Dump trailer hydraulics

[1gr8bldr]

I think the reviewer was confused or maybe he thinks 9/16 18 SAE is a special thread. You may need a reducing bushing because your hose fittings are probably 1/2" or 3/8" on your cylinder. TSC or any hydraulics supplier should have them. Most dump and tilt trailer builders have since relocated their hyd. pumps from under the bed to inside a tongue box for longevity and easier maintenance. You may want to consider this for safety.

Something worth considering. Thanks

 

[George2615]

Something worth considering. Thanks

Both of my trailers have the pump safely in a tongue box that I can lock up plus it's out of the weather.

 

[Ivan49]

Something worth considering. Thanks

You can go to a hyd place and buy any size fitting you want with the size for your hose ends on it and straight threads on te other. We use to call them ports. I have made thousands of holes with these threads in them over the years. You can get them big enough to stick your fist in if needed. I was a machinest for 26 years and we built die cast machines. If you need I can get the chart out of my tool box and tell you what size you have, but I think it is a number 8 fitting. I have a jar full of them as I used to bring them home when a rebuild was done on a machine. Some of these machines had 4000 PSI systems

 

[Xfaxman]

So, it sounds like I need a single acting pump with seleniod and plug the top hole on the ram.------------------------------

You need a vented plug, air has to get in and out.


My concern is that the top of the cylinder bore is pitted and the oil is leaking past the piston.

That may be why there is a hose added there.

 

[jenkinsph]

You need a vented plug, air has to get in and out.
View attachment 388128

My concern is that the top of the cylinder bore is pitted and the oil is leaking past the piston.

That may be why there is a hose added there.

Good point about the leaking cylinder, if he is using this commercially he may need to change it out too. I hate breakdowns on my jobs and do my best to prevent them, IT IS CHEAPER.

 

[zing]

..... So I disconnected the hose on top of the reserve tank and added about 1/2 quart, probably much less. Most I spilled on the ground because the air could not be displaced with the oil coming in that 5/16 hole. I was worried about the safety arm since it was loaded so I parked my skidsteer with the forks as a back up. Test run. It starts up strong and fast as ever but quickly starts to slow. This time doing the same thing but at a lower point. Then I let it down. It came down twice as fast as I had ever seen. I could release the down button and it will hold without leak down. But, par for most of my projects, something must have blown because all my fluid came out between the reserve and pump. It is on the bottom side hidden by part of the frame. .....

Something is wrong here. It alost seems like there is a blockage between the reserve tank and the pump (or somewhere), or poor plumbing, and a non-vented system. The fluid/air in the top part of the cylinder has nowhere to go, so as you extend the cylinder it is compressing the air until it cannot compress it any more. That's why when you put more oil in it, it raised even less than before. The compression in the top of the cylinder is why when you released it, it came back down faster than usual. I don't know these systems very well, but if adding extra oil made it raise less than before and come down faster, than it seems to me that you are compressing the air in the top end of the cylinder (and maybe the hose and the top of the reserve tank) and there is no way for the oil and air to escape. If that is the case I am surprised though, that you didn't blow that low pressure hose off.

If the blockage happened gradually due to rust or crud slowly choking something off, than that would explain why the system got gradually worse over time and why it is now running out of fluid since the fluid in the reserve is not available to the pump anymore.

Like I said, I don't know these systems very well but there has to be a blockage somewhere if adding oil makes it raise less than before and then come shooting back down. Maybe someone who does know the systems could explain where that blockage could actually be, or if I am just talkinig foolishness?

 

[1gr8bldr]

You need a vented plug, air has to get in and out.
View attachment 388128

My concern is that the top of the cylinder bore is pitted and the oil is leaking past the piston.

That may be why there is a hose added there.

Mine too. So the plan was to cap off the top hole. But what if it is getting past the seal, what is going to happen? It seems it would lock itself?? Should I leave the top open for a test run to be able to observe if it is leaking? If it is, do I put new seals in this type like I have done on my skidsteer hydraulics... or is that not the typical fix? LOL, I could run a hose from the top back to the reserve tank, but this time have a vent plumbed in

 

[J_J]

If the seals are leaking, you fix it like any other cyl.

If it is leaking enough to flow out the vent, then it surely needs fixing.

How do you know it is an SA cyl, could it be a DA cyl?

 

[George2615]

Mine too. So the plan was to cap off the top hole. But what if it is getting past the seal, what is going to happen? It seems it would lock itself?? Should I leave the top open for a test run to be able to observe if it is leaking? If it is, do I put new seals in this type like I have done on my skidsteer hydraulics... or is that not the typical fix? LOL, I could run a hose from the top back to the reserve tank, but this time have a vent plumbed in

That's a good possibility that the piston seals are bad. You've already establish the pump is a power up and gravity down so there is no reason to have a hose on the top port. The previous owner apparently thought he solved the leaking seal problem by adding the return hose back to the tank. I hope that's not what happened or you may be rebuilding or replacing the piston. You probably do have fluid on both sides of the seal at this point. It can't hurt to open the top port for a test run. Just stand clear and don't get under the box.

 

[J_J]

To solve the mystery,remove the rod end hose and raise the bed.

If there is fluid on the rod side, it should flow out the rod end port. If you hold the lever in the raise position, if the seals are leaking, fluid will continue to flow out, and that is bad.

You then need a rebuild or reseal. Then reinstall the breather plug.