Operating or wrecking the National Collection
12 May 2003
To preserve a rusty heap, or to enable people to
appreciate how railways operated in the past? This was the tricky
question handled by Richard Gibbon at our May meeting. Many in the
museum profession see it essential that the patina of age is retained,
but Richard felt that if the public were to properly appreciate the
vehicles preserved at the NRM, they must be able to see them in their
operating state. This brings complications in that the museum
environment is different from that it experienced in service as was
illustrated with pictures of the superheater elements on the Duchess.
In service, wear was due to erosion by ash, but in preservation
corrosive condensation within the tubes was a much greater problem.
Wherever possible, the museum will retain the
original material, in some cases calling for ingenious repair methods
when replacement was the obvious solution. Here the role of the museum
and a preservation railway differs. Where replacement was the only
solution, the museum would retain the replaced part. Hence, when the
side sheets of the Duchesses' tender were replaced to meet current
loading gauge limits, an original was retained with its scuff marks
caused by the streamlined casing.
Pete Waterman had agreed that the restoration of the
Super D used the original design practices. In a couple of instances
these had required the re-learning of old skills. In accordance with
LNWR practice, the bottom of the tender was made up of a large number of
small plates - reputedly, the off cuts from the plate shop. Riveting
together 2 plates has no fears, 3 can be tricky, but having four plates
meet at one spot is nearly impossible. Eventually, by relearning old
practices the museum had succeeded. A more interesting case was that of
brazing the copper cuffs onto the ends of the superheater flues. Every
attempt failed as the molten metal dripped out, until that is the tubes
were hung vertically! There is no record that Crewe brazed the cuffs
on with the tubes vertical, but it did look as though the museum had
discovered how they had done it.
This brought Richard onto the subject of skill
retention. At present, the museum was able to draw upon a pool of
engineers who had served their time in heavy engineering. However,
changed education practices meant that there were many fewer coming into
engineering by this route. As an attempt to retain the skill base,
efforts were in hand to enable the museum to take on 2 apprentices.
This would go some way to preserving skills from the steam railway.
However, the expertise for building large locomotive boilers has already
gone and Richard could see the time when all the present mainline
locomotives were stopped because their boilers were no longer steamable,
and repair was impossible.
Safety regulations inevitably move forward as our
experience grows. However, attempting to apply modern standards to
heritage vehicles or structures can be a nightmare and had caused
Richard many sleepless nights. An example of this was the foot bridge
from Percy Main which is prominently displayed in the Main Hall. Before
the public could be allowed to cross it, it had to be subject to a
proof test. In accordance with current regulations, this proved to be
the equivalent of 500 people. We were left to consider on our next
visit to the museum whether it was possible to get anything like that
number on the bridge at any one time!
After a lively discussion period, Richard closed
with an explanation for the missing 3rd beat on the Super D. At some
time the frames became bowed, moving the pivot on the weigh shaft
upwards. On many locomotives this might not be significant, but the
Super D used Joy valve gear which relies upon the upward movement of the
connecting rod. A previous experiment on 2 members of the class had
shown that 3rd beat could be restored by mounting the shaft in modified
bearings. Would the museum allow a similar experiment on 9395?