Husqvarna 123HD60 Workshop Manual page 46

7
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 bearing's roller retainer must also cope with high temperatures and
friction. It is therefore extremely important when servicing to check 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 cylinder's combustion chamber. 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.
Always replace the sealing rings and gaskets when servicing the crankcase.
44
Crankshaft and crankcase
Dismantling
Dismantle all components so that only the
crankcase and crankshaft remain.
Remove the 4 screws holding the clutch
housing against the crankcase.
502 50 18-01
Separate the crankcase halves.
Lift out the crankshaft.
Clean the gasket cement from the sealing
surfaces.
Dismantling
Dismantle all components so that only the
crankcase and crankshaft remain.
See the respective sections for detailed
information if necessary.
Remove the key for the fl ywheel.
Remove the 4 screws holding the clutch
housing against the crankcase.
Remove the clutch housing and the fuel
tank.
Take care not to lose the rubber bushings
that guide the fuel tank in place.
Remove the 3 screws holding both crank-
case halves together.
Separate the crankcase halves. A special
tool is not required but it may be diffi cult
as the halves are sealed together with a
so-called "fl uid gasket".
The crankshaft has a snug fi t in the
crankshaft bearing.
Lift the crankshaft out of the crankcase
half on the starter side (a special tool is
not required).