Sundstrand Sauer Danfoss Series 20 Piston Slippers

The two pistons standing up are in good shape. They will sit flush up against the thrust or swash plates. It needs to be able to turn freely and been at all the right angles.

The piston cap next to the two pistons is scored pretty bad. If you can feel the marks with your fingernail, it is time to replace the pistons. It could have been caused by contamination in the hydraulic fluid. And where there is discoloration there may be improper fluid or water in the fluid. Again if marks are so deep you can feel them, replace your part.

The piston cap that is at the bottom left, you can definitely use again. There is no nicks,burrs or contamination marks anywhere on there.

The cap in the bottom right has some scratches on it, but not deep enough to warrant changing the piston. And it can be lapped down still and be within the tolerances.

If you need further information on this topic, please let us know.

800-361-0068

sales@hydrostatic-transmission.com