|Dave Mitchell was the Engineering Director of Wadebridge
(34007) Locomotive Ltd and as such was the person who was responsible for
overseeing the restoration of 34007 Wadebridge from Barry condition back
to steam. He worked for Southern Locomotives at Swanage, knows an awful lot
about Bulleids and is a self-styled "Bulleid Fundamentalist"!
"As a Bulleid Fundamentalist I do try to be pragmatic about what Bulleid 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 Bulleid 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
in between 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!
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!
Text copyright Dave Mitchell
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This page was created 10 March 2003