Metso MP1000, Technical Reference Manual

Page: 94 / 180

SECTION 2 - GENERAL INSTALLATION INFORMATION
2-20
MP SERIES CONE CRUSHER TECHNICAL REFERENCE MANUAL
2.8.9 Percent Elongation Method
General method for tensioning V-belt drives.
1. With the V-belts or bands on the drive at NO
tension, measure the outside circumference (slack
O.C.) of the belts or bands.
2. Record this measurement to the nearest millimeter
(1 /16").
3. Multiply this recorded length by a elongation
factor multiplier which is shown in Table 2-7 and
add this amount to the initial measurement.
4. Elongate the belt to this new reading.
EXAMPLE
Type belt = Standard 8V
(Optibelt for MP1000)
Initial tape reading = 9017 mm (355")
Elongation factor (from Table 2-7) = 0.006 (Multiplier)
which is 0.6% (percent)
New length reading = 9017 mm (355") initial r
[9017 mm (355") initial reading x 0.006 elongation
factor] = 9017 mm (355") + 54 mm (2-1/8") or 9071 mm
(357-1/8").
Therefore, on an installation with an 8V belt and an
outside circumference measurement of 9017 mm (355"),
the motor sheave should be moved away from the crusher
sheave until the steel tape reads 9071 mm (357-1/8") for a
properly tensioned drive.
5. Periodic belt tension checks must be made and if
retensioning becomes necessary, decrease the
center distance until there is no tension on the
belts or bands, then measure the outside
circumference (slack O.C.) of the belts or bands.
Retension the drive following the method just
described.
It must be pointed out that the
TENSION-DEFLECTION METHOD is the
preferred method of tensioning V-belts unless
using banded belts.
Usually the first sign that indicates retensioning is
necessary is belt slippage. This slippage will show up in
loss of power and speed at the crusher sheave and in a
high rate of belt and sheave groove wear. These
conditions are usually accompanied by belt “squeal” and
also a heating up of belts and sheaves. These conditions
are readily apparent and can be detected by simply
looking, listening, and feeling.
2.8.10 Tensioning Procedure for Standard or
Banded V-belts for a New Crusher Installation or
When a New Countershaft Bushing With New
V-belts Has Been Installed
1. Tension the belts or bands to a value that is
obtained by using the MINIMUM MULTIPLIER
as shown in Table 2-7.
2. Run the Crusher WITHOUT material for a period
of 2 hours. See INITIAL START-UP AND
BREAK-IN PROCEDURE in Section 11 .
3. After the 2 hour period, retension the belts or
bands to the MAXIMUM MULTIPLIER as shown
in Table 2-7.
4. After 1-4 hours of full load operation, the belts or
bands should be checked and if necessary
retensioned to the MINIMUM MULTIPLIER as
shown in Table 2-7.
5. Periodic belt or band tension checks must be made
and if retensioning becomes necessary, the
tensioning process should be repeated and the
tension set to the MINIMUM MULTIPLIER as
shown in Table 2-7.
2.8.11 Tensioning Procedure for Standard or
Banded V-belts When a New Countershaft
Bushing Has Been Installed and Using the
Existing V-belts or Bands
1. Tension the belts or bands to a value that is
obtained by using the MINIMUM MULTIPLIER
as shown in Table 2-7.
2. Run the Crusher WITHOUT material for a period
of 2 hours.
3. Periodic belt or band tension checks must be made
and if retensioning becomes necessary, the
tensioning process should be repeated and the
tension set to the MINIMUM MULTIPLIER as
shown in Table 2-7.
2.8.12 Tensioning Procedure for Standard or
Banded V-belts When New Belts Have Been
Installed With Existing Countershaft Bushing
1. Tension the belts or bands to a value that is
obtained by using the MAXIMUM MULTIPLIER
as shown in Table 2-7.
2. After 1-4 hours of full load operation the belts or
bands should be checked and if necessary
retensioned to the MINIMUM MULTIPLIER as
shown in Table 2-7.
3. Periodic belt or band tension checks must be made
and if retensioning becomes necessary, the
tensioning process should be repeated and the
tension set to the MINIMUM MULTIPLIER as
shown in Table 2-7.
2.8.13 Retensioning Procedure for Standard or
Banded V-belts Using Existing Bands or Belts
1. Periodic belt or band tension checks must be made
and if retensioning becomes necessary, the
tensioning process should be repeated and the
tension set to the MINIMUM MULTIPLIER as
shown in Table 2-7.