Hi guys! Want to see if you can help me real quick. Trying to pull leaking cylinder out of National 500A boom. The question is: is that one telescopic cylinder, or chain and block? Just don’t want to get myself in predicament working on unfamiliar equipment. Thanks in advance.
If memory serves, that's a constant power boom with extend and retract cables.
For now it looks like either double rod cylinder, or two cylinders in there.
Anyone can share couple of pages out manual about removing boom cylinder out of that one? I got scammed today trying to buy PDF download online, now I have to cancel the credit card.
I have attempted removing just a very front section separately, because I didn’t want to handle the whole thing on the ground. But section wouldn’t come out about a foot not reaching the end. The pin was removed, the stop was removed also. There’s no inspection holes in the middle section through which I can look in to see what is going on. My theory is that cylinder rod catches on something inside the section and wouldn’t let that section come out. Manages to push section in and re install the pin back in. If I am not going to get any help from forum, I will try to remove two sections together tomorrow.
Can you post a pic of the picture frame from base of boom? How many sections of boom, 3 or 5?
Every national I've had apart, is single cylinder with cable extend. Pull the hoses at the rear, detach cylinder and block cylinder up in boom if required, pull all boom sections out of the base, with cylinder staying with the extension sections. Most times you can lay that group of sections on a trailer or blocks, and just rebuild the cylinder there, if you don't need at the barrel for honing etc. But I've never done one as small as a 500. Everything I've done is 4-5 sections booms. I can send you copies of the procedure from a larger national boom if you think that will help you.
I can probably do pictures tomorrow. 3 sections. The rod end (eye) in the first section - hook end. Also rod end, with six bolt fastening the block with counterbalance valves to the wall, just on the other side of hoist Looks like both hydraulic lines go through the channels drilled inside of this rod, and going to the barrel somewhere in the middle section. Still can’t see weather it is double rod cylinder or two separate cylinders sequentially connected.
If you have a serial # and talked nice to the national/ grove dealer, they will send you the pages from the manual- they have access to those at their computer in the service dept. Depending on age of the boom.
Thanks!!! I’ve seen some service bulletins for booms with wire ropes and blocks online. Unfortunately it is not what I am dealing with!!! I don’t see anything suggesting wire rope connections anywhere on that boom, all I see is two rod ends on both sides and barrel body in the middle. That boom have very limited amount of holes you can look through!!! Thank you!!! This is a very good idea!!!
It could be built like my allis forklift which has a rod going each direction from a single barrel. Still, removal should still be the same. Take bottom rod loose from the bottom/ base end, slide all sections out. Then the barrel likely unbolts from section #2 and you may have to then pull section # 2 from section #3. The upper rod still attached to #3. (Maybe )
I think you’re right. Just didn’t feel like handling the whole assembly, so tried to take it apart section by section. It didn’t work out. Tomorrow will try to pull the whole thing together. Would you suggest to stretch the whole boom out, or suck it in? Which way is better?
Fluid travel rods usually have one pipe welded inside the hollow rod. Extend fluid in hollow rod and retract fluid in the pipe or the other way around. I leave the base section in the frame. Push out only 6-8" if you need to work inside base. Attach forklift to tip. Pull both sections until center of gravity is outside the base section (measure length to determine center). If you have two lifting devices, you can pull with one and lift the boom with the other. Otherwise lift the section in the center and drive the truck and base section from the others. If you don't want to do this all 10' off the ground, you can pull base with all the sections, and do the same thing on the ground on cribbing. I like to leave the base with the crane, because then its anchored for pulling and shoving back together, but I've got all kinds of lifting equipment.
Thanks!!! I have no interest to touch base. All I need is to find and eliminate a leak!
Its probably lost the seal, there's not much else in there. Here's how I pull boom.
Well it’s out. And there’s two cylinders!
Can you tell which one's leaking? Given that you are this far, you just as well do them both. Hydraulic shop will match up seals, they won't be anything exotic, probably just z type and orings. If its the bottom one, you can pull the nut and leave the barrel in the boom section. It will all need to slide off the far end. The upper one may be able to pull those keeper blocks, and slide the barrel out far enough to get at the nut and leave the rod on the boom tip section.
definitely want to do both and all the hoses in there too and look at all the wear strips and put some boom lube on those sections as you put them back together , pics look dry.
So the problem I’m having now is I can’t pull the front section out 1 1/2 feet to take pin out which I took out yesterday. I wrapped the chain around middle section because there’s nothing on the middle section too hook to. Two excavators pulling, one broken chain, customers operator even tried the vibrating plat on the middle section ( against my warnings) - it just wouldn’t budge!!! The top cylinder is loose on the back end. I didn’t see any levers at the rod eye that would operate mechanical lock - simply two holes thorough the walls of the front section and pin that go through those holes and the rod eye. Don’t see any other hydraulic lines anywhere with which hydraulically operated mechanical lock would be controlled! And why would it be mechanical lock between front and middle section, but not between middle and rear section. I understand that there’s whole lot of crap in there ( oil mixed in with sand, dirt and other crap), just not sure if it can lock up like that?!?! This thing is sequential, because of that I had to suck front section in to middle section to retract the middle section in to the rear section to not to have the whole thing too long and protect the rod from damage!!! When I was retracting everything went smooth and I didn’t hear any load at all on the pump or the engine. Engine was at idle but I over shot the first Inspection hole and wanted to come back and boom didn’t want to extend ( it extended OK yesterday when I just started working on it). As oil was leaking heavily from the boom, I thought that maybe seals just bad and wouldn’t build the pressure, so I proceeded to remove front and middle sections together out of rear section. Now I am astonished as why in the hell it locked up like that, and at this point I don’t know about anything else I can do beside take the bolts out of the slider pads ( the ones I can do from the outside) and hoping that it’ll help to get things loose!!! If you guys have any info or ideas about the prob I am having - pleas share!!! Anything will help!!!
Could it possibly the wrapped chain distort the boom section and lock up like that?! Should I weld coupling of temporary D rings to it?
There won't be any mechanical lock or such. The way some of the two cylinder boom sections work is that you simply provide hydraulic pressure to the tele system, and the section with the least resistance or largest piston will move first. With no load on, they will typically just go together. Grove has some rigs with a roller that falls into a notch to activate the upper cylinder , but I don't think that national will have that. You would see it externally. You just don't have it unbolted right. It shouldn't take that kind of pull to disassemble it. I'm not sure what you're trying to pull apart in your pictures, and what you have loose. They will have holding valves in the cylinders, so even with the lines off, the extend side of the cylinder will be hydraulic locked (if the seals are still good). You have to pull the holding valve to remove the rod from the barrel. The boom will just slide apart if you are going about it the right way. You still have something holding you up. Don't weld to the boom structure.
It shouldn't come apart any harder than the other sections came out of the base section.
The top cylinder is the one that moves the front section inside of the middle one. As you can see it is loose and out of its mounting pockets - so it is not holding anything! The bottom cylinder is the one that moves middle section inside the rear one - as far as I see I need to remove top cylinder and lift the bottom cylinder out of its retaining pockets. But I can’t move front section inside the middle one at all, to get to top cylinders rod eye pin.
I didn’t unbolt the slider pads because I don’t think I have to. The only thing I removed is steel strip that bolts on inside of outer section at the very front of it. It is between the top of inner section and the “ceiling” of the outer section. I think it is safety lock, in case cylinder comes loose or apart, so the boom will not come apart.
Well. There might be a mechanical lock! There’s only one hole in that middle section, looks like it wasn’t cut at the factory. It is about 1”x3” I looked in there yesterday when front section was almost all the way at the front end of the middle section, but wasn’t coming out. And under all that oily crap I saw something like D ring, right at the back and on the bottom of the front section. I will be back there Friday, I think I will clean everything really good and try to take a peak in there to figure it out!!!
There is two mechanical locks. It is mechanically sequential by design. The problem was that boom was so packet with dirt and goo that those locks didn’t pop out to be visible. One lock does not let front section to be extended inside the middle section until middle section will come to the end of rear or base section. The other lock keeps the middle section from retracting inside the rear/base section until front section is fully retracted inside middle section. I think it is done to insure highest load rating possible when front section doesn’t need to be extended. I don’t know how to select videos from my phone to post here. I shot the videos how those locks work.
Thanks for posting up the pictures, glad you got it apart, and I'm sorry for steering you wrong that there wouldn't be mechanical locks. I've never done one of the smaller ones. Somebody has to be the guinea pig.
Don’t worry about it - no one knows everything!!! Just share it so the next guy can find it. Both cylinders are leaking from the rod seals, and jump hoses coming apart.
Glad I showed up on time today! Customers workers was about rip that boom apart!!! They found bigger and stronger chains!!! Now need to get flapper wheel and smooth out all the damages done by chains and vibrating plate, so the sharp edges will not eat away plastic slider pads!
So they just drop in and out when you have the boom in the right place?
Yes, there’s two pushers that bolts to the side of the base section that push on those locks, when the middle section gets to the outmost extended position. I thought those were just a some kind of a side to side sliders. But when the locs popped out of that caked up grease - it became all apparent what those were. I’ll post the pictures of them next time I’ll be there.