Doxford Top Piston Guides
 

Following on from Fullagar Engines #22; When Doxford were developing the P-type, they ran an LBD with the bottle guides very slack to see the effect of not having top piston guides. However, they were a bit worried and so fitted white metal sleeves around the side rods to act as a guide. They found very heavy wear on the white metal but it was not in the port/starboard direction from the ship rolling as they expected but in the fore/aft direction. After some investigation they found this was due to the the side rods oscillating due to the compression/combustion forces acting around inner dead centre. The bottle guides and the white metal sleeves were removed and never replaced. One development tick for the P-type and J-type.