Issues with loader dump after overpressure/blown line L5460

TheOldHokie

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Equipment
L3901/LA525, G2160/RCK60, G2460/RCK60
Apr 6, 2021
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Myersville, MD
windyridgefarm.us
I was able to find the hydraulic schematics in the service manual. I’m convinced the issue is with the load check valve not fully operating.
Yes, I looked at that yesterday. As I suggested remove and inspect it. Its just a one way poppet.

Unfortunately, if its damaged replacements are NLA. I know in the past components (poppet??) from other valves have been successfully swapped in.

Dan
 
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TheOldHokie

Well-known member
Lifetime Member

Equipment
L3901/LA525, G2160/RCK60, G2460/RCK60
Apr 6, 2021
12,893
7,320
113
Myersville, MD
windyridgefarm.us
I know this seems like a possibility but its a reverse flow check on the pressure out port. Your tests show that port is working fine. I can not visualize how the load check could block the return port.

Dan
 

CdnSldr.ret

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Aug 26, 2021
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NW Ontario, Canada
I know this seems like a possibility but its a reverse flow check on the pressure out port. Your tests show that port is working fine. I can not visualize how the load check could block the return port.

Dan
It has been a few years since I’ve had to read hydraulic schematics, but the load check operates in the return circuit does it not? Supply pressure actuates the load check to allow return flow.
 

TheOldHokie

Well-known member
Lifetime Member

Equipment
L3901/LA525, G2160/RCK60, G2460/RCK60
Apr 6, 2021
12,893
7,320
113
Myersville, MD
windyridgefarm.us
It has been a few years since I’ve had to read hydraulic schematics, but the load check operates in the return circuit does it not? Supply pressure actuates the load check to allow return flow.
No. The load check operates on the pressure out port.

Example:

When the loader is in a raised position pressure in the lift work circuit is held by the glands on the spool. They block both ports.

If the spool is shifted to further extend the cylinder the glands are repositioned to divert pump flow to the output port and simultaneosly open the return side.

The load check valve keeps the pressure port shut until pump side pressure builds and exceeds the existing pressure if any in the work circuit. At that point pump pressure forces the check valve open and flow goes to the cylinder. This prevents any held load from sagging as the port transitions to open and pressure builds.

Dan
 
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