The most perfect locomotive -- N&W's J -- and Its TOP Speed of 128 mph!!!

nw-mailing-list at nw-mailing-list at
Sun Sep 10 13:56:41 EDT 2006

Old saying: 'be careful what you ask for - you might get it'. Let's try to
put the claims about steam locomotive speed accomplishments in proper

First; as to the LNER Pacific "Mallard". The record, carefully documented,
was set on a 0.5 percent downgrade and the chart showed 125 mph was sustained
with only a momentary 'blip' at 126 mph. Maybe someone bumped the table ?
Not usually mentioned is that the inside rod bearing was badly damaged during
the speed run, and the locomotive was taken off the train at the next stop.

No other claim was as carefully documented. A German Class O-5 'Hudson"
achieved 124.5 mph on a level run in 1936. With 90 1/2 inch drivers, the O-5
was probably capable of higher speed, but that nation's government had other
priorities at the time.

In addition to various claims for the N&W's Class J, others exist for the
NYC's # 999 (112.5 mph in 1893) and PRR's # 7002 (120 plus mph in 1905). As
these are not fully documented,
and measurements were crude at best, they remain as 'maybe's'.

As to frequent claims that two cylinder locomotives with 'small' drivers
(think the J's 70 inch) were not capable of speed; depends more on ample
passageways for steam, careful design for exhaust velocity, and springing and
balancing of the drivers.

One last point: Sir Nigel Gresley was, IMHO, overrated. I have read
extensively on the subject; some British authors noted that his valve gear designs
were often modified behind his back by staff who copied from other British
designers. And the conjugated valve gear used on the Mallard and other
locomotive classes had problems. As bearings on the links wore, the inside third
cylinder assumed as much as one half of the total piston thrust. Great idea on
paper; flawed in practice.

Anyway, Mallard does hold the DOCUMENTED steam locomotive speed record.

Jerome Crosson
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