I have a L555 serial number 624???. so it is a old machine after 4 yrs getting back to work on it. Previous owner locked out hand control for the boom hyd controller. I don't use or intend to use aux hydraulics on the machine and was wondering if I could bypass this section of the hydraulics. The main charge line from the oil cooler burst. They offer a cap to block this off, but can I just install a plug into hose fitting for return from aux hydraulics controller? I don't want to go to expense of hydraulic hose for something I don't or won't use.
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Help Support SkidSteer Forum:
Only if you want to blow your hydraulic pump up. You need to go to the NH website and to their parts catalog and identify which hose or line you are referring to. You are talking about the valve where the couplers go out on the front of the boom, correct? You can remove the aux hyd out of the circuit quite inexpensively, but it may not be a job you want to tackle. You will need to remove the fuel tank so you can remove the main hyd control valve. A fitting needs to be removed and a plug installed. The return line from the aux valve will also need to be disconnected and the main return line capped.
The Valve I'm referring to has a charge line that is T'ed off the oil cooler line on the main hyd control valve and has a line that goes to each side of machine (capped off on each side) and the other line goes to the aux hyd control valve with two lines going to connectors and other return line. On my machine it is located on the right front corner of cab and has cable running to right control stick, which has been bolted in place. Messicks calls it a Boom Hydraulics Control Valve. I'm guessing it may be for controlling a grappler or maybe a snow plow attach. I hope this may clear it up some.Only if you want to blow your hydraulic pump up. You need to go to the NH website and to their parts catalog and identify which hose or line you are referring to. You are talking about the valve where the couplers go out on the front of the boom, correct? You can remove the aux hyd out of the circuit quite inexpensively, but it may not be a job you want to tackle. You will need to remove the fuel tank so you can remove the main hyd control valve. A fitting needs to be removed and a plug installed. The return line from the aux valve will also need to be disconnected and the main return line capped.
The way the system is setup is:.........In the main control valve is a fitting that is commonly referred to a pressure beyond fitting. It's purpose is to supply pressurized oil to the aux valve and prevents the free flow oil thought the main control valve from returning to the sump, or oil cooler in this instance. The only oil being returned through the main control valve to the cooler is oil that is exhausted by the cylinders when they move. All other oil is directed to the aux valve. Since no pressurized oil can return to the cooler though the main control valve it must return through the aux valve. If you cap the return line from the aux valve or the pressure line from the main control valve the oil will have now where to go and will either cause the pressure relief valve to pop off or blow your hyd pump. To eliminate the aux valve you must remove the pressure beyond fitting from the main control valve and just install a plug into the valve and then remove the return line from the aux valve at the main control valve and cap each of them.The Valve I'm referring to has a charge line that is T'ed off the oil cooler line on the main hyd control valve and has a line that goes to each side of machine (capped off on each side) and the other line goes to the aux hyd control valve with two lines going to connectors and other return line. On my machine it is located on the right front corner of cab and has cable running to right control stick, which has been bolted in place. Messicks calls it a Boom Hydraulics Control Valve. I'm guessing it may be for controlling a grappler or maybe a snow plow attach. I hope this may clear it up some.
I will retrace the lines and let you know. I will pressure wash everything and drop bottom plate for clearer view of things.The way the system is setup is:.........In the main control valve is a fitting that is commonly referred to a pressure beyond fitting. It's purpose is to supply pressurized oil to the aux valve and prevents the free flow oil thought the main control valve from returning to the sump, or oil cooler in this instance. The only oil being returned through the main control valve to the cooler is oil that is exhausted by the cylinders when they move. All other oil is directed to the aux valve. Since no pressurized oil can return to the cooler though the main control valve it must return through the aux valve. If you cap the return line from the aux valve or the pressure line from the main control valve the oil will have now where to go and will either cause the pressure relief valve to pop off or blow your hyd pump. To eliminate the aux valve you must remove the pressure beyond fitting from the main control valve and just install a plug into the valve and then remove the return line from the aux valve at the main control valve and cap each of them.
Thanks Mike, after reading your reply, I went out and retraced the lines. I think I have it now, the line I thought was a charge line is a return line to oil cooler line and I can remove hose and cap. The lower hose on the aux hyd valve is the charge line and I need to remove it and plug at the main hyd control valve. Once this is done I can remove the aux hyd control valve and the boom hyd control valve without any problems. While I'm in the main control valve I will have it cleaned and rebuilt.I will retrace the lines and let you know. I will pressure wash everything and drop bottom plate for clearer view of things.
I want to make sure you understand that you must remove the fitting from the main control valve also. You replace this fitting with a standard oring sealed plug. When you remove the fitting you will see there is a hollow stem on the end of it with orings. Thjs stem is what prevents the oil from returning through the return port of the main control valve. The plug you will install does not have this stem. When the fitting is removed the oil will now circulate back to the cooler through the regular return port.Thanks Mike, after reading your reply, I went out and retraced the lines. I think I have it now, the line I thought was a charge line is a return line to oil cooler line and I can remove hose and cap. The lower hose on the aux hyd valve is the charge line and I need to remove it and plug at the main hyd control valve. Once this is done I can remove the aux hyd control valve and the boom hyd control valve without any problems. While I'm in the main control valve I will have it cleaned and rebuilt.
I understand about the plug, now to get all the lines off the control valve to remove it. You had told me before that I needed to pull main hyd control valve to check for a bad pressure relief valve. So will also have it rebuilt at this time. If I get into trouble I will reply back. Thanks for your help so far.I want to make sure you understand that you must remove the fitting from the main control valve also. You replace this fitting with a standard oring sealed plug. When you remove the fitting you will see there is a hollow stem on the end of it with orings. Thjs stem is what prevents the oil from returning through the return port of the main control valve. The plug you will install does not have this stem. When the fitting is removed the oil will now circulate back to the cooler through the regular return port.
Thanks for your help Mike. I got all the boom hyd valve and the aux valve off, capped return line at the oil cooler Tee and a plug in the main control valve. Refilled machine with the strainer cap off and everything works good. Hydraulics operate like new.I understand about the plug, now to get all the lines off the control valve to remove it. You had told me before that I needed to pull main hyd control valve to check for a bad pressure relief valve. So will also have it rebuilt at this time. If I get into trouble I will reply back. Thanks for your help so far.
