873 turbo arms sinking

[TedsMech]

So I've been lurking for a long time and finally have come across something I haven't been able to find any info on. We have an 873 turbo that cant keep it up (the arms that is). The machine works fine in all other respects. Its just when you lift the arms up in the air they start falling the moment you let off the pedal. I have done some trouble shooting and this is what I know so far. The problem is not in the linkage or adjustment. The valve doesn't have any scratches or heavy wear. I do not believe the cylinder seals are the problem due to the fact that if you shut the machine off with the arms in the air they still sink slightly but then stop (I would figure if the seals were shot the arms would just continue to sink as the pressure in the cylinder equalizes). With the arms in the air and the machine off the emergency release does let the arms drop when activated. When you let go of the emergency release the arms continue to fall briefly but do come to a stop after 2 or 3 seconds. I'm kind of at a loss here. What would let the arms continue to drop after the emergency release is shut off but then eventually come to a stop??? I'm almost bald from scratching my head... do any of you have any ideas on this?

 

[bobbie-g]

That does sound perplexing. I only know what I've learned here re hydraulics, so can't really offer any good advice. Any possibility of air in the system? Even if so, it should work itself out quickly if the reservoir is full. How does the bucket act if you have a full load of dirt and curl it up? Same sagging, or is it OK? I've not experienced anything like droopy lift arms or bucket with my 863. ---Bobbie-G

 

[TedsMech]

That does sound perplexing. I only know what I've learned here re hydraulics, so can't really offer any good advice. Any possibility of air in the system? Even if so, it should work itself out quickly if the reservoir is full. How does the bucket act if you have a full load of dirt and curl it up? Same sagging, or is it OK? I've not experienced anything like droopy lift arms or bucket with my 863. ---Bobbie-G

The tilt cylinders operate normally and their position seems to have no effect on the sinking action of the arms. As far as air in the system it hasn't been opened up (hydraulic wise) in years so I don't think that would be the issue. I did have the spool valve (I believe that's the proper name) for the lift circuit out to inspect it but didn't find any clues there. the only thing the changes the sink rate of the arms is a load. I've been picking up a rockhound with it and it almost instantly falls down with that kind of load.

 

[flyerdan]

The tilt cylinders operate normally and their position seems to have no effect on the sinking action of the arms. As far as air in the system it hasn't been opened up (hydraulic wise) in years so I don't think that would be the issue. I did have the spool valve (I believe that's the proper name) for the lift circuit out to inspect it but didn't find any clues there. the only thing the changes the sink rate of the arms is a load. I've been picking up a rockhound with it and it almost instantly falls down with that kind of load.

I would suspect the emergency release valve. A quick way to tell would be to shut it off with a load suspended, and listen at the valve with one of those mechanic stethoscopes to see if you can hear any fluid moving in it while the lift arms fall.
I haven't looked at the flow chart to see how it's all plumbed together, but that seems a logical place to start.

 

[TedsMech]

I would suspect the emergency release valve. A quick way to tell would be to shut it off with a load suspended, and listen at the valve with one of those mechanic stethoscopes to see if you can hear any fluid moving in it while the lift arms fall.
I haven't looked at the flow chart to see how it's all plumbed together, but that seems a logical place to start.

They only fall all the way while the machine is running. With the arms suspended and the machine off they stop falling soon after shutdown. If I pull the release they start dropping like normal but when I let go they continue to drop for 3-4 seconds before coming to a stop... they slow down gradually to a stop during that time. when I release the valve I do not hear any fluid flow through that valve.

 

[TedsMech]

They only fall all the way while the machine is running. With the arms suspended and the machine off they stop falling soon after shutdown. If I pull the release they start dropping like normal but when I let go they continue to drop for 3-4 seconds before coming to a stop... they slow down gradually to a stop during that time. when I release the valve I do not hear any fluid flow through that valve.

So I spoke with a very helpful tech at a local bobcat dealer. He believes it is either a relief valve in the valve body or a poppet valve on the underside of the valve body. Either way its more involved than what were equipped to handle so its going to go to the dealer for them to run a few tests and then repair the faulty component. I will update this thread when we receive the machine back so someone in the future can get something out of all of this, thanks to everyone who responded with ideas, much appreciated.

 

[qtband]

So I spoke with a very helpful tech at a local bobcat dealer. He believes it is either a relief valve in the valve body or a poppet valve on the underside of the valve body. Either way its more involved than what were equipped to handle so its going to go to the dealer for them to run a few tests and then repair the faulty component. I will update this thread when we receive the machine back so someone in the future can get something out of all of this, thanks to everyone who responded with ideas, much appreciated.

Did you ever fix this problem?