Conveyor hydraulic question

[muddstopper]

mudstopper: That's incredible. Thanks for taking the time.
Can't imagine what goes into something more complicated, like a processor.
I too have been watching some of the other Lunch Box series.

I call KevinJ for advise when I cant figure things out. I just found the lunchbox videos. Another site I refer to from time to time is . While I was laid up after surgery, I watched every video in the series. 40 years working with hydraulics and just now learning how some of those parts actually work

 

[Sandhill Crane]

keven j:
I may have misspoke on which line from the flow control is return to tank. It isn't as obvious as I thought in the photo as the tank and pump are not shown. In the third photo the lower line appears to be from the pump but not certain. There is definitely a third port however.
Photos of original set up do show it..

 

[ChoppyChoppy]

Smaller line at the top of the tank (abive the suction line is the return

 

[ChoppyChoppy]

Did you plumb that?

It's back assward from how I'd do it.

Id have gone valve, then flow control. The way you have it, the up down and belt motion is both controlled by the flow control.

The return line from the valve should be at the top of the tank, not bottom. Suction lines at the bottom, return at top.
Block that tank flange and T into the top port. Or weld another fitting in the top. (Tank flange is about $5)

Also replace those hose clamps with T bolt clamp.
The return hose can be downsized too, I'd bet 1/2" would be fine. 1" is good to 70gpm.

 

[Del_]

Did you plumb that?

It's back assward from how I'd do it.

Id have gone valve, then flow control. The way you have it, the up down and belt motion is both controlled by the flow control.
That is a flow divider and sure looks like the correct way to plumb it.


The return line from the valve should be at the top of the tank, not bottom. Suction lines at the bottom, return at top.
Block that tank flange and T into the top port. Or weld another fitting in the top. (Tank flange is about $5)
The return line is at the top of the tank and suction at the bottom.

Also replace those hose clamps with T bolt clamp.
The return hose can be downsized too, I'd bet 1/2" would be fine. 1" is good to 70gpm.
The return line should be larger than the pressure line because in cylinder retraction mode the return flow is higher than the pressure by the exact amount of fluid that the rod displaces, which can be significant.

 

[muddstopper]

Del, I think Valley has a point concerning the flow control location. The original Cv was a single spool to control just the conveyor. I suspect Sand just installed the new double spool valve and connected the conveyor cyl with out changing any thing else. Valley is correct that as plumbed, the flow control is effecting the cyl performance as well as the hyd motor. Whether or not it should be changed could be debated. As for moving it to the motor circuit, would this move make the hyd cyl uncontrollable. As I see it, the conveyor lift probably isnt used that much so I doubt it would make much difference.

 

[Del_]

My mistake. I was thinking the flow control valve was dividing flow between the hydraulic log splitter ram and the conveyor. I see now that the conveyor has it's own motor and hydraulic system.

 

[kevin j]

OK so it is a priority divider as I assumed. Just confirming 3 hoses.

Everyone's comments are correct. It originally controlled the flow to the motor in both directions. If it was after the control valve it would only control one direction and would have to have a free flow check in the reverse direction thus no control of reverse direction. Quite appropriate where they put it originally.
Once the second function has been added the flow control will control the speed of both ( or the total flow the sum of the two if both levers are move at the same time,) I would suspect that you want far less flow to the lift cylinder anyway so the speed is still being metered by feathering the control lever. I would leave the flow control as is just it's easier and no real disadvantages

- return flow should always go into a tank below the oil level or have a downpipe that gets it down below the oil level or there will be serious aeration. So the one going into the bottom of the tank I would definitely leave in place.

- OK seeing the return flow from the priority flow control going to the top of the tank, this is a long shot but it's possible that the bypass returning above oil level is aerating the oil and causing compressible oil plus air mixture driving the conveyor. That would remain with air in the hoses and would cause some compression when you start the circuit up.
however that should not of changed when you put a different valve in.

you said this issue only occurs first start up of the day and after that the conveyor moves right away at startup. i'm not sure why that would happen under this theory. if the oil is aerated it should be sluggish on each start up and each time you start the conveyor on and off even when the engine continues to run

try these things: 1. check your oil in the tank and see if it looks milky or foamy after you've run the system. that would indicate aeration. can you see the return oil when the system is running? Maybe through the fill port or with one of those fancy little cell phone fiber optic cameras would be cool. Can you tell if the oil is coming into tank above the surface?
2. start the conveyor in the morning note that sluggish start, run a little bit then leave the engine on but move the control valve to neutral to stop the conveyor. Let it sit a few seconds and restart with the control lever is it sluggish when you start and stop the conveyor with the engine continuing to run
3. extend the return hose from the flow control if needed and poke it through the fill port down to the bottom of the tank so you know it's below the oil level. you will have to wire the hose in place because once the system starts the oil pressure will push the hose out of the tank and make a mess. Then cover the opening from dirt then run the conveyor as normal and see if this issue occurs the next morning when you restart

as I said I don't quite understand why this would change with the new valve that you installed if the hose connection to the tank has not changed but I learned long ago cover all the obvious bases first then start looking for things that may or may not make sense.


-power steering pumps are usually vane pumps and probably 1000 psi max on most cars. Most of them have a priority divider built into the pump, because you want constant speed steering not sluggish during when parking and superfast during at freeway speed. The priority divider gives a constant gallon or so flow to a typical power steering system.
I saw an older government publication about making a hydraulic log splitter from a power steering pump and a Briggs motor. Thousand psi at one and a half gallons a minute doesn't strike me as a worthwhile project

 

[ChoppyChoppy]

My raise/lower is orificed and the flow control I normally run wide open, I had that in mind on the plumbing.
I have it at the end of the conveyor so the guy stacking in the truck can adjust the speed or stop it if he needs to.


Return should be at the top of the tank, away from suction lines. Best chance to cool and get air out.

Now if it's above the oil level or not is debatable, either way is ok. Best IMO would be just slightly under oil level.

Some equipment I have returns to the top of the tank, it doesn't aerate the oil. Some of the stuff is 35 yrs old with 20,000+ hrs.


Something I'm not seeing is a filter. That'd be a good idea to install.

Our big conveyor has it's own 6hp engine and hydraulics. It's got 8000+ hrs on it. When it's first fired up it takes a good 10-20 seconds before the chain starts moving. I've never worried about it.

"Don't fix it till its broke".. or... "if it's not broke, leave it the **** alone!"

(Things my Dad says... paraphrased and translated to English)