Bobcat 600 Sheave questions

[MikeHall]

I really don't think the oil type is the problem. I wouldn't bother changing it.
I'd say that quick connect setup is your problem. Having a q.c. hose looping back onto itself doesn't sound right to me. Have you tried removing the hose completely?

I just tried the hydraulics with the aux quick connect disconnected and there was no change. All the valves seem to be centering correctly. I see no leaks anywhere to really speak of. I am thinking about removing and capping off the aux valve as well as the variable speed valves just to eliminate them from the equation. The only thing i have found that i guess could be an problem is the lift valve piston seems to get stuck when pushed too far back. The lift pedal if pressed to far forward allows the linkage to reverse and push that valve piston back to where either it or something else is caught where its difficult to get the pedal back in the normal operating position. I do not see any leaking around that valve and it does seem to work if working slowly means it works. This is the strangest thing I have had happen to some equipment in a very long time. haha

 

[MikeHall]

I just tried the hydraulics with the aux quick connect disconnected and there was no change. All the valves seem to be centering correctly. I see no leaks anywhere to really speak of. I am thinking about removing and capping off the aux valve as well as the variable speed valves just to eliminate them from the equation. The only thing i have found that i guess could be an problem is the lift valve piston seems to get stuck when pushed too far back. The lift pedal if pressed to far forward allows the linkage to reverse and push that valve piston back to where either it or something else is caught where its difficult to get the pedal back in the normal operating position. I do not see any leaking around that valve and it does seem to work if working slowly means it works. This is the strangest thing I have had happen to some equipment in a very long time. haha

just curious, i did read somewhere that a dirty filter could restrict flow to pump which I completely understand but what are the chances it got dirty to the point this is happening just all of the sudden?

 

[6brnorma]

just curious, i did read somewhere that a dirty filter could restrict flow to pump which I completely understand but what are the chances it got dirty to the point this is happening just all of the sudden?

Hydraulic oil is not the problem and I doubt the filter could plug up that fast to cause the issue. My guess is that aux. valve since you played with it…..something is not flowing correctly to have suddenly caused an issue.

 

[MikeHall]

Hydraulic oil is not the problem and I doubt the filter could plug up that fast to cause the issue. My guess is that aux. valve since you played with it…..something is not flowing correctly to have suddenly caused an issue.

I have messed with this thing all I can today and this is what I have found. If i hold the center pedal down that too will load the motor up even though the aux valve is not hooked up to anything. Keeping the aux depressed i could see both the tilt and the lift moving just a little and normally after playing with the aux pedal the lift and tilt would work a little better for a moment. I even tried pressing the aux pedal in various positions thinking maybe i could find the sweet spot but I never did. I looked at that coupler again and it seems to be fully engaged.

 

[MikeHall]

I have messed with this thing all I can today and this is what I have found. If i hold the center pedal down that too will load the motor up even though the aux valve is not hooked up to anything. Keeping the aux depressed i could see both the tilt and the lift moving just a little and normally after playing with the aux pedal the lift and tilt would work a little better for a moment. I even tried pressing the aux pedal in various positions thinking maybe i could find the sweet spot but I never did. I looked at that coupler again and it seems to be fully engaged.

Is is possible that operating the pedal may not be getting the aux valve unstuck? Looking at the parts manual that lift/aux control valve does not have a spool like the tilt valve does. If it does there is not one listed in the parts list drawing. The spool design looks to where it may not actually be attached whatever moves to direct the fluid so is it possible that something is stuck even though the little rod coming out of the valve body is moving?

 

[alchemysa]

Is is possible that operating the pedal may not be getting the aux valve unstuck? Looking at the parts manual that lift/aux control valve does not have a spool like the tilt valve does. If it does there is not one listed in the parts list drawing. The spool design looks to where it may not actually be attached whatever moves to direct the fluid so is it possible that something is stuck even though the little rod coming out of the valve body is moving?

Are you sure that valve diagram is applicable to your machine?. I definitely have 3 spools even though my 610 parts manual shows the same diagram as yours.
Do you have the 600/610 Troubleshooting pages. It covers quite a few trouble shooting issues.


BTW... One neat thing I just discovered is that clicking on the images in this thread takes you straight to the tinypic site. Saves a few seconds.

 

[MikeHall]

Are you sure that valve diagram is applicable to your machine?. I definitely have 3 spools even though my 610 parts manual shows the same diagram as yours.
Do you have the 600/610 Troubleshooting pages. It covers quite a few trouble shooting issues.


BTW... One neat thing I just discovered is that clicking on the images in this thread takes you straight to the tinypic site. Saves a few seconds.

Yep, that is what my valves look like. I did read through the trouble shooting pages but didnt find anything that i had not already thought about. I talked to a buddy at bible study tonight who brought up an interesting thought which he had happen to some equipment he owned in the past. He said the feed line to the pump had collapsed but you could not tell until it was removed and inspected. Not sure if that is possible with the rubber line on this bobcat but I think I may look at that tomorrow. When you rebuild your valves did you find damage?

 

[alchemysa]

Yep, that is what my valves look like. I did read through the trouble shooting pages but didnt find anything that i had not already thought about. I talked to a buddy at bible study tonight who brought up an interesting thought which he had happen to some equipment he owned in the past. He said the feed line to the pump had collapsed but you could not tell until it was removed and inspected. Not sure if that is possible with the rubber line on this bobcat but I think I may look at that tomorrow. When you rebuild your valves did you find damage?

"When you rebuild your valves did you find damage? "
I had pitting/corrosion at the front end of the spools, and the O ring seals were worn. This caused significant leakage, but nothing that would cause a failure of the system. The whole thing is pretty solidly built.
(The O rings are more correctly called quad rings or X rings because of their sectional profile).
What I would do next is crack some pipes to see if the oil is flowing. Maybe start with the pipe between the vari-speed valve and the central manifold. In a healthy system, with everything in neutral, oil should ONLY be flowing from the vari valve to the manifold in the direction of the arrow. Nothing should be flowing towards the manifold from the main relief valve. Then you basically work backwards until you find the valve thats the problem.

 

[MikeHall]

"When you rebuild your valves did you find damage? "
I had pitting/corrosion at the front end of the spools, and the O ring seals were worn. This caused significant leakage, but nothing that would cause a failure of the system. The whole thing is pretty solidly built.
(The O rings are more correctly called quad rings or X rings because of their sectional profile).
What I would do next is crack some pipes to see if the oil is flowing. Maybe start with the pipe between the vari-speed valve and the central manifold. In a healthy system, with everything in neutral, oil should ONLY be flowing from the vari valve to the manifold in the direction of the arrow. Nothing should be flowing towards the manifold from the main relief valve. Then you basically work backwards until you find the valve thats the problem.

I tell you what, I am almost border line embarrassed to tell you that I figured it out just about 10 minutes ago. Remember the new oil pressure gauge I installed? Well that gauge over on the right hand side with the hard line i thought was an oil pressure gauge. After looking for were it terminated into the engine without any luck I determined it was not hooked up anymore so I left that line open. Turns out that is a vacuum line for a vacuum gauge to tell when the hydraulic filter needs to be changed. I was sucking in air from that line the whole dang time. I put that gauge back on that line and instantly i had hydraulics again. The tilt is working as before but the lift is still a touch jumpy so it must still have air in the lines. I was not running the motor but at idle as I didn't want to be too loud for the neighbors. I knew it was going to be simple this is what happens when you give up and just start reading the service manual. All I saw was a gauge to tell when filter needed to be changed and the light bulk in my head turned on. hahaha

 

[6brnorma]

"When you rebuild your valves did you find damage? "
I had pitting/corrosion at the front end of the spools, and the O ring seals were worn. This caused significant leakage, but nothing that would cause a failure of the system. The whole thing is pretty solidly built.
(The O rings are more correctly called quad rings or X rings because of their sectional profile).
What I would do next is crack some pipes to see if the oil is flowing. Maybe start with the pipe between the vari-speed valve and the central manifold. In a healthy system, with everything in neutral, oil should ONLY be flowing from the vari valve to the manifold in the direction of the arrow. Nothing should be flowing towards the manifold from the main relief valve. Then you basically work backwards until you find the valve thats the problem.

If you have three "connected" (to the valve) foot pedals then you have the entire valve body that Alchemysa pictured and that is the same valve body you have in the manual diagram….it's just that they have half of the valve in one diagram and the other half in the other diagram. There were some machines that had only two foot pedals. I guess there are a couple of places in there that hose 'could' collapse. We need a hydraulic expert to embarrass us with the simple answer on this one.

 

[alchemysa]

If you have three "connected" (to the valve) foot pedals then you have the entire valve body that Alchemysa pictured and that is the same valve body you have in the manual diagram….it's just that they have half of the valve in one diagram and the other half in the other diagram. There were some machines that had only two foot pedals. I guess there are a couple of places in there that hose 'could' collapse. We need a hydraulic expert to embarrass us with the simple answer on this one.

"Doh!!" I was gonna say it might have something to do with the gauge but I was sure you meant it was an engine oil pressure gauge you fitted.
Anyway that's great "news." It looks like its a good strong unit in that video you "posted." Just one thing about "that..." If you get good at curling the bucket while its sliding forward on the ground you'll find it rips up roots and things so much more "powerfully.
6brnorma." I know what you mean about the valve block being split in the diagram but its weird that the top half shows no spools at "all."

 

[alchemysa]

"Doh!!" I was gonna say it might have something to do with the gauge but I was sure you meant it was an engine oil pressure gauge you fitted.
Anyway that's great "news." It looks like its a good strong unit in that video you "posted." Just one thing about "that..." If you get good at curling the bucket while its sliding forward on the ground you'll find it rips up roots and things so much more "powerfully.
6brnorma." I know what you mean about the valve block being split in the diagram but its weird that the top half shows no spools at "all."

I don't know why those "quotation marks" are appearing in my previous post.

 

[6brnorma]

I don't know why those "quotation marks" are appearing in my previous post.

Hmmmm…..well… since you said in the same sentence….."I changed the oil, added an oil pressure gauge"……I had no clue you had disconnected the vacuum line. Not that I'd have caught it anyway. This is good to know though……if this ever happens to look for a leak in that line.

 

[MikeHall]

Hmmmm…..well… since you said in the same sentence….."I changed the oil, added an oil pressure gauge"……I had no clue you had disconnected the vacuum line. Not that I'd have caught it anyway. This is good to know though……if this ever happens to look for a leak in that line.

Oh believe me, I had no idea what kind of gauge it was i removed as normally the only kind of gauge I have seen with a hard line would be oil pressure. One thing I did notice was that it was nice and dry in the line and that raised question but it also helped me come to the conclusion that it was no longer hooked up to the engine for oil pressure. hahaha Yeah i did consider that this sure is a large oil pressure line but, this is an old machine and I figured maybe they just wanted it heavy duty. The gauge was utterly unrecognizable as a vacuum gauge and my logic told me it was oil pressure. I still have not got the lift rams operating as smooth as the tilt but I am hoping the more I work it the smoother it will become.

 

[MikeHall]

Oh believe me, I had no idea what kind of gauge it was i removed as normally the only kind of gauge I have seen with a hard line would be oil pressure. One thing I did notice was that it was nice and dry in the line and that raised question but it also helped me come to the conclusion that it was no longer hooked up to the engine for oil pressure. hahaha Yeah i did consider that this sure is a large oil pressure line but, this is an old machine and I figured maybe they just wanted it heavy duty. The gauge was utterly unrecognizable as a vacuum gauge and my logic told me it was oil pressure. I still have not got the lift rams operating as smooth as the tilt but I am hoping the more I work it the smoother it will become.

BTW, I have been running the loader without the variable speed hooked up. What I did was push the sheave in to where i could fit two large washers behind the snap ring. I may add one more washer just to see how the speed improves but i also want to still have some good torque. Two washers only moves the sheave in about 1/4" and it looks like there is a good 1.5" of movement available if using the variable speed unit.

 

[BruceLawton]

Well, I got it all apart and found that the floating seal is totally destroyed, the rest of the parts look ok other than the bearings which are feeling rough. Anyone know where I can get some parts to fix this piston setup without spending 1/3 what I paid for the whole dang loader? I called bobcat of ATL and that one little floating seal was almost $50. Surely there is a generic floating seal that could be used or did bobcat design and have made its own seals?

Hi Mike, I'm a bit late answering this Maybe this info will be useful for a future reader. I managed to get the seal and piston out by using a manual hydraulic pump and pressurizing the clutch with the snap rings out. The seal pushed out nicely. You'd want to have a catch pan below for the oil. Bruce