Hello, My machine suddenly has a problem in that the blade will no longer stay in the air, drops to the ground in a few seconds while the machine is running. The hydraulics will hold the machine off the ground when then blade is pushed down so the problem is only in one direction. i suspect that the problem is in the control valve because i can hear the valve bypassing fluid in the center position. I rebuilt the lift spool with new orings, u-seals and dust seal but the result was no change at all. does anyone have an idea where to look to solve the problem? thanks
check the relief valve
will do. thanks for the reply.
Also it could be the nut came off the piston on the lift cylinders
Thanks, I am trying to see if I can isolate the problem to one of the cylinders.
It turned out to be a bad seal in one of the lift cylinders. i let the cylinder bypass pressure for quite a while and sure enough one cylinder got nice and hot at the location of the seal.
You most likely already know this, but what was holding the machine off the ground was the difference in the volume of the cylinder. The end with the rod displaces less volume and the oil can’t bypass the seal. But oil can bypass to the side of the cylinder with the greater volume.