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Cat 320 ....Hydraulics area little slow ????????????????????

Discussion in 'Excavators' started by Cat_man320, Jan 9, 2013.

  1. Cat_man320

    Cat_man320 Well-Known Member

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    I have an older 320 cat along with several other Cat excavators. Its a 9KK model circa 2000. The excavator is a little slower than the other ones .
    I was wondering can the hydraulic pump be adjusted a bit to increase speed ? Thanks for any input .
     
  2. jey_c

    jey_c Senior Member

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    Call a mechanic, I mean a good mechanic. And never try to adjust the hyd. pump before you put gauges and test all the hyd. system to see why the machine is slow
     
  3. Totallyplant

    Totallyplant Member

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    A Pressure drop can make the machine slow. If the machine working pressure is good then it might be worth checking the fuel system if the engine isn't running at full RPM. If the pressure in the pump is as it should be then this is a good indication that the hydraulic pump is okay. Another option would be to adjust the hydraulic pump, but this will depend on the type of pump in the machine.
     
  4. Aron

    Aron Member

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    The pressure drop,maybe cause the machinery slow.But the pressure is the same as before.It is not the hydaulic pump problem.Which part is slower?
    The working equipment?or the machinery moves slower?
     
  5. Cat_man320

    Cat_man320 Well-Known Member

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    Thanks for the replies. The 320 is slower on every movement. I never run my machines at full throttle , some operators say you have to but I don't. I usually run my 320 at 7 or 8 but never 10 . I save a lot of fuel and do just as much work . It may be that the pump is worn and cannot produce pressures needed, but I don't know for sure .
    So the pump can be adjusted to perform better ?? Thanks again .
     
  6. Totallyplant

    Totallyplant Member

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    Sounds like you really need to get an Engineer to look over this machine for you - to start with they will need to check the working pressures on the machine and then check your pump pressure, for example if the pump pressure is good but the working pressure on every service is low it could indicate a main regulator valve problem. If both the working pressure and pump are low then it would indicate a problem with the pump. If this is the case an Engineer would need to look at the hydraulic pump to see if it can be adjusted. Without seeing the pump ourselves it's difficult to actually confirm that this is possible in the case of your machine (there are some pumps which can't be adjusted - theoretically the pressures are set when the pumps are manufactured). Where you aren't using the machine on full throttle you will get the same pressure but less oil flow to the machine - this may make the machine a little slower. http://totallyplant.com
     
  7. Per Eriksson

    Per Eriksson Senior Member

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    Most of the times it's an engine issue, fuel or governor control.

    On your's I'd start with a governor control calibration without even hesitating.
     
  8. John C.

    John C. Senior Member

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    Making sure that any fuel suction screens are clean is usually the most cost effective place to start. Air filters are another item often over looked. Pressure reliefs may have lost a little because of work hardening of the springs but those are easy to adjust. The pumps them selves are adjustable for flow but unless you absolutely know what you are doing, you are best to leave that to a professional.
     
  9. Bob/Ont

    Bob/Ont Senior Member

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    You need a hyd tune up. First check out the engine under full load with pump control over ridden. Then callibrate the speed dial and the PRV valve. Then dig and see if it improves. If still sluggish tee a couple of gauges into the NFC lines at the pump to ensure the pressure is dropping to around 100 PSI when working. If they are not dropping off when circuits are used the Slow return check valve may be backing out and need tightening up. It's in the same aluminium valve body as the cooler bypass valve. Then all pressure relief valves are set to spec.
    Later Bob
     
  10. Cat_man320

    Cat_man320 Well-Known Member

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    Thanks gentleman for the advice . I am no hydraulic expert and some of this may be over my head because I can't pinpoint the different valves . My machines are regularly maintained with complete filter changes, I would have no problem doing some procedures if I had a hydraulic service book that explained what each valve does and where its at . Right now I'd be like a bull in a china shop, I can't go messing with things I know nothing about. I doubt that the cat dealer(Toromont) here in Newfoundland would have a hydraulic specialist that knows much more than me unless he gets into the service and procedures of the hydraulic system . I'm trying to find a hydraulic service manual that can tell me exactly what to do and the correct procedures to follow . I don't mess with anything I know very little about .
     
  11. Jam

    Jam Well-Known Member

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    Hello bob... Out of curiosity how is the slow return valve adjusted? I see it has two blanking plugs on the top. I had a look down into one of them and could see a spring assembly crossing inside. Would I be right in thinking the big return pipe going to the tank has to be opened off and the adjuster sits in the middle of this fitting?
     
    SouthSask likes this.
  12. oldtom

    oldtom Well-Known Member

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    Cat man 320 at 12 years you don't say hr meter reading you pump may bedown om flow what most miss that the modern hydraulic excavator is just a hydraulic power pack if flow's down cycl times will be slow your Cat dearler should have some one and tooling to carry out hydraulic test to pin point problem's
     
  13. Bob/Ont

    Bob/Ont Senior Member

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    Jam, the slow return check valve usually comes loose and backs out so far it can hardly open at all. This raises the back pressure on the pump and the NFC valve feels thi spressure and holds the pumps at minimum output.
    Later Bob
     
  14. jimson

    jimson Well-Known Member

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    I might be clear off base, does the machine have fine swing control? Could it be switched on? I had a machine with it and i never used it, didnt know anything about it. One day the switch got flipped when i took the seat belt off and threw it to the side. When i got back on the machine everything operated slow. It took a while to figure that one out. Just an idea.
     
  15. Jam

    Jam Well-Known Member

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    Cheers bob. Does anyone have an illustation of this valve setup on a little 312bl serial 9fs. Im just going through her before the weather comes good again and would like to check it. Any help with regards to checking the valve would be appreciated
    Thanks
    James
     
  16. Bob/Ont

    Bob/Ont Senior Member

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    Jim, I will try to look up a pic for you, but in the mean time look at your hyd lines as they return to the cooler and back to the hyd tank. The lines (several) should connect to a block of aluminium. There should be a line from the main control valve and tee'd into it a line to the swing motor. This is the slow return check valve that holds back pressure for the swing motor make up valves to prevent swing motor cavitation as you release the swing lever and it travels around on it's own. Then there should be an other line back to the filter at the tank. This is the cooler bypass valve. It allows cold oil to bypass the cooler and return to the tank with out bursting the cooler.
    Later Bob
     
  17. Jam

    Jam Well-Known Member

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    I had another look at this earlier. Here is the valve body with the two valves

    [​IMG]

    My swing motor line doesnt appear to be tee'd into body it goes into the side of the main chest

    [​IMG]

    I opened the blank plug nearest the cooler lines and could see a 13mm nut and thread below. This has a little locking tap on the back of it so would i be right in saying it should be fine?

    [​IMG]

    I then opened the front plug to see a spring assembly which i presume hold the backpressure in the system

    [​IMG]

    Is there anyway of telling is the back pressure to spec? The reason im checking through these bits is every now again if working on a batter when you leave go the swing the house may slow to nearly a stop and then turn away slowly for another few degrees on its own. It might only happen once a week but im curious to get to the bottom of it.

    Thanks
    James
     
    Last edited: Jan 24, 2013
  18. Nwufor

    Nwufor Member

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    Jam you hijacked the solution to the initial problem...now you're talking about your own...I have a similar problem and am trying to follow up to a solution....
     
  19. Welder Dave

    Welder Dave Senior Member

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    Should start a new thread as this one is from 2013.