Hello everyone!
I am new to this site and have not been able to find a thread with the same issue I am having.
I purchased an old ex county single axle International 4700 dump truck with a Heil 1715 dump body on it. When I lift the bed I have to raise the rpms to get the bed moving. When I move the raise lever to the hold position the bed will drift down until it full closes and I can’t get it to stay partially raised.
I started throwing parts at it by first re-sealing the hydraulic cylinder. That was pretty straight forward however this cylinder was unlike any I have worked on in the past. It has an internal bypass poppet valve. From what I can tell it allows oil to flow through a small orifice to the other side of the gland as you are raising the dump bed and extending the cylinder. When the cylinder reaches full stroke a spacer hits the end of the cylinder cap and pushes against the end of the “poppet” and closes it. I may have a misunderstanding of how this works but I think that is right. One I re-sealed the cylinder the bed was still drifting.
I went ahead and installed a new open center Cross spool valve since it was almost as cost effective as replacing the relief valve and resealing the old one. The new valve came with a new relief valve and all I had to do was install it on the truck. Well to my surprise the dump bed still drifts.
A few other things to note are in the process of changing out the spool valve I noticed the hydraulic pto driven pump was leaking so I went ahead and put a seal kit in it. I also capped off the line to the hydraulic cylinder and installed a pressure gauge to see if the pump was making enough pressure. It made it to about 2500psi before it stalled the truck out and killed the engine.
Has anyone had experience with anything like this in the past? I’m wondering if the cylinder could still be the problem and somehow that internal bypass poppet valve is not working properly. It seems like if it would let too much oil by when lifting the bed it would make it difficult to raise and then would allow the bed to drift as the oil wasn’t staying on just one side of the gland. I have attached a break down of the cylinder and parts list.
Thanks in advance for any help or recommendations! I can still use the truck but I would like to fix this issue so I can tailgate material more efficiently.
I am new to this site and have not been able to find a thread with the same issue I am having.
I purchased an old ex county single axle International 4700 dump truck with a Heil 1715 dump body on it. When I lift the bed I have to raise the rpms to get the bed moving. When I move the raise lever to the hold position the bed will drift down until it full closes and I can’t get it to stay partially raised.
I started throwing parts at it by first re-sealing the hydraulic cylinder. That was pretty straight forward however this cylinder was unlike any I have worked on in the past. It has an internal bypass poppet valve. From what I can tell it allows oil to flow through a small orifice to the other side of the gland as you are raising the dump bed and extending the cylinder. When the cylinder reaches full stroke a spacer hits the end of the cylinder cap and pushes against the end of the “poppet” and closes it. I may have a misunderstanding of how this works but I think that is right. One I re-sealed the cylinder the bed was still drifting.
I went ahead and installed a new open center Cross spool valve since it was almost as cost effective as replacing the relief valve and resealing the old one. The new valve came with a new relief valve and all I had to do was install it on the truck. Well to my surprise the dump bed still drifts.
A few other things to note are in the process of changing out the spool valve I noticed the hydraulic pto driven pump was leaking so I went ahead and put a seal kit in it. I also capped off the line to the hydraulic cylinder and installed a pressure gauge to see if the pump was making enough pressure. It made it to about 2500psi before it stalled the truck out and killed the engine.
Has anyone had experience with anything like this in the past? I’m wondering if the cylinder could still be the problem and somehow that internal bypass poppet valve is not working properly. It seems like if it would let too much oil by when lifting the bed it would make it difficult to raise and then would allow the bed to drift as the oil wasn’t staying on just one side of the gland. I have attached a break down of the cylinder and parts list.
Thanks in advance for any help or recommendations! I can still use the truck but I would like to fix this issue so I can tailgate material more efficiently.
