Tonnage Rating of Locomotives

[nw-mailing-list at nwhs.org]

A Tonnage Rating is what a locomotive will pull over a section of railroad
in tons.

 

It is usually based on the ruling grade ( steepest grade ) on a particular
piece of railroad.

 

By using a formula with the percent of the grade and the tractive effort of
a particular class of locomotive as the basis,the railroad could come up
with a tonnage rating for that class of locomotive.

 

The grades from Lynchburg to Naruna are steeper and more numerous than the
grades from Naruna to Durham so naturally the Tonnage ratings are lower.

 

Many times railroads did not give tonnage ratings for passenger
locomotives,particularly on branchlines,because passenger train sizes were
not large enough to tax the power of the locomotive.

 

         John Barnett

        Raleigh N.C.

 

  _____  

From: nw-mailing-list-bounces at nwhs.org
[mailto:nw-mailing-list-bounces at nwhs.org] On Behalf Of
nw-mailing-list at nwhs.org
Sent: Monday, July 31, 2006 12:12 AM
To: nw-mailing-list at nwhs.org
Subject: Tonnage Rating of Locomotives

 

To all,

 

Would someone please explain the Tonnage Ratings of Locomotives found in the
Employee Time Tables.  This request is related to my earlier posting
concerning the Tonnage Rating on the Durham District and locomotive
limitations that are implied.

 

In the Norfolk Div. #9 ETT, effective March 9, 1919, the Tonnage Rating of
Locomotives listed for the Durham District Southward from Lynchburg to
Naruna is 620 for Class T, 520 for Class G, and 470 for Class F.  From
Naruna to Durham the ratings change to 720 for Class T, 620 for Class G, and
570 for Class 570.

 

Class G and F locomotives are listed at higher ratings for other areas in
the Division.  Class T isn't even listed anywhere else for the Division.
Classes Z-1, M-2 SH, M-2, M and W are listed, just not for Durham.

 

I am guessing that 1) the Durham District's track, bridges, and other
structures couldn't support the larger, heavier and more powerful
locomotives, and 2) the business for the Durham District didn't require the
1st class power.

 

But what numbers does the Tonnage rating refer?  Also, what about passenger
locomotives such as Class V?  Would it be assumed anything smaller than a T,
G, or F would have been allowed?

 

Thanks, 

 

Chuck Stewart

Bahama

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