Atlantic Coast Line R-1 4-8-4's

[nw-mailing-list at nwhs.org]

Bill,

N&W J #604 was operated on a 21-car, 1,506-ton train
as part of comparative tests with PRR T1 #5511 in
1948.  I ran some time-distance diagrams as part of an
in-process article for the Arrow on this subject and I
believe they would be useful to determine what a J and
R1 could do up to 70 mph.  These are my figures, not
part of N&W’s test report.  I hope to have better
information next week if I can learn more about the R1
this weekend.  Heading to Roanoke for three days at
the archives.  Maybe Railway Mechanical Engineer
magazines can shed more light on the details of the
R1.

Here’s how a quick comparison would look.

A J would require about 5.0 miles and 6.4 minutes to
reach 70 mph., and would probably balance out at 91-92
mph with this load.

Using a similar evaporation rate to the J, but not the
same amount of steam (the R1 had a smaller boiler than
the J), an R1 would require about 8.6 miles and 10.4
minutes to reach 70 mph, and balance out at about
83-84 mph.  As a check, this same format indicates
that the R1 would reach 73 mph in 11 miles and 12
minutes, very close to the figures you cited, so the
comparison method looks OK.  This sort of estimate is
not all that precise, in spite of the parade of
numbers. 

If the R1 were forced and produced the same amount of
steam as the J, the results would be different.  The
R1 would then require about 6.8 miles and 8.5 minutes
to reach 70 mph and balance out at 85-86 mph. 
However, this performance level would cost more in
coal and water.

Based on the above comparison, I believe that the J
would exceed the R1 in acceleration by about 3.6 miles
and 4 minutes with a 1,500 on train to 70 mph.

Dave Stephenson




	
		
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