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4.13 Changing the transmission ratio (only for machines with an adjustable drive option)
This option allows you to alter the machine for a 50Hz or 60Hz power supply with minimum effort.
Remove the pulley guard.
Loosen the 4 bolts of the blast motor (do not remove them).
Loosen the 2 tension nuts. The belts will be untensioned now.
For the 50Hz configuration place the 2 V-belts into the smallest two grooves of the bottom pulley. (see
figure below)
For the 60Hz configuration place the 2 V-belts into the biggest two grooves of the bottom pulley. (see
figure below)
Check the pulley alignment and correct if necessary.
Tension the V-belts by tightening the tension nuts. For an accurate result a tension gauge needed.
2 ways to tension the v-belts:
Measuring belt tension by deflection:
Put the tension gauge in the middle of the span length of the V-
belt. The deflection must be 3.5mm by a deflection force of 11N for a new belt. For used belts the
deflection must be 3.5mm by a deflection force of 9N.
Measuring belt tension by frequency:
Turn on the frequency-finding device. The laser light will turn on.
Tap or pluck the free belt span to induce vibration in the belt. Hold the laser probe no more than
25mm off the free belt span, with the laser facing the outside of the belt. Check the frequency being
displayed on the frequency-finding device. For new belts the frequency must be 103Hz. For used belts
it must be 96Hz.
If no tension measuring tool is available there is another way to have an
indication
of the
required belt tension. This method only works when original Blastrac belts are used. There are 2
marks placed at the back side of the motor bracket. Tighten the tension nuts till the motor
flange is close to the mark. For the 50Hz configuration use the highest mark and use the lowest
mark for 60Hz configuration.
