User`s guide

Chapter 4 ______________________________________________________________ Maintenance
VAISALA______________________________________________________________________ 141
Replacing Bearings of WAA252
Replacement of the bearings should be done only by a trained
technician. First steps from 1 to 14 are for disassembling and second
steps from 1 to 11 are for reassembling. The numbers in parenthesis
refer to Figure 111 on page 143. To replace the ball bearings of
WAA252, follow the procedure below:
1. Loosen the set screw (with an Allen key) and carefully remove the
cup assembly.
2. Loosen the hex nut of the green MIL-connector at the bottom of the
sensor body with a 22-mm tool.
3. Loosen the three capnuts (1) at the bottom of the sensor body with
a 7-mm tool.
4. Remove the body cover and the O-rings (2).
5. Release the connector (3) of two white wires from the power
supply board (4).
6. Loosen the three nuts (5) at the bottom of the power supply board
(4) and remove it with a 7-mm tool).
7. Loosen the shaft heating foil (6) (use pliers).
8. Loosen the set screw of the rotating transformer assembly (7) (use
an Allen key).
9. Loosen the spacer screws (8) with a 6-mm tool.
10. Remove the sensor board (9) together with the rotating transformer
assembly (7).
11. Remove the retaining ring (10) (use narrow-pointed pliers) and the
bushing (11) from the shaft tunnel.
12. Remove the upper bearing (12) after pulling out the shaft.
13. Remove the retaining ring (13) at the shaft.
CAUTION
Be careful not to bend the connector pins.
CAUTION
Handle the rotating transformer carefully, do not drop or hit.
CAUTION
Handle the shaft carefully, do not drop or hit.