GRAUPNER heim UNI-Mechanik 2000 Mode D'emploi page 59

UNI-Mechanics 2000
M3 x 16 screws as shown.
Locate the end of the main rotor shaft 4448.43 which has a cross-hole positioned about 26 mm
from it, and fit that end of the shaft through both bearing holders from above, and then fit two or
three shim washers on the end followed by the crown gear; you should now be able to push the
pin 4448.21 through the cross-hole below the flange.
Note: as the outer edge of the crown gear engages behind the layshaft pinion, the best way to
install it is as follows: first leave the main shaft projecting from the bottom bearing just far
enough to enable you to fit the shim washers onto it. Now swivel the ring gear into place behind
the pinion and slip it onto the end of the main rotor shaft. The main shaft can then be pushed
right through.
Now pull the main rotor shaft upward, so that the cross-pin engages fully in the channel in the
underside of the crown gear flange. The crown gear now rests on the bottom rotor shaft bearing
via the shim washers, and engages with the pinion 4448.41 on the tail rotor drive unit. Fit the
annular clamp 4448.156 on the top end of the main rotor shaft and slide it down until it rests
against the top rotor shaft bearing; there should be absolutely no axial play in the shaft between
the bearings. Now check that the tail rotor drive unit runs correctly: the pinion 4448.41 should
mesh smoothly with the crown gear, without any detectable play, but equally without any
tendency to jam or bind at any point. If the system is stiff, you need to fit additional shim
washers between the crown gear flange and the bottom bearing; if there is any detectable play,
remove shim washers to eliminate it.
It is important to carry out this adjustment very carefully, as the durability and longevity
of the tail rotor drive system depend upon it.
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