My rear remotes cylinders bleed done suddenly when pressured up to a certain point. Manuel says there is a Relief Valve and also a Safety Valve located where remotes plug in at rear of tractor. What should I check first?
M7040 Rear Hydraulics
- Thread starter Hooverw
- Start date
We need a more complete story to help you.
The safety valve has nothing to do with your rear remotes unless you are talking about the cylinders which control the 3 pt hitch arms.
Are you talking about hydraulic cylinders on implements which are plugged into your tractor's rear remote outlets?
Do you have a loader? If so the rear hydraulics section in the tractor WSM info is incomplete. The loader valve relief valve limits how high the pressure can go at the rear of the tractor.
Take some time and explain in detail which is happening and when it happens.
Dave
Yes, problem is with implement cylinders on a hydraulic grader blade. Also a cylinder center link on the 3 pt hitch. There are no problems with draft link function. I do have a loader
The hydraulics on your tractor are called open center.
When you try to lift a bucket of gravel with your loader, the relief valve you experience limiting how much you can lift only functions when the loader valve joystick is calling for movement. If you fill your bucket with gravel, lift it a foot off the ground and then manually shovel more gravel into the bucket, the pressures in the hydraulic system will continue to rise to deal with the additional load you are shoveling into the bucket. The relief valve is not in the circuit because the joystick is in a neutral position. Eventually hydraulic pressures will rise until something breaks. A hose, or a cylinder.
The 3 pt hitch is a little different not to be confused with rear remote hydraulic outlets. A relief valve limits how much you can lift on the 3 pt hitch. Once you have lifted a heavy implement on the 3 pt arms and start driving with this weight in the air, bumps in the road impose shock loads on the 3 pt hitch. This is where the safety valve comes into operation. It is set at a much higher pressure than the relief valve. If you hit a bump with a heavy implement raised, the safety valve will dump pressure and in doing so lower the implement a b it as this fluid is dumped.
In looking at the hydraulic schematic in the WSM, I do not see any connection of the safety valve with the rear remote outlets.
The hydraulic flow from the main pump is first to the loader valve and then using the loader valve's power beyond port hydraulic flow goes to the rear of the tractor. There is a relief valve in the loader valve and because it is first in the open center circuit, its pressure setting limits how high the pressure can get even at the rear of the tractor.
The relief valve at the rear can be adjusted but it will never go higher than the loader valve setting as the loader valve reiief is bleeding off pressure
A $30 hydraulic gauge with a male quick connect fitting will allow you to check where your relief valves are set..
First unplug a quick connect to a loader line and plug in your gauge. Engine at max rev;s, move joystick to send fluid to the gauge. Read max pressure. Do not do this for more than a few seconds as you are over heating the hydraulic fluid.
Second, plug your gauge into a rear remote port and test in the same way.
If you have a LA1153 loader the max pressure is 2,873psi
If you have a LA1353 loader the max pressure is 3,002 psi
The rear relief valve should be set at 2,632 to 2,773 psi which is 100 psi less that the loader relief valve.
I still do not understand exactly what is happening with your rear implement. Could it have its own relief or cross over relief to protect itself?
Dave
I
I pressure checked a rear remote outlet, I have two sets for operating two different cylinders, and you are correct pressure there is little over 2600 as you stated. I have two new cylinders on the rear grader blade. I just hooked it up and going to do more trouble shooting
Please provide make and model of your grader blade.
Are you familiar with Cross Over Relief valves? They are often used on front blades to allow the blade to move away from an object it has just hit. Oil is allowed to flow from one blade cylinder to the other so no oil leaks externally but the shock on the front blade is greatly moderated.
Dave