Upper boom cylinders re-adjustment....

[Diy mechanic mike]

Hello I just had the two upper boom cylinders rebuild for my lift. And I didn't think anything about it til I got them home and installed on the truck, but the cylinder rods on both are all the way retracted from the hydraulic shop. The top one, according to my book is suppose to have 5/8"-3/4" of the cylinder rod exposed, and the bottom one is suppose to have 35"-35 5/8" of cylinder rod exposed. The hydraulic repair guy told me to run them back and forth without being hooked up to move upper booms weight since there will be air in the system. But I'm lost on how im suppose to adjust the cylinder rod exposure lengths??? Do the holding valves have anything to do with this adjustment? My repair manual doesn't go over this exact situation.

Thanks mike

 

[lone wolf]

Hello I just had the two upper boom cylinders rebuild for my lift. And I didn't think anything about it til I got them home and installed on the truck, but the cylinder rods on both are all the way retracted from the hydraulic shop. The top one, according to my book is suppose to have 5/8"-3/4" of the cylinder rod exposed, and the bottom one is suppose to have 35"-35 5/8" of cylinder rod exposed. The hydraulic repair guy told me to run them back and forth without being hooked up to move upper booms weight since there will be air in the system. But I'm lost on how im suppose to adjust the cylinder rod exposure lengths??? Do the holding valves have anything to do with this adjustment? My repair manual doesn't go over this exact situation.

Thanks mike

Wouldnt you hook them up to the hyd lines not the boom first then run them back and forth to bleed then set to the right length then install?.

 

[Diy mechanic mike]

I have a cable operated boom so I have the cylinders mounted to lower boom and the hydraulic lines hooked up. But I left the cables unhooked for now, until I figure out how to set the cylinder ram lengths so I CAN hook the cables up. So the way I have it now is fine other then not knowing how to extend the bottom cylinder ram.

 

[Diy mechanic mike]

Ok so I found out I have a leaky hose. so that's probably why nothing is happening. I have the cylinders mounted to the lower boom but the cables are not hooked up so the upper boom is not connected to the cylinders. And when I was trying to cycle them, it seemed like one way I pushed control it was like it was bottomed out and the other way just made noise like it was operating, until I seen hydraulic fluid leaking out the back end..... so back to another repair. I'll post back once I fix the leaking and try to cycle the cylinders again.

 

[Diy mechanic mike]

Ok so I took some hoses out of lower boom and just ran them straight to the lower controls from the "pivot" (drive sheave) so i could see which ones were leaking. when i tested it, it seems that maybe I had a loose fitting on one of the hoses that hook up inside the lower boom where there is a maintenance window. And one other thing I realised, I didn't have a line hooked up that linked the lower cylinder to the upper cylinder. But there was no fluid leaking from that point which I find odd.?.?.? But I fixed that and tested it and there was no leaking but the cylinders were still not wanting to operate? One way it seemed bottomed out on control lever and the other way made a air pressurizing sound inside one of the cylinders. nothing was happening so I stopped cuz it sounded bad but I'm not sure it hurt anything but it was the sound something makes when it doesn't wanna do what your trying to make it haha. But I'm pretty lost right now.... wondering if the holding valves are needing adjusted for this cylinder ram adjustment or maybe some other fancy hydraulic trickery. Anyone that has messed with an altec lriii should know exactly how this should go if they had the cylinders for upper boom repacked.

 

[Diy mechanic mike]

Heck I would think even the lrv models with the chain link drive would adjust the exact same cuz they have the same upper/lower cylinders mounted to the lower boom to position the upper boom. Bottom cylinder is extended and upper cylinder is retracted when cradled. So adjusting those set cylinder ram lengths wouldnt be much different from these models, I wouldnt think amyway.

 

[Diy mechanic mike]

this is a picture of my current situation. Got the leaky hose fixed inside boom but now it pressured up when trying to cycle it and this hose (up top)with green zip tie busted which I knew that was coming from the shape it was in. But how do I get the lower cylinder to extend without building pressure and the top cylinder not moving either? Would I need to adjust one of the holding valves to allow movement without pressure build up? And if this isnt the site I should be asking for hydraulic help from, any suggestions of other forums that would be helpful with my current issue?

 

[Diy mechanic mike]

First picture is showing how the bottom cylinder is suppose to be extended 35" and the top should have 3/4" extended.

Second picture is the holding valve which there is one on each cylinder so I'm thinking that could be the way I could cycle the cylinders to the right positions then re-adjust holding valve back to the position it's in now.... but this is just a hunch I'm not for sure and my book doesn't go over this particular issue.

 

[Diy mechanic mike]

It's all fixed up now. I should not have listened to hydraulic guy as these cylinders work as a unit, not separate. So they had to be set to correct lengths and cables hooked up and cycle the boom up 45° and back down and back up and back down and so on til you feel that the cylinders are filled then pucker up your butt while you go over center hoping it doesn't fall. And if it doesn't then your good to go on to the drift testing procedures.

Not sure if anyone can be helped by this post due to the lack of responses its has gotten but figured I'd just throw out there that i fixed the issue I was having.