Sundstrand Sauer Danfoss Series 20 Part 1 Hydraulic Transmission Start Up

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

Methods of Transmission Start UP
After the transmission has been put in, take out the threaded plug from the side of the main pump housing. When reading the charge pressure at the port, you will need a 600 PSI gauge with a short section of hose. The threaded port is 7/16 x 20 straight thread O Ring. And you need to put in the charge pump inlet a vacuum gauge for reading the inlet vacuum.

Make sure all your fittings are tighten.

Fill up the pump and motor cases drain openings with the appropriate fluid.
It is suggested that all fluids be passed through a ten micron filter. Then re-install and tighten all case drain lines.

Then loosen the charge pump line, coming from the filter/reservoir, at the inlet to the charge pump.

Make sure the reservoir has fluid in it. When the fluid is at the loosened hose at the charge pump inlet, put in and tighten the hose and keep filling the reservoir. Also, leave the reservoir cap a little loose, so air can escape.

After the first start up, you need to disconnect the control linkage to the pump control valve. This lets the pump to stay in positive neutral.

If the primary mover is;
Engine: (diesel, gasoline or LP) – take the coil wire, close the injector rack or make sure the gas is turned off, turn the engine over til the charge pressure get up to 30 PSI or more.

Electric Motor: toggle the starting circuit til the charge pressure gets up to 30 PSI or more.

Start up the primary mover and try to keep it and sustain it at 750 RPM pump shaft speed for about five minutes. This lets the system fill up at the proper level. During this procedure, pressure surges can be seen on 600 PSI gauge.
That is normal. When running at 750 RPM idle, the pump charge pressure needs to be at 100 PSI over case pressure. If you do not get the appropriate level, then shut down the unit and find your problem area, before continuing on.

We will be continuing this conversation, so please comment or ask questions.
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email: sales@hydrostatic-transmission.com