How to change from clockwise rotation to ant-clockwise rotation OR vice versa.
Please follow these instructions step by step in order to avoid irreparable damage.
1) Loosen and withdraw screws, remove front flange, keeping rear end cover on the pump body.
2) Remove drive shaft gear and bushing from the body.
3) Now mark the position on the body using a felt pen.
4) Remove drive gear from the body and refit it in to the hole where the drive shaft gear was fitted.
5) Remove the drive shaft gear from the bushing already removed.
6) Fit the drive gear back in to the hole where the drive gear was fitted (lower position in sketch).
7) Refit bushing in to the pump body carefully, making sure the bushing is fitted in exactly the same position at it was in the beginning (using felt pen marks).
8) Rotate and refit flange 180°.
9) Insert and tighten screws to the recommended torque (ensure that gears turn as you tighten the body bolts).
This also applies to a single rotation gear except that a clockwise pump can be run as an anti-clockwise motor.
What you ar actually doing is ensuring that the bearing feed is taken from the lower pressure side. If this is not done, you will force oil at high pressure in to the bearing chamber resulting in the shaft seal passing oil under the unacceptable pressure being put on it which can permanently damage the unit.