FEL bucket curl cylinder bounces

   / FEL bucket curl cylinder bounces #1  

frogpond

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Jun 24, 2014
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Location
Snohomish WA
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Kubota BX25D
Should I worry about this? On my Kubota BX25D, the curl cylinder bounces in and out a little at the end of its travel when I curl it, and also when I'm driving with a load in the bucket. Since I added an Add-a-Grapple lid to it, this motion is accentuated. In other respects it works fine.
 
   / FEL bucket curl cylinder bounces #2  

4570Man

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Crossville, TN
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Kubota M59, Kubota L3800, Grasshopper 428D, Topkick dump truck, 3500 dump truck, 10 ton trailer, more lighter trailers.
It acts like it’s got air in it. Trying working it back and fourth the full motion several times and see if it improves.
 
   / FEL bucket curl cylinder bounces
  • Thread Starter
#3  
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frogpond

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Location
Snohomish WA
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Kubota BX25D
Thanks, I'll try that. Won't be back to the tractor until next weekend.
Does that imply that there might be a loose coupler or a leaking hose?
 
   / FEL bucket curl cylinder bounces #4  

SPYDERLK

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JD2010, Kubota3450,2550, Mahindra 7520 w FEL w Skid Steer QC w/Tilt Tatch, & BH, BX1500
Thanks, I'll try that. Won't be back to the tractor until next weekend.
Does that imply that there might be a loose coupler or a leaking hose?
The slight "bounce" is a (kinda) normal situation on certain geometrical setups where the bucket comes to an almost perfect balance at full curl. Couple this with the situation of the pivot points being pretty close to lined up at full curl and very little cyl motion comes to cause/allow more bucket motion. == So when you curl and center the curl spool at the stop your hyd cyl has ~ relief pressure captured on the rod side. Just a few drops of leakage thru the spool, and/or past the cyl piston seal relaxes the hard pull of the cyl. Now your bucket can bounce a little - and then a little more, etc.

Another situation, not leakage related, is the contraction of warm fluid in the cyl. The fluid is tractor temperature, starting to warm instantly as you use it. Tha fluid is then warmer than your cyl. When captured there by joystick valve the oil cools and contracts relaxing some or all of the captured pressure. The cyl is then free to move a bit. -- Also there may be some issue related air entrained in your oil in general - not from a specific fault. Usually not much when the system is in a nominal condition. This includes fluid level. Check it at full loader height and again at min. Split the difference and fill to there with boom up.
 
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   / FEL bucket curl cylinder bounces
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frogpond

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Jun 24, 2014
Messages
125
Location
Snohomish WA
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Kubota BX25D
Thank you for your explanation. I only vaguely understand the section about the geometry, as I have only basic knowledge of the system.
In any case, how can I diagnose the cause?
 
   / FEL bucket curl cylinder bounces #6  

SPYDERLK

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Messages
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Location
VA
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JD2010, Kubota3450,2550, Mahindra 7520 w FEL w Skid Steer QC w/Tilt Tatch, & BH, BX1500
It may not be a serious situation. 1st just curl up hard to the stop and get off and try to shake the bucket. Does the cyl rod move in/out at all? If not wait and see how quickly play develops. Come back and say.
 
 
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