the permissible bolt tension is limited either by the strength of the bolt material (max. stress 80% of the
yield strength), or by the maximum permissible surface pressure on the resin.
Steel chocks
The top plates of the foundation girders are to be inclined outwards with regard to the centre line of the
engine. The inclination of the supporting surface should be 1/100 and it should be machined so that a
contact surface of at least 75% is obtained against the chocks.
Recommended chock dimensions are 250 x 200 mm and the chocks must have an inclination of 1:100,
inwards with regard to the engine centre line. The cut-out in the chocks for the clearance bolts shall be 44
mm (M42 bolts), while the hole in the chocks for the fitted bolts shall be drilled and reamed to the correct
size (Ø43H7) when the engine is finally aligned to the reduction gear.
The design of the holding down bolts is shown the foundation drawings. The bolts are designed as tensile
bolts with a reduced shank diameter to achieve a large elongation, which improves the safety against
loosening of the nuts.
Steel chocks with adjustable height
As an alternative to resin chocks or conventional steel chocks it is also permitted to install the engine on
adjustable steel chocks. The chock height is adjustable between 45 mm and 65 mm for the approved type
of chock. There must be a chock of adequate size at the position of each holding down bolt.
Product Guide Wärtsilä 34DF - 3/2012
127
Product Guide
15. Foundation
