GRAUPNER Heim Eurocopter Bo 105 CBS Mode D'emploi page 57

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Bo 105 CBS
Now fit a spacer sleeve 4619.22 on each shaft, and slide the second ballraces on as far as they
will go. Press the steel inserts into the bevel gears until the threaded holes line up exactly with
the holes in the bevel gears, and fit the M4 grubscrews. Note that the shaft bore must be left
unobstructed. The illustration shows the complete angle gearbox assembly; however, the bevel
gear units should not be fitted in the housing initially, as the drive shafts have to be installed
first.
1.6.2.2 Cutting the tail rotor drive shaft to length
Slide the quick-release sleeve 4618.58 along the tail rotor drive shaft to the point where the
shaft's pre-formed end is located inside the sleeve, then slip the collet 56.0 with grubscrew
(loose for the moment) on the shaft. Cut the shaft to a length of exactly 745 mm (don't throw
away the part you remove). Cut down the teflon guide sleeve to 530 mm length, and fit a ring
about 3 mm wide cut from fuel tubing (supplied with the mechanics) on each end. Slip the guide
sleeve on the shaft and fit one of the two angle gearbox bevel gears on the rear end of the shaft
so that the shaft projects on the inside (the gear end) by 1 - 2 mm. Tighten the grubscrews
lightly in this position.
Fit the other piece of shaft into the second bevel gear, projecting by 1 - 2 mm on the inside in
the same way. Grind a flat in the steel shaft in the area on which the grubscrews engage, using
a grinding stone or small cut-off disc. Apply thread-lock fluid to the grubscrews; tighten one
grubscrew so that it engages fully on the ground flat, then tighten the opposite grubscrew. Fit
both bevel gears in the housing as shown in the illustration, and temporarily screw the two
housing shells together.
Fit the shaft in the fuselage from the rear, coupling sleeve first, so that the short shaft can be
fitted through the tail rotor opening at top rear. Engage the pre-formed end of the shaft in the
quick-release coupling yoke 4618.57, and slide the sleeve over it fully to close the coupling.
Now screw the angle gearbox to the fuselage shell using four M2 x 10 screws, and check that
the short shaft (leading to the tail rotor) projects through the tail rotor opening without any
tension at any point (however, it should not be central!). The shaft leading forward to the
mechanics should run into the quick-release coupling in a smooth curve, and rest lightly on the
bottom of the tail boom at the front end. It is essential that the shaft should not be under
pressure (i.e. too long); there must be a small amount of clearance in the yoke of the quick-
release coupling.
Check the shaft length as follows: when the angle gearbox is screwed to the fuselage, there
must be at least 1 mm clearance between the shaft and the front coupling yoke.
Place the tail rotor on the model, slipping the shaft into the coupling as far as it will go. This
shaft is over-length at present, and must now be cut to final length: measure the distance
between the underside of the tail rotor and the support surface on the vertical stabiliser; the
drive shaft must now be shortened by the measured distance plus 1 mm clearance. Dismantle
the whole assembly (angle gearbox and both shafts), cut the shorter shaft to the correct length,
then grind a flat in the shaft where one of the grubscrews of the tail rotor will engage.
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