slow loader goes fast with cylinder unhooked.

[funny farmer]

A couple months ago I was screwing around with my tractor and I noticed that the loader was dumping super fast. It's always been on the slow side, to slow for me. I noticed the pin holding the cylinder on the right side had come out so it was just the left cylinder working the loader. My question is why? The right cylinder still moved in and out, so it still worked. Maybe there痴 something wrong with it? I was thinking of hooking up the right one and unhooking the left one to see if it was just as fast or it worked at all. At the time all I did was hook the right one back up again and used it at it's normal slow speed. When I say slow I mean at least 7 seconds from full curl to full dump. Compared to about 2.5 seconds without the right one hooked up. Didn't think about it again till this morning. Maybe I'll play around with it today. Was thinking when I start pushing snow maybe I'll unhook the right cylinder so I dumps fast since weight won't be that much of an issue. It's a ford 4000 with selecto-speed, and a workmaster 888 loader.

 

[JB4310]

Just a guess but if you notice it moving faster with a full bucket dumping maybe it's the weight, only has one cylinders resistance to work against, doesn't sound safe and could damage something on the loader I would think.
JB.

 

[Farmerford]

funny farmer:

Gravity, I think. When dumping gravity pulls the bucket down. So the holding cylinder (the one hooked up) receives all the fluid from the pump and allows the bucket to move down about twice as fast. Once the bucket is at full dump, the pump output then extends the unattached cylinder. But curl should be much slower, since the pump now retracts the unattached cylinder completely before the attached one moves.

 

[funny farmer]

They will both move at the same time, and the bucket was empty at the time, and then it curls at the same speed it dumps so i don't think it's gravity. But then again, if there is wieght on the 3 pt. like a heavy hay bale, the bucket dumps slower yet, but i think thats due to more pressure in the system itself.

 

[dynasim]

IF only one cylinder is moving, you only need to move half as much oil, so they will move twice as fast(exactly twice). The cylinders are hooked up in parallel so the flow is normally split between them. If you hooked them up in series, they would alway move that fast, but the force applied would be half as much, just as if there were only one cylinder.

Chris

(You can't hook them up in series for other reasons(the shaft side is a different size than the non-shaft side).

 

[funny farmer]

I was just thinking that there was something wrong with that cylinder, that would explain how painfully slow it was.

 

[dynasim]

I need to read the post with more care. My expanation doesn't cut it(you said the cylinders were both moving). Sorry, and I don't have an explanation.

Chris

 

[J_J]

See if this makes any sense. Both the cylinders are getting the same volume, but the cylinder not hooked up is seeing min pressure, where as the other cylinder is seeing the pump pressure because it is under a load, and pressure is only developed when there is some resistance. I have a gage on my lifting cylinders, and when I am lifting just the arms with no bucket , very little pressure is produced, and I can see that on the gage. I can also see spikes going above pump pressure when I am using the bucket hard, as heavy load over bumps.

 

[Soundguy]

I would think the hyds would be lazy and extend the unloaded cyl first, then it would hit it's max, an then the pressure would come up and move the loaded cyl.. fluid power, like electons is usually lazy and takes the path of least resistance..

for all intents and purposes, pressure in all common areas of the system will be almost equal.

soundguy

 

[funny farmer]

So are we all agreeing that theres isn't anything wrong then? From what I understand thats just the way hydrolic systems work.

 

[jinman]

So are we all agreeing that theres isn't anything wrong then? From what I understand thats just the way hydrolic systems work.

What you should see with one cylinder's pin disconnected and dumping the bucket is as follows:

1. As the bucket starts to move, the disconnected cylinder goes in the opposite direction of the connected one.

2. As the bucket swings down and the connected cylinder reaches maximum extension, the unattached cylinder begins to extend and also reaches maximum.

This is because the unattached cylinder is in parallel with the attached one. The weight of the bucket wants to pull the attached cylinder down, but the flow of hydraulic fluid from the pump is limited. Therefore, the attached cylinder sucks fluid out of the top of the unattached cylinder until it reaches maximum extension, when the pressure from the pump then sends fluid to the disconnected cylinder and pushes it out to its maximum extension. If both cylinders are extending together, then there is something really, really strange going on.

Watch your cylinders closely. I'd bet what I describe above is what is happening. Your slow normal operation is due to your tractor not having a lot of hydraulic flow to the FEL. Your pump probably only has 4 gpm maximum while newer tractors have 8-10 gpm or more.

 

[Knight]

Some loader control valves deal with slow dump speed by having a regenerative dump built into the curl spool valve. Instead of circulating oil through pump, oil is bypassing the tractor pump and just redirected back into the starving side of the cylinder and using the weight of the load to speed up the dump.
If you don't have this option built in, then you will have a slower dump speed and I would say that is normal.

 

[funny farmer]

I finally got the tractor started today,(had problems due to the cold) I took out that pin and operated the controls to see what was really happening. You guys were right, the left piston fills up with fluid first, and then the right one will extend out. It makes sense to me now with that scenario playing out; I thought it was the other way around which didn't make sense. I started feeding out round bales today with only the one cylinder hooked up, and the way the bucket was bouncing and putting that much more pressure on the one side, I made a decision to hook it back up. Guess I'll just deal with it being slow. Thanks for all your comments and advise, it wasn't a serious issue, just my curiosity.

 

[kennyd]

Does your tractor have a externally driven hydraulic pump? Like that's driven from a belt or shaft? If so, then you might be able to upgrade the pump to one with more flow.

 

[J_J]

I have three hydraulic pumps on my Power-Trac, and one of them is driven by the fan belt. I would think you would be able to hook up another hyd pump. with more capacity, and therefore give better response.

 

[J_J]

I have three hydraulic pumps on my Power-Trac, and one of them is driven by the fan belt. I would think you would be able to hook up another hyd pump. with more capacity, and therefore give better response.

Perhaps there is a way to combine the flow from two different pump, by using check valves and adding a tee fitting to combine flow and send it to the loader valve.

 

[funny farmer]

thanks everyone, I think I'll just stay with what I've got. I've dealt with it the last 5 years so I'll just have to accept it.