[34C]

...the DB started an experiment and equipped a T38 tender with coal bunker cover flaps. The purpose was to protect travelers from internal and external pollution of fast-moving passenger trains...

Did it work? (The greater hazard for UK passengers was water spilling from an overfilled tender on the water troughs found on many faster lines. If the carriage windows of the first coach were open, the interior could be significantly wetted, with water that was not that clean...)

 

[34C]

In 'HO territory', I believ there was just the one US Railroad that employed water pick up on the move from 'track pans': the NYC. Their little problem as loco power and the required water volume to operate them grew, was actually rupturing a tender during water pick up. Hinged tank top covers of considerable surface area were the answer, to allow free escape of both air and water as necessary.

 

[34C]

Not really, loco crew did not like the fitting, loose coal used to jam the mechanism...

Call me unsurprised, even a relatively modest fixed top side fairing on the original four tenders for the streamlined A4 were not liked. When tasks like trimming the coal bunker were essential to reliable operation, anything that impeded this work was undesireable.

But it certainly makes an interesting variant in model form.

 

[34C]

Coming to this somewhat late, even these weren't a foolproof asset (in UK operation at least). I recall an account collected from an LMS crew,that having set the pusher going to move coal forward, an up to that moment unsuspected large block of coal finished up wedged about two feet behind the shovelling plate, so inside the coal slide, and totally unbreakable with the tools on the footplate while running. So off they came, in possession of a Duchess otherwise in the pink of condition...

The fault clearly lay 'somewhere' between the mine sources and the railway, was the required size grading specified, and/or were the mining concerns capable of meeting the grading requirement?

Regarding the latter, from my late Father in law I have one of his many 'career treasures', a 1920's book relating to the engineer's appraisal of coal for whatever end purpose it was purchased. The sheer scale of the test methods alone gives a good idea of the potential problems with coal supply, and he told me that his 'worst ever' experience was 70% of the quoted calorific value, the ash content (combined fusible and non-fusible) correspondingly circa 10x the quoted average: so bad that the assessment had to be prematurely stopped as the test apparatus was choked...