How can you check if your cylinders are functioning properly and not bypassing? I seem to have lost a lot of bucket curling strength. If the bucket does not bleed down with a heavy load is that an indicator the cylinders are good, or could it still be bypassing? Another step in my trouble shooting.
thanks
First of all, Is the cylinder of DOUBLE ACTING type? (two hoses to cylinder)
IF NOT DOUBLE ACTING TYPE (one hose to cylinder), and bucket is beeling down, the CONTROL VALVE is leaking on its own (on the pressurized capped side A port side).
IF IT IS A DOUBLE ACTING type of cylinder, and bucket is bleeding down, ity is little more complex situation....it can be the same valve leak as above....it can be the piston seal leak over to the rod side, but all that oil will not fit on the rod side, so the volume of the piston rod have to leak out thru the control valve (on the rod side B port or the capped side A port).
So it can be a few different combinations of problems but allways the control valve have at least a part of the leaks, minimum the rod-volume.
It is common (normal) that control valve leaks over time when load induced pressure sits on the port. Manufacturer can tell how many cc per minute valve is supposed to leak at a certain pressure. eak data should be available for, P to A and B, A and B to tank, and P to tank if it is a closed center valve. With these normal leaks, it will take many hours for bucket to bleed down in.
All this concider NO external leaks.
Note:
If the actuator have a 1 to 1 ratio, like a hydraulic motor, (or a cylinder with rod on both sides of piston, or two identical cylinders X-connected to each other), load induced pressure can bleed down with motor leak only, but of course also thru valve leak...