Dingo 950p releasing tension on grapple in neutral?

[Hyakkimaru16]

Okay, I have an old dingo that I recently purchased. It's a 1997 dingo 950p made by dingo Australia before Toro bought them out. I completely rebuilt the machine, rebuilt all the hydraulic cylinders, put a new motor on it painted it etc. Here's my problem. I just recently bought a grapple and the hydraulic valve for the auxiliary hydraulics does not have a spring or anything. When you push it forward it stays forward and the same for reverse with a neutral detent in the middle. The valve was seized when I got the machine and I had to disassemble it and of course I lost a little detent ball. I replaced it with a BB from a BB gun which was not big enough and the detent is hard to find now but, onto the problem. When I'm using my new grapple, say I pick up a log, I will push the hydraulic lever forward squeezing the log tight, and then once the log is tight in the grapple I will return the lever to neutral only for the grapple to lose tension and drop the log. I have to leave the auxiliary hydraulic lever in the pumping position closing the grapple for it to hold anything. My first thought would be maybe the factory fittings are worn out so I have a new set coming upgrading from the old style fittings to the new flat face style fittings which needed to happen anyway because like every attachment these days has flat face fittings. So, other than that what else could stop the grapple from holding pressure and neutral? I thought the antibactflow was in the hydraulic fittings themselves. I'm somewhat new to equipment and this is my first machine. I work on diesel trucks so this is somewhat new to me but not over my head, I kind of want to just replace the auxiliary hydraulic valve but it is no longer available except from Australia and it cannot be shipped here so I will have to replace it with something else that would fit in the same place and happen to have all the same thread types. Seems complicated. I will start by replacing the old style fittings with new flat face fittings and reinstalling the flat face fittings that came on my grapple back onto it. Is there anything else I should look for? Here is a picture of the machine for anyone curious. This is after painting it. Went with Ford blue. I put a 22 horsepower motor from harbor freight on it, hasn't missed a beat. Awesome little machine. I added 210 lb of counterweights to the rear stand this afternoon and picked up a 10 ft water oak log that was roughly 2 ft across. Was a little bit tippy but it picked it up. I wouldn't move fast with it but I was pretty impressed for a log full of water to be picked up by such a small machine with tires. But I had to leave the auxiliary hydraulic control all the way forward until I got the bucket tilted back or the grapple would release. Let me know what y'all think, thanks, Tristan.

 

[thenne1713]

Suspicion is a leaky control valve or check-valve, but maybe design? A hydraulic shop would put on test bench w/ gages. If you expand jaws and then shut off engine/ pump, can you manually close jaws with control in neutral? Neutral maybe just designed to mechanically release fluid back to reservoir? Or are any switches/ solenoids involved to bleed a cylinder back to reservoir?

 

[northmanlogging]

Okay, I have an old dingo that I recently purchased. It's a 1997 dingo 950p made by dingo Australia before Toro bought them out. I completely rebuilt the machine, rebuilt all the hydraulic cylinders, put a new motor on it painted it etc. Here's my problem. I just recently bought a grapple and the hydraulic valve for the auxiliary hydraulics does not have a spring or anything. When you push it forward it stays forward and the same for reverse with a neutral detent in the middle. The valve was seized when I got the machine and I had to disassemble it and of course I lost a little detent ball. I replaced it with a BB from a BB gun which was not big enough and the detent is hard to find now but, onto the problem. When I'm using my new grapple, say I pick up a log, I will push the hydraulic lever forward squeezing the log tight, and then once the log is tight in the grapple I will return the lever to neutral only for the grapple to lose tension and drop the log. I have to leave the auxiliary hydraulic lever in the pumping position closing the grapple for it to hold anything. My first thought would be maybe the factory fittings are worn out so I have a new set coming upgrading from the old style fittings to the new flat face style fittings which needed to happen anyway because like every attachment these days has flat face fittings. So, other than that what else could stop the grapple from holding pressure and neutral? I thought the antibactflow was in the hydraulic fittings themselves. I'm somewhat new to equipment and this is my first machine. I work on diesel trucks so this is somewhat new to me but not over my head, I kind of want to just replace the auxiliary hydraulic valve but it is no longer available except from Australia and it cannot be shipped here so I will have to replace it with something else that would fit in the same place and happen to have all the same thread types. Seems complicated. I will start by replacing the old style fittings with new flat face fittings and reinstalling the flat face fittings that came on my grapple back onto it. Is there anything else I should look for? Here is a picture of the machine for anyone curious. This is after painting it. Went with Ford blue. I put a 22 horsepower motor from harbor freight on it, hasn't missed a beat. Awesome little machine. I added 210 lb of counterweights to the rear stand this afternoon and picked up a 10 ft water oak log that was roughly 2 ft across. Was a little bit tippy but it picked it up. I wouldn't move fast with it but I was pretty impressed for a log full of water to be picked up by such a small machine with tires. But I had to leave the auxiliary hydraulic control all the way forward until I got the bucket tilted back or the grapple would release. Let me know what y'all think, thanks, Tristan.

bypassing the spool valve, if it was seized when you got it, its probably pitted and letting fluid by (it doesn't take much)
and frankly with it not returning to center on its own is a great way to get someone killed.
It could also be the relieve valve, which should be adjustable, but from what you've described its time to replace the spool valve.

also the flat faced fittings are more expensive then the JIC fittings, and prone to more failures.... cause parts are expensive and they want us to keep buying parts, if your hose shop talked you into this, find a new hose shop.