|Dave Mitchell was the Engineering Director of Wadebridge (34007)
Locomotive Ltd and was responsible for overseeing the restoration of Wadebridge from scrap condition to full operation. He works for Southern Locomotives at Swanage, knows an awful lot
about Bulleids and is a self-styled "Bulleid Fundamentalist"!
"As a Bullied Fundamentalist I do try to be pragmatic about what
Bullied was trying to achieve when he designed his locomotives. I write the
following to explain the real reason why the lagging on the boilers of the
Bullied Pacifics became soaked with oil and subsequently caught fire. This
will, I hope, dispel all the mythical rubbish that has been written about the
oil baths fitted to Bulleid's pacifics. A few years ago, when in
conversation with the late Harry Frith senior, he explained to me the root
cause of all the trouble. Harry had finished up at Eastleigh works as Chief
Erecting Shop Foreman, where these locos were repaired, and therefore was well
qualified on the subject.
The driving axleboxes are lubricated from missionary trays located in the
cab via trimmings which are feeding oil all the time that the trimmings are in.
Consequently, when the loco is standing (e.g. in a station or inbetween duties
etc.) oil would run out of the axleboxes, most of which ended up in the wheel
pockets of the BFB wheels - bear in mind that there are four feeds per axlebox.
On starting away the oil was flung up under the casing and into the lagging.
With time it also attracted brake block and ballast dust etc., thereby
providing the fuel!
The source of ignition was a heavy brake application, which threw up sparks and
ignited the gasses from the sump breathers which, in turn, set fire to the
lagging. A regular supply of the oxygen that is so essential for good
combustion was drawn up under the casing, aided and abetted by the loco's
What was done to prevent it? The material the brake blocks were made of was
changed to a different grade of cast iron which reduced the sparking and the
boiler had belly lagging sheets fitted to the underside which encapsulted the
lagging. The first ten Merchant Navies were fitted with splashers, but these,
presumably to save weight, were discarded for all the other locos. Steam
cleaning was introduced (pictures exist of this being carried out) and the
problem was drastically reduced by these preventitive measures. You don't
read so much about the fires that occurred on the class 47s, which were prone
to catch fire for similar reasons!
Yes, the oil baths did crack, but you must remember that the 40 gallons of oil
contained therein when the loco was on the move was being pumped via an oil
gallery and ejected through spray pipes over the motion. The excess oil ran
down the sides of the oil bath, some did, obviously, exude from the cracks, but
not in the copious quantities that you read about. The significant loss of oil
would have occurred through the breathers, as gassing would be constant.
One final point, if you were to use a Ferrarri to get to work instead of your
Fiesta, say, then would you not expect to use more fuel? They might have hauled
one or two coaches one way, but often as not they came back with 10 or 12. I
find it hard to believe how petty and small minded people can be with regard to
these locos, but maybe fame attracts controversy and jealousy? Yes, the
problems that were encountered were unique, but what of it? The Bullieds were
It also must be noted what Bullied was trying to achieve in the short space of
time he had in the post of CME. All things considered I think he and his team
did very well with the resources they had, coping with his original ideas and
methods of working."