CX240 Low power

[GaryHoff]

Hi,

I have a cx240, with the cummins engine. I am not satisified with the hydraulic performance of the unit, as it seems to have a hard time even picking its tracks off the ground when digging. The pressures are in spec (5000psi standard and 5400psi power lift). The unit also has a long stick on it. I want to turn up the pressures, and was wondering how high would be ok without risking pump damage? Or has someone ran into this issue before, and had a simple fix?

Thx

 

[John C.]

What brand is this CX240?

 

[willie59]

I'm gonna take a guess he's talking about a Case CX240 John C.

Pressure is 5000 psi, and you want to turn it up to what? How did you obtain this pressure reading, onboard display? Is it only the boom that doesn't have good down force pressure (picking tracks off ground)? Is it possible boom relief valve faulty? Possibly piston seal bad in boom cylinder?

 

[GaryHoff]

Sorry, let me clairify.
It is a case cx240
My issue is lifting power. Most excavators have strong enough hydraulics that the stick and boom can drag around the machine easily. They also tend to have enough hydraulic power that if the operator was to try and pick something too heavy up, the machine would simply lift its back tracks up, rather than stall the hydraulics.

Currently this case cx240 isnt able to drag itself around. It seems to be lacking in hydraulic power.

Pressures were checked on the onboard screens, and with a gauge. They were within 20psi of each other, so I am assuming the computer is reading correctly.

It seems to me that the boom is the main concern for low lift power. With a heavy load on the bucket, the boom will go a certian height and stop, at that point the boom will not go up any more, but the stick is still able to go out.
There is a circuit relief for the boom circuit, but if that was faulty, shouldnt the main pressure read lower with the boom stalled up?
If boom cylinder seals were bad, shouldnt a load drift down or slowly drop?

The circuit reliefs should all be set to 5700psi.
Now for the loaded question. How much pressure increase is too much? Im thinking of turning all the pressures up 500psi.

What pressures are Deere and Komatsu running?

 

[John C.]

When the Japanese excavators took over the market they specifically designed them to not be able to throw themselves around at all. You use the breakout force of the bucket to load it and not the crowd and boom force. The days of picking up till the back of the excavator tipped forward are pretty much done. I had a Komatsu rep tell me one time that if we wanted a crane we should go buy one.

As far as turning up the pressures go, it might not do you any good if the system is load sensing. Basically the pumps will destroke to minimum output when they get to around 4900 PSI and you will only have enough pressure to hold the weight where it is. The other thing you need to consider is the extra wear and tear you will put on the soft parts of the system. You probably have six wire hoses from the pumps to the main valve but probably 4 wire from the valves to the implements. In any hydraulic machine you will have huge spikes in pressure the are so sudden and short that the hard parts won't feel it. The soft items like hoses and O ring seals will absorb those shocks for awhile but they can only take so many of them and they give up.

You can do what you want if it is your machine and money. Just remember who gets the blame if and when something happens that you didn't expect.