Tensioning Of V-Belts; Tensioning Of Flat Belts - S&P CXRT Serie Instrucciones De Montaje Y Mantenimiento

Service and repair
1. Motor slide rails (2 pcs)
2. Motor fastening bolts (4 pcs)
3. Adjustment bolt (2 pcs)
4. Adjustment bracket (2 pcs)
5. Adjustment bracket fastening bolt (4 pcs)
Fig. 4.3 GT-3 080...100 tensioning the belts.
When using new belts, the belt tensions must be checked
and belts tensioned, if necessary, after about 30 minutes
of operation. Belt tensions must be checked at 6 month
intervals. The belts must be kept clean and protected from
oil and direct sunlight.

4.4.3 Tensioning of V-belts

For proper functioning of a belt, the drive requires
correct belt tension. If the belt tension is too slack, there
is a danger of belt slippage, causing premature wear
of the belts. If the belts have been tensioned too tightly,
there is a danger that the motor bearing service life
will be consider-ably shortened. Even an over-tensioning
of 25% can shorten the bearing service life by half.
Fig. 4.4 Belt span, deflection and deflection force.
1. Measure the belt span length CC [m]. For example,
belt span CC = 1.2 m.
2. Desired deflection dL = 15 mm/length meter. For
example, deflection dL = 15 mm/m * 1.2 m = 18 mm.
3. Measure the perpendicular deflection force F,
which is obtained by deflecting dL (by 18 mm).
4. Compare deflection force F to the table 4.1. If the
measured deflection force is between the values
given, the tension is satisfactory. If the tension is less
than the lower value, the belts are too loose.
New belts should be tensioned to the higher value
of the measuring force, as the belts will stretch
during the drive-in period.
Table 4.1 Deflection forces of the V-belt.
Belt profil Diameter of smaller pulley
67 - 95
SPZ
100 - 140
100 - 132
SPA
140 - 200
160 - 224
SPB
236 - 315
224 - 355
SPC
375 - 560

4.4.4 Tensioning of flat belts

Fig. 4.5 Measurement distance of a flat belt.
1. Install the motor and fan belt pulleys on their shafts
without tightening the sleeves.
2. Install the belt over the pulley and move the
engine so that the belt will straighten, but will not
be tensioned.
3. Align the belt pulleys using a ruler and tighten
their sleeves.
4. Fasten the motor loosely so that it can still be
moved on the slide rails.
5. Measure the longest free belt span DD, rounded
down to the nearest 100 mm. For example,
if CC = 865, then DD = 800 mm. The belt must not
touch the belt pulley within the measuring distance.
6. Remove the belt, place it on an even surface
and mark the free belt span mentioned in the
previous section on the belt with a pen.
7. Install the belt on the pulley again and tension
it by means of slide rails, with the motor and fan
shaft being as parallel as possible.
8. Stop tensioning when the belt has reached the
correct stretch according to the table 4.2.
9. Rotate the belt drive by hand. If the belt moves
axially to either direction, this is due to the
fact that the shafts are not parallel. This situation
can be corrected by means of slide rails so
CXRT, GT
Force F (N)
10 - 15
15 - 20
20 - 27
28 - 35
35 - 50
50 - 65
60 - 90
90 - 120
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