loader malfunction

[GordonCole]

In clearing trees with a grapple attachment on my M7040 with LA 1153 loader, I have had two malfunctions. While pushing over a tree, the grapple gave a loud bang and the hydraulics ceased working. There was no blown hose or apparent leaks. The switch would cause the hoses to flex but the cylinders will not move, but do not appear jammed. I continued to work without the grapple hydraulics and experienced a similar loud bang from the loader and now the loader will not curl the grapple attachment. It simply falls to a down position. The hydraulics to raise and lower the arms works fine there is pressure to curl the grapple down, but nothing to raise.
Again no apparent leaks and there does not appear to be any problem with cylinders or hoses. Any suggestions???? Thanks

 

[Stumpy]

If I had to guess I'd say that loud noise was the piston seals in the rams letting go but it could've also been the sound of snapping metal. When the bucket falls does it drop like it's swinging free on a hinge or does it closes somewhat slowly like a screen door with a damper piston? The later means it's likely the piston seals. Regardless I think it's time to open one up and see what the damage is.

 

[Lil Foot]

If I understand correctly, It sounds like you broke off (or stripped) the nuts holding the piston & seals to the rams. I have seen the same symptoms on the newer style FELs that use only one curl cylinder, after heavy back dragging with the bucket on rocky ground.

 

[GordonCole]

Turns out you are right. It was the nuts stripping off the end of the pistons. Happened on both the loader arm and one side of the grapple.