Started with the dismantling. Encoderwheel is pressed onto the shaft; had to make a (impact-)puller and pulled it off preheated. Motorshaft was really tight in the bearing and I did not want to apply too much heat to the bearing, so made a tool to push it out.
1. Oil pump (does not work in reverse)
2. Bearings (possibly not designed for maximum torque in reversal). Did read some yells on the internet that you would destroy all
Oil pump:
It indeed does not work in reverse operation. You could simply swap the tubes, then it will pump again, but the internal pressure regulation valve does not work anymore. This could lead to extremely high oil pressures popping hoses or destroy the plastic drivegear (due to the higher drive torque at high pressures).
Solution 1: Mount an additional oilpump. Have seen something like that on this forum
Solution 2: Modify the original oilpump. I went this way and made a quick test setup.
-> Pressure regulation valve seems to regulate the pressure at around 1 bar. First video in the Insta post below (could not upload movies here)
-> When running the original pump just in reverse direction, there is no pressure regulation, second video
-> After have modified the pump, regulation is stable at 1 bar when running in reversal, last video
How did I modify the pump ?
-> Original pressure regulation valve is located between both hose connections. Behind the cover cap is a spring and a piston.
-> There are three ports. 1. Piston actuation (the regulated pressure), 2. pressure relief (back to the suction side of the pump) and 3. venting of the piston rear side.
-> What has been modified:
1. Closed the original piston actuation port with a turned piece (left on the picture). Inside has M6 thread, but that was just to be able to pull it out when it wouldn't work as expected. Piece is made of stainless steel (what I had around) and presses into the preheated pumphousing. This piece pushes the initial position of the piston 4mm forward. So the original 'relief' port now actuates the piston.
2. Made a new pressure relief port. This is de large oval port at the side of the pump. Just milled by hand (dremel). You can see the groove in the piston, that's not the piston top. The relief now unloads directly to the bottom of the transmission. Only drawback of this could be the generation of air bubbles in the oil which could be picked up by the pump if the bubbles don't disappear quick enough, but I don't expect any issues when that happens since we are just pumping some oil around mainly for cooling, not lubricating shell bearing or other air-bubble-sensitive things.
3. Closed the original 3mm venting hole (inside in the pump, not on picture) by threading and closing it with a M4 setscrew. Drilled a new 3mm venting hole on the side of the pump.
4. Compensated the cover cap for the 4mm moved piston travel to get the same spring force.
5. Original oil pickup filterhousing (mesh thingy) did not fit anymore. Tried to find a universal one (in the industrial hydraulic world), but it was difficult to find something that fits, so made one myself. Turned something from an aluminium bar that takes the original mesh filter and slides over the pump connection. Kept into place by the original plastic mount (grinded some unneccesary plastic away with the dremel).
Some pictures:
