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jdemarisj
11-06-2005 14:53:41
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Re: JD 450 hydraulic in reply to Alan Ky, 11-06-2005 14:28:43
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Under normal usage, the relief valve or valves should not be doing anything. They are only there to protect the system from extreme overload when the machine is overworked - like when the bucket comes to the end of its travel or is overloaded. You probably have a bad cylinder packing. You didn't mention if the machine is a 450, or B, or C, etc. Some machines only have one main system relief valve, some in additional have others that protect individual functions, i.e. "circuit relief valves." Regardless, they are normally closed except in extreme or emergency conditions. When they DO go off, they make noise and create a lot of heat. But, so does heavy work. What is possible it that you have one leaking and is thusly creating excess heat. That's rare, but possible. If you suspect this - start the machine and feel how warm different areas get - and try to ascertain which area is getting hot first. All the relief valves will be in a control valve body - either the one for the main loader - or perhaps in additional valves if you have other options like a backhoe, rear ripper, etc. It is much more likely that your heating problem is caused by a blown or leaking-internally hydraulic cylinder packing. When that happens hydraulic oil bypasses internally, creates lots of heat, but the machine still works okay. Again, start the machine cold, use it, and put your hands on the cylinders and see which one is heating up fast. You might also notice just by leaving the bucket up in the air and turn the machine off. See if anything settles - the boom or the bucket curl - if so, you have at least narrowed down the problem to two cylinders instead of four. If you wind up repairing a cylinder, don't forget to clean out the hydraulic suction filter-screen that is hidden, under the oil, at the bottom of your hydraulic tank - it tends to get neglected since many people assume the only filter is the cartridge filter up towards the top of the tank.
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