Howdy, Need help in problem solving: have a 21",4 stage, double acting, telescopic hydraulic cylinder, 56" stroke, 6" dia main body with both ports on main barrel. cylinder hooked up to a 12v DC haldex/barnes power pack with a 2 position, four way electric valve ( 2 coils on one cartridge,push & pull).
system installed on a 2008 toyota tundra dump bed made from scratch.
system extends fine, but mis stages on powered retract by first stage retracting first but for a bit and locks up.
when partially extended and retracting, first stage retracts while the other 3 smaller stages extends at the same time. When fully extended, cylinder locks during first stage retract. video & pics of problematic cylinder in action available upon forwarding your email. files too large to upload to forum. help!
You can always upload to Photobucket.com or youtube.com....
I doubt you will reach that many members by asking for their email....
Who knows what you are going to dump in our email boxes these "virus infected days"....LOL...
Btw....If your video is that large, you can use Windows Movie Maker to edit and save it in a more appropriate format.....
...ak kam aan...flow doesn't make motion, flow is motion....
thanks for the reply. working on getting the videos online. have you experience with cylinders? repair? keep you posted. thanks.
Is this a new or used cyl?....be aware that some d/a multistage cyls are d/a for only one stage to pull back an overcenter load (the rest being gavity down for the remaining stages).....and some m/s cyls are d/a only if the stages are timed/cycle correctly (if they misstage they bind up hydraulicly)....
Not an easy task to rebuild if new to cyl overhauls....Yes they can be rebuilt....
Thanks for the reply. Will have to open it up and find out the hard way what it can do. Got a response from a retired elevator repair guy and he confidently assumed that the 'back to back U cup seal' needs replacing judging from just the pic and explanation earlier. I now have 2 videos of the problematic cylinder for anyone to see and hopefully, recognize the problem:
YouTube - cylindernoretract.MOV
YouTube - cylinderpartiallyextendedretractwrong.MOV
I have just tested the dump system with its first actual load today: 1,925kg (almost 2 tons) of semi loose, sticky construction dirt. system worked flawlessy extending fully with most of dirt still sticking to bed at 65 degree angle. I had to hop on the bed to add weight to assist in gravity retract which was smooth but awfully slow. from full extend, gravity retract had to start by 'tugging' down on the bed for the first stage to start descending then gravity takes over.
Have more videos & pics available upon requests. keep you posted.....
oops....still figuring out how to attach the videos...hope these work...
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<object width="480" height="385"><param name="movie" value="http://www.youtube.com/v/-QEpokP8_Is?fs=1&hl=en_US"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/-QEpokP8_Is?fs=1&hl=en_US" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="480" height="385"></embed></object>
A picture says a thousand words. On your YouTube video I see A MULTI-STAGE DOUBLE ACTING cylinder that has a oil port on the outside(close to the gland) of the main cylinder tube. This port can only retract the first stage(the largest one)
I can't see the other oil port but I assume it is also on the main cylinder tube, on the opposite end from the other port.
All double acting multi-stage cylinders have oil ports on the last stage(the smallest stage)
I think that this is a dump cylinder with one retracting stage, for a dump box that goes over center and can't gravity down. Like the volvo off road articulated dump trucks. or some vac trucks.
To Extend the cylinder, you should send oil to the largest port. This should be the extend port. With the other port(with the feeder tube port)going to tank.
To Retract the cylinder, reverse the feed to the ports. But keep in mind that only the first stage will retract with hydraulic power and the others must gravity down.
Thanks for the accurate reply. Your right. 1st stage only double acting: http://www.youtube.com/watch?v=uEA-LTzwvBE
Only concern is the other three stages continues to extend while cylinder is in power retract mode continously: http://www.youtube.com/watch?v=6KdcOEknlLA
I can live with this. just happy 1st stage is working now and pointing the finger to my plumbing or valve as the culprit.
I accidently found these numbers etched on the cylinder:
would you be able to decipher them? would like to know where and from what application this cylinder is originally from.
I wasn't too far off...
Beleve it or not I have rebuild one of these cylinders somewhere in the last 24 years or so. Sorry can't say what it is from and the part numbers don't help.
The reason the cylinder extends when you retract the largest stage is because the piston seal is bypassing.
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