Help with hydraulic on a metal bandsaw

[Roger Feeley]

I have a Grizzly band cutoff saw with a hydraulic cylinder to let the blade lower slowly. As hydraulics go, this one is pretty simple. It has a valve that lets you raise the blade without resistance. Then there’s a knob that lets you control the rate of the cut. It goes up fine but I have to lift it almost to vertical and lower it to get the adjustable rate to engage.

I have questions
1. It seems to me that my problem is in the valve. There’s some sort of flap that bypasses the adjustable valve on the way up. The problem is when the fluid changes direction, the flap doesn’t close right away. Am I close?

2. If I take this apart, how do I flush the air out?

[Bill Dufour]

Sounds like the check valve is sticking. To bleed I would crack the top fitting to allow air out while applying slight downward pressure. They can not be bleed totally but a little air is not a problem at such low pressures.
Bill D

[Ronald Blue]

I reread your comment and changed my comment. It sounds like it may have lost some fluid and has air in it. That would cause it to require raising it fully. It should be possible to add fluid to it. A small container of hydraulic jack oil would be great. I could be completely wrong. Photo of it possibly?

[Tom M King]

There might simply be air in the cylinder. Google how to get air out of a hydraulic cylinder or jack.

[Roger Feeley]

I’ll take a closer look in the morning.472771

[Mitch schiffer]

I would guess it is low on oil and in turn has air in the system.

[Tom M King]

I thought I would have to replace a jack on a shop crane, but decided to look for a youtube video, and sure enough, there are a number of them. It's been so long ago that I forget exactly what I did, but it worked, and I didn't have to replace the jack.

[Ronald Blue]

Despite the sticker saying otherwise removing the line is going to be necessary. Unless you submerge it in a tub of oil and cycle it and reattach the line while submerged it's going to have some air trapped. That might be the method they used initially.

[Roger Feeley]

Despite the sticker saying otherwise removing the line is going to be necessary. Unless you submerge it in a tub of oil and cycle it and reattach the line while submerged it's going to have some air trapped. That might be the method they used initially.
Ronald,
You have provided me with a really useful tidbit. I have been racking my brain trying to figure out how to do this without submerging the whole thing. The best I could come up with is to put the thing in a plastic bag. I put a small amount of fluid in the bag and start wrapping the bottom parts tightly using stretch wrap, leaving the place where I disconnect the pipe at the top. Finally, I add enough oil to submerge that one part.

I’m thinking that he last place to leave unconnected would be the elbow nearest the piston rod. While I have it submerged, I just work the piston until I don’t see bubbles. Right?

[Ronald Blue]

Ronald,
You have provided me with a really useful tidbit. I have been racking my brain trying to figure out how to do this without submerging the whole thing. The best I could come up with is to put the thing in a plastic bag. I put a small amount of fluid in the bag and start wrapping the bottom parts tightly using stretch wrap, leaving the place where I disconnect the pipe at the top. Finally, I add enough oil to submerge that one part.

I’m thinking that he last place to leave unconnected would be the elbow nearest the piston rod. While I have it submerged, I just work the piston until I don’t see bubbles. Right?

That's what I would do. While submerged work the rod in and out. When you see no more bubbles reattach the line submerged if you can. The sequence of reconnecting sounds correct. Good luck.

[Roger Feeley]

That's what I would do. While submerged work the rod in and out. When you see no more bubbles reattach the line submerged if you can. The sequence of reconnecting sounds correct. Good luck.

will do. I think I’ll wait until I get some closed cell foam to fill the spaces between the tubing and the cylinder.