The time-between-overhaul (TBO) of low speed marine diesel engines is largely determined by the piston running behaviour and its effect on the wear of piston rings and cylinder liners. Addressing this, Sulzer introduced a package of design measures in 1999, which are now standard on all new RTA engines and retrofittable to existing engines.
The TriboPack technology enables the TBO of cylinder components, including piston ring renewal, to be extended to at least three years and also allows a further reduction in the cylinder lubricating oil feed rate. The design measures (Figure 12.29) are:
— Multi-level cylinder lubrication.
— Fully and deep-honed cylinder liner with sufficient hard phase.
— Careful turning of the liner running surface and deep honing
of the liner over the full length of the running surface.
— Mid-stroke liner insulation and, where necessary, insulating tubes
in the cooling bores in the upper part of the liner.
— Pre-profiled piston rings in all piston grooves.
— Chromium-ceramic coating on the top piston ring.
— RC (Running-in Coating) piston rings in all lower piston grooves.
— Anti-polishing ring at the top of the cylinder liner.
— Increased thickness of chromium layer in the piston ring grooves.