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9.11
Definition of static pull to apply on belts
Static pull depends on:
a) The wheelbase between the two pulleys (belt length).
b) The load due to static pull of the belt.
c) The number of belts.
d) The winding angle of the smallest pulley.
e) Average speed.
f ) Etc.
The diagram in Fig. 11 for belts with an XPB profile in relation
to the wheelbase indicates the correct tensioning Tc (belt sag
with a dynamometer load of 71 N.
Lf= Wheelbase mm
Conclusion: with a wheelbase of 400 mm and with a
dynamometer, loading the belt branch with 75 N as indicated
in Fig. 12, a "te" bend of approximately 8.4 mm is obtained.
Lf = Wheelbase
te = Belt bend
Fe = 75 N Dynamometer load
Note
. Unless otherwise stated by the supplier of the belts,
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control of proper pull and its relative re-tensioning should be
performed after no less than 30 minutes of motion necessary
for the normal adjustment of the belts. Best performance and
durability will be achieved with proper tensioning.
Note
. In case of necessity or for routine maintenance, never
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replace a single belt but the complete set.
10
START-UP AND OPERATION
10.1
Preliminary checks
Before start-up, ensure that:
The suction line is connected and pressurized
(see par. 9.4 - 9.5 - 9.6) and the graphs in par. 9.8.
1. The suction line guarantees a durable hermetic seal.
2. Any shut-off valves between the supply source and the
pump are fully open. During start-up the outlet line must
have free discharge to facilitate the expulsion of air from
the pump manifold and assist rapid priming of the pump.
3. All suction and outlet fittings and connections must be
properly tightened.
4. The coupling tolerances on the pump/transmission axis
(half-joint misalignment, Cardan joint tilt, belt pulling,
etc.) remain within limits required by the transmission
manufacturer.
Fig. 11
5. Oil in the pump casing is at level, verified with a dipstick
(pos. , Fig. 13) and exceptionally with a level indicator
(pos. , Fig. 13).
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In case of prolonged storage or long-term
inactivity, check proper functioning of the
suction and outlet valves.
10.2
Start-up
1. At first start-up, verify that the rotation direction and the
supply pressure are correct.
2. Start-up the pump in no-load conditions.
3. Check that the supply pressure is correct.
4. Check that the rotation rpm during operation does not
exceed the nominal rpm of the pump.
5. Let the pump run for a period of no less than 3 minutes,
before putting it under pressure.
6. Before each pump stop, reset pressure by means of the
control valve or with any relieving devices and reduce to a
minimum rpm (activation with combustion motors).
Fig. 12
28
2
Fig. 13
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