Rotor Timing - VERDER JEC JRZLF Series Operation And Maintenance Manual

Rotor Timing

Rotor timing must be precisely maintained to provide maximum pumping efficiency, yet prevent
contact between rotors during operation. If pumping efficiency is below expectations, or if rotors
contact during operation (within rated differential pressure), check rotor timing and adjust if incorrect.
Also check rotor timing after any gearbox dismantling when the gears are removed and/or replaced.
Check Rotor timing as follows:
2. Assemble each rotor in its normal location on the drive shaft and the idle shaft. Assemble each
rotor bolt and tighten hand tight.
3. Rotate the shafts 30 degrees and measure gap as illustrated by arrows. Rotate the shafts 60
degrees the opposite direction and measure gap as illustrated.
4. The Rotors are correctly timed when the gap measured at both locations are equal. If the gap is
unequal, adjust the timing as follows.
5. Rotor timing is determined by the relative
location of the two helical gears (18) on
the shafts. Gear spacers (13) are used to
adjust the location and the timing.
When adjusting timing, move only
one of the two gears.
6. Place the wooden dowel between
the rotors.
7. Bend away the tab of the lock washer
(19) on one shaft. Loosen the lock
nut and temporarily insert shim stock
between the gear and gear spacer.
Tighten the lock nut, reassemble the
rotor in its correct location, and
recheck rotor timing.
* If Rotor timing is correct, remove the gear and replace added other spacer or add a shim equal in
thickness to the shim stock temporarily added. Reassembly the gear and gear nut, tighten to the
correct torque, and check rotor timing again to confirm that it is correct.
* If rotor timing is incorrect, but closer to equal than original measurement, repeat previous step
adding addition shim stock.
* If rotor timing is incorrect and more unequal than original measurement, remove temporary shim
stock from one shaft and add instead to the other shaft.
8. Repeat above procedures until the timing gap is equal after gear spacers are in place and gear nuts
are tightened to correct torque.
9. Reassemble pump.
17
Figure 21