Medway Queen – Rebuild of a Dunkirk Veteran Part 2
Focus On Main Engine Equipment
(Words G. Stewart – Pics Dave Elms & G. Stewart)
This is the second of a series of articles charting the progress of the rebuild of Clydebuilt paddler PS Medway Queen – Dunkirk Veteran.
The previous article focused on the the various engine parts arriving at Abel’s Albion Dockyard in Bristol prior to Christmas. Since this time a number of additional parts have arrived on site and the fabrication of the sections of riveted hull has commenced – this article will focus on these various pieces of Main Engine.
This first shot shows the Main Engine “entablatures” which provide a housing for the crankshaft main bearings as well as locating the crankshaft on the correct centerline to mate with the paddle shafts. There are three entablatures in total – the slightly wider one you can see in the background of the photo would be in the centre – it is wider as it has to withstand the force of both the Low Pressure (LP) and High Pressure (HP) cylinder connecting rods. As a result the bearing housing is also twice the width of the other two. The shots of Loch Lomond’s Maid of The Loch which has a similar machinery configuration makes a good comparison.
The part arrowed “A” would attach to corresponding mounting pads in the hull of the vessel’s engine room. The transverse hull frame onto which these pads would be fixed would be slightly heavier steel than the others to accommodate the increased weight it would have to bear. Part “B” also attaches to the ship’s hull but instead of a transverse hull frame it would more than likely be the bulkhead between the engine and boiler spaces – a piece of this bulkhead can be seen to be still attached in the photo. Part “C” is the bearing housing which contains a main bearing shell made of white metal. A corresponding shell bolts onto this via the two large studs that can be seen just below the arrow. Finally part “D” is the piston rod slide – the piston rod cross head and slippers slide up and down this part which would be lubricated with either grease or oil.
Moving on we have a photo of the LP cylinder cross head with part of a slipper still attached.
This part of the engine connected the piston rod to the crankshaft connecting rod thus converting the in / out (linear) motion of the piston rod to a rotating motion in order to drive the crankshaft round. The piston rod bolts through the cross head (Part “A”) while a U shaped link would connect either side of this area via small bearings. Part “B” shows the white metal slippers which permit the cross head to move up and down the slide on a bed of grease or oil.
The photo below shows the same equipment in position on Maid of The Loch.
Finally – for this report anyway – we look at the condenser. This unit turns the exhaust steam from the LP cylinder back into water so it can be returned to the boilers and re-used. This is achieved by circulating water (in this case it would be sea water) through a bank of tubes (Part “A”) inside a drum or casing. The forementioned exhaust steam is admitted to this drum from the LP cylinder (Part “B”) and is condensed back into water through the subsequent contact with the cold tubes.
Medway Queen’s condenser (shown below) will require a new casing and a re-tube but it is hoped to retain the end caps (Part “C”) and the steam inlet (Part “B”).
Well that’s all for now – apologies if the content is a bit overly “techy” but I don’t see the point in showing you all these pics unless I explain what they’re for and where they go!!
If you want to track the overall progress on Medway Queen why not visit the Medway Queen Preservation Society’s Ship Yard Blog.
Thanks as always to Dave Elms for providing the photos!!
[signature name=”Gavin Stewart”]