Hello heavy equipment forums, just bought a broken sd70f pad foot roller. Runs good. Vibrates, steers. ..wont move. doesn't lug engine at all. Has some electrical issues. The direction control cable is connected to the pump and appears to be twisting the shaft as it should. Hydro fluid is clean and clear. Would the e brake system be capable of bypassing pump movement fluids or would it try to move and the brakes would hold it? The e brake on this is a dash electrical switch, and doesn't seem to be releasing, I had to lift it on and off the trailer.. Have a suspicion that ill be removing this drive pump to figure out what happened. Have some literature coming from eBay. All I could find were the maintenance/ operation manual with some hydro and electrical schematics. No complete parts books. If any of y'all have any suggestions or ideas, I'm all ears! Thanks for reading. Chris
Can't offer any words of wisdom, but can offer some schematics. Check your messages.
Possibly. Some of the systems had a bypass valve that sent control pressure for the pump servo to tank when the e-brake was on. A hydraulic/electrical schematic would help.
Thank you for the schematics. No charge pressure seems to be the issue for now. This is a sauer m46 duplex. Charge pressure also unlocks brakes. Pulled the back section off to check out the charge pump and found a gear pump with a keeper pin that seems too short for its purpose. Got dark and cold so I didn't get to fully investigate. I think the whole charge pump may have been spinning. Was getting zero pressure revved up or idle. Will report back when I know more. Really appreciate the schematics. Try to get some photos of the situation.
Charge pump was good. The spool in the shunt valve was stuck. The neutral relay that controls this valve was also non responsive. The fuse block and ignition switch were corroded beyond use as well. Thank you again for that hydraulic schematic. Got this thing handled before the book from eBay even made it here!
machine still ruining good with this fix? A friend of mine has a sd45 with similar issues.
Yep. That solenoid on the side of the pump can and will keep the drive pump in neutral. The spool in the solenoid should move freely. I pulled the whole control plate off the side of the pump, knowing what I know now, I'd have played with the spool a little longer. I think a magnet and a pin to push it down and pull back up a few times would have gotten it working faster. Pulling the whole thing could have been an issue if the gasket had torn..
Sweet, I think we’ll try the magnet trick you’re talking about and see if we can get it working. I’ve got a 98 Sd 70 that I’m having a hard time finding a torque hub for the drum. You know of anyone/where that might have parts for these?