 4449 and 765 ran on Metra territory.

I'll run the numbers Monday (don't have the program at home) and post the results.

Tim Pitzen
Roadway Engineer
Metra

No one has commented, to use a presumably archaic term, on the quality of draftsmanship presented here. I took a wee taste of drafting back when you sharpened your pencil with a pen knife and a bit of sand paper and I well know I could never do work of this quality. We always initialed our much lower quality work, but I can't find one on this fine drawing. Too bad. Thanks for posting this. d

I look forward to your numbers Tom.

VIctor A. Baird

Http:/www.erstwhilepublications.com

wabash2800 Wrote:
-------------------------------------------------------
> I look forward to your numbers Tom.
>
> VIctor A. Baird

Tom who?

Tom Pitzen. See above.

Victor A. Baird
http://www.erstwhilepublications.com

HotWater Wrote:
-------------------------------------------------------
> >
> Tom who?

Here's a builder photo of the loco.

Victor A. Baird
http://www.erstwhilepublications.com

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czuleget Wrote:
-------------------------------------------------------
> I see the rear driver is 70" and the next is shown
> to be 62". That's an 8" difference Why it must be
> an error.

Look at the arrows with each dimension. 62" is the driver casting; 70" includes the tire.

Wabash M-1 engine and tender


LOADING IS TYPE 1
Here are the Cooper's E calculations for a Wabash Class M1 locomotive and tender for various bridge spans. The rating varies depending on the length of the span and the axle load and spacing. For a 35' bridge span, the rating is E-63.

Below is the axle load and spacing. Load is in thousands of pounds divided by 100. Axle spacing is in decimal feet (1" = 0.083').

Tim


LOAD SPACING
36.05 7.17 - Engine truck lead ale
36.05 5.50 - Engine truck axle
67.90 6.08 - First drive axle
67.20 6.08 - Second drive axle
67.40 6.08 - Third drive axle
67.90 11.00 - Fourth drive axle
63.90 14.67 - Trailing truck axle
48.50 4.42 - Tender
48.50 4.42 - Tender
48.50 9.58 - Tender
48.50 4.42 - Tender
48.50 4.42 - Tender
48.50 0.00 - Tender

Wabash M-1 engine and tender


|SPAN FT.| BENDING FT KIPS | E |END SHEAR KIPS | E | FLOOR BEAM REACTION KIPS | E |
| 8. | 136. | 67.9 | 84. | 61.1 | 100. | 57.0 |
| 10. | 170. | 60.5 | 94. | 62.8 | 120. | 60.2 |
| 12. | 227. | 56.7 | 101. | 57.7 | 135. | 57.9 |
| 13. | 259. | 54.5 | 108. | 58.5 | 147. | 59.9 |
| 14. | 300. | 54.6 | 115. | 59.5 | 159. | 60.9 |
| 15. | 348. | 55.8 | 121. | 60.3 | 169. | 61.7 |
| 16. | 399. | 57.0 | 126. | 59.2 | 177. | 62.3 |
| 18. | 500. | 58.9 | 134. | 57.5 | 192. | 63.2 |
| 20. | 602. | 58.3 | 147. | 58.8 | 205. | 62.7 |
| 25. | 891. | 58.4 | 172. | 60.8 | 237. | 62.8 |
| 30. | 1270. | 61.9 | 190. | 60.2 | 270. | 62.6 |
| 35. | 1652. | 63.2 | 210. | 60.8 | 299. | 61.3 |
| 40. | 2055. | 62.7 | 226. | 59.9 | 326. | 60.3 |
| 45. | 2483. | 62.0 | 239. | 58.5 | 358. | 60.3 |
| 50. | 2987. | 62.8 | 255. | 58.5 | 386. | 59.9 |
| 60. | 4053. | 62.4 | 290. | 59.2 | 447. | 58.4 |
| 70. | 5245. | 61.4 | 325. | 58.8 | 504. | 57.0 |
| 80. | 6515. | 60.3 | 362. | 58.3 | 556. | 55.9 |
| 90. | 8053. | 60.3 | 399. | 58.1 | 605. | 55.4 |
|100. | 9679. | 60.1 | 430. | 57.3 | 652. | 54.9 |
|120. | 13506. | 58.6 | 482. | 55.5 | 740. | 54.4 |
|140. | 17777. | 57.3 | 536. | 54.6 | 826. | 53.7 |
|160. | 22239. | 55.9 | 584. | 53.5 | 909. | 52.9 |
|180. | 27228. | 55.4 | 630. | 52.6 | 991. | 52.0 |
|200. | 32575. | 54.9 | 676. | 54.3 | 1072. | 51.2 |
|225. | 39837. | 54.7 | 730. | 50.8 | 1171. | 50.2 |
|250. | 47645. | 54.3 | 782. | 50.0 | 1270. | 49.3 |
|275. | 56072. | 53.8 | 835. | 49.3 | 1368. | 48.5 |
|300. | 65078. | 53.3 | 886. | 48.6 | 1466. | 47.9 |
|350. | 84926. | 52.2 | 988. | 47.6 | 1661. | 46.7 |
|400. | 107191. | 51.2 | 1089. | 46.7 | 1854. | 45.8 |