At our Hydrostatic Pump Repair Site, we offer many types of Hydrostatic Transmission Repair and information relating to Hydrostatic Parts
Today we will discuss:

Sundstrand Sauer Danfoss Series 90 Charge Pump Change

Service Bulletin SB-8906

The original charge pump had two port plates, one on each side of the gerotor.  And if the charge pump displacement was lower than the highest for the pump’s frame size, the inside port plate was usually thicker than .050 inches outside port plate.

The latest charge pump will have two  .050 inches thickness port plates one on each side of the gerotor. Also, it is at it’s maximum  for the pump’s frame size; one or two spacers will be needed between the outside port plate and charge pump cover.

And the position of the key way in the charge pump shaft got changed to make sure the arrangement of the drive key is in the gerotor.  The new charge pump shaft for 75-100 cc frame size now has 2 key ways. The 55-75-100 cc also changed from being beveled to square end on the end of the shaft nearest to the pump end cap.

If you need further info on this, please leave a comment or call us at

800-361-0068

email: sales@hydrostatic-transmission.com