Hitachi Hose Rupture Valve

[auy_tong2]

Hi, I would like to ask if somebody has any idea why my hose rupture valve is losing pressure arm is dropping in netural and oil is leaking to the return line... I checked the valve and seems ok..

1 line goes to pilot pressure from the control valve
2 line is for return line
3 line im not sure... it also goes to return line?

 

[uffex]

Good day
HRV has two leaking possibilties 1/ the spool 2/ the shock valve most probable. Strech the arm out rest on the deck - plug the main line and test (mesaure bofore & after) > same proceedure plug the shock drain line. This will tell you where the fluid is leaking. Post a photo of the valve maybe can help some more .
Kind regards
Uffex

 

[auy_tong2]

Good day
HRV has two leaking possibilties 1/ the spool 2/ the shock valve most probable. Strech the arm out rest on the deck - plug the main line and test (mesaure bofore & after) > same proceedure plug the shock drain line. This will tell you where the fluid is leaking. Post a photo of the valve maybe can help some more .
Kind regards
Uffex

thanks for the reply, its leaking in the big hose return line..and the arm is dropping...could it be the relief valve?
checked everything inside and is ok...expect for the relief i havent checked

 

[auy_tong2]

you main line-pilot line?
shock drain line - the check valve?
drain line -?

 

[auy_tong2]

plug this line going to drain. stops the arm going down...

 

[uffex]

Good day
Normally you will have three lines connecting the HRV 1- the large main line from the main valve block 2- a small release line that connects with the line from the remote control valve in the cabin 3- a middle size drain line for the back side of the spool and port relief valve. I cannot be absolutely certain from the illustration however I would suspect you have spool leakage. However as a rule the fluid would lock up at the main valve spool thus preventing leakage. Is there any identification on the HRV.
Kind regards
Uffex

 

[auy_tong2]

Good day
Normally you will have three lines connecting the HRV 1- the large main line from the main valve block 2- a small release line that connects with the line from the remote control valve in the cabin 3- a middle size drain line for the back side of the spool and port relief valve. I cannot be absolutely certain from the illustration however I would suspect you have spool leakage. However as a rule the fluid would lock up at the main valve spool thus preventing leakage. Is there any identification on the HRV.
Kind regards
Uffex

this diagram would help?thanks

 

[auy_tong2]

if you are saying large line that is what i plug and stop the leaking...the 2 other hose are small ones..

 

[uffex]

Good day
The diagram is good but it relates to boom cylinders not an arm cylinder, the very small line is pilot and has nothing to do with leakage unless it has pressure all the time holding two spools open (Unusual). The fluid is locked in the negative side of the arm cylinder by three valves in your example 1/ The HRV 2/ MCV 3/ An additional lock valve between MCV & HRV.
If fluid can pass the HRV it will simply pressurize the lock valve effectively stopping the leak.
Any fluid getting past the lock valve will be blocked by the main control spool, although some leakage at this point is normal I find your statement that the fluid is passing the HRV main line difficult to understand.
Kind regards
Uffex

 

[auy_tong2]

Good day
The diagram is good but it relates to boom cylinders not an arm cylinder, the very small line is pilot and has nothing to do with leakage unless it has pressure all the time holding two spools open (Unusual). The fluid is locked in the negative side of the arm cylinder by three valves in your example 1/ The HRV 2/ MCV 3/ An additional lock valve between MCV & HRV.
If fluid can pass the HRV it will simply pressurize the lock valve effectively stopping the leak.
Any fluid getting past the lock valve will be blocked by the main control spool, although some leakage at this point is normal I find your statement that the fluid is passing the HRV main line difficult to understand.
Kind regards
Uffex

the pilot line is the only one going to the control valve if i will follow the hydraulic hose and the 2 remaining hose is going to the tank drain... the big hose which i plugged also goes to the tank.drain..

 

[uffex]

Good day
Give me a photo of the valve mark where the lines go so I am clear what you have.
Kind regards
Uffex

 

[auy_tong2]

im guessing the large line is this in the diagram going to tank drain and the relief is the one causing the leak...because even if i plugged the leaking port... everthing goes well on the function on the arm cylinder...

 

[auy_tong2]

Good day
Give me a photo of the valve mark where the lines go so I am clear what you have.
Kind regards
Uffex

thanks tomorrow i will take a picture thanks