Two Stroke Cylinder Head

     
  Early engines were often fitted with two part cylinder heads.In this example the outer cover is of cast steel, symmetrical in shape and is held down onto the cylinder liner flange by long studs screwed into the cylinder jacket.The centre piece is of spheroidal graphite cast iron and carries the fuel valve in the centre, also the starting air valve, the relief valve and the indicatorcock. Cast iron is not a suitable material for modern two stroke cylinder covers. The cylinder cover must be able to withstand the gas loads which tend to try to deform its shape. Cast iron is not good at withstanding bending stresses, which is why steel is used. The cylinder cover is tightened against the top of the cylinder liner by means  of nuts and long studs fitted in the cylinder frame .
The nuts are tightened by means of hydraulic jacks.

    Modern covers are manufactured from steel forgings, drilled for bore cooling. This was            introduced on the Sulzer RND engine . On a modern uniflow scavenged engine,     there will be  a large central pocket for the exhaust valve, and pockets for the fuel injectors (2 or 3), air start valve and relief valve together with a drilling for the indicator cock and a bore for the start air inlet. Sealing between the cylinder cover and cylinder liner is obtained by means of a sealing ring, made of mild steel