Linkbelt stalls with dipper arm function

[Ratmotorhead]

Thanks guys for the quick responses. I do have a valve under my right footrest that does not have a pedal on it ,along with both left and right track controls. I will see if it is functioning properly and not stuck.i assume that could be a partial open in the circuit, and not allowing my pressure to reach the correct values. I am not one to know my hydraulic symbols as good as some,thank you. Another question I have is that I do not have a way to control my mode switch, there is a solenoid on the regulator block that when I supply voltage it bleeds off pressure back to tank . I leave it disconnected when in use ,but I could use more info on its use to the regulator. I am understanding that when the engine is at full throttle the regulators are mechanically operating? I will try stalling the tracks and see what happens . I will work on it again this weekend thanks guys

 

[Ratmotorhead]

Hello men, back at it again with my excavator today. I found the straight travel valve to the right of my foot travel valves and after marking hoses ,I removed it, it was froze up. After cleaning and reassembly I noticed when putting air hose pressure to it it still slightly seeped air,although it functioned correctly. It was a pretty basic valve . Next I capped off hoses on machine,since I wanted to have no chance leakage using valve, and started it up. On my pressure guages attached to dipper in and dipper out lines at hyd valve,at full throttle it shows 1500psi not even touching the handles. When I put dipper in to relief ,it went to 3000 psi With dipper out to relief 3000 psi. But still cannot increase relief in both sides 3000max with screw all way in. Also I have full power on right track but no power on left track, forward or reverse. I did try to stall motor with tracks on left or right and it would not stall , but seemed to go to relief. I did have both tracks with power when straight valve was installed, but not with it capped. Any ideas

 

[John C.]

I take it you capped off the pedal in the cab that works the straight travel function. The valve I'm talking about is in one of the main control valves. I'm wondering if it is stuck as well.

 

[Ratmotorhead]

Thanks for the response. That is true I did cap off the straight travel valve ,and it was froze up , I freed it up and it does return to center ,back to close. If one of the spools in the left or right hydraulic valves were stuck would that make left track stop functioning? I will put straight travel valve back in this afternoon and see if my left track comes back ,then check out spools for dipper in out and tracks I believe I see valve Jon .C is talking about,it looks like its in left valve bank

 

[Ratmotorhead]

Just came in this evening from working on excavator.this is what I've got. I removed and inspected spool from left hand hyd valve which I believe is the one Jon .C is talking about. It moved freely in its bore and all orfices are open. I put it back on and put straight travel valve back on after cleaning and freeing up. After start up I still have no left track and dipper still bog when curling in. This week I will pick up more fittings to check if pressure is getting to each end of valve that I cleaned. That should be pilot pressure I believe.

 

[Ratmotorhead]

Back on the excavator this morning. I pulled the spool for my left track, and it is free I reassembled and checked pilot pressure to each end and had 550 lbs for forward and reverse, although it wants to move,it won't. Right track works fine. Then I decided to check each pump for relief pressure. With guages attached to my test ports on pump 1 and pump 2 . When curling bucket in for relief on first pump I got 4000 psi , and 500 lbs on the other guage. When checking second pump with dipper curled in to relief I got 3000 psi and both guages went to 3000 psi and engine started to stall. Shouldn't those pressures be separate at this point? What is open in that circuit that is allowing pressure to other pump. Could regulator be stuck?

 

[John C.]

The spool you are looking for is above the left side travel. The schematic shows it as the first spool on the left side valve. If you look it is only a two position valve and the lines cross in the shifted position. It is likely behind a plug and doesn't show with a big casting like the directional spools do. When you are operating the bucket function the straight travel function is either stuck in the shifted position and allowing both pumps to feed the one function or something is causing it to shift which would be one of the small spools on the ends of the directional valve spools leaking by and shifting the valve.

 

[Ratmotorhead]

Thanks for the reply John C. I found spool you were talking about,it is to left of track spool in the left hyd valve bank. I made sure it moved freely and cleaned its components. On one end it has a tee which comes from the pump regulator and continues over to the right side hyd valve at the dipper in spool ,I will try to check that spool tonight or tomorrow, that might explain pressure at same time on 1and2 pump checks. Thanks

 

[Ratmotorhead]

Hello men, put some more test fittings on today . I am still searching for an open circuit. The test fittings I put on are on the output lines of my number 4 and 5 pumps. These are shown on my schematic as the bottom two pumps below main and pilot. When running engine at wot I got 0 psi , the smaller of the two goes directly to spool John C spoke of . I cannot find any pressures in my books for these smaller pumps,and only the smaller has a relieve which goes back to tank, this tells me something is open ,or stuck. By the way this is a new pump I put on last summer.

 

[John C.]

4 and 5 pumps? You should have two mains and a pilot pump. A logger will have a grapple rotation pump and that's it. Maybe shows us on the schematic what you are speaking of?

 

[Ratmotorhead]

 

[Ratmotorhead]

This is pump 4 and 5 which goes directly to the spool John C. is referencing. This is a new pump that I installed last summer. I will check it for pressure output this weekend. I still believe I have an open circuit somewhere.

 

[John C.]

I forgot that this was a straight C model. I've never seen that before but I think you are on the right track.

 

[Ratmotorhead]

Pulled out valve under plug in left hyd valve and it was stuck polished it up ,made it free . Also same in right side valve . Reinstalled and ran, still no left track , still bogs , and pressure still goes up in both pumps when under test. Hmmmmmm. I also lifted right track in air, and left track walked machine with good power. Sit it down on ground,lift boom up and no left track. Weird.

 

[Ratmotorhead]

I've also noticed, straight down the middle of left and right hyd valves between the pipes, boom up boom down,stick in stick out,etc, is a plug at each location . My parts book showed these as check valves with poppets. These are mainly on the left valve, right valve mostly are plugs. Any correlation here? I will start inspecting these this weekend if it ever stops raining here in north east Ohio. If anyone knows any good heavy equiptment men in this area that know about the old basic pilot hydraulics without all the electrics and solnoids, give me a shout out, thanks

 

[John C.]

I'm guessing your are talking about theft check valves. The hold and implement in place until the pump has enough pressure generated to move the implement.