Help with loader problem

[rockquarry]

I dont know what type of fitting it is. I do know that when we (my father-in-law, It was his brush hog) we just went to the local farm supply store got a 6-8' length of hydraulic hose and some NPT fittings. so I can only guess its NPT. I didnt use teflon tape. I seem to remember reading somewhere about not to use teflon tape on hydraulic stuff. dont remember where i read it of if it was in reference to just to not use in on a certain type of fittings. either way I'll take it apart tomorrow and put some tape on it then go through the whole pushing it against the stops to get the relief valve to open and get all the air out and see if that helps.

Thanks for all your help and info guys even if i dont get this thing to work right.

Jeff (rockquarry) Ill post some pics sometime so you can see how I came up with my user name

 

[RonMar]

Getting the relief to open dosn't really make any difference other than letting you know you cycled the ram as far as it is going to go. What does make a difference is cycling the rams when they are pointed up(lift arms at full height) and when pointed down(lift arms as low as possible but will still allow full bucket travel). It is like a doctor/nurse getting air out of a cyringe. they point the port on the cyringe(needle) toward the ceiling so the fluid forces the air out first when they push the plunger.

Air and fluid don't separate well in the confines of the small lines. The air and fluid will separate guite easilly in the larger space of the cylinder with the air of course going to the top. You need the port to be at the highest point so the air exits first and the fluid last, forcing that air all the way back to the valve where it will continue on into the resovoir and separate from the oil completely. With the lift arms down low, the port on the push side of the bucket cylinders is at it's highest point. With the lift arms at their highest, the port on the ram end of the bucket cylinders is on the top. If there is a lot of air, this may take a few cycles in each position to get it all out.

 

[john_bud]

Ron,

My understanding is that holding the control until the relief opens does do some good. For one it gives the air time to get past the packings and out of the cylinder. It also is a positive indication that the ram is moving to it's full extents. Could be wrong, but that's how heavy equipment mechanics trained me to do it. It has worked for me every time I have rebuilt a cylinder and installed it dry.

jb

 

[RonMar]

Holding the lever with the safety relieving does keep the system at full pressure and does indicate that the ram has reached it's full travel. It can force air out of the rod packing, it can also force air past the piston seals, but that is just relocating the air to the other side of the piston. That air can't go anywhere on the other side unless fluid is pushing it. I do trip the safties, but that is just to let me know it has gone as far as it can go. I don't as a rule hold them there. I have always relied more on piston position and cycling to remove the air from hydraulic systems.

 

[rback33]

You are definitely experiencing cavitation. The fact that it is intermitent really proves that. The weight of the bucket and rocks pulls the cylinder rods out faster than the pump can cylce it through to the base end of the cylinder. AS mentioned before, using regen and/or operating at higher rpms are the only ways to help/solve the issue. Regen makes it go away, higher RPM's helps reduce it. BTW, it does not hurt anything. It is just annoying sometimes.

 

[schmism]

a few quick points on cavitation

Cavitation - Wikipedia, the free encyclopedia

I most of the descriptions for it i didnt feel properly describe whats happening.

In the simplest terms it occurs then the fulid flow around a surface seperates from surface because it can no longer maintain lamanar flow.

generally cavation is considered a VOID in the liquid. (not air) as the "bubble" colapses a tremendious amount of energy is releaseed. (there is some debeate weather this colapsing energy (under the right conditions) can be considered cold fusion) anyway with the release of the eneargy is assocated with sound and sometimes light (or other electromagnetic radiation). The energy release is sufficent to vaporize the material makeing up the surface of that the fluid seperated from on a microscopic level, however if left to continue long enough it can cause physical degigration of the surface. IE if you look at the wikipedia link it shows a turbine that was worn down due to cavatation.

although this wear is usualy only a significant issue in extremly high speed applicatications such as steam turbines.

 

[rockquarry]

Well I tightend all the fittings and checked for leaks and found no change in the problem. I do believe it is pulling the cylinders out faster than the pump can handle. no big deal I just wanted to know why. Thanks all

Jeff