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  #1   IP: 78.151.195.213
Old 02-01-2019, 01:39 PM
Atlas404 Atlas404 is offline
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Default Slow digger rams

Hello folks, hoping some hydraulic experts on here can help me with my 1998 atlas 404 mini digger. It has 2360hrs on the clock and overall works and tracks fine with plenty of power.

Here a pic of the old beast!



The only thing bothering me with it is the speed of the dipper and bucket rams is rather slow, still plenty of power but slower than the boom. I have had the bucket and dipper rams rebuilt with new seals and no change. I have also tried swapping the hoses over under the floor of the machine so that the boom service was on the dipper service and the dipper ram still moves slowly, which to me just leaves the hoses?

So i removed some hoses today and noticed that every ram has a different sise hose diameter at one end from the other, iím guessing this is wrong and restricting the flow?

Here are some pics of my findings







Could this be the route of my problems? I think the big hoses are 3/8 and small 1/4

Cheers
Greg
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  #2   IP: 78.145.10.216
Old 03-01-2019, 01:27 PM
Atlas404 Atlas404 is offline
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Default Re: Slow digger rams

Changed small diameter hose on the dipper today and still the same
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  #3   IP: 5.70.73.194
Old 04-01-2019, 11:09 AM
digger man digger man is offline
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Default Re: Slow digger rams

Hi,

You mite have more luck posting on www.planttalk.co.uk , this is where people have moved to......
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  #4   IP: 82.69.69.187
Old 04-01-2019, 06:22 PM
Uffex1900 Uffex1900 is offline
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Default Re: Slow digger rams

Good day
When you say it is slow have you timed the cylinder with full engine speed?
Arm in cylinder out often has the possibility to increase the flow many machines have some form of restriction on the negative side of the cylinder that may be a smaller hose on your machine. Suggest you begin with timing the cylinder Atlas should be able to tell you what the time should be.
Kind regards
Uffex
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  #5   IP: 151.230.151.118
Old 20-01-2019, 07:09 PM
Edenboy Edenboy is offline
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Default Re: Slow digger rams

I'm not sure what type of hydraulic pump you have on your machine but it could be that. If its a 2 stage or 3 stage pump you'll find each segment of the pump operates different operations. (dipper and bucket one segment, blade and left track another segment etc) Try using one of your slow operations and pulling say the blade lever at the same time until it pressurises? If it has more power it will probably be one stage/slices of your pump is cracked, worn or seals have gone.
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  #6   IP: 78.145.10.216
Old 23-01-2019, 09:32 AM
Atlas404 Atlas404 is offline
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Default Re: Slow digger rams

Think its time i bite the bullit and upgrade to a new machine as not worth splashing out on pumps etc. I am on a job just now shifting just over 100 ton of type 1 with it and it digs strong all day just a tad slow on the cycle times, not sure what the times should be, atlas sent me a manual which is all in German lol

I think the pump is split into two, it has one large inlet pipe and two smaller pressure pipes coming from it, am gony guess parker gear pump?

Just weird how swapping the fast boom service to the dipper ram still remained slow which to me still points to rams/hoses, anyway iím just going to live with it till another machine comes along.

Quite fancy volvo ec15b next, thanks for your replies folks

Greg
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  #7   IP: 78.145.10.216
Old 23-01-2019, 09:36 AM
Atlas404 Atlas404 is offline
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Default Re: Slow digger rams

Still out earing though

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  #8   IP: 212.88.42.35
Old 27-01-2019, 04:30 PM
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V8Druid V8Druid is offline
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Default Re: Slow digger rams

sorry matey ..... didn't pick up on this here, but have seen your issues on P&C forum.
it's certainly an odd issue for sure and the fact that it's not altered by swapping service lines around??
what are the ram rods like ... no signs of bends or binding in the glands ?
might possibly be seals bypassing under working pressures, but not bad enough to bypass without being pressurised??
or
even pistons loose on rods and bypassing that way, but would expect them to bypass unloaded too if that were the case.

new seals is an easy try/fix
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  #9   IP: 78.145.10.216
Old 28-01-2019, 08:46 AM
Atlas404 Atlas404 is offline
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Default Re: Slow digger rams

I took the rams and pistons to a hydraulic specialist to have the piston and gland seals changed. I never gave them the cylinders tho as i left them on the machine due to pins being stuck. Either the cylinder bores are worn or they have fitted wrong seals and still allowing bypassing perhaps.
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  #10   IP: 212.88.42.35
Old 28-01-2019, 09:30 AM
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V8Druid V8Druid is offline
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Default Re: Slow digger rams

Quote:
Originally Posted by Atlas404 View Post
I took the rams and pistons to a hydraulic specialist to have the piston and gland seals changed. I never gave them the cylinders tho as i left them on the machine due to pins being stuck. Either the cylinder bores are worn or they have fitted wrong seals and still allowing bypassing perhaps.
unlikely that will have occurred, I'd have thought, so may well not be the issue if it is still the same
the pipe work being different sizes end for end is obviously not going to help either as the flow rates will be different in smaller bores ... a given pressure will only flow a given amount of oil in a particular bore size but the returns should be to open ports so should therefore flow more easily ..... however as said the smaller bore has limits
be worth trying to equal up the return bores with the other sides of the rams.
are the boom cylinder hoses equal?
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