Hydraulic Question-Restricted Orifice Fitting

[Bl8tant]

I installed some modifications to my hydraulic log splitter, and I needed to slow down one of the cylinders. I found and installed restricted orifice fittings on the work ports of one of the hydraulic control valves. They definitely work! It slowed the cylinder down to a crawl (which is what I wanted). Now for a few questions for those with hydraulic know-how...

Specs:
6.5 HP motor
11 GPM Barnes Pump
Prince Log Splitter control valve
3.5" Bore, 1.75" Rod cylinder

When I cycle the cylinder, it is obvious that the motor labors a little bit and the cylinder moves very slow (which is good in my case).

1) Since the orifice in the fitting is soooo tiny, and the pump is trying to push 11gpm through it, do you think it is causing the pump to go to the 2nd stage (and that's why the motor labors a little)? Or is it actually forcing 11gpm through that little hole?

2) Since the fluid is being forced through a tiny hole it must have incredible velocity. Is there any chance that the tiny stream could erode the hose?

3) Judging by the fluid, it appears that the tiny orifice causes a lot of aeration. OR...does the pump itself induce some aeration and it's normal? The cylinder with the restricted orifice(s) is seldom cycled ,so even if it is the source, it should not create a problem?

4) This question is a genreal one......My pump seems noisy to me. The whine from it can be heard (loudly) over the engine. Is that normal? I just don't know how noisy these things can be. It works fine (the splitting ram moves at the same speed since new,it kicks down in the hard stuff, etc) but I just don't recall the pump always being so noisy. I changed the filter (my splitter was built with the filter on the suction side) and it sounds the same. I have plenty of fluid.

Sorry for the long post and zillion questions, but I wanted to see what other folks have to say.

Thanks

 

[redprospector]

I know just enough about hydraulic's to keep myself in trouble, but................ I don't think your pump should be making that much noise, and air in the system is your enemy.
One thing I do know is that by restricting the flow that circuit will generate a lot more heat in the system.

Andy

 

[Lignum]

When I changed out my pump, the new orifice used a 1/2 inch npt, the old pump used a 7/16 fpt. The larger orifice made my pump a whole lot quieter, and the fluid does not get near as hot.

 

[Heavyopp]

Air??

It almost sounds like the pump is cavitating or being starved of fluid. There shouldn't be any air in the fluid even when forced thru your restrictor.

Something is wrong.

When the pump kicks down into the high pressure low flow mode it should not labor your engine. I think it should do just the opposite. Kinda like when you shift you bicyle in to 1st gear when going up hill.

I don't have a solution but somethings not right.

Jer

 

[triptester]

Bl8tant, I believe you answered all your own questions correctly.

 

[Bl8tant]

heavyopp

Are you sure about the air? I always thought that a certain (small) amount of air would become entrained in the oil even in a normal (unrestricted) system. (That's why it's recommended to keep the return port and outlet ports on the tank seperated and not pointing at each other - to allow air a chance to escape before being recycled back into the pump). I will try running the splitter without running oil through the circuit with the restricted orifice fittings (I installed a selector valve so that only one circuit is active at a time) and see if the oil still looks slightly aerated.

I'm just not sure what is an acceptable level of aeration. If the answer is zero, then I have some work to do. My first inclination is to eliminate the suction side hydraulic filter even though the filter is new.

Could a faulty pump induce air?
I wonder if a bearing might be going bad?

I had the engine off, and turned the pump by hand....I could feel some resistance in a spot or two, but I thought it was trying to pump oil. My pump is below the oil level......should it turn smoothly throughout the whole rotation or will you feel resistance as it picks up the oil? Just turning it by hand I managed to pump about a tablespoon of oil out in just a few rotations.

 

[leon]

log splitter ugh!!!!!

I installed some modifications to my hydraulic log splitter, and I needed to slow down one of the cylinders. I found and installed restricted orifice fittings on the work ports of one of the hydraulic control valves. They definitely work! It slowed the cylinder down to a crawl (which is what I wanted). Now for a few questions for those with hydraulic know-how...

Specs:
6.5 HP motor
11 GPM Barnes Pump
Prince Log Splitter control valve
3.5" Bore, 1.75" Rod cylinder

When I cycle the cylinder, it is obvious that the motor labors a little bit and the cylinder moves very slow (which is good in my case).

1) Since the orifice in the fitting is soooo tiny, and the pump is trying to push 11gpm through it, do you think it is causing the pump to go to the 2nd stage (and that's why the motor labors a little)? Or is it actually forcing 11gpm through that little hole?

2) Since the fluid is being forced through a tiny hole it must have incredible velocity. Is there any chance that the tiny stream could erode the hose?

3) Judging by the fluid, it appears that the tiny orifice causes a lot of aeration. OR...does the pump itself induce some aeration and it's normal? The cylinder with the restricted orifice(s) is seldom cycled ,so even if it is the source, it should not create a problem?

4) This question is a genreal one......My pump seems noisy to me. The whine from it can be heard (loudly) over the engine. Is that normal? I just don't know how noisy these things can be. It works fine (the splitting ram moves at the same speed since new,it kicks down in the hard stuff, etc) but I just don't recall the pump always being so noisy. I changed the filter (my splitter was built with the filter on the suction side) and it sounds the same. I have plenty of fluid.

Sorry for the long post and zillion questions, but I wanted to see what other folks have to say.

Thanks

Ok before the problem gets any worse: or if you have a blown hose or get hurt


You need one-two way needle valve(restricted flow in, free flow out) on the barrel side of the cylinder to solve your problem period!!!!!!!!!!


You are blowing oil across the relief valve after the pumps drops into the lower stage and that adds air and heat to the oil-not good with a small tank.

The oil is cavitating and hammering against all the surfaces in the hydraulic system.

leon

opcorn:

 

[Orange Hill]

I am wondering if you can turn your two stage hydraulic pump into a single stage on the compression stroke. You would not be working your pump, motor, or hydraulic fluids to death and you would get a slower speed. Restricting your flow is working your splitter hard and burning more fuel. What if you put a larger diameter cylinder to slow it down? What about a stop that prevents you from fully pulling the lever all of the way open on the compression stroke. You can feather the hydraulics on a back loader but I don't know if the spool valves on a splitter work the same way or if it would wear out the valve.

Just out of curiosity why the need for slow speed?

 

[Bl8tant]

Orange:
"Just out of curiosity why the need for slow speed?"

I was afraid someone would ask I have a horz/vert splitter. Once the big logs are quartered into manageable size (vertical splitting), I prefer to finish splitting in the horizontal mode (easier on my back). There was one minor problem that anyone with one of these splitters is familiar with......the motor/tank etc is right at your feet and hinders the working zone. SOOOOO....I build a sliding mechanism that allows the whole beam to be extended 14" out from the rest of the frame. Now I have plenty of room to work. The cylinder and hydraulic circuit referenced in this thread are used to power the beam in and out. I used a selector valve to divide the pump output to either the extend circuit or to the splitting circuit. The extend circuit needed to move very slowly for safety reasons and the resricted orifices in that circuit seem to do the job. I had never used them before and just wanted some feedback on pros/cons.

Keep in mind that the circuit used to power the beam in/out may only cycle a couple times per day. Base recommendations on that duty cycle.

 

[bigjake]

Did i miss something .Did you put a bypass on it when you changed the
speed of the ram. Things cavatate becouse they either get air or most of the
time the low pressure makes the fluid boil .

 

[Bl8tant]

bigjake,

Either you missed something or I don't understand your question.

 

[turnkey4099]

Orange:
"Just out of curiosity why the need for slow speed?"

I was afraid someone would ask I have a horz/vert splitter. Once the big logs are quartered into manageable size (vertical splitting), I prefer to finish splitting in the horizontal mode (easier on my back). There was one minor problem that anyone with one of these splitters is familiar with......the motor/tank etc is right at your feet and hinders the working zone. SOOOOO....I build a sliding mechanism that allows the whole beam to be extended 14" out from the rest of the frame. Now I have plenty of room to work. The cylinder and hydraulic circuit referenced in this thread are used to power the beam in and out. I used a selector valve to divide the pump output to either the extend circuit or to the splitting circuit. The extend circuit needed to move very slowly for safety reasons and the resricted orifices in that circuit seem to do the job. I had never used them before and just wanted some feedback on pros/cons.

Keep in mind that the circuit used to power the beam in/out may only cycle a couple times per day. Base recommendations on that duty cycle.

That is one of the things I have against the verticle/horizontal splitters - all that gear right in the operator's way.

You can fine tune your restrictor fittings to move the in/out faster by drilling out the a bit bigger - don't know if that will alleviate or at least cut down on the problems.

Rube Goldberg method?? Feed that cylinder through the restrictor with the output from the splitter cylinder? Should take the load off the pump trying to squeeze all that oil through a small hole...or not?


Harry K

 

[Bl8tant]

Now that everything is up and running, I tested the extend/retract extensively yesterday. The restricted orifice is definitely the source of the (minor) aeration. I don't think it's hurting anything, as the aeration dissapates quickly. BUT, the cylinder almost seems too slow, so I may just remove the restricters all together and see what happens.

As for my noisy pump.....I'm starting to suspect that it may be bearing related. The whine changes with RPM, but seems unaffected by load. If anything, it gets quieter under load. Since it seems to work fine, I'll just run it til it breaks and wear hearing protection in the meantime. I've been looking for a good excuse to upgrade to a 13GPM pump anyways. When/if the pump ever fails I'll probably put a new filter assembly on the return side. They are cheaper and it will be less messy to change the filter. One thing they don't mention in the owners manual is that a suction-side filter mounted below the oil level will allow all the oil to drain out as soon as you remove the filter....the few paper towels I put under the filter to catch the "drips" I was expecting were quickly drowned in about a gallon of oil by the time I got the new one screwed back on. I was wrong to assume that there was some type of check valve that would prevent a "mini-geyser" of oil.

 

[triptester]

Bl8tant,

can you post pics of your beam extender.

 

[Bl8tant]

Can do.....probably. I grabbed the camera to take pictures yesterday and the batteries died as soon as I hit the power button! :censored:
Of course my stockpile of batteries got used up in all the power hungry toys our toddler got for christmas!

 

[Bl8tant]

pictures as promised

Trying anyways. It was raining and I didn't get any really good close-ups or a shot of the beam extended. The motor was another upgrade (I went from an L-Head Briggs to an OHV). Changed the Lovejoy insert from Buna to Hytrel. I also made a handy-dandy detachable handle for the beam to assist in raising the beam to the vertical position but it's not visible in the pics.

I assume one can tell from the pictures how the thing operates. This was not a cheap or practical upgrade, it's just something I wanted to do. Total cost (including engine) was probably around $600. That's just $300 short of what I paid for it new. I get cabin fever in the winter and these kind of projects keep me sane.

First picture shows the whole setup

Second picture is the selector valve

Third is the directional valve for the beam extend/retract. The restricted orifice fittings are the swivel adapters threaded into the bushings in the directional valve.

The fourth picture is what I drag the thing around with.

The fifth pictures is just another example of what I do in my spare time. It a special type of oiless, high-pressure, low-volume compressor that I built for work. It's used to run air-powered groundwater sampling pumps.



The only drawback (not for me) is that the splitter must remain hooked to the hitch. The tongue gets light when you extend the beam. BUT...I always leave it hooked up when splitting so it's no big deal to me.

 

[turnkey4099]

Can do.....probably. I grabbed the camera to take pictures yesterday and the batteries died as soon as I hit the power button! :censored:
Of course my stockpile of batteries got used up in all the power hungry toys our toddler got for christmas!

A bit OT. Camera batteries: I use 4 rechargeable and keep two of them charged and carried in the bottom of the camera case. Nothing more annoying than to be way out in the boonies with dead batteries.

Harry K

 

[Bl8tant]

Not trying to derail my own post, but does anyone have a picture or .pdf of one of the old Didier logsplitters? My dad has one that was branded as Sears Craftsman. It's almost as old as me and we have split 100's of cords of wood with it. THEN...Last year I modded it as well, but forgot to take any "before" pictures. The thing was so low to the ground it was a real backbreaker. I raised the whole platform, extended the tongue, added logcatchers, etc. We just put a new motor on it. The old 5hp Briggs was completely worn out. It still started easy and ran fine but had NO power. I checked the compression and it would not develop more than 5lbs of compression. I still can't believe it ran.

 

[triptester]

That is a nice looking mod of the splitter. I was wondering if by using a roller or two the assembly could be positioned by hand and locked in place.

On the Didier, all the pics I can find are after they have been modified so people other than midgets can comfortably use them.

 

[Bl8tant]

My original plan was to develop a manual sliding mechanism or one powered by an electric linear actuator. The actuator needed electric, so I decided against that. For a manual version, I couldn't find any type of slide other than extremely expensive linear slide tables ($1000+). So I made my own sliding mechanism.
You mention rollers.....could you describe that more or a sketch? I am planning to build a second prototype and need ideas. The hydraulic extend version I built is a neat gimmick, but far too costly to be practical.