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Slow Excavator Hydraulics

P

PAPS Landscape

Member
Joined
Mar 22, 2005
Messages
13
Hello guys... I have a PC75 Komatsu excavator, with about 4000 hrs. I have noticed that the hydraulics are starting to slow down... cant move the stick as fast, curl the bucket as fast.. etc.. anyway to turn that back up and make the machine a little bit faster.. its still plenty manageable, but like most guys, like that fast quick feeling when you pull on the controls.. thanks for input.
 
AtlasRob

AtlasRob

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Feb 8, 2008
Messages
1,982
Location
West Sussex UK
Occupation
owner operator
filters

T_S_S said:
when was the last hydraulic oil and filter change
?
Click to expand...

Its amazing how many people dont realise that (A) there is a hydraulic oil filter, or (B ) by 4000hrs the oil probably should have been changed. I say probably as different machine manufacturers recommend different hours.

Definetely the first place I would check.
 
W

WVBartMan

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Joined
Mar 25, 2008
Messages
15
Location
West Virginia
Occupation
Excavation Manager
Paps: We have a 2001 PC75R-2 and it has two hydraulic filters. One you can wash out and the other is the standard replacable cartridge type. I would highly recommend cleaning/replacing your filters and see if that cures your problem.
 
John C.

John C.

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Filters and oil are one part of the issue but probably not the whole story.

You might have just gotten used to the feel and are now so fast at running the machine it seems slow. Run a cycle time on the boom up function. Stretch out the stick, open the bucket and set it on the ground. Now with the engine at full throttle, snap the boom control to full up and then time how long it takes to top out. It should be about 4 seconds or less. 4.5 seconds is getting slow while 3.5 seconds is very fast.

The other item to check is the fuel strainer in the priming pump suction fitting on the engine. They always have a brass or plastic strainer in the banjo bolt that plugs up over time. It has been the biggest source of agitation on those machines that I can remember.

Good Luck!
 
P

PAPS Landscape

Member
Joined
Mar 22, 2005
Messages
13
i believe we replaced the hydraulic filter at the top of the tank, where else would there be one, that I am not missing? maybe I will drain the tank and try new fluid, the problem is that there is a lot of fluid in the pistons, so how do you really fully drain the system?
 
AtlasRob

AtlasRob

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Feb 8, 2008
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Location
West Sussex UK
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owner operator
Hyd oil change

PAPS Landscape said:
maybe I will drain the tank and try new fluid, the problem is that there is a lot of fluid in the pistons, so how do you really fully drain the system?
Click to expand...

Unless the machine has had a catastophic event in the hyd system, which has put a lot of foriegn debrie in the system ( which I dont believe you have )then a change of the oil in the tank is considered an oil change. Be careful, draining the tank may drain the pump. ( Atlas has a butterfly valve to stop this ). Get expert advise / manual to make sure you know how to purge air from pump after oil change. A $100 oil change can become a $1000 pump replacement if you are not careful.
This may not be relevent in you case, BUT PLEASE CHECK.!
 
W

woberlin

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Dec 14, 2004
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111
Location
malvern, ohio
Occupation
excavating contractor/bodyshop owner
There is also a strainer @ the bottom of the tank. You may want to check your throttle linkage. My hydraulics were slow when I got my pc-75, and I finally looked at my throttle linkage and was only getting about 2/3's full throttle. Makes a big difference! Not sure why it was set that way, but it was. There is also another fuel filter on the firewall in the engine compartment by the tank.
 
G

Gothgirl

Member
Joined
May 3, 2010
Messages
5
Location
Kalorama Vic
Komatsu PC series excavator

PAPS Landscape said:
i believe we replaced the hydraulic filter at the top of the tank, where else would there be one, that I am not missing? maybe I will drain the tank and try new fluid, the problem is that there is a lot of fluid in the pistons, so how do you really fully drain the system?
Click to expand...

Yep, there are 2 filters for the hydro system.
One, in the top of the hydro tank and is spring loaded to help keep it in place and for anti-hammer and usually a paper inside metal element type, the other is fully submersible in the bottom of the tank as a screw-on type made of very fine metal mesh and is washable(solvent).The only time to replace the bottom one is if its been too damaged.
 
O

osei owusu

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Feb 4, 2013
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4
Location
ghana
pls try and check your hydralic filter and when wasthe last time you change your oils and filters check all filters
 
T

Techmuch

New Member
Joined
May 5, 2018
Messages
2
Location
West Sacramento
PAPS Landscape said:
Hello guys... I have a PC75 Komatsu excavator, with about 4000 hrs. I have noticed that the hydraulics are starting to slow down... cant move the stick as fast, curl the bucket as fast.. etc.. anyway to turn that back up and make the machine a little bit faster.. its still plenty manageable, but like most guys, like that fast quick feeling when you pull on the controls.. thanks for input.
Click to expand...
Check your safety or potentially meters.
If some one disconnected them and put them in wrong position it will do exactly what you did tell about.
 
RjMaan

RjMaan

Active Member
Joined
Mar 23, 2018
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Location
Pakistan
I think it is some kind of issue in oil. You should change the oil or see whether their is some kind of leakage in the hydraulic system or not.
 
EatsCookies

EatsCookies

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May 7, 2018
Messages
3
Location
Dothan, AL
OK I haven't looked up the breakdown for your Komatsu, but pretty sure you have 2 hydrostatic pumps in that unit. You can change the oil and filters now, but, if the situation doesn't improve, then the pumps are prolly at issue, and when the pumps are changed you will have to have the system flushed all over again. With hydrostatic pumps, this is not a do-it-yourself project. Sorry. Too many variables and too many high-dollar things that can go wrong, so you will want to go to a reputable place to get your equipment fixed.

I kinda got ahead of myself, but I would suggest getting those pumps pressure checked to see if it's the pumps, or if an oil change will suffice.
 
T

Techmuch

New Member
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May 5, 2018
Messages
2
Location
West Sacramento
I just fixed same issue on my PC 28.
If it is only slow on one direction , toward
the cab, it is potentiometer problems. Sistem "thinks" you are about to hit the cab and slows stick/bucket down.
If it slow in every direction, then it is hydraulic problem.
 
r20d12

r20d12

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Joined
Nov 29, 2009
Messages
123
Location
oklahoma
Occupation
heavy equipment field tech since July 1990
Is the engine bogging down under a load or does the engine pull down farther than it should when you bottom out a cylinder? Proper engine rpm is very important. If its not turning fast enough, your not moving as much oil which will slow your machine down. If it pulls down under a load you could have a plugged fuel filter or air filter. If engine rpm drops when you bottom out a cylinder then you could have something causing your pump to put out too much flow. The pump can actually stroke enough to make the engine die. There are automatic controls in the system that regulate engine rpm and hydraulic pump flow.
 
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