Hydraulic Cylinder Leak Down on Box Blade???

[ovrszd]

I really don't anticipate it being an issue, and if it is, it's clearly operator error for not having the cylinder retracted all the way which engages the lock mechanism when the scarifiers are down.

Yeah, I'm very diligent about that when using mine. I scold my boys anytime they are going to use it about the same thing. Once that lock mechanism is activated the cylinder isn't carrying any load.

 

[ovrszd]

You would be able to extend the rod with the relief valves wedged open. What is so odd is the ability for the rod to retract. The only way that is even possible is if there was air in the cylinder, a LOT of air.

Here is an example that everyone can understand. Cylinder full of fluid with rod extended = a glass of water full to the top. Now if you can put your finger into that glass of water with out spilling any, then that is how the rod can be pushed back into a fluid filled hydraulic cylinder.

In other words, it is impossible for the rod to be pushed into the cylinder. It is only possible if there is a void. (air) Glass of water is not full.

Yeah, and where did he get all that air?

 

[Piston]

He had previously said "retracting". And by the video, it appears to be "retracting" (getting shorter). This is the scenario that several knowledgeable hydraulic members have said is impossible. I'd like some clarity on that subject as well. :confused3:

I can certainly understand how it would be impossible for the cylinder to retract without any air present. After Mtnviewranch explained it, it makes perfect sense.

I MUST have had air in the cylinder even though I would have bet that I didn't.

I can see why you could extend it, but it would sort of defy physics to retract it (with zero amount of air in the cylinder).

Certainly can learn a lot on this forum! (If one is willing).

 

[ovrszd]

I can certainly understand how it would be impossible for the cylinder to retract without any air present. After Mtnviewranch explained it, it makes perfect sense.

I MUST have had air in the cylinder even though I would have bet that I didn't.

I can see why you could extend it, but it would sort of defy physics to retract it (with zero amount of air in the cylinder).

Certainly can learn a lot on this forum! (If one is willing).

Yep. And I believe the biggest problem in these discussions are the variables that all posters know nothing about. The inability to fully extend/retract the cylinder to purge air would be such a variable. On my BB the linkage allows the cylinder to reach full stroke without raising the BB off the ground because of hinged linkage. Maybe not on this BB??

 

[Piston]

I was able to fully extend and retract the cylinder to purge the air from it, but in my case it didn't purge all the way out like I thought it did.

 

[jenkinsph]

Yep. And I believe the biggest problem in these discussions are the variables that all posters know nothing about. The inability to fully extend/retract the cylinder to purge air would be such a variable. On my BB the linkage allows the cylinder to reach full stroke without raising the BB off the ground because of hinged linkage. Maybe not on this BB??

First I have the same box blade as Matt. If the rippers are set for full depth you have to raise the box blade to lock in the lower position. The down force is reduced with the valves operating correctly and will not force the rippers into the locked position while sitting on a concrete floor. That also prevents damage to the linkage.

When Matt was cycling the cylinder as I suggested to purge the cylinder the valves were held open by the trash. He has not said whether he raised the box blade prior to attempt to cycle the cylinder. That could have left air behind the cylinder piston.

 

[MtnViewRanch]

Yep. And I believe the biggest problem in these discussions are the variables that all posters know nothing about. The inability to fully extend/retract the cylinder to purge air would be such a variable. On my BB the linkage allows the cylinder to reach full stroke without raising the BB off the ground because of hinged linkage. Maybe not on this BB??

How is this possible? So your scarifiers only engage by tilting the box forward? The scarifiers need to go below the cutting edge to do any ripping.

I'm at a loss of understanding here. If you have time, a picture would be worth many words in this scenario. I would like to understand what is going on to allow this to happen on your box blade.

 

[Piston]

Yes, I was cycling the cylinder full stroke, and holding the valve open/closed for a couple seconds as well.

Remember that it has been this same way for some time. I'm. It sure how long but I had used it some prior to changing out the seals. This is new box blade for me so it may have been this way for a long time, perhaps why I paid so little for it in the first place.

I believe the trash in the port was contributing to not being able to purge all the air out.

Regardless, it's working excellent now. I just went up to check and it's still in the up position from yesterday evening.

That is really my biggest concern, and I'm happy with it now.

I definitely learned a lot!

Steve,
I looked up the part I would need to replace, and it is $68 from Messicks. I may just order it and replace it before springtime.
(Most likely I'll forget though )

 

[bigdeano]

I wonder if you removed the peeling thread on the end of the piston rod shown in the picture in post #15 and I pointed out in post #17. If it breaks off it could damage something in your hyd system. A piece of it is most likely what got into the check valve. Just wondering.

 

[jenkinsph]

Matt, for $68 bucks I would get it ordered and fixed before you have a much larger parts bill. Just me.


bigdeano keeps referencing the wire over the nut, isn't that a safety wire he is seeing?