Contents:

• >  introduction
• >  inlet valves
• >  exhaust valves
• >  valve gear
• >  expansion gear

The inlets are fitted with double-beat drop-valves mounted above whilst the exhausts use piston drop-valves under the cylinder ends.  Each pair of inlet valves are connected to a steam chest located between them above the cylinder.  Each pair of exhaust valves are connected to an exhaust main running alongside the cylinder below floor level.

The 10 in. diameter inlet valves sit into a liner bolted inside the valve chamber casting, allowing it to be removed along with the valve for machining of the seating faces.  Both valves and liners are of gunmetal and were cast from the same melt to ensure equal thermal expansion. Metallic packing is used on the valve stem.

The 14 in. diameter exhaust valves are constructed in three pieces and are fitted with solid rings. The valves fit inside cage liners which are mounted in the two level exhaust chamber. Graphite yarn is used in the valve stem glands.

The inlet valve closing is spring assisted, with the final lowering onto the seat controlled by an pneumatic dash-pot.

The cylinder drains and blow-off valves form part of the exhaust chamber assembly.  Condensed water is collected in the upper section of the exhaust chamber and manually drained into the lower section by a quarter-turn tapered plug-valve.  The blow-off valves discharge directly from the upper into the lower sections.  From there, water was carried into the exhaust main, but how it was drained from the main is unknown.