Hoist got stuck in the up position

[fattyphatcakes]

The other night I was dumping chips at a customer's house. The hoist on my dumper got stuck for a minute in the up position. Hitting up, then down, broke it loose and I got it back down. The motor was making a lot of noise too (while it was stuck). I don't know jack about hydraulics, any ideas on what's wrong? It's never done this before. Any suggestions on how to educate myself on fixing problems like this, I don't want to get stranded somewhere because I can't get the dump back down.

 

[ROLLACOSTA]

I suggest you look up a hydraulic engineering company and get it checked out , messing around with propped or unpropped dump bodys is not my idea of fun,sounds like your return valve is sticking

 

[Dadatwins]

Could be low fluid in the reservoir and air got sucked into the lines. Running a hydraulic pump dry for even a short time can be very bad, check your fluid level. If the system has a filter, has in been changed recently? Do not work on the system with the PTO engaged. Like Rolla said if you are not sure what you are doing get a pro to check it out. Never work under a lift body that is not propped up with a good support, and be careful when checking lines, they are under extreme pressure and can cause serious injury. Good luck.

 

[Crofter]

check the linkage that controls the valve. could be cable. The noise could be relief valve squeeling. Good advice on the safety issues. More than a few have died under truck boxes!

Frank

 

[fattyphatcakes]

Thanks for the replies, I'll check that fluid level, and there is a support on the dump body that folds down while your under there. I don't have an interest in doing everything my self, just enough knowledge to be dangerious (so to speak). I suppose it should be brought in for service, I bought the truck used this last summer, it was previously owned by a nearby municipality.

 

[fattyphatcakes]

I just put almost a quart of atf into the system just now.

 

[ShoerFast]

Stay safe!,,,,,

Fattyphatcakes
Stay safe, the support built into the box is just a start, an extra support of at least a 4x4 is safer if you have to get anything valuable in the way.
Crofter is on the right track, IMO, as the stuck - in - up, may also be why it doesn't go down. Back in the day, I had worked for Rod's right at Baseline and Broadway, as a mechanic, thats the type of fun stuff Rod would often take on to work on.
Getting it to work on its own is a way better choice then trying to lower it by cracking a line or anything!
Not that I know whats wrong, but I will offer to take a look if your stuck on getting someone out to fix it. This snow and weather will give me some down time this week. Just an offer if you find that the rock or the hard place are not working.
Kevin

 

[skwerl]

Wow, lots of safety admonishment. I'll consider the 'don't squash yourself' bases already covered.

Gotta figure out if the stickiness is in the linkage/cable or in the hydraulic valve itself. Locate the valve and work the lever back and forth to determine exactly what is sticking. Rusty or gummy linkage can usually be freed up with WD40. Worn or broken linkage may need to be welded or replaced.

If the stickiness is in the valve itself, you may be better off dealing with someone who specializes in hydraulics. Sometimes those valves can be serviced, other times you just pop it out and replace it with a new valve (can be pricey depending on your setup).

 

[treesurgeon]

my dump is starts down very slow when its cold out. if you have water in the system it may play havoc with the valves. some trucks that have been in service many years have never had the fluid changed. theres not much of a filter on some trucks either depending on the size. this adds to the problem.

 

[JeffHK454]

Some dump beds have no "power down" only gravity. Only thing it could be is the directional valve that diverts the hyd. oil from "push" side of the cyl. back to tank , which is the "hold" position of the valve. In this "center" position the bed will stay at the desired ang. until you ether raise it or lower it. If the pump made a lot of noise it was receiving pressure , only thing that saves you from damage in this instance is your relief that's set at the high end of your operating PSI. Worked on many 1 ton dumps from my local municipale garage with this exacte problem, change the control valve. The popit valve gets worn and hangs in the bore , it can be dangerous ! When they get worn they can drift down or become uncontrollable which is bad!

Worn parts in a hydraulic system will make for a slow moving and hot running circuit.

Be careful , these small dumps that use a scissor type mechanism are full of "amputation" points.

Jeff

 

[fattyphatcakes]

I went out to take a picture (still only about 20 degrees outside) but the hoist was going up very slow. Decided to wait til later. Is this kinda extreem slowness normal when it's cold, or does this thing need some work, or both?

I'll post a pic of the hoist later, to help those of you who are "specl'atin about a hypothisis". (name that film)

I think the hoist does have power down, the motor runs.

 

[Crofter]

I would get a pressure guage in ther to find out what is going on. As pointed out things can get messed up inside the valve. The noise could be either from the pressure relief valve actuating or it could be pump cavitation due to restriction of pump intake. Restricted intake could well be worse in the cold. I had an experience with a hydraulic hose that had a loose and doubled up inner liner that intermittently created blockage. That took a bit of detective work to find. Hope it is something simple.

 

[fattyphatcakes]

Here's some pics to give you all a better idea of the setup. I left the files large so that you can zoom in, sorry to our dial up brothers.

 

[ShoerFast]

As it's not totally clear in the pictures,,,,, I would need to see it in person.
It looks like it's a NC return, 3 way on the pump, it would have a single pole duel throw switch (toggle up and the pump starts,,, toggle down and the NC opens the ram to return) The reason then as to why it wouldn't return is the shuttle valve is not allowing the ram to return, (fld - tank) it looks like someone has redone the ground in the past, and it has an exposed connection (were the wire color changes) but the quickest way I know to make a quick test is to just toggle the switch and listen to the clank it makes,,, a good healthy valve makes a sound double click,,,, a sick valve seems to make more of a thump, or no sound at all. The logical start point would be to replace or clean that valve.

Buy all means that valve should not be removed with out "zero" pressure on the ram!

As former Crew Chief for the Jet Dragster Earthflight, our solenoid's valves (the NHRA rules for the afterburner needed a NO return) would only fail if there were more them 5 thousand people watching,,,, with this valve, it's clear that it would wait till it has a huge load!

 

[JeffHK454]

Sorry, I thought it was a PTO driven set-up . It looks to be a single acting cyl. , can't tell if its got a line going to the top of the tube. These self contained power units have a toggle activated solenoid valve in the little manifold next to the reservoir , these solenoids get weak and generate a poor field that slows the valve activation which is made slower by cold weather.

Shoerfast is correct , first inspect the valve if it works properly then what moves the valve is most likely the culprit.

Jeff