Why Liners are Generally Thinner at the Bottom than at the Top ?

             The hoop stress on the liner is dependent on the gas pressure within the cylinder, as the piston progresses downwards the gas pressure decreases. Any section of the liner has therefore to be strong enough to resist gas pressure above the top piston ring as the piston descents on the power stroke. The liner may therefore be made progressively thinner in sectional thickness to suit the lower gas pressure towards its lower part.

            By making the liner progressively thinner, the rate of heat transfer from the thicker section is increased as the heat flows downwards to the thinner section which is cooler, both by reasons of gas temperature and because the thinner section transfers heat more easily to the cooling water.