Hydraulic pressure dropping during pallet change

I've been getting an intermittent alarm on the machine for low hydraulic pressure following a pallet change SOMETIMES.

The hydraulic pressure is dropping during the "hook up" part of the pallet change, and this is observed with a slower than normal time to raise the hook. The pallet change will normally complete, but a low hydraulic alarm will sometimes stop the machine.

Anybody experienced this? Any ideas of where I should start looking? Hydraulic reservoir is topped off and strainer is clean. Shop is 75 degrees.

When was the last time you changed accumulator?

You have a fluid restriction somewhere causing low flow. Check hydraulic pickup screen in the tank (a b**** to get to), and there should be a hydraulic filter in the system that may need changed.

Hansdie said:

When was the last time you changed accumulator?

Click to expand...

Never changed accumulator. (machine is only three years old) Is this considered a wear item? Fluid was changed 6 months ago...going to change it again to see if it helps.

Red James said:

You have a fluid restriction somewhere causing low flow. Check hydraulic pickup screen in the tank (a b**** to get to), and there should be a hydraulic filter in the system that may need changed.

Click to expand...

There is a 60 micron screen directly above the tank...it was perfectly clean. Is there another one INSIDE the tank? (didn't see one in the manual)

As far as an accumulator, you normally check the nitrogen charge in the accumulator. The static pressure in the accumulator should be about 15% below the operating pressure of the system. It is charged with the machine off. The second thing to check is your hydraulic pump after you checked the screens. You most likely have a variable displacement pump. The pump delivers fluid at a constant pressure and variable volume depending on demand. The pump may not reacting fast enough to change the volume delivered and keep the pressure constant. Hope you have a gauge right at the output of the pump. Watch the pressure as you actuate your hydraulics. The pressure should not drop excessively. If it is dropping below the set point of the pressure indicator it will fault out. It is an indication that the adjustable swash plate in the pump is not reacting fast enough to increase the volume of flow.

John