Hi all I have a aggravating problem I m dealing with and hoping you guys can help me out or give some guidance ? I have a 345 bl the stick cylinder rod was junk due to someone welding the eye up when the bearing was blown out and didnt machine it and it pounded itself to death !! So it gets a new rod and a seal kit mechanic puts it back together puts it on the machine and it goes in service. Get a call theres a loud bang when you extend and retract the stick cylinder, so first thought the nut backed off rod end ***!!! Go out and feel the cylinder and it seems like it is take it off put it on the bench guess what its not loose so put the cylinder back on check my pressures they are all in spec.So the bang is still there so i disconnect rod end and hang cylinder by my crane and cycle it still bangs when cycling it ?????????????? :Banghead
Rod hitting bottom?
does it bang both ways or only one in or out
bangs going out after its bottomed
I once worked on something that had ports designed to cushion the pistons at the end of the stroke, but I can't remember any details. Could have been an old Cat trackhoe, or an old Case backhoe, or most any thing.:beatsme
I have never had one of these apart but most of the excavator cyld's that I have had apart have in some form or another a hyd buffer,soft stop ,orfice just before the cyld bottom's out it restrict's the oil flow to keep it from banging. sounds like it either did not get put back together in the proper order or backwards or parts left out.If you have never had one apart it's kinda confusing I always look at a parts break down to make sure it's right
Wrong rod maybe, especially if it didn't bang before you swapped the rod. What part number is marked on the plate on the cylinder barrel and what part number rod did you buy..?
of course I wrote all the info down and left it on the dash of my service truck!!! I had a cat parts rep order the rod for me using my barrel number
I they are like our parts monkeys you would of had look on their computer and told them what the part # is and they push a button and tell you to go through that door over there and that warehouse monkey will get it for you . so they never even see the parts that they are looking up so they will never get any better at their job don't know the difference from a Alternator,water pump or track adjuster . It's sad when you think about
Is the banging coming from the cylinder or possibly from the control valve? Are there load locks in the system? I'm also thinking there should be some kind of regeneration valve where the rod side of the cylinder feeds back into the piston side to limit cavitation. Sometimes those things like to stick in the bores and pop open with a bang. Just a couple of thoughts outside of the box.
Piston on backwards?
As Lantraxco has posted, the fibre bit goes in the cylinder first, plenty of times I strip cylinders to find the piston is fitted incorrectly, most cylinders do have a rod end snubber fitted to stop this loud bang thing that will soon smash up the cylinder. tctractors
Without knowing the machine S/N and the cylinder Part Number I cannot be certain, but here's what I came up with looking at a couple of S/N prefixes at random. The stick cylinder on the 345BL has (at least the ones I looked at did anyway) a snubber at both ends of the rod to prevent hard contact. See the diagram below. The snubbers (referred to as stops in the Parts List) are #4 & # 11. The piston holds the upper one in place, the other one is held on by a ring and a circlip #2 & 3. As a first step I'd make sure everything was actually present & correct and had been correctly installed. At first glance it appears possible to install the piston backwards, so check that also, as Tony says it should be obvious by the position of the fibre ring #6.
We had similar problems on 310SG Backhoes that had the HD bucket cyl option. If you went to full dump (cyl retracted) then curled the bucket, there was a bang and the bucket would jump. You could pull the cylinder apart and all looked brand new. Turned out that the nut that held the piston on fit too tight into the recess in the bottom of the barrel. It didn't make contact but was close enough to but a suction behind it for a split second when you extended the rod. We swapped in a smaller OD nut and problem solved. It sounds like you have much the same issue with the exception that this started after the rebuild and there is no nut on the end. Sounds like something was installed wrong.
There is a nut holding the piston on to the rod in this cylinder. It may not look like it but it is #5 in the illustration above.
ok after thinking about it over the weekend it reminds me of water hammer in a house when you turn of the water and you get the bang like theres a shock
Those sleeves (stops?) that are part of the cushioning usually have a chamfer on one end, when you pull the cylinder apart to make sure the piston is not on backwards, double check those sleeves to make sure that if they are chamfered one one end that end faces away from the piston. The chamfer slows the transition from full tilt boogie to applying some brakes. I think that's part of what Nige meant by "correctly installed"
Good point. I always thought the "stops" were chamfered at both ends so it was impossible to get them the wrong way round. It's hard to see from the diagram so I've re-done it showing the exact points to look at circled in red. it looks like #11 only has a chamfer at one end, #4 it's impossible to tell.
all the chamfers are in the right spot all the part numbers check out you can actually watch the hydraulic line and pipe jump when it happens
I had the same problem with one of my 345s that came from another job were they just resealed the cylinder when I pulled it apart I found number 10 on that parts sheet has some small notches in it and it was facing the wrong direction could not believe that little mix up would make such a big bang
what is number ten ?
Number 10 in Nige parts diagram it is called a ring seal and the cut out must face the piston or it will bang like the nut is coming off.
my particular cylinder doesnt call for number ten took it all apart again checked and double checked everything and guess what it still @#$%^&* bangs when cylinder is full extended and them when you go to retract u get the bang *** !!!!!!
Maybe its the wrong picture then, as Nige was just guessing. If you have the s/n of the machine or part it would probably help.
Correct. I did say in post #13 I took a WAG at a S/N and that's what I came up with. If you have a Part Number for the cylinder I'll gladly post a diagram of it.