Running a Sauer series 20 without a thrust plate

     Series 20 Sauer Danfoss axial piston closed loop pumps - classic series that's been on the stage for the last... well, I am not sure for how many, but maybe more years that I have on my shoulders (is it 33 now?..).

     Despite of the fame, immortality and the fact that this field-fire-and-water-proven design is well known among hydraulic businesses and workshops all over the world, every once in a while a skillful individual happens to work on a series 20 pump for the first time in his life, and occasionally omits a part of two during the assembly. Such predicaments constitute a great benefit for this site, because they give practical answers to purely theoretical questions like "what would happen if I forgot to mount the ... (insert a part name)?".

    This particular example is about the part number 29, namely the thrust plate (check out the exploded view and the cut-view), which was "accidentally dismissed" during an overhaul. Without it the piston slippers are forced to work inside the thrust plate cavity of the swashplate (best seen on the cut-view) - which starts to machine the brass slippers to a new shape as soon as the swashplate tilts to its maximum angle.

    It took only five minutes of "work" to give the piston shoes the new "rounded appearance", which can be seen on the last four pictures. The pump was stopped because it was making a very unusual noise and couldn't reach nominal pressures.

    So, now you know what happens to a Sauer series 20 pump when you try to run it without a thrust plate!