Dump Trailer Problem

[Silver_Knight]

I have a 6x12 Texas Pride dump trailer with a single pump and a single hydraulic cylinder. It is a power up gravity down model. I bought it new about two years ago and almost immediately the trailer started having problems lowering. I would have to get up on top of the trailer to put extra weight to get it to lower from the highest position. Here lately I have to do this when it is not even in the highest dump position.

I live about 4.5 hours away from the factory and don't really use it very often so I really would hate to take it to them for repair. The other day while it was in the lifted position I decided to take loosen the hydraulic lines to see if it would start lowering, which it did not. I actually took both lines completely off the pump and it would not lower until I got up in the trailer for the extra weight. And now it drops a few inches and stops, drops a few inches stops and so on until half way down then smooth the rest of the way.

I think by doing this, it rules out any pump issues. Does this indicate a bad hydraulic cylinder?

 

[Heywood Jannockitov]

Are the hinge pins on the dump box seized, rusted, bent, preventing the box from overcoming the resistance from the hydraulic cylinder? Are the pins greaseable?

 

[Silver_Knight]

They are not greasable or rusted and do not think they are bent. I did squirt oil the best I could yesterday and went up and down about 10 times without any noticable change.

 

[Silver_Knight]

Forgot to mention that fluid only came through one hose..up and down. The other hose that is connected near the part of the cylinder that where the shaft come out did not have any fluid flowing in it.

 

[Wis Bang]

Maybe the internals of the hydraulic cylinder are loose, or incorrectly installed and are cocking and hanging up until you apply extra pressure? Unlike a tractor trailer which has alot of weight, it wouldn't take much resistance to slow/stop your dump body.

Unless there is some kind of check valve you should have gotten oil from at least one line.

 

[J_J]

Forgot to mention that fluid only came through one hose..up and down. The other hose that is connected near the part of the cylinder that where the shaft come out did not have any fluid flowing in it.

Since you are using a single action cylinder, the port with out a hose is the vent hole, and has no fluid in it. On your motor assmbly, there is a solenoid to release fluid back into tank. Make sure the trailer is down all the way. There is probably an adjustment so you can control the close/down speed. Take whatever is in the port out and clean it and blow air through it. It should be just a filter to keep out dirt/dust.

 

[J_J]

In a single action cylinder, you are putting fluid in the push side, and when you release the valve, the fluid come out that same port back to tank, and the trailer bed should drop, based on the fluid flow, which is usually metered by a valve. Clean out this valve.

Probably something like this.

https://www.surpluscenter.com/item.asp?UID=2009082014480959&item=9-1479&catname=hydraulic

 

[Skyco]

He said it had TWO hoses!
My power up gravity down dump trailer only has ONE hose. There is no need for two, sounds like they may have put the wrong cylinder config on it.
Where does the other end of the hose connected to the top port, where the rod comes out, go, what is it attached to?

 

[J_J]

How about some pictures of the cylinder, and the solenoid set up?

The shaft end hose is probably just hooked up, but gong nowhere , maybe has a filter on the end of the hose.


They make a kit for double acting pump. maybe something got mixed up some whee.

 

[Silver_Knight]

Here you go. I think the hose on the bottom of the picture is the pressure and the top hose is the vent. BTW, the oil in the picture on the frame and cylinder is from me oiling the cylinder and end bearings and pins. There are no leaks.