GRAUPNER heim Starlet 50 Mode D'emploi page 59

Starlet 50
1.4 Assembling the main gearbox
Fit the tail rotor drive unit, the layshaft assembly and the main rotor shaft bearing holders
between the mechanics side frames 4450.9 and 4450.10, and fix them in place using M3 x 16
socket-head cap screws; don't tighten the screws fully at this stage. Fit a shim washer 4450.40
and the dome bearing holder on the main rotor shaft from the underside. Slide the main rotor
shaft through the bottom rotor shaft bearing and the crown gear 4450.20A, working from the top,
and position it in such a way that the dowel pin 4450.37 can be pushed through the bottom hole
in the main rotor shaft. Now pull the main rotor shaft up as far as it will go, and check that the
dowel pin engages fully in the recess in the underside of the crown gear. Now you can fix the
dome bearing holder between the mechanics side frames using further M3 x 16 socket-head
cap screws, and check that there is absolutely no axial play in the main rotor shaft between the
bearings; if there is, fit further shim washers under the circlip to eliminate it. Take care not to fit
too many or too thick washers, as this could place the bearings under stress.
To add or remove shim washers always loosen the dome bearing and remove the main
rotor shaft by reversing the order of operations required to install it (see above). On no
account remove the circlip to gain access to the washers!
The first step in establishing the correct gearbox clearance is to set the meshing clearance of
this gearbox stage slightly too tight, i.e. the gears should mesh „hard" against each other. If this
is not the case, i.e. if there is already significant clearance between the gears after you have
assembled the main mechanical system and screwed the parts together, then you will have to
turn the bottom main rotor shaft bearing 4448.12 through 180° and re-install it. If that is still not
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