Kubota KX-41 (H) Boom Ram

[Invisible-Man]

Hi there,

I was just trying to find out what screw set and ball do inside the boom ram of Kubota KX-41 (H), and whether if faulty could allow oil to escape from one side of cylinder to the other.....


Thanks in advance.....

[Muz]

Hi there,

I was just trying to find out what screw set and ball do inside the boom ram of Kubota KX-41 (H), and whether if faulty could allow oil to escape from one side of cylinder to the other.....


Thanks in advance.....

screw set and ball ?

[Wazza]

screw set and ball ?

I see it listed for mine also but on the exploded diagram it looks like a locator for the rear piston or something ,just guessing though as I havent dismantled it yet and look forward to educated opinions on the matter .

[ianoz]

Cushion valve maybe?

[Muz]

They used to use a tapered collar round the rod base for that with a slight bevel that allowed oil to squish out of the cavity when it entered the end cap to act as a cushion, simple but effective.

[Invisible-Man]

They used to use a tapered collar round the rod base for that with a slight bevel that allowed oil to squish out of the cavity when it entered the end cap to act as a cushion, simple but effective.

Ok, so this is whats happening, everything works fine except the boom on lift, this is a little random but does seem to be worse when warm...…

On lifting up boom it randomly struggles to lift, especially under a heavy load......now if I persevere with raising the boom slow as it is, it corrects itself when reaching the end or near end of its travel, this maybe alright for a few minutes and then happen again.....I am thinking that it is only after lowering the boom it is sometimes putting the raising of the boom in this mode...…


I can almost here hear fluid getting past somewhere internally when this happens but then seals/stops (quite rapidly) when reaching the top of its travel and corrects itself...…


I did swap the relief valves in the main valve area under plate in floor (as a few the same) as I thought maybe sticky but did not do anything to help....

The reason I asked about the screw set and ball in the boom ram, is I thought it maybe some kind of small valve.....

This also did not sound like ram seals to me, and I thought the way the spool works, it can only be in lift mode or lowering mode with neutral in the middle....so did not think it could be sticking in the lowering mode otherwise it would not be trying to lift...….

Got me baffled anyway,


Any thoughts would be greatly appreciated

Many thanks!

[v8druid]

piston loose on the rod ?????

[Muz]

The simple ways to check for ram or internal seal faults are to rest the boom/bucket on a post, connect the ram inlet to the outlet and knock the post away to see if it drops, if it does so reasonably quickly, you have oil bypassing the seals inside,. I assume you can use the ram to jack the machine off the ground ok ? (which would be trying to pull the pack off the rod internally). Could also be something mashed up inside, or fouling the oil way at the port entrance .. probably worth stripping it anyway to inspect it, and then at least you can eliminate it if all is well

[Invisible-Man]

The simple ways to check for ram or internal seal faults are to rest the boom/bucket on a post, connect the ram inlet to the outlet and knock the post away to see if it drops, if it does so reasonably quickly, you have oil bypassing the seals inside,. I assume you can use the ram to jack the machine off the ground ok ? (which would be trying to pull the pack off the rod internally). Could also be something mashed up inside, or fouling the oil way at the port entrance .. probably worth stripping it anyway to inspect it, and then at least you can eliminate it if all is well

Thanks for that Muz, would you go for Kubota ram seals at over £100 or are the ones you see on eBay etc alright at about £30.....

Thanks again....

[Muz]

Thanks for that Muz, would you go for Kubota ram seals at over £100 or are the ones you see on eBay etc alright at about £30.....

Thanks again....

The seals will be ok, the risk is whether they will be sized correctly. If I'm using a machine shop to remake parts of a ram, I usually just get them ro reseal it at ebay prices cos they can measure and get the correct aftermarket seals as they do it

[Invisible-Man]

The seals will be ok, the risk is whether they will be sized correctly. If I'm using a machine shop to remake parts of a ram, I usually just get them ro reseal it at ebay prices cos they can measure and get the correct aftermarket seals as they do it

Thanks again Muz,

So if I could get original set of Kubota seals (for decent price) there would be no concern about correct sizing?

and if so, is it a job that can be done as a confident first timer with no specialist tools as such?

Appreciate the help!

[v8druid]

Thanks again Muz,

So if I could get original set of Kubota seals (for decent price) there would be no concern about correct sizing?

and if so, is it a job that can be done as a confident first timer with no specialist tools as such?

Appreciate the help!

confident and competent are two different things

cylinders can be a bast*rd to dismantle ...... and can need specialist words to make 'em co-operate like "undo you ****ing bas**rd, tw*ting thing "

[Muz]

A ram that small should come apart quite easily, you will need a good stillson wrench to get the end cap off and will mark it in doing so, but you can buff the teeth marks back off and re paint. Leave the bottom pin in and take the top one out, lay the ram horizontally and support the rod eye end with a block... get the wrench on the end cap and undo it, undo feed pipes and get a tray ready to catch oil when you withdraw the piston .. nothing to it

[Invisible-Man]

A ram that small should come apart quite easily, you will need a good stillson wrench to get the end cap off and will mark it in doing so, but you can buff the teeth marks back off and re paint. Leave the bottom pin in and take the top one out, lay the ram horizontally and support the rod eye end with a block... get the wrench on the end cap and undo it, undo feed pipes and get a tray ready to catch oil when you withdraw the piston .. nothing to it

I managed to buy an original Kubota pack of seals for £30 + £6 postage, so real happy with that...…

Are there any re-tightening torques to worry about?

Thanks again Muz!

[Muz]

I managed to buy an original Kubota pack of seals for £30 + £6 postage, so real happy with that...…

Are there any re-tightening torques to worry about?

Thanks again Muz!

Ok.. did you do the ram drop test then ?