Cylinder on my Dump Truck blew up

[EddieWalker]

I have a 1983 F600 gas engine dump truck. It has a 5 yard bed and with sideboards, I can get 6 yards in it.

The hydraulic cylinder that lifts the bed has always leaked a little, but never enough to worry about it. Lately that leak has increased to the point I need to add oil to it twice a day. The last time I added oil, I thing I put too much in.

I had run a few loads with it and was moving king of fast. I had just dumped a load and then I lowered the bed rather quickly. I think there excess hydraulic oil couldn't move fast enough and the preasure was too much for the bolts holding on the cylinder cap.

BOOM!!!

I'm in trouble. The bed is down and there's no hydraulics to lift it. I parked it by the shop and tried to lift the bed with my loader without any luck. It just twisted everything and I was afraid I'd just make it worse.

I decided to jack up the bed an block it. Jack some more and block some more.

Eddie

 

[Bluecheck546]

Eddie , disconnect the hydraulic lines attached in to the cylinder. From what I'm understanding your return line is under pressure. Best, if you want to move the dump bed, disconnect those lines and the try with your FEL. Good luck, and be carefull.

 

[EddieWalker]

Once there was enough room to work, I had to figure out how to get it out of there. I look at it and my imaginatio plays tricks with me. Sometimes I can see the bed moving and my head being crushed under it. This doesn't help me get anything done.

You can see in the first picture the cylinder cap and how it came off. The next picture shows the bolts and nuts that I found on the ground in a puddle of hydraulic oil.

The hoses proved to be too tight for me to get off the cylinder, but I was able to get them off the pump. The rest of it was fairly simple. The third picture shows the cylinder almost out.

It was much heavier then any other cylinder I've ever rebuilt. It was VERY HEAVY!!!

Once I got it on the ground, I still couldn't get the hoses off. I came up with a breaker bar that will hold a wrech and give me more leverage. It's pretty simple and something I should have made years ago.

Eddie

 

[EddieWalker]

I don't know what the threads were rated that broke, so I bought Grade 9 bolts and cut the head off of them. Then I cleaned up the remaining part of the old bolts and welded the new ones to the side of the old ones. I figured this would keep everything lined up right.

Then I cleaned it up real good. I rebuilt the piston and replaced the seals. Then put it all together with a little silicone for good measure on the cylinder cap.

Now it's just a matter of the bed staying in the air long enough for me to put it back in without crushing my skull.

Eddie

 

[kmdigital]

Interesting that the cylinder has two hoses to it. I used to have a small dump truck with the scissor lift cylinder very similar to this, and it only had one hose on the bottom, and a vent with a mesh filter on the other opening. Obviously, the weight of the bed was required to retract the rod.

Is yours actually two way, where you can force the bed down as well as up?

 

[cp1969]

Eddie, I'm sure you've looked already, but most dump beds have a rod or metal bar of some sort to lock them in the partially up position so they can be worked on. You're bed doesn't have one? I'm assuming it doesn't so try to get something like a 4x6 or something wedged between the frame of the truck and the main rails of the bed. This board would run across the frame, not parallel to it, close to the hinge pins. Don't take out the boards you're using; just put this one in for extra insurance.

BTW, now would be a good time to add that bar for the next time you have to work on it.

 

[Kendall69]

You do realize that the jack and 4x, is an accident waiting to happen. That thing can kick out and kill you.
Just FYI

 

[TrippleT]

Eddie, do you pop the bed when you have it up dumping? Over time it may have just fatigued out there if you do. There should be a valve in there to bypass the fluid to keep it from doing something like that. How large of a reservoir does your truck have? It shouldn't have pressure on the down side.
And, it would be a good idea to put some steel supports under that bed to keep it from falling on you. One time is all it takes. Of course you know that, but just want to keep you safe there.

 

[john_bud]

Eddie,

Pretty quick fix!

 

[MadReferee]

Interesting that the cylinder has two hoses to it. I used to have a small dump truck with the scissor lift cylinder very similar to this, and it only had one hose on the bottom, and a vent with a mesh filter on the other opening. Obviously, the weight of the bed was required to retract the rod.

Is yours actually two way, where you can force the bed down as well as up?

That's a double acting cylinder and uses hydraulics to retract the cylinder. A single acting cylinder with one hose will use gravity.