Edwards nEXT85 - Bearing Preload Familiarisation; Figure 4 Locating the Preload Tool (NW40 Variant Shown)

In order to become familiar with how to recognise bearing preload aer a service, it is
recommended that the instrucons in Bearing preload familiarisaon on page 10 are
followed.
Bearing preload familiarisaon
CAUTION:
Ensure all tools are clean and free of dirt and grease to avoid contaminaon of the
rotor.
This procedure should be performed with the pump placed in the vercal posion.
1. Place the preload tool onto the inlet of the turbomolecular pump. The force probe
must be located into the centre of the pump inlet with the adjuster legs engaged
onto the magnec bearing adjuster nut Figure 4 on page 10. Supporng the
preload tool body in posion while performing the preload check is recommended.
2. Apply pressure by pushing the test plunger unl a change in preload can be
detected. Releasing the test plunger will return the preload back to its original
posion. Pressing and releasing the test plunger slowly while performing this check
is recommended.
Note:
Detecon of the bearing preload can be recognised by a disnct sound. This may be
accompanied by a sensory feel through the tool and pump body. If a change in preload
cannot be detected, it may be possible to carry on with the service but with cauon.
CAUTION:
If the pump has suered any damage (i.e. the rotor does not spin freely or quietly), it is
recommended that the service is not carried out and that the local service centre is
contacted for advice.
Figure 4
Locang the preload tool (NW40 variant shown)
1. Preload tool force probe
2. Preload tool body
3. Preload test plunger
4. Preload tool adjuster legs
5. Magnec bearing adjuster nut
B8G2-00-840A - Pre-service
Page 10