Tonnage Ratinds and weather Reductions for locomotives

NW Mailing List nw-mailing-list at
Mon Dec 17 17:04:24 EST 2018



Do you figure cold weather tonnage reductions were specified for the
difficulty of taking tonnage uphill or for braking tonnage downhill? Or


John Garner


From: NW Mailing List [mailto:nw-mailing-list at] 
Sent: Monday, December 17, 2018 11:01 AM
To: nw-mailing-list at
Subject: Tonnage Ratinds and weather Reductions for locomotives


It is true cold weather can have very adverse effects on trainline air

In the 70's & 80's a normal eastbound coal train out of Williamson was 120
cars.  On one particular January day the temperature was around 0 degrees.
Due to the temperature sufficient air pressure (60 lbs.) could not be
obtained on the rear of the train. Our train had been reduced to 80 cars and
after sometime the required air pressure was obtained and after a lengthy
brake test we departed Williamson.  During this trip the air pressure
dropped to 56 lbs. Fortunately  we did not have trouble with sticking
brakes.  As we entered Elkhorn Tunnel the air pressure was till around 55
lbs. on the rear.  As we passed thru Elkhorn the air pressure rose to 60
lbs. After exiting Elkhorn tunnel  speed of the train increased to 25mph and
air pressure on the rear dropped to 55lbs. Staying at this pressure all the
way into Bluefield Yard. 

I can only assume the reason for the air pressure to rise while moving thru
Elkhorn tunnel was the temperature inside the tunnel and due to the length
of the tunnel, the heat from the exhaust of the locomotives caused the air
in trainline to warm and  expand and to not be so heavy.  

Also in cold weather it was not uncommon for ice to form in the air hose and
trainline (I assume from condensation) restricting the air flow.  Rubbing
Alcohol would be poured into the air hose and as the air moved thru the
trainline the ice would melt allowing sufficient air pressure to be obtained
on the train.


-Jeff Hensley.


                    From: NW Mailing List 
Sent: Saturday, December 15, 2018 8:36 PM
To: nw-mailing-list at <mailto:nw-mailing-list at>  
Subject: Tonnage Ratings and Weather Reductions for Locomotives

By time-table instructions train tonnage in the steam era was reduced as
ambient temperatures fell. Reductions were as much as 25% at temperatures
below 0 degrees F (Rating G).


Were there multiple reasons for this reduction? Was the primary reason the
increased rolling resistance of cars with friction bearings? Were other
factors involved?


Thanks,  John Garner,  Newport VA 

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