ChrisK

I have a new dump trailer (I know I know.. its not a boat trailer.. but bear with me here) and for some reason it does not want to go down all the way. It is a 14K lb trailer with 2 10K lb chief rams to lift and lower it. It powers up and down, not gravity down...

so here is whats happenin... it goes up fine, no issues...

When i lower it its fine for awhile but when it gets about 1-1.5 feet from the bottom it starts to shake and make an awful noise, I originally thought this was due to it being new, not sure now though... then it stops about 4 inches from bottoming out.. will not go down all the way. The pump still runs like its trying to lower it, and the bobcat is IN the trailer.. it alone is 9300lbs! im at a loss here.. i have raised and lowered it multiple times, but it just refuses to go all the way down.

Chris Sunkin

There are a couple of pieces that are in that system- or at least should be. They may be causing your problem. First is something called flow control- that's a device that restrains the fluid from coming out too quickly when you're lowering. Most are nothing more than an orifice but some are a bit fancier. Probably not the problem but you should know about it. Second, most likely the system has a velocity fuse. This cuts fluid off if a line bursts. Sometimes they can be overly sensitive- especially on a new system. If it's false-setting, it can cause problems. You can try removing these items VERY CAREFULLY and see if the trouble goes away. Obviously, you're going to want to restrain the bed from coming down prior to doing anything- I'd suggest an overhead hoist with load-rated chains or straps and maybe a safety stand as well. The last one is a bad cylinder- if the clearances are too tight or you got a bad piston seal, you'll have these problems.

In every new system we add an additive made and sold by Caterpillar. It's called "hydraulic oil additive", part number 1U-9891. This stuff will usually cure new-cylinder-chatter but won't help one that binds.

If this is a new unit, why not let the seller take care of it?

WARPARTY36

Could it be as simple as air in the hydraulic system?

ChrisK

I am hoping they will take care if it if nessisary.. Once I took out the bobcat at the jobsite(I had to loosen the hose on the pump to release the pressure and letting the bed lower) it went up and down fine.. it still chattered a little but went all the way down.. I have not tried it yet since i have been home to see if it does it again with the machine in it... I did talk to the dealer this morning, and he said the chatter is normal for the first dozen times or so, and that there is probably also air in the lines... he also said that it not going all the way down may be due to the battery not being fully charged. I guess the "down" valve is electro magnetically controled and activated by the current. I did find this magnet and when i removed it from the shaft it would not go down when the button was pressed, but go UP.. confirming i found the correct shaft it was attached to. he also said of course if it continues to bring it in to him.. but i am slammed the next few days, as if that was a BAD thing.

ChrisK

alright... well, it seems to be binding only when the machine is in the trailer.. same thing happened again.. Machine was in, and wont go down all the way... take the machine out, and all is well.. seems its time to make a trip back to the dealer... not sure how to fis it.. everything is welded into place.. the only things that move are the 4 hindges at the pivot point, and the attachment points for the cyclinders.