Operating Manual
The rotor timing (synchronisation) is set-up in
the factory. If the rotors become
unsynchronised, they may be retimed using
the following procedure.
The cause of the fault should be
established and eliminated before
proceeding.
To adjust the timing of the rotors, first remove
the gearcase end cover, once the cover is
removed the timing gears will be exposed.
To retime the rotors, only one of the timing gear
retainers need to be released sufficiently, to
allow the rotors to be tapped into a position
where they are synchronised. The rotors are
correctly synchronised when the clearances at
the measurement points are equal.
Use feeler gauges to measure the clearances
at the positions illustrated, and adjust until
equal, the pump is then correctly timed. Tighten
the screws of the torque locking assembly to
the correct values and replace the gearcase
cover.
To remove the timing gears the following
procedure is recommended.
1. Drain lubricant.
2. Remove rear gearcase cover.
3. Release torque locking assemblies.
(refer to page 23 - 8.2)
4. An extractor tool may be required to pull
the gear off. Because the gearcase has
twin lubricated chambers lubricant may
drain out when the top gear is removed.
The bearing lip seal fits behind the top shaft
rear bearing housing. The lip seal runs on a
boss at the back of the timing gears, and
prevents the top chamber lubricant from draining
into the bottom chamber. If the lip seal is to be
reused care should be taken when extracting it
not to damage the sealing edge, otherwise a
new lip seal should be fitted. To refit a seal, it
should be pressed evenly into the hole, and a
flat plate or dolly used to drive it home.
Measurement
Point
Measuement
Point
Diagram of Rotors Showing Timing
10.5 Fitting the Timing Gears
1. Fit the rotors to the shafts to establish the
timing.
2. Check that the bearing lip seal is fitted.
Check that the boss on the back of the
gear is smooth, and smear some lubricant
onto it.
3. Slide on the gears. Where gears are
marked as pairs they should be refitted
with the timing marks aligned.
4. Fit the torque locking assemblies, and
torque 'one' of them up. Adjust the timing,
before tightening up of the last gear.
10.2 Timing Adjustment
10.3 Timing Adjustment
Removing the timing gears is a reasonably
simple operation though difficulty may be
experienced in sliding the gears off the shaft. If
this is the case an extractor tool may be required.
For this purpose threaded holes are provided in
the gears.
10.4 Lip Seal - Removal & Refitting
34
