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Help! My Wacker RD12 has a mind of its own

Husaberg

Member
Joined
Sep 1, 2021
Messages
17
Location
US
My low-hours roller is uncontrollable
Even if started in neutral it will take off full speed in forward or reverse
It does not matter which way the controller is pointing and once moving the controller has no effect in either direction or speed
The controller cable is intact
The vibratory function works
What do I check next?
 

Husaberg

Member
Joined
Sep 1, 2021
Messages
17
Location
US
UPDATE

I’ve been operating the roller and trying to figure out why the controller does not control the speed or direction of the machine. In doing so, the roller slowly started losing drive. The steering and vibration still function perfectly but now the machine rarely moves in either forward or reverse. Once in a while, when started, it will jump up and down like it’s possessed or more probably trying to go forward and reverse at the same time

I’ve been reading the manual and going through the troubleshooting steps for the drive system

1. The tow/bypass valve works normally

2. The drive control cable works normally

3. I have not been able to test the drive pump and relief valve because I am waiting for an adapter for the pressure gauge (I suspect the answer lies here)

4. I have made sure the drive motors are not bound and turn freely

5. I have not checked fluid flow through the drive motors because I don’t want to make a huge mess and it doesn’t make sense to do so until completing step #3

While checking, I have disassembled the two tandem mounted pumps (exciter and drive) and everything looked normal to my eye

My question is this- if there is a problem with the relief valve in the drive pump, is that fixable? I don’t see any mention of that in the manual (see attached)
 

Attachments

  • RD12_Repairs_Manual.pdf
    7.1 MB · Views: 2

Husaberg

Member
Joined
Sep 1, 2021
Messages
17
Location
US
UPDATE #2
Less than 100 PSI coming out of drive pump in both forward and reverse
Flow from tank into pump seems good
Is my pump fried?
Anything else to check?
 

Husaberg

Member
Joined
Sep 1, 2021
Messages
17
Location
US
UPDATE #3
Well, looks like it's the drive pump
I've got an experienced tractor mechanic doing the teardown now
Hoping for an easy/quick fix
 

Husaberg

Member
Joined
Sep 1, 2021
Messages
17
Location
US
UPDATE #4
I got lucky!
The problem was simple to fix
The roll pin at the bottom of the swashplate shaft sheared off
See 72 in diagramDrivePump.png
Hope this helps someone else down the road
 
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