CXRT, GT
that the belt stays in the middle when rotating
the drive.
10. When the belt has been tensioned and it stays in
the middle when rotating, the motor slide rails
securing bolts are tightened.
Table 4.2 Flat belt tensioning lengths.
Distance between the marks
Before tensioning
(mm)
Typ: F-0, F10, 2,8 %
100
102.8
200
205.6
300
308.4
400
411.2
500
514
600
616.8
700
719.6
800
822.4
900
925.2
1000
1028
4.4.5 Replacement of V-belts
In connection with a belt replacement, the motor must be
moved so that it is easier to remove the old belt and place
the new belt on its place on the belt pulley. Do not use
any tools to remove belts from a belt pulley. If there are
several belts on a belt drive, they all must be replaced at
the same time. It is always best to use belts which belong
to the same manufacturing batch, i.e. belts which have
the same measurement deviation of the manufacturing
tolerance. In connection with the tensioning check that the
pulleys will be completely parallel and aligned. The exact
alignment of the pulleys is very important for the sake of
Fig. 4.6 The exact alignment of pulleys is important.
10
After tensioning
Typ: F14, F25, A-2, A-3, 2,5 %
102.5
205
307.5
410
512.5
615
717.5
820
922.5
1025
Service and repair
the low vibration level of the fan. Proper alignment
lessens the wear of the belt flanks.
4.4.6 Replacement of belt pulleys
If a belt pulley is changed, for example, to change
the speed, ensure that the maximum rpm, as given on
the motor rating plate, is not exceeded and that the
motor output is sufficient for the new operating point.
To avoid endangering the service life of the bearings,
the highest allowed tightening forces, as stated
for the motor and the fan, are noted in dimensioning
the belt drive. All factory fitted pulleys have a Taper
Lock type belt pulley fastening.
Removal of a belt pulley:
Remove screws No. 3 (2 pcs) by using an Allen key
Fig. 4.7. One (or two) of the removed screws is screwed
in removal hole No. 4, and the screw should be
tightened so that cone sleeve No. 2 and belt pulley No. 1
will be separated from each other. A belt pulley must
never be removed with a tool. Even a light impact might
cause damage to the bearing.
Fig. 4.7 Taper Lock belt pulley.
Installing a belt pulley:
Clean the pulley hole and sleeve inside and out with a
rust protection compound, ensuring that there is no
debris on the surfaces. Oil the cone surface lightly and
grease the screws. The sleeve is installed on the pulley
and screws are screwed loosely into place in holes No. 3.
The pulley is pushed onto the shaft with the sleeve (The
sleeve fastens itself on the shaft and the pulley moves
slightly along the sleeve when tightening. Then alignment
is made and the screws are tightened, each in turn,
evenly). The belt pulley is placed as close as possible to
the bearing, not at the end of the shaft. Check the
alignment once more when the screws have been
tightened for the last time. Fill the pull-out holes, e.g. with
stiff grease, in order to prevent dirt from entering. Tension
the belts after this according to the previous instructions.
If the drive is exposed to dust, it is possible that, for
example, sand particles can remain between the belt and
the belt pulley, which then grind the pulley flanks into a