The Bluebell Railway has issued its latest report on Maunsell Q Class 0-6-0 No. 30541 at its locomotive workshops at Sheffield Park.

The examination of pistons and valves on steam locomotives is a routine procedure that is regularly undertaken. The process is usually carried out at anything from 20,000 miles upwards.

An indication that an examination is due may be shown by a lack of power; problems with the drain cocks such as blockage; and failure of the cocks to close, which could be due to broken pistons rings.

To remove the pistons and valves, it is often necessary to dismantle some of the structures in front of the cylinders. It is also often necessary to remove the piston and valve covers themselves.

After extracting the pistons and valves, the rings on these components are examined and measurements made of the diameter along the bore of the piston and valve. Any changes in the diameter can be corrected by reboring the piston or valve, a process which has been undertaken on No. 30541.

The boring equipment used originated at Eastleigh Works. It consists of an electrically-driven worm gear operating a shaft with a cutter head attached. Central alignment is obtained by a front mounted cage, bolted to the studs used to hold the cylinder cover as seen in the photograph below.

Once the bored diameter is consistent throughout the length, new pistons and valve heads can be machined and new rings ordered.

The motion of 30541 has been removed and now re-erection is starting, with the slide bars already in place. In addition to this work, it was necessary to fabricate new main steam pipes. The new ones have been fabricated and can be seen in the following photograph.