Saure Sundstrand pump and Motor rebuild

jd4310man · Apr 20, 2015

I have an older hydrostatic pump and motor out of an old swinger loader. They were made by Saure Sundstrand, which is Danfoss today. Both are model 20 series, the pump is a 22 and the motor is a 21. They are wore out and in need of a rebuild. Does anyone know how much it would cost to rebuild these components? I am looking into a local shop to do this but am not sure what im up against as I never had to have anything like this rebuilt before. Any input is appreciated. Thanks.

oldnslo · Apr 21, 2015

Depending on the exact model I believe both of those models are semi obsolete so you had best do some checking around to see if these can be rebuilt. I suspect yes but not sure on the cost.

According to my old Sauer information the size 22 is 4.26 CIR & the size 21 is 3.15 CIR

CIR = Cubic Inches per Revolution

I believe Sauer has authorized service centers or possibly places like Attica Hydraulics or Hydraulic Parts Source may rebuild them also.

jd4310man · Apr 21, 2015

Not sure if they are obsolete? Im looking at Flint Hydraulics Hydrostatic Pump & Motor Repair, Hydraulic Pump & Motor Parts, Remanufactured Hydrostatic Pumps & Motors They seem to carry parts for these components. I will have to ship the parts to them and they will do a free evaluation before they commit to fixing them. Sounds pretty good to me? I never shipped anything this heavy before, going into uncharted waters here. Will be interesting for sure.

MHarryE · Apr 22, 2015

They are no longer in production but were widely used in mobile equipment applications and so there are many outfits that will rebuilt. Quite often, however, companies have an exchange program. They will take your core, evaluate the condition, estimate a core value and ship a rebuilt unit of the proper configuration. I visited one such company to inspect damage on 6 units from one of my products. They were in a stack of similar products. I was told that they stored cores until they reached some economic quantity where they could have a semi-assembly line process. Those tend to be the most reliable units.

jd4310man · May 29, 2015

Update: I sent the pump and motor out to Flint Hydrostatics in Memphis Tennessee, Got them back and installed and now it moves great and has lots of power, but its surging when moving. When moving in either direction its surging. now I assume they replaced all the major wear parts inside these things and it has good power. It will really put a load on the engine and will even stall it. Is there some kind of adjustment that would cause the pressure to surge? I am using automatic transmission fluid as the decal indicated by the hydro tank.

CJONE · Jun 2, 2015

Most hydrostatic systems have a suction filter, you did completely service and clean the hydraulic system right? If not the pump and motor will not be long for this world. DO NOT run it until you find out why it is surging and fix it. I do probably 1 complete system a month so I am very familiar with these units. Surging is almost 90% in the suction system. The other 10% is the charge pressure relief but that is rare. Flint Hydrostatics knows what they are doing so again my bet would be your suction for the pump. One of my customers did not fix a suction problem and a $150 dollar filter head cost him a $7500 hydrostat on startup! CJ

jd4310man · Jul 4, 2015

CJONE, Thanks for responding. I did flush the system multiple times, and I changed both filters. Could there be a suction screen on the tank that could be clogged? I appreciate the help.

CJONE · Jul 7, 2015

Yes, there very well could be. You have to make sure there is open flow to the hydrostat inlet, no restrictions. The charge pump has to receive a clean unrestricted flow. Put a vacuum gauge at the inlet of the Hydrostat if you cannot find a blockage, if you do obviously fix it. If not run the unit at max rpm and if you see any better than 5HG at the gauge or it is surging up and down find out why. I have found rags, dead birds, oil container labels you name it floating in tanks and randomly restricting suctions. CJ

Swinger_Parts_4_Sale · Feb 27, 2025

Hello,
I stumbled onto your post about looking for swinger loader parts, if you are still needing parts feel free to send me a message, I may be able to help you. I used to work for the company that manufactured the Swinger loaders before they were discontinued and obtained a lot of the information, build sheets, material list, vendor/supplier information and lots of other stuff. I am currently in the process of having some of the more common parts & obsolete parts reproduced based off original drawings & specifications.