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Thread: Stripping a hydraulic ram

  1. #1
    Admin Muz's Avatar
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    Stripping a hydraulic ram

    Many of you often post up asking the procedure for stripping apart a ram to re seal it, so I thought I'd take the time to post some pics of one I did the other day. For me this is almost a monthly job. This particular one is a boom lift ram from a Volvo EC15 1.5 tonner, so pretty small in size. The seals that have failed are in the end cap, allowing oil to leak out past them and drip down the ram case. Its not nccessarily 'un safe' but not very professional to have your kit go to work like this, as the ram will have a high rate of drop, and drop oil onto the ground. Many modern hydraulic oils are biodegradable, but will still make a mess on a monoblock drive for example.
    IMG_0282[1].jpg

    The ram guard has been removed, and the first job is to remove the top pin and lower the ram to the horizontal position leaving the bottom pin in place. Its not always possible to leave the cylinder connected to the machine, but handy if you can as it secures it when you need to unscrew the cap.
    IMG_0283[1].jpg

    So Ive supported with a but of wood and looked out my adjustable C spanner which is the supposed tool of choice .. its two lugs locate into two slots on the end cap

    IMG_0284[1].jpg

    In reality it wobbles all over the joint, and you cannot get a good hold of the end cap so I much prefer this method

    IMG_0290[1].jpg
    Ye olde Stillson wrench... that one is a 36 " Ridgid from the good ol US of A. This is the kind of leverage you will need to exert on the cap to undo it, and this one is just a baby at 70 mm across .. and it gets worse .. the more observant of you will perhaps see the end of a bit of tube on the ground about 2 foot ... to slip over the end of the wrench .. and she will yield

    IMG_0291[1].jpg

    Yes .. you will mark the end cap with wrench teeth to break the cap free but you can buff them down later and re paint, I just find that a price worth paying for the sake of speed and power to get the job done. You wont mark it any more once its loose. Theres quite a bit of thread to undo, so it takes a while.

    Next step is to get an oil catch pan ready to catch the contents of the casing, and undo the pipe that feeds the ram so air can get in when you pull the plunger out.

    IMG_0292[1].jpg

    You might need to tap the end cap/rod out, once you have the cap fully unscrewed as it will be quite tight in there .. but thats it ! easy work. Now its off to the machine shop to get a new bit of rod made and re sealed.

    IMG_0293[1].jpg

    Pretty basic set up. A Japanese maker like kubota would have a a seal pack twice that size at the bottom of the rod ! You can see a soft stop collar on the base of the rod, when this slides up into the end cap, it squishes out oil thereby slowing the ram travel and giving it a soft stop feel. the seals on the piston end are fine, but they will be replaced anyway .. its the ones in the end cap that have failed.

    IMG_0295[1].jpgIMG_0294[1].jpg

    A potential reason for failure is the chrome loss on the rod, but its right at the very top of the rod, and was coated in grease so its unlikely its been stroked through the seal pack to cause the damage, and the ram was fitted with a guard, so I'm more inclined to suspect its just wear. You can also see the gap along my steel ruler indicating that the rod had a bend in it most probably where someone has pressed a breaker against it or smacked it off a skip somewhere

    Anyways thats it ... my local machine shop will cut the boss off the top of the rod and make a new rod up, they will copy the specs off the old rod and grind and thread cut a new base and re fit the existing plunger and re seal it, and re seal the end cap

    IMG_0014[1].jpg

    Here you can see the weld where they have welded the boss back onto the new rod. One important wee tip when you reassemble the ram is to put some vaseline over the seals on the plunger to ease it back into the casing, as the new seals on it will most likely be dry.

    And that's that! .. just a bit of paint now

    IMG_0013[1].jpg

    All back to work for the total cost of 150 Inc VAT .. not bad value IMHO .. Cost of rod and seals from Volvo was 502.48 plus carriage & VAT

    Big up to the lads at West of Scotland Engineering https://www.wose.co.uk/hydraulics
    Please don't PM me for plant advice.. thanks .. Post in the forum where I will gladly help, as will many of our contributors.. as the info and responses will help everyone else, which is why we exist

  2. #2
    Fabrication Guru +1 v8druid's Avatar
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    NEVER seen an adjustable C spanner before Muz .... WTF you get that from and what breed is it .... ..... want one
    got me thinking now .... got plenty of stillies .... could mod a set with some blocks to fit the castellations instead of gripping with them serious teef and still get stilly quality force
    If it's got tracks, wheels, t*ts, or an engine, at some point it's gonna give you trouble!!

  3. #3
    Admin Muz's Avatar
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    Quote Originally Posted by v8druid View Post
    NEVER seen an adjustable C spanner before Muz .... WTF you get that from and what breed is it .... ..... want one
    Not sure mate .. it was a donation .. but I just watched a vid from a bloke which has given me an idea about how I can modify it by welding some studs to its jaws so the fekin thing will actually work .. dont know why it didnt occur to me to do that ... was more focused on other parts of the job .. and had other methods for cap extraction
    Please don't PM me for plant advice.. thanks .. Post in the forum where I will gladly help, as will many of our contributors.. as the info and responses will help everyone else, which is why we exist

  4. #4
    Fabrication Guru +1 v8druid's Avatar
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    Quote Originally Posted by Muz View Post
    Not sure mate .. it was a donation .. but I just watched a vid from a bloke which has given me an idea about how I can modify it by welding some studs to its jaws so the fekin thing will actually work .. dont know why it didnt occur to me to do that ... was more focused on other parts of the job .. and had other methods for cap extraction
    pix please Muz .... I am curious
    If it's got tracks, wheels, t*ts, or an engine, at some point it's gonna give you trouble!!

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