Thermodynamics, DBHP and related technical matters

Perhaps unfairly, I don't consider 232U1 particularly significant in the grand scheme of French locomotives. It showed some sensible thinking in terms of simplifying operation and mechanical refinement, but didn't achieve the conceptual leap and increased power of 242A1 (on which the stillborn French 2-10-4 was based). The later Baltics occupied a fairly niche role in French motive power, only eight in total within three sub-classes, and I wouldn't say they particularly distinguished themselves compared to the much more numerous 'P' classes in terms of power or economy.

 

According to Terry Essery, the first time he fired a 9F was on a goods train, at night. Admittedly, the stock was short-wheelbase stuff, but they were going fast enough that when they pulled up, the guard said to the driver that he thought they were going to have him off the road - yet Terry said he parked a mug of tea on top of the handbrake column whilst they were going at whatever speed it was, and it didn't move; all he saw was tiny concentric ripples on the surface of the tea, spreading out from the centre.
And what about the driver whose Gresley Pacific failed on an up express to Kings Cross, and the only available spare engine was a 9F which was shunting coal wagons? The driver said that she just felt so smooth, that he just let her run - yet, according to a passenger . . . was it O S Nock? . . . she was doing 92mph at one point, and until he walked down the platform at Kings Cross to take a look, he'd assumed that the spare engine was one of Gresley's!

 

See Posts 71 and 73.

 

A gentleman named Steve has running expirience with 9F and Austerities and the american 2-8-0.
The austerities are by common consent unfit for human consumption doing more than 45 mph.
They shuttle fore and aft due to having no reciprocating balance.The benefit is they give no hammerblow.
Piston and crosshead of 9Fs must be more or less the same mass and they are 40% balanced fore and aft.
Harmfull ness of vibration grow with square of velocity ratio so a 9F at 60 is more uncomfortable than an austerity at 45 and more harmfull to track.

 

I'd agree with all that except for the upper speed of a WD before the shuffling sets in: 25 mph was nearer the mark!

 

When I posted that I had failed to notice that it already had its own thread https://www.national-preservation.com/threads/the-sar-class-26-red-devil-to-be-restored.1128656/

 

No worry, a happening like this is well worth mentioned in several areas.

Knut