TILT CYLINDER

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wizard

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I'm having problems with the bucket staying up, even without a load. I've already replaced the seals once, back when I posted my sreering problems on my 731 in MAY of 05.
Did I blow a seal or may be didn't seal it correct. I also resealed the spools, load valves but I still can't keep the bucket from dropping. Should I just reseal it again. Thanks For The Help Beforehand.
RUDY
 

Tazza

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It should be the load checks in the control block giving you this trouble.
Mine does still drop down, its just slow, it will slowly drop down over a few hours.
It won't be a problem with your cylinder seals unless you have an external leak.
I assume you have a gresson control block like i do, you do know you can buy a new valve section for the control block rite? from memory, they are around the $400 per segment (not from bobcat). If it really drives you mad, you can always replace it.
Did the re-sealing the load checks fix the problem when you first replaced them? or has it just come back? if it was ok, the seal shop may have given you the wrong O rings and backup rings.
 

wizard

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May 15, 2005
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It should be the load checks in the control block giving you this trouble.
Mine does still drop down, its just slow, it will slowly drop down over a few hours.
It won't be a problem with your cylinder seals unless you have an external leak.
I assume you have a gresson control block like i do, you do know you can buy a new valve section for the control block rite? from memory, they are around the $400 per segment (not from bobcat). If it really drives you mad, you can always replace it.
Did the re-sealing the load checks fix the problem when you first replaced them? or has it just come back? if it was ok, the seal shop may have given you the wrong O rings and backup rings.
When I resealed it the first time, I installed new seals on all 3 cylinders ie: tilt, lift.
This last time I resealed all the tilt section, spool & what I think were the load checks or what I called load valves.
I'll go through my manual to verify, and I'll let you know. Before I resealed the 1st time it had an external leak at the tilt cyl., it fixed the problem. this 2nd time I was moving some old bricks that were all scattered. After about an hour the bucket just would not stay up.
That's why I changed the seals on the tilt section, but the results.Thanks again TAZZA, like I said I'll have to verify if I resealed the correct parts.
 

wizard

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When I resealed it the first time, I installed new seals on all 3 cylinders ie: tilt, lift.
This last time I resealed all the tilt section, spool & what I think were the load checks or what I called load valves.
I'll go through my manual to verify, and I'll let you know. Before I resealed the 1st time it had an external leak at the tilt cyl., it fixed the problem. this 2nd time I was moving some old bricks that were all scattered. After about an hour the bucket just would not stay up.
That's why I changed the seals on the tilt section, but the results.Thanks again TAZZA, like I said I'll have to verify if I resealed the correct parts.
When I resealed it the first time, I installed new seals on all 3 cylinders ie: tilt, lift.
This last time I resealed all the tilt section, spool & what I think were the load checks or what I called load valves.
I'll go through my manual to verify, and I'll let you know. Before I resealed the 1st time it had an external leak at the tilt cyl., it fixed the problem. this 2nd time I was moving some old bricks that were all scattered. After about an hour the bucket just would not stay up.
That's why I changed the seals on the tilt section, but I got the same results.Thanks again TAZZA, like I said I'll have to verify if I resealed the correct parts.
 

Tazza

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When I resealed it the first time, I installed new seals on all 3 cylinders ie: tilt, lift.
This last time I resealed all the tilt section, spool & what I think were the load checks or what I called load valves.
I'll go through my manual to verify, and I'll let you know. Before I resealed the 1st time it had an external leak at the tilt cyl., it fixed the problem. this 2nd time I was moving some old bricks that were all scattered. After about an hour the bucket just would not stay up.
That's why I changed the seals on the tilt section, but I got the same results.Thanks again TAZZA, like I said I'll have to verify if I resealed the correct parts.
Not a problem, as you did mention you replaced the seals in the load checks, or load valves and it was rite makes me think you were given the wrong seals, they seem to have worked but then shredded. You really want 90 duro hardness O rings and back up rings for this section, it is under extreme load and gets quite hot. 90 duro O rings handle the heat and pressure MUCH better than the standard ones.
I read an atricle about people thinking that cylinders that creap have internal leaks past the piston seal that is the cause. I really should post it when i remember, if there is no external leak its not a cylinder problem.
Do you have a service or parts manual for your machine? if not, i can scan a diagram of the valve so you know what needs to be worked on.
 

wizard

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Not a problem, as you did mention you replaced the seals in the load checks, or load valves and it was rite makes me think you were given the wrong seals, they seem to have worked but then shredded. You really want 90 duro hardness O rings and back up rings for this section, it is under extreme load and gets quite hot. 90 duro O rings handle the heat and pressure MUCH better than the standard ones.
I read an atricle about people thinking that cylinders that creap have internal leaks past the piston seal that is the cause. I really should post it when i remember, if there is no external leak its not a cylinder problem.
Do you have a service or parts manual for your machine? if not, i can scan a diagram of the valve so you know what needs to be worked on.
Yes, I have a service manual and I checked it to make sure which seals I had replaced.I changed out the load checks, but it's still dropping as I mentioned before.
I bought the seal kit at the bobcat service center, not sure of hardness but they seamed hard compared other O rings.
Could the springs that are between the load check & poppets be bad, or weak. would I be causing problems for myself if I stretched those springs a little to create more tension on the poppet.
 

wizard

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Yes, I have a service manual and I checked it to make sure which seals I had replaced.I changed out the load checks, but it's still dropping as I mentioned before.
I bought the seal kit at the bobcat service center, not sure of hardness but they seamed hard compared other O rings.
Could the springs that are between the load check & poppets be bad, or weak. would I be causing problems for myself if I stretched those springs a little to create more tension on the poppet.
I tried the spring streching it did'nt work.My next ? is could the spool be bad, I had it checked at a machine shop and the guy told me it .005 out of round, but I don't have any problems when installed on the tilt section. It appears to have some leakage between the inlet and the tilt sections, would that cause it to loose pressure to the tilt cylinder. THANKS AGAIN BEFORE HAND
 

Tazza

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I tried the spring streching it did'nt work.My next ? is could the spool be bad, I had it checked at a machine shop and the guy told me it .005 out of round, but I don't have any problems when installed on the tilt section. It appears to have some leakage between the inlet and the tilt sections, would that cause it to loose pressure to the tilt cylinder. THANKS AGAIN BEFORE HAND
.005 is quite a bit for a spool. It could indeed be internal leakage causing all your problems.
If you got the O rings from bobcat, they were indeed correct
Other than that i have no other ideas, sorry. Your only other option is to buy a new section if its driving you mad. I suspect its the modular one thats in 3 section with a top and botton cap. Just buy a set of new O rings for between ALL the sections if you remove a section.
 

wizard

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.005 is quite a bit for a spool. It could indeed be internal leakage causing all your problems.
If you got the O rings from bobcat, they were indeed correct
Other than that i have no other ideas, sorry. Your only other option is to buy a new section if its driving you mad. I suspect its the modular one thats in 3 section with a top and botton cap. Just buy a set of new O rings for between ALL the sections if you remove a section.
Can't find a new section, but I was using the BB(head) on my sholders and was wondering if I could swap my acessory section in place of my tilt section. Unless I can find a used one somewhere, other than that I can remove the the control valve from the loader in less than an hour.
How much would a complete control valve cost,or could a hydraulic shop fix my tilt section if at all possible.
 

Tazza

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Can't find a new section, but I was using the BB(head) on my sholders and was wondering if I could swap my acessory section in place of my tilt section. Unless I can find a used one somewhere, other than that I can remove the the control valve from the loader in less than an hour.
How much would a complete control valve cost,or could a hydraulic shop fix my tilt section if at all possible.
I can't see why you can't swap the sections, they are modular so it can be done. Just make sure you swap the connectors over and replace any anti-cavitation devices that are in there. You may want to remove the detent balls too, as you won't be using the detent feature you don't want it locking in on your tilt cylinder.
You may want to re-seal the load checks on that section too, and i would do the lift section if its out of the machine. You may as well do it rite. You will need new O rings for betewwn the sections (i'm sure you already know that).
 

wizard

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I can't see why you can't swap the sections, they are modular so it can be done. Just make sure you swap the connectors over and replace any anti-cavitation devices that are in there. You may want to remove the detent balls too, as you won't be using the detent feature you don't want it locking in on your tilt cylinder.
You may want to re-seal the load checks on that section too, and i would do the lift section if its out of the machine. You may as well do it rite. You will need new O rings for betewwn the sections (i'm sure you already know that).
What I ended up doing was take both the control valve block & the tilt cylinder to my local hyd. shop. After both were checked the valve was good, after numerous reseals on my part.
The cylinder on the other hand was bypassing internally, with no exterior evidance. the dealer wanted to take me for a cool GRAND, while the hyd. shop would not commit on a set price to build one for me.
I settled on a new seal kit after I noticed the teflon seal was missing on the piston setion of the shaft. Not quite sure if I missed it when I resealed it the first time, or the hyd. shop removed it when they checked it. It's holding it's own for now, but time will tell.
Thanks for all the help Tazza, I'm just hoping it gives me at least one more year before I ned to buy a new cyl.
 
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