© Edwards Limited 2012. All rights reserved. Page 33
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Maintenance
A705-61-880 Issue M
11.Wipe clean the oil drain-plug (3), then fit a new bonded seal (4) to the drain-plug.
12.Fit the oil drain-plug (3) and bonded seal (4) to the oil drain-port (5).
13.Fill the gearbox through the funnel, with the correct grade and quantity of oil. Allow the oil to drain into the
gearbox and then check the level on the oil sight-glass (refer to Section 5.3).
14.Remove the funnel and refit the oil filler-plug (12) and bonded seal (13) to the oil filler-port (1).
15.Dispose of the used oil safely: refer to Section 6.2.
5.8 Relubricate the high-vacuum bearings
The frequency of relubrication of the high-vacuum bearings depends on the operating temperature of your pump;
Table 13 shows the recommended frequencies. For maximum pump reliability, we recommend that you change the
gearbox oil when you relubricate the high-vacuum bearings: refer to Section 5.3.
Use the following procedure to relubricate the high-vacuum bearings:
1. Refer to Figure 9. Remove the three M8 bearing cap retaining bolts (5) which secure the bearing cap (4) on the
drive rotor shaft; ensure that you do not accidentally remove one or more of the bearing carrier bolts (8, see
detail A), which are next to the bearing cap retaining bolts. Remove the bearing cap (4) and the bearing cap
‘O’ ring (3).
2. Repeat Step 1 to remove the bearing cap (6) and bearing cap ‘O’ ring on the driven rotor shaft.
3. Use a clean lint-free cloth to remove as much old grease as possible from the inside face of the bearing
caps (4, 6) and from the top of the bearings (2). Do not use your fingers for this operation.
4. Inspect the bearings (2) for obvious signs of wear or the presence of debris. If the bearings are worn, contact
your supplier or Edwards for advice.
5. If the bearings are in a satisfactory condition, use a suitable syringe to force approximately 50 g (1.8 oz) of new
Fomblin RT15 grease into the bearings so that a smooth layer of grease covers the case and bearings. Do not put
too much grease in the bearings or the pump will run hot.
6. Use a 24 mm A/F spanner to turn the drive rotor shaft (1) in the correct direction (7) three or four complete
revolutions.
7. Press any grease forced out of the bearings back into the bearings.
8. Refit the bearing cap (4) with a new bearing cap ‘O’ ring (3) on the drive rotor shaft. Apply a suitable thread
sealant (for example, Loctite Screwlok 242 or equivalent) to each of the three bearing cap retaining bolts (5)
and refit the bolts to secure the bearing cap.
9. Repeat Step 8 to refit the bearing cap (6) on the driven rotor shaft.
10.Dispose of the old grease safely: refer to Section 6.2.
Table 13 - Recommended frequencies for high-vacuum bearing relubrication
Pump operating temperature
(measured at the point shown in Figure 1, item 3)
Recommended frequency
of high-vacuum bearing relubrication
30 to 45 °C, 86 to 113 °F Every 18 months
46 to 60 °C, 115 to 140 °F Every 12 months
61 to 75 °C, 142 to 167 °F Every 6 months
76 to 90 °C, 169 to 194 °F Every 3 months
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