Case 430 cracking hydraulic pumps

Hello all,

Everyone has been very helpful in the past, hopefully someone will know the answer to my new questions. I have a mid 60s Case 440 gas with the model 22 loader and model 21 backhoe. The story as best as I can tell is that the backhoe was digging out a stump and the operator didn't feel as though it had enough grunt, so they adjusted the main pressure relief valve up higher on the backhoe control valve. After this a hydraulic line blew and after that the hydraulic pump wear plate cracked in half. I wasn't aware of the part about the main hydraulic pressure relief being turned up. I obtained a new pump, installed it and was told that the blow off pressure should be 2500 read on the boom cylinder. Well when checked the pressure wouldn't go over 2000psi. I believe that this was because the booms pressure relief valve was blowing off. I have also since found out that the setting is supposed to be 1650psi. Well i put the new pump in and raised one of the stablizers and as soon as it reached the top of its stroke the new pump cracked just as the previous one had. I am wondering where I should be looking for the problem? Is the main pressure relief valve the culprit and not blowing off soon enough to save the pump or is the problem else where? Thanks.
 
I do not have a 430CK book but in my 420B book it shows loader specs
Main relief set at 1475psi
Overload relief valve set at 1600psi
the above scans are for the backhoes control valve, start with the loader valve first then do the backhoe if you need the instructions for doing the loader valves let me know, even though the 430 valve/controls may differ the setting should be very close to these cnt
a88596.jpg

a88597.jpg
 
Thanks case nutty, looks like you think that I should be going after the pressure reliefs as the culprit. I guess I will have to back off all of the pressure reliefs and start there.
 
My dad have a pump that kept craking and found out that someone had installed a heaver spring and/or some shims in the pressure relief to increase the pressure.
 
(quoted from post at 19:39:59 11/09/12) Thanks case nutty, looks like you think that I should be going after the pressure reliefs as the culprit. I guess I will have to back off all of the pressure reliefs and start there.

The main relief is the one that is causing the pump to crack, on rare occasions a hose will seperate internally and cause a blockage which could destroy a pump but let's assume thats not a problem. The relief in question is in the section that is the first in line from the pump and has preference over all other reliefs, hence it's name "main relief". Once it is set properly you can use the info given to check all the other reliefs. You need not lower all valves, concentrate on the main relief.

Most newer units had the main relief contained in the loader valve which controlled the pressure in both loader and hoe but some early ones had the hoe valve first in line. Generally, the pump output line went to the valve that contains the relief and the relief was contained in the first section where the oil comes into the valve.

mEl
 
mEl Thank you for your insight. So your thought is that the main pressure relief which is supposed to save the pump from over pressurizing itself is not set or functioning properly. In order to determine where that main pressure relief is should I follow the pressure line off of the pump and follow where it goes to determine the location of the main pressure relief? I would assume that the loader has a main relief on it as well? In the info that I have it refers the 'Main Pressure Relief' on the backhoe control valve plate. Is this then the Relief that protects the whole system? Thanks!
 
(quoted from post at 05:52:06 11/10/12) mEl Thank you for your insight. So your thought is that the main pressure relief which is supposed to save the pump from over pressurizing itself is not set or functioning properly. In order to determine where that main pressure relief is should I follow the pressure line off of the pump and follow where it goes to determine the location of the main pressure relief? I would assume that the loader has a main relief on it as well? In the info that I have it refers the 'Main Pressure Relief' on the backhoe control valve plate. Is this then the Relief that protects the whole system? Thanks!

My first thought is that something as late as a 430-midsixties should have the later hydraulic system as per the 530 CK. Is the section posted representative of the system you have or does the pressure pipe come to the outside of the loader control valve and the inside hose go back to the backhoe valve, a series circuit with the loader valve in the first position as far as flow is concerned?

Could you post pictures of the hose routing from the pump back of describe in detail how the system is hosed up, which component receives oil first. If as I suspect, the pump flow comes to the loader valve first, the relief is in the loader valve.

I suspect that there is a drastic difference between the 420 and the 430 systems and the diagram shown is correct for those models but may not pertain to your unit. Is there a CK designation anywhere on the hoe or loader.

Post more info please or pictures would be even better.

mEl
 
mEl I do have a 580B service manual(should be very close to same specs as a 580CK and maybe a 530CK) and can scan some thing if it will help, I posted the 420 specs as a guide line for pressures mainly let me know if I can assit further cnt
 
Thanks guys,

The tractor is currently at my father in laws so I can't take a look at it or take pics for a couple days. I have a service manual for the Model 22 loader and backhoe. The literature is consistent as far as how the backhoe and loader look but the manual says that they loader is run off of the hydro pump for the eagle hitch and the backhoe is run off of a pto driven hydro pump on the back of the machine. Both of these statements are wrong since the hydro pump is front mounted to the tractor. I will have to get a look and follow the piping to find where everything goes and in what order. So if they pressure line goes first to the loaders control valve that means that the main relief valve will be in that, if it goes to the backhoe control valve then that means that the main relief is back there? Also I just wanted to sum up that everyone seems to think that the reason for the cracked pump is that the main relief being set to high? After I put the replacement pump in I ran the loader up and down without issue, then I when to put the rear stabilizers up and when it hit the top of the stroke the engine stalled, I figured that the throttle was just to slow so I started it back up, moved the throttle up a bit and put the stabilizer all the way down and when it bottomed out is when the pump cracked. Thanks!
 
yes I would say some one really cranked down on the main pressure relief way to much on the pump, that is why we always screwed a guage in to the system before changing any relief cnt
 
Was able to take a look today at the routing for the hydraulics today. The pump outputs to the backhoes control valve first. It comes out of the control valve on the opposite side to head to the front bucket control valve. I assume that this means that the main bypass valve in the backhoe control valve is the main safety?
 
(quoted from post at 19:39:22 11/11/12) Was able to take a look today at the routing for the hydraulics today. The pump outputs to the backhoes control valve first. It comes out of the control valve on the opposite side to head to the front bucket control valve. I assume that this means that the main bypass valve in the backhoe control valve is the main safety?

If that is the way its routed I would see if the relief is in the first section where the oil enters the valve and if so Iwould back that relief way down and after a repair I would carefully adjust it back up. It would be advisable to remove it to make sure all parts are ok and nothings plugged or stuck.

mEl
 
Thanks mEL,

Yes the relief valve is right where the main hydro line enters the manifold. I have the repair manual for the loader and backhoe sections with diagram breakdowns. Any idea where I might be able to get parts if needed for the relief valve? I have been unsuccessful trying to find parts breakdowns for this model 22 loader and backhoe. Thanks!
 

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