Crankshaft And Crankcase; Dismantling - Husqvarna 545RXT AT Workshop Manual

Crankshaft and crankcase

The task of the crankshaft is to transform the reciprocating motion of the piston to rotation. This requires a stable
design withstanding immense pressure and rotational and bending strain, as well as high rotational speed. In addition
the connecting rod is exposed to large acceleration and retardation forces as it moves between the top and bottom
dead centres. This puts special demands on the bearings that must withstand quick changes in load. Moreover, the
roller retainer of the bearing must also cope with high temperatures and friction. It is therefore extremely important
when servicing to inspect the roller retainer for cracks, wear and discolouration caused by overheating.
The crankshaft is journalled in the crankcase on heavy-duty ball bearings. In addition to the journalling point for the
crankshaft, the crankcase acts as a scavenging pump for the fuel/air mixture when this is "sucked" from the
carburettor and is forced into the combustion chamber of the cylinder. The crankcase must be perfectly sealed so as
not to affect this pump function. There cannot be any leakage from the crankshaft, between the crankcase halves or
between the crankcase and the cylinder.
CAUTION! Always replace the sealing rings and gaskets when servicing the crankcase.
CAUTION! Make sure the crankshaft and crankcase are clean before assembling the product.
WARNING: Always use protective gloves when handling hot objects.

15.1 Dismantling

WARNING: Always use protective gloves
when handling hot objects.
1. Dismantle all components so that only the crankcase
and crankshaft remain. See the respective sections
for detailed information.
2. Remove the 2 bolts and lift off the protective cover
from under the crankcase. See figure 1.
Note: Use the 2 bolts to thread the holes when you
install the protective cover to a new crankcase.
15 Crankshaft and crankcase
Fig. 1
English – 69