Hitachi EX75UR-5

[Locofitter]

Hi there,

I'm looking for a bit of advice with regards to our EX75UR-5, from scowling the forum for a while I thought this would be the best place from the wealth of knowledge here.

In a nutshell, it suffered a bit of a fall which caused the dipper ram rod to bend slightly. Machine was still used for a few hours after which evidently scored the internal diameter of cylinder bore to heck. Had trouble finding a used/new/reconditioned ram so went for the repair with a local engineering firm that's highly trusted. Costly but oh well.

I have very limited experience with working on excavators but this lead me to do a few basic checks on the machine and it's components.
I changed the final drive oils, the stench from many-a-year old oil made me gag, feels smoother in the final drives now.
Noticed the track tension is quite out but it looks like the tensioning wheel is almost at its max lateral adjustment, I have thought about taking a link out but appears this will ruin the sprockets.

Found all pivot bushes worn, quite a lot of movement at the pivot points. Looking at making/changing bushes ourselves. Slew ring has approx 2-3inch of rotational free movement, this seems on the verge of ok.
I have asked a manufacturer for the workshop, service, parts and user manual for this machine to which I was quoted just under £500. Bit of a joke as evidently it's a product that has no support anymore, does anyone know where I could find these manuals?

If anyone has any experience with this machine, your knowledge would be very much appreciated.
Will keep the overhaul project updated.

Thanks,

loco.

[Muz]

Well it looks like you are doing all the right things ... gear oil does stink a bit after its started to break down. Where/how were you measuring the play on the slew, boom/bucket fully out perhaps ?

As to tracks, I assume they are steel, If the pads are welded to the chains, they can be pinned and bushed to bring them back to the correct pitch, if the pads are bolt on then you would be better to replace the chains as it will give longer life. In general the sprockets will need replaced too. You are correct in what you say about taking a pad out, it changes the pitch a lot and wears the sprockets quickly. Are the tips of the sprocket teeth sharp yet? like cut your finger sharp ?

[v8druid]

Well it looks like you are doing all the right things ... gear oil does stink a bit after its started to break down. Where/how were you measuring the play on the slew, boom/bucket fully out perhaps ?

As to tracks, I assume they are steel, If the pads are welded to the chains, they can be pinned and bushed to bring them back to the correct pitch, if the pads are bolt on then you would be better to replace the chains as it will give longer life. In general the sprockets will need replaced too. You are correct in what you say about taking a pad out, it changes the pitch a lot and wears the sprockets quickly. Are the tips of the sprocket teeth sharp yet? like cut your finger sharp ?

How does it change the pitch Muz Pin centres remain the same ...... just one less link to rotate around the length of a track's full revolution.
I can understand the sprockets being worn by tired chains with extended centres

ON EDIT
there's a guy on ebay doing manuals for just about anything on CD PDF

[Muz]

How does it change the pitch Muz Pin centres remain the same ...... just one less link to rotate around the length of a track's full revolution.
I can understand the sprockets being worn by tired chains with extended centres

Hmm ? just re-quoted a dealer of old, without thinking about it .. perhaps thats only relative to systems that had sprockets at either end like some old 803's I came across .. but .. if one sprocket was an idler it shouldn't ? got me thinking now as to what he meant, and I can see what you are saying. Clearly with a centre to centre difference in pins, the wear would be greater, perhaps he meant that taking a pad out just exacerbates that and causes faster wear because the pitch is even further out on an increasingly worn track?

[Locofitter]

Many thanks for your rapid replies,

Bearing in mind I've only worked on excavators for a stupidly small amount of time, I'm applying what I think to be common sense when doing that exam so I may have done things completely wrong.

Firstly put the boom up so bucket was just off the ground, with the stick horizontal to the ground and then gently drove the bucket into the ground whilst watching all the pivot points as it gently lifted the machine off the ground.
Noticed theres quite a lot of of multi-axis play in the pivot that connects the boom to the upper structure of the machine, which worries me as it appears that the cab will have to be taken off to get to this pin. Not too sure though.
After this, I brought the bucket back up so it was roughly 2inch off the ground then tried to manually push the stick so as to slew the machine. This is where I found the 2-3" rotational slop in the ring. Cant do much about this as parts aren't available for it anymore it seems so I reckon its a case of pack it out with grease to slow the wear rate down.

Whilst doing this I noticed there was also quite a lot of play in the boom to stick pivot and also the knuckle which is situated at the top of the boom, I'll add a photo of the machine as not many have apparently seen a machine like this before.

With the tracks, I rotated the cab 90degrees so bucket is parallel with the RH track then lifted the machine, had about 3 finger widths of tension from the bottom rollers on this track, same again the other side but had 4 or 5 finger widths.
Sprockets seem ok and quite meaty, not knife-sharp yet.

From memory, the track pads are steel and 400mm wide. They appear to have had the rubber pads bolted on at some point but all have been torn off/worn away. Track pads also appear to be bolted onto the chain gang.
I took the assumption of removing a link catalysing wear rates as it looks like a link length doesnt equal to the amount of travel on a the tensioning wheel when the tracks were new (going off scoring on the channel the tensioning wheel yoke sits in), putting excessive strain on the link pins thus wearing pins and sprockets quicker. Again, going off complete novice theory here so I'm probably totally wrong.

With regards to bushes, to try and void getting a plant engineer in to line weld and line bore the pivots, I was looking at making my own from a material called Vesconite.
I have to keep costs as minimal as possible as we are a heritage railway, thus a charity.

[Locofitter]

Cant seem to post an attachment, managed to find this photo. We have the same model.

[v8druid]

although it doesn't seem a popular thing to do ....... I like this style of knuckle boom on smaller m/c.s and have been fancying/casually looking for a 5.5t Hanix, who also seem to favour this set up ..... I am NOT lover of king posts but want an offset facility .... plus I understand that the Hanix/Nissan 5.5s were built like tanks and lift like **** .... have a mate who has a customer with one local and going to go see if I can't have a play to see what it's like

I'm also reliably informed that this style knuckle is well popular in their homeland so quite a few 'grey' imports about with 'em on.

Down side, especially for Lee, is all the pins and bushes to wear ..... TBH .... as long as all bosses are bushed and not worn to the point that they've worn into the bosses .... shouldn't be too much of a job to just re-bush with new pins, without any line boring being necessary

It's either a knuckle .... or gonna have to build me a smaller VA-r for a conventional boomed m/c .... no way am I going king post!!

[Locofitter]

Never had it apart, apart from the dipper ram. Not overly sure how to take the boom off, lifting isnt a problem as we have a road rail excavator too.
I was looking at those ebay manuals on CD but something isnt sitting right about it. Someone said they would send me the manuals but then went quiet on me, cheers then!

More headaches to keep me busy I suppose.

[Muz]

shouldn't be too much of a job to just re-bush with new pins, without any line boring being necessary

Agree with that

It's either a knuckle .... or gonna have to build me a smaller VA-r for a conventional boomed m/c .... no way am I going king post!!

Whats put you off so much ? .. having operated both , using a dozer blade and king post offset gives you a much bigger arc than a boom offset ever will .. bit of a pain to prop up your machine on the dozer if you had to do it, but it works ?

[v8druid]

Agree with that



Whats put you off so much ? .. having operated both , using a dozer blade and king post offset gives you a much bigger arc than a boom offset ever will .. bit of a pain to prop up your machine on the dozer if you had to do it, but it works ?

I've yet to see a king post that looks man enough for the job Muz, with the exception perhaps of the Hydrema's king posts on the 800 to 1200 series m/c.s ..... 'kin solid

They all always look too fragile to me, but agree with you that they give you a much greater reach ..... as long as you don't break 'em

I've op.-ed plenty of king posted stuff and it's real handy, in a tight spot

[Nobody]

What is this about changing the pitch if taking out a link, i dont get it??

Also, king post is crap

[Locofitter]

I don't fully understand it either and its not what I was getting across.

What is this king post? Does anyone have any expertise to offer on the aforementioned problems, please?

[Muz]

What is this king post?

The bit that holds the boom onto a digger with offset

Does anyone have any expertise to offer on the aforementioned problems, please?

which one ?

[Locofitter]

Thought so. A planetary gear set on ours.

All of the presented issues.

[v8druid]

I don't fully understand it either and its not what I was getting across.

What is this king post? Does anyone have any expertise to offer on the aforementioned problems, please?

Thought so. A planetary gear set on ours.

All of the presented issues.

I've yet to see one of these I'd trust, other than as previously mentioned Loco




What's the planetary set reference to Boyo ???

If you're talking 'bout all the worn pins etc., I've already said that you'll need to see if you can get away with simply replacing bushes and pins if the bosses aren't affected..... but'll possibly need to strip it down to see perhaps?

Gonna have to go back and have a re-read for the rest