# Dump Trailer not lifting



## RockmartGA

I've got a 6x12 dump trailer. It's been sitting for a couple of months. Doing some spring cleanup and was going to take a load to the landfill. It lifted about halfway and then started "shuttering" and wouldn't lift anymore. When I got it home, it would only lift about one foot.

Appears to have adequate battery charge (based on the sound of the motor, but I'm still going to hook it up to the charger just to be sure.). Also has a normal hydraulic fluid level.

Are there any inherent issues with these electric/hydraulic systems that I should look for before I go wrenching on something that I don't need to?

Specs:

12 volt electric / hydraulic unit. All-in-one with reservoir.

Twin hydraulic, single action cylinders. I.e., power up, gravity down.


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## urednecku

First thoughts, any chance the filter is clogged? Water in the system? Just what came to mind, until somebody with some knowledge comes by.


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## hog987

Will you got all the simple stuff looked after( battery charge, oil level, filter), see if they help. Are there and grease nipples anywhere under trailer? Sometimes the pins can get rusted and stiff making things harder. Release valve not working right.

But check all the simple stuff first.


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## mlappin

Is the breather plugged on the oil reservoir? If it's plugged once enough oil is pumped out it will build a vacuum, once it has a vacuum oil can't flow into the pump.


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## askinner

Silly question, but is it overloaded or loaded too far forward? It sounds as though it has two stage hoist cylinders, and it is getting to the second stage where the force of the cylinders isn't as great, and it is going over relief. Could be a weak relief, would need to verify with a guage. Should be roughly around 2-2500 psi.


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## NDVA HAYMAN

If its shuttering, could be air in the system. Try bleeding it by cracking the hoses.


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## markty32

i have a tipper do this once as well it was low on hyd oil

check oil

check battery

check filter

my filter was blocked


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## Greasy30

Mine has a solenoid that went out and caused the trailer not to raise/dump. Might want to check that if it has one.


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## German Farmer

I agree with the grease first. You would be surprised how much that matters, but definitely sounds like air in the system now. Question would always be if you have a vented reservior it should take care of it, but if not crack the line as mentioned above.

When you get the cylinder all the way up, put some safety chalks under the bed and inspect the shaft and seals of the cylinder. If the shaft has pitting or rust it will cause the seal to go bad. Look at the cylinder attachments and the frame to make sure you don't have a structural integrity problem.

My brother DOT trailers at his shop and these are things we would check for in general.


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## deadmoose

Rockmart did you get it figured out?


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## RockmartGA

I was going through some old posts and realized I never shared what I found.

The main issue was a clogged suction strainer on the hydraulic pump. However, one thing led to another and I ended up fixing several other issues as well.

1. Clogged suction strainer. One shouldn't see clogged hydraulic strainers on a two year old, lightly used trailer that is stored under a shed. Which leads to #2:

2. The hydraulic fluid reservoir was shop built. Now, there is nothing wrong with shop built. However, it needs to be CLEAN metal and free from any debris. I almost had a heart attack when I dipped a magnet into the fluid and pulled out a wad of welding wire and slag.

3. The hydraulic fluid reservoir was not vented. Tank needs to be vented to allow easy flow in and out.

4. Since the trailer was power up and gravity down, I assumed the hydraulic cylinders were single action. I was wrong. They were double action cylinders with lines to one end and the other end plugged. When the trailer was lifting, it was compressing air in the second, plugged section of the cylinder.

I cleaned the strainer, bought a new hydraulic reservoir from Northern Tool for $99, flushed all lines and cylinders with new oil, and installed a vent plug on the cylinders as well as the reservoir.

Works better than new. I now realize the shop where I bought the trailer didn't have a clue about how hydraulics worked. It was a great deal - I thought. Sometimes you get exactly what you pay for.....


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## R Ball

We bought a 16' PJ goose neck dump, 14000#... Had to send the first one back. It was catching on its own frame. Sold the second one after it wouldn't dump approx 11500 pounds. 
Bought a dump truck and now no problems. Never liked that battery over hydraulics anyhow.
The basic use for the trailer and now the dump truck is hauling saw dust. Horse bedding.


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