Maintenance Videos

Zeno Academy

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Zenit Group | 04 May 2021

UNIQA - CHOPPER knife shim adjustment

  1. Lift the pump by the top handle using a hoist of suitable capacity (the weight of the pump is indicated on the rating plate)
  2. Temporarily fix the knife with 3 screws at 120°
  3. Loosen the knife lock screws WITHOUT completely undoing them
  4. Make sure that the knife separates from the pump body by a few millimetres
  5. Prepare the blades for the adjusting the shim
  6. Insert the shims at each screw, starting with the thinner ones (0.5 mm)
  7. Tighten the screws
  8. Check with a thickness gauge that the shim between knife and blade is between 0.2 and 0.4 mm
  9. Check the shim also between knife and impeller hub
  10. Check that it is between 0.3 and 1.4 mm
  11. If the shim adjustment is not correct, repeat the operation by inserting other shims to obtain different thicknesses
  12. Once you have found the optimal shim, loosen the knife lock screws
  13. Use a small slotted screwdriver to loosen the knife from the pump body
  14. Tack the missing screws WITHOUT tightening them
  15. Insert the same number and type of shims used for each screw
  16. Fold the shims inwards so that they do not protrude
  17. Tighten the knife lock screws by hand in a criss-cross order
  18. Undo each screw in sequence and re-tighten them by applying Loctite 243 threadlocker or equivalent
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