WÄRTSILÄ WARTSILA 26 Product Manual Download

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A “multi-duct” casting is fitted to the cylinder head. It connects the following media with the
cylinder head:

●

charge air from the receiver

●

exhaust gas to exhaust system

●

cooling water from cylinder head to the return pipe

4.2.9

Camshaft and valve mechanism

The cams are integrated in the drop forged completely hardened camshaft material. To provide
the required rigidity to deal with the high transmission forces involved, the fuel cam is located
very close to the bearing.

The bearing journals are made in separate pieces which are fitted to the camshaft sections
by means of flanged connections. This design allows lateral dismantling of the camshaft
sections.

The camshaft bearings are located in integrated bores in the engine block casting. The built–on
valve tappet unit bolted to the engine block makes maintenance easy.

The valve tappets are of piston type with self-adjustment of roller against cam to give an even
distribution of the contact pressure. The valve springs make the valve mechanism dynamically
stable.

Variable Inlet valve Closure (VIC), which is available on IMO Tier 2 engines, offers flexibility to
apply early inlet valve closure at high load for lowest NOx levels, while good part-load
performance is ensured by adjusting the advance to zero at low load. The inlet valve closure
can be adjusted up to 30° crank angle.

4.2.10

Camshaft drive

The camshaft is driven from the crankshaft through a fully integrated gear train.

Camshaft gear is shrunk on camshaft. Adjusting of timing is possible by means of oil pressure
on the gear wheel.

4.2.11

Turbocharging and charge air cooling

The charge air module for the V–engine is a casting in which the charge air cooler is
accommodated and which supports the turbochargers.

For the in–line engine the turbocharger support and the charge air housing are different
modules. Connections between turbocharger, charge air cooler and scavenging air duct as
well as the connections to the cooling water systems and turbocharger housing(s) are
integrated. This construction eliminates the conventional piping outside the engine.

The selected turbocharger offers the ideal combination of high-pressure ratios and good
efficiency at full and part load.

The turbocharger is supplied with inboard plain bearings, which offers easy maintenance of
the cartridge from the compressor side. The turbocharger is lubricated by engine lubricating
oil with integrated connections.

The turbocharger(s) is (are) as standard located at the driving end, but can also be mounted
on the free end.

The charge air cooler is of the one-stage type for in-line engines and of the two–stage type,
consisting of HT and LT cooling water sections, for V-engines. Treated fresh water is used in
both sections. The charge air cooler is an insert type element and can easily be removed for
cleaning the air side.

The water side is accessible through removal of the cooler end covers.

Wärtsilä 26 Product Guide - a9 - 7 September 2016

4-3

4. Description of the Engine

Wärtsilä 26 Product Guide