Ref. M210758EN-A
MAINTENANCE AND REPAIR
Ball bearings must be checked once a year visually and by
rotating the sensor shaft. To do this, remove first the cup
assembly as instructed below (A1.). The shaft should spin
smoothly and should not create any detectable noise.
Replacement of the bearings should be done only by a trained
technician. Steps A1 to A15 are for disassembling and steps B1
to B10 are for reassembling. The numbers in parenthesis refer to
Figure 3.
A1. Loosen the set screw (use allen key) and carefully remove
the cup assembly.
CAUTION Be careful with the connector pins, do
not bend them.
A2. Loosen the hex nut of the green MIL-connector at the
bottom of the sensor body (use 22 mm tool).
A3. Loosen the three capnuts (1) at the bottom of the sensor
body (use 7 mm tool).
A4. Remove the body cover and the O-rings (2).
A5. Release the connector (3) of two white wires from the
power supply board (4).
A6. Loosen the three nuts (5) at the bottom of the power
supply board (4) and remove it (use 7 mm tool).
A7. Loosen the shaft heating foil (6) (use pliers).
A8. Loosen the set screw of the rotating transformer assembly
(7) (use allen key).
A9. Loosen the spacer screws (8) (use 6 mm tool).
A10. Remove the sensor board (9) together with the rotating
transformer assembly (7).
CAUTION Handle the rotating transformer
carefully, do not drop or hit.
A11. Remove the retaining ring (10) (use narrow-pointed pliers)
and the bushing (11) from the shaft tunnel.
A12. Remove the upper bearing (12) after pulling out the
shaft.
CAUTION Handle the shaft carefully, do not drop
or hit.
A13. Remove the retaining ring (13) at the shaft.
A14. Remove the lower bearing (14).
For reassembling the sensor:
B1. Install the bearings in reverse order.
NOTE Be careful when assembling the
bearings.
B2. The rotating transformer assembly (7) is reinstalled
together with the sensor board (9). Its (7) set screw is not
fastened until in step B7, when the power supply board
has been reinstalled and the gap adjusted.
B3. In assembling, push the transformer (7) as far up as
possible towards the shaft tunnel.
B4. Reassemble the spacer screws (8), the power supply board
(4) and tighten the nuts (5).
NOTE Make sure the four pin connector (15)
installs properly.
B5. For adjusting the gap, place a 1.2 mm feeler gauge
between ferrite coils (parts 4 and 7) (preferably use 30
mm wide feeler gauge).
B6. Place a screwdriver tip into the slot between the top end
of rotating transformer assembly (7) and the shaft tunnel,
and pry until the air gap between ferrite coils is 1.2 mm
(0.047") (use feeler gauge for measuring).
CAUTION The ferrite coils are breakable, do not
try to adjust the gap by prising them.
B7. When the gap is right, fasten the set screw of the rotating
transformer assembly(7).
CAUTION Make sure the rotating transformer
assembly rotates freely without
touching the lower part at any rotary
position of the shaft.
B8. Reconnect the shaft heating foil (6) and the connector of
two white wires (3).
B9. Reassemble the body cover (2) with new O-rings.
B10. Tighten the three capnuts (1) and the connector nut.
B11. Install the cup assembly as instructed in mechanical section.
Spare parts: Order number:
Cup assembly for WAA252 WA35066
Set of bearings and gasket 16644WA
0602-001
Figure 3 WAA252 Assembly
