Hitachi EX27u Low Pressure ?

Discuss excavators here
User avatar

FOWLER MAN
Posts: 2358
Joined: Wed Dec 09, 2009 11:28 pm
Real name: fred evans
Has thanked: 1295 times
Been thanked: 1111 times
Flag: Wales

Re: Hitachi EX27u Low Pressure ?

Post #11 by FOWLER MAN » Tue Jan 23, 2018 10:45 pm

Hello again John,
I'm pretty confident that the machine should have cleared the air from the system by now.

If I may I'd like to make a few observations. :think: Firstly I don't think you should expect the machine to lift itself effortlessly with the blade on the ground behind as it will then be attempting to lift the whole weight of the machine whilst with the blade off the floor you are virtually only rocking it on its tracks.

The boom ram is mounted to give maximum power to lift the arm ,not to exert maximum downward pressure.
The power at the ram is in direct proportion to the piston area and when you lift the boom it utilises the whole of the piston area to produce maximum power.
On the downward stroke the cross-sectional area of the of the rod must be deducted from the area of the piston face reducing the power proportionately. :geek:
Also, because the same volume of oil will be pumped into both ends of the ram and it will take less oil to fill the rod end, the ram will travel faster when closing. This has the effect of gearing up the system and also reducing power on the downward stroke. :ugeek:
I haven't seen how your machine performs, but you may well be worrying about nothing. :roll:
The pressure test will give you the answer. :thumbup:
Fred


Topic author
le.maisonniau
Posts: 47
Joined: Sat Nov 26, 2011 9:15 pm
Real name: John
Location: France
Has thanked: 36 times
Been thanked: 6 times
Flag: France

Re: Hitachi EX27u Low Pressure ?

Post #12 by le.maisonniau » Sat Jan 27, 2018 11:52 am

Hi Fred,
Sorry I am just getting back to you, I didn't spot my topic had gone into 2 pages :roll:
:bow: You are absolutely correct. :bow:
My Mate came over on Thurs and we (he mainly) took off the dipper ram and replaced a leaky seal [1 hour] There is now NOT ONE drop leaking anywhere on the m/c- well impressed :claphands:
He forgot his pressure guage but we exercised the m/c and I walked him through my concerns over the boom not raising up the m/c.
He told me exactly what you have said and that the m/c wouldnt/couldnt lift up as I was expecting.
The m/c is well up to spec pressure wise as well, even without testing the pressure, judging by how easy and quickly I can lift the m/c up on the blade etc. how quickly and smoothly all other rams work.
I understand now your physics on the rams etc. and as you point out the dozer Ram has a much larger cross sectional area and shorter stroke, which is why it works as you describe.
Many thanks for you informative reply and again a confidence boost.
I just need to wait for the rain to stop so I can get outside and give the new bearings on the tracks a test, then it is just tidying up the body panels, adding a couple of whizzy LED worklights (Just got some off Amazon 16LED in a 4x4 matrix 48watt 6500k for 8euro each :thumbup: Hope they last :lol: ) and then get the m/c up my woods for some serious work. :thumbup:
When you come to a fork in the road - take it :dizzy:


Topic author
le.maisonniau
Posts: 47
Joined: Sat Nov 26, 2011 9:15 pm
Real name: John
Location: France
Has thanked: 36 times
Been thanked: 6 times
Flag: France

Re: Hitachi EX27u Low Pressure ?

Post #13 by le.maisonniau » Sun Jul 04, 2021 9:44 pm

Update:
Amazed at how much time has passed since my last post in 2018 - it way past time for an update on my Hitachi EX27u, etc.

The rain did stop (2018 :D ) so I managed to get out and test the new roller bearings and idler track cogs which I stripped down completely, freed up the grease cylinder and smoothed the track/rail it slides on.
All working a treat, stripped off the side panels and gave the subframe a good paint before putting the drive and tracks back together.


Managed to do lots of digging around the house in 2019 and 2020. added lots of whizzy lights, USB charger for phone etc.
The LED working lights are great, I will post a picture of them, quite pleased with my lighting panel work inside too :-)
Few little jobs around the Hamlet digging for neighbours ;)

2021, after brief stay in Hosp January for a major op (Old mans stuff) and as I am having to take things easy (70 this Aug :lol: ) I am doing lots more digging, I now have a huge job landscaping around a pool for a new neighbour. I am also looking for another tractor to pull the Indespension trailer, which I cannot get registered in France due to serial number plate missing !!! guy I bought it from skittled back to UK and lost contact with him - hmmm. :cry:

(got my eye on a Ford 6640 SL :lol: )


So, during this last bit of work, a couple of issues have arose, perhaps someone can enlighten me ?

#1 with the bucket placed 'barely' on the ground, there is no power to do a side-sweep, i.e a bit of smoothing or levelling, similarly if I try and push the bucket up a bank to do a bit of grading, there is no power either. (No power as in trying to slew the bucket on the ground results in zilch.

I have power for normal digging, lifting a full scoop etc. but not in these two cases !!

So today, I drained the oil and put in new hydro filters and also cleaned the cleanable suction filter, it is spotless inside now, added fresh HVI - 46 oil, air purged and it now sounds great and lifts itself off the ground on the blade and boom ok in my woodyard, so I will do a test sweep in the next week when I go back to work :-).

#2 final drive motors, I also changed the oil in these two guys, flushed them out and filled up with fresh. The old oil wasn't too bad, just a minor smell of burn (Sulphur !). Then with the m/c raised off the ground the tracks whizz around nicely and also very nice in hi-gear, BUT when on the ground the RHS seems to lack oomph ! that is the m/c seems to favour the LHS track, I will have a look at the control levels, maybe they can be calibrated?

Can anyone suggested a way I can check to see if the track motors are working correctly ? how to check if it is a planetary gear thing or hydraulics.


#3 I have 3 clogged grease points
1 on the bottom of the kingpin (top one is fine)
2 on the ram at the bottom of the main boom
3 on the end of the pivoting ram (the one that turns the boom left or right, not swiveling)
I have taken the nipples off, poked and prodded, but NBG, the one at 3, has a bush in, which I can get at, so possibly put in a new bush?


Finally, I also added a grapple which works fine on the two fitted pipes, but I don't have pipes or switching so that I can rotate the grapple, Is this an easy mod? where would I start ?

Cheers guys, stay safe
When you come to a fork in the road - take it :dizzy:


essexpete
Posts: 4053
Joined: Fri Jul 13, 2007 12:43 am
Real name: essexpete
Has thanked: 848 times
Been thanked: 678 times

Re: Hitachi EX27u Low Pressure ?

Post #14 by essexpete » Mon Jul 05, 2021 12:11 am

What area in France John if you don't mind me asking?


Topic author
le.maisonniau
Posts: 47
Joined: Sat Nov 26, 2011 9:15 pm
Real name: John
Location: France
Has thanked: 36 times
Been thanked: 6 times
Flag: France

Re: Hitachi EX27u Low Pressure ?

Post #15 by le.maisonniau » Mon Jul 05, 2021 8:35 pm

Hi, Im in the Limousin (Haute Vienne) or now its Nouvelle Acquitaine, not far from Limoges
When you come to a fork in the road - take it :dizzy:


Return to “Excavators”

Who is online

Users browsing this forum: No registered users and 2 guests