The Lavender Line
Isfield Station
Nr Uckfield
East Sussex
TN22 5XB

Lavender Line News

23rd December 2014

Overhaul update on 0-4-0VBT Cockerill Yvonne

All steam locomotive’s have to undergo annual boiler inspections, then every ten years they undergo a more stringent overhaul and inspection process which requires the boiler to be removed from the locomotive, stripped of its fittings and have the boiler tubes replaced. This allows an independent boiler inspector to make a thorough inspection of all parts of the boiler including ultrasound thickness readings on parts of the boiler which are normally hidden behind the cladding sheets and between the locomotive frames.

The major inspection for the somewhat unusual Cockerill Vertical Boiler locomotive, Yvonne, is now due, which has necessitated taking Yvonne out of service so the boiler can be prepared for inspection and maintenance. Although it is an extensive project, owners, Colin & Lisa, are committed to getting the work done as quickly as feasible so that Yvonne doesn’t stay out of service longer than necessary. So far, work completed includes the removal of the ash pan and firebars, draining the water tank, boiler and pipework, as well as removal of the boiler inspection hatch and mudhole doors to allow access to the insides of the boiler. All 120 circulation tubes were removed from the boiler and the boiler fittings and connected pipework have been removed and taken off site for refurbishment or storage. The many bolts holding the upper section of the cab have been removed – requiring the use of the gas torch for those subjected to the rigours of being inside the water tank for ten years! Over the last two Sundays, Yvonne has been seen outside the shed over the pit where our CME, Chris has been helping Colin to cut out the old boiler tubes. Yvonne’s boiler tubes are unusual in that they are “Thimble Tubes”, so named because they are closed at one end. They are like test tubes hanging down from the tubeplate at the top of the firebox into the fire and they are full of water in normal operation. These tubes provide a large heating surface to aid rapid steam production. There are 120 tubes, each 2.25” diameter and with access to the inside of the boiler being through a single inspection hatch, it is not an easy job. However, 68 tubes have now been removed so only 52 to go!

Once the remaining boiler tubes have been removed, the boiler will be subjected to a deep clean using the jet washer and the firebox and main flue tube will be needle gunned to remove any loose material. The next step after that will be to remove the cab roof, chimney assembly and finally the boiler from the locomotive. The inspector will then be booked to assess the work that is required and the boiler will go off site to a professional boiler repair company for the renovation works.

Whilst the boiler is away, there will still be plenty of work to do as other parts of the loco will undergo some maintenance whilst the frames and internal parts of the loco are more accessible. The water tank will also be thoroughly cleaned and painted inside to provide protection. The work will all take time but once complete will mean that Yvonne will be in excellent condition and can be steamed for another 10 years, including her centenary in 2020.