patrick344
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- Massey 1533
Good day , looking for the psi setting for my pressure relief valve for my 2008 massey ferguson 1533 hydrostatic. Thanks
Pressure setting for hydraulic relief vale on a 2008 massey 1533 hydrostat.
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rScotty
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Patrick, I don't know the answer to your tractor, but here is some info that might help.
Relief valves are usually set to provide protection for the weakest part of the system.
In most modern utility tractors with open hydraulic systems - like yours - the components are rated to be run at 3000 psi max. Most of the components like hoses and fittings are rated to perform at that pressure and still have a decent safety factor. Bursting pressure is usually at least twice that.
It is common to set a system for 10% under max, so you will find service departments often set to 2700 psi. I like to run my tractors with less stress and tend to set in the 2300 to 2500 range. Start low, you can always increase it.
Old farm tractors pre-1990 commonly ran in the 1200 to 1800 psi range and did just fine. Lower pressure just required larger cylinders.
Tractors with a FEL almost always have a relief valve built into the control assembly. Three point lifts also have a relief valve. If the tractor has power steering it will have a relief valve for that system too.
If the flow to the power steering is set by a proportional valve then some of those have a relief valve as well. Backhoes can have several relief valves for different motions. Any implement that has a PTO driven pump needs one as well.
Relief valves are simple and inexpensve insurance. They are basically a ball or poppet valve held shut by spring pressure. When the pressure is exceeded, the valve opens and all the flow goes through a return line directly to the sump.
A relief valve is usually built to make a loud squeal when it actuates. That will sure get your attention. You've heard that sound in cars when the steering is turned against the stop. Tractors are louder.
How do you plan to set it? Normally it is done with a good accurate gauge and hand tools. A few types of relief valves are set with shims under the spring that holds the valve shut. Others have a threaded screw and lock nut to preload that spring.
Good luck,
rScotty
Relief valves are usually set to provide protection for the weakest part of the system.
In most modern utility tractors with open hydraulic systems - like yours - the components are rated to be run at 3000 psi max. Most of the components like hoses and fittings are rated to perform at that pressure and still have a decent safety factor. Bursting pressure is usually at least twice that.
It is common to set a system for 10% under max, so you will find service departments often set to 2700 psi. I like to run my tractors with less stress and tend to set in the 2300 to 2500 range. Start low, you can always increase it.
Old farm tractors pre-1990 commonly ran in the 1200 to 1800 psi range and did just fine. Lower pressure just required larger cylinders.
Tractors with a FEL almost always have a relief valve built into the control assembly. Three point lifts also have a relief valve. If the tractor has power steering it will have a relief valve for that system too.
If the flow to the power steering is set by a proportional valve then some of those have a relief valve as well. Backhoes can have several relief valves for different motions. Any implement that has a PTO driven pump needs one as well.
Relief valves are simple and inexpensve insurance. They are basically a ball or poppet valve held shut by spring pressure. When the pressure is exceeded, the valve opens and all the flow goes through a return line directly to the sump.
A relief valve is usually built to make a loud squeal when it actuates. That will sure get your attention. You've heard that sound in cars when the steering is turned against the stop. Tractors are louder.
How do you plan to set it? Normally it is done with a good accurate gauge and hand tools. A few types of relief valves are set with shims under the spring that holds the valve shut. Others have a threaded screw and lock nut to preload that spring.
Good luck,
rScotty
Harry in Ky
Veteran Member
Are you having hydraulic problems that may be pressure related, or are you just curious?
No long winded answers here. The hydraulic system ( remotes, three point, any auxiliaries) should be 2250 PSI or slightly above. That does not apply to the hydrostat relief pressures.
dfkrug
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Yeah, HST relief pressures will be 4000-6000psi for forward/reverse, and about 150psi for charge pressure. For most CUTs with HST in the modern era (last 30y or so). These RVs have test ports.