Crankshaft And Crankcase Dismantling And Assembly - Husqvarna 322 Workshop Manual

7
The task of the crankshaft is to transfer the up and
down motion of the piston to rotation. To do this
requires a stable design withstanding immense pres-
sure, 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 top and bottom dead centres. This
puts special demands on the bearings that must
withstand quick changes in load. Besides, the bear-
ing's roller retainer also must cope with high tempera-
tures and friction. Therefore it is extremely important
when servicing, to check the roller retainer for crack-
ing, wear and miscolouration due to overheating.
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Crankshaft and crankcase
Dismantling
Dismantle all components so that only
the crankcase and crankshaft remain.
Now lift the crankshaft out of the
crankcase.
The crankshaft is journalled in the crankcase on
heavy-duty ball bearings. In addition to the
journalling point for the crankshaft, the crank-
case acts as scavenging pump for the fuel/air
mixture when this is "sucked" from the carburet-
tor 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 either from the crankshaft
or between the crankcase halves or between the
crankcase and the cylinder.
Always replace the sealing rings and gaskets
when servicing the crankcase.
Dismantling
Dismantle all components so that only
the crankcase and crankshaft remain.
Refer to respective sections if neces-
sary for detailed information.
Now lift the crankshaft out of the
crankcase.
Remove the bearings (sliding fit) and
the spacers.
Assembly
Check the crankshaft as set out in the
section "Inspecting the crankshaft" in
the Workshop Manual.
Clean the contact surfaces in the
crankcase.
Fit new bearings on the crankshaft with
the open side facing in towards the
crank disc.
Lubricate the big end bearings with a
few drops of engine oil and position the
crankshaft in the crankcase.
Fit all other components in the reverse
order as stated for dismantling.
Refer to respective sections in the
Workshop Manual if necessary.
Leak test the crankcase in accordance
the instructions in the Workshop
Manual.