Any hydraulics experts know the answer to this question.
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  1. #1
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    Any hydraulics experts know the answer to this question.

    I just reconditioned a chipper and the hydraulic pump for the infeed wheels has a 3/4" hose and connections on the suction from the hydraulic tank. I wanted a shut off valve in the line so if it blew a hose I could close the valve and not have to lose all the fluid. I had a 1/2" ball valve and all the adapters need to adapt it to the suction line. I got the machine running today and it seems to work ok but I got to thinking that maybe it was a bad idea to reduce the size of the suction line to the pump. What do you think? will reducing it to 1/2" reduce the amount of oil flow being compressed by the pump and will this make a problem for the system over time. The pump runs at about 1000 rpm and if the chipper slows down from a chipping load the pump will slow down too since it is run indirectly by the chipper shaft.

  2. #2
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    Re: Any hydraulics experts know the answer to this question.

    I don't know squat about flow rates, PSI's etc but there is a guy on another forum that knows quite a bit about the subject. I wonder if he's still kicking. Goes by the handle of TUDOR.
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  3. #3
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    Re: Any hydraulics experts know the answer to this question.

    It is not a good idea to reduce the size of the suction line to the pump. If the pump has to work to hard to suck the oil from the tank it can cause aeration of the oil and this will damage the pump.
    Mike

  4. #4
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    Re: Any hydraulics experts know the answer to this question.

    Why not just put a 3/4 valve on it? But I my opinion it probably won't make much difference as I doubt there is that much flow on that infeed pump.

  5. #5
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    Re: Any hydraulics experts know the answer to this question.

    Quote Originally Posted by ronsii View Post
    Why not just put a 3/4 valve on it? But I my opinion it probably won't make much difference as I doubt there is that much flow on that infeed pump.
    I can , I just had the 1/2" stuff around. I agree that the infeed rollers probably do not use that much power. I have no idea what amount of flow is there . This is an old 80 something Morbark 12" Disc chipper. I reconditioned it to use for one job and then I am going to sell it. It originally had a 65 hp Wisconsin V4 . The guy I got if from used the engine on something else. I adapted that Zenith 4 cylinder Hyundai Engine on to it. So now it has 85 hp at 2600 rpm. The disc is spinning at around 1000 rpm. I wish I could get it spinning at around 12-1300 rpm since I have 20% more HP but the physical restraints of the design will not allow it. I believe the original engine ran at 3000 rpm and used approxametly the same size drive sheave. So I do not think I will be able to utilize the extra power to its full extent. I think I could go up one more pulley size , that would get me to around 1090 RPM. I want to run it for a while to see how well it uses the hp before I do that though. No sense in speeding it up if it bogs down at the rpm it runs at now. I guess I will change the 1/2" ball valve out with a 3/4 just to be on the safe side. I sure do not want to weaken the infeed roller power just to save $20 on parts.

  6. #6
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    Re: Any hydraulics experts know the answer to this question.

    Have you tried the chipping part of it out to see what happens? I think I'd do that first just to see how it 'feels'.

  7. #7
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    Re: Any hydraulics experts know the answer to this question.

    Quote Originally Posted by ronsii View Post
    Have you tried the chipping part of it out to see what happens? I think I'd do that first just to see how it 'feels'.
    I am going to give it the acid test. Its a 12" chipper so I am going to feed it an 11-12 Inch log and see what happens but I think I will sneak up on it a couple inches at a time by starting with a 6" branch . It will be some time this week that I test it out. I have a short punch list of stuff that I need to do to it first before I get too serious with it.

  8. #8
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    Re: Any hydraulics experts know the answer to this question.

    The damage caused by restricting the pumps inlet will more than likely not be noticed when you "test" the chipper as above. However the damage will shorten the life of the pump and possibly other components in the hydraulic system. As i was taught by an oldtimer many years ago, "if the manufacturer could have used smaller components they would have as it would have saved them a lot of money based on the quality of the machines sold". The good thing about modifications like this is that they keep many people employed in the service industry.
    Mike

  9. #9
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    Re: Any hydraulics experts know the answer to this question.

    It may or may not work depending on position of the tank related to the pump. Also look at the other fittings in the system many times there might be a 3/4 hose but a fitting has it choked down to 1/2 or less. If you are at all worried I would just buy a bigger valve. Suction side doesn’t have to be anything special
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  10. #10
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    Re: Any hydraulics experts know the answer to this question.

    Quote Originally Posted by thegary View Post
    I just reconditioned a chipper and the hydraulic pump for the infeed wheels has a 3/4" hose and connections on the suction from the hydraulic tank. I wanted a shut off valve in the line so if it blew a hose I could close the valve and not have to lose all the fluid. I had a 1/2" ball valve and all the adapters need to adapt it to the suction line. I got the machine running today and it seems to work ok but I got to thinking that maybe it was a bad idea to reduce the size of the suction line to the pump. What do you think? will reducing it to 1/2" reduce the amount of oil flow being compressed by the pump and will this make a problem for the system over time. The pump runs at about 1000 rpm and if the chipper slows down from a chipping load the pump will slow down too since it is run indirectly by the chipper shaft.
    ok im confused???? if you blow a hose why dont you just shut the chipper off and stop pumping fluid? why do you need a valve?? do you think if a hose blows and you shut the valve faster than just shutting the chipper down??? then you starve the pump and can cause damage to the pump..hydraulic fluid is cheap compared to a new pump...I have a pto driven brush bandit chipper, it will do up to 10 inch logs, there must be a reason the manufacture doesnt put any valves inline on the hydraulics...

  11. #11
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    Re: Any hydraulics experts know the answer to this question.

    I think he want to stop the 'seep' through the pump as most of this older stuff flows pretty good even when off.

  12. #12
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    Re: Any hydraulics experts know the answer to this question.

    Quote Originally Posted by Hobbytime View Post
    ok im confused???? if you blow a hose why dont you just shut the chipper off and stop pumping fluid? why do you need a valve?? do you think if a hose blows and you shut the valve faster than just shutting the chipper down??? then you starve the pump and can cause damage to the pump..hydraulic fluid is cheap compared to a new pump...I have a pto driven brush bandit chipper, it will do up to 10 inch logs, there must be a reason the manufacture doesnt put any valves inline on the hydraulics...
    Ill tell you what , if that thing blows a hose it will empty that 8 gallon hyd. tank in probably 20-30 seconds. It will take 3-5 minutes for that 300 + pound disc to stop and that pump will be spinning dry for several minutes no matter what. The biggest reason i want it on there is to work on the system without it going all over the place. The way it was with no valve you would need to drain the tank to replace any part of the fluid system. Ronsil hit the nail on the head!

    They don't put valves on for the same reason car makers do not put drain plugs on transmissions or grease zerks on steering components.
    Last edited by thegary; 08-18-2019 at 04:37 PM.

  13. #13
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    Re: Any hydraulics experts know the answer to this question.

    Quote Originally Posted by leightrepairs View Post
    The damage caused by restricting the pumps inlet will more than likely not be noticed when you "test" the chipper as above. However the damage will shorten the life of the pump and possibly other components in the hydraulic system. As i was taught by an oldtimer many years ago, "if the manufacturer could have used smaller components they would have as it would have saved them a lot of money based on the quality of the machines sold". The good thing about modifications like this is that they keep many people employed in the service industry.
    You are probably right and that is why I started this thread. If I had no concern I would not have posted it. Yes it probably would not show up until it is too late. I already said I was going to change it.

  14. #14
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    Re: Any hydraulics experts know the answer to this question.

    Quote Originally Posted by farmshop View Post
    It may or may not work depending on position of the tank related to the pump. Also look at the other fittings in the system many times there might be a 3/4 hose but a fitting has it choked down to 1/2 or less. If you are at all worried I would just buy a bigger valve. Suction side doesn’t have to be anything special
    There are no other restrictions in the system . I did not think it through when I put the valve on and it dawned on me after it was all buttoned up and I gave it a test run. The only info I have found in regard to the sizing of the suction is to use one pipe size larger than the discharge line. I believe the discharge is 3/8 but I am not sure and like leightrepairs said The maker would have used small components if they felt they could . So I am going to change it out for 3/4 stuff that way I can sleep well and have no doubts.

  15. #15
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    Re: Any hydraulics experts know the answer to this question.

    Just for reference, generally the fluid velocity in a suction line should be less then 4 feet per second and the velocity in a pressure line should be less then 25 feet per second. If the original manufacture built using what are industry accepted practices this would allow 5.5 gpm for the pump which would be 4.1 ft/sec in the suction line, assuming it has a 3/4 inch id and that would make the pressure line velocity about 16 ft/second. All that being said it would be better for the pump if in the event of a hose failure if you just left the ball valve open while the machine coasted to a stop, the oil will probably be done spraying out before you can close the valve and closing it will cause the pump to suck air and dirt in through the shaft seal.
    Mike

  16. #16
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    Re: Any hydraulics experts know the answer to this question.

    The 3/4" valve is the way to go, and the reason Morbark does not install a shut off valve on the suction line is because sooner or later some one would try to use the machine with the valve shut. A closed suction on a hydraulic pump causes serious cavitation and in a very short time makes the inside of the pump look like some one threw a hand full of sand it.

  17. #17
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    Re: Any hydraulics experts know the answer to this question.

    If you do with the ball valve I would recommend using a zip tie on the handle to prevent someone closing the valve

  18. #18
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    Re: Any hydraulics experts know the answer to this question.

    They make ball valves that can be locked open or closed.
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  19. #19
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    Re: Any hydraulics experts know the answer to this question.

    I have 2 swathers that have a 2" suction hose at the bottom of the tongue. The tongue is the oil tank. So, I don't have a problem with a ball valve. It's pure Hell to drain those tongues, and it's pure Hell to replace the supply hose without draining those tongues.

    If you're worried about accidental operation of the valve...………..TAKE THE HANDLE OFF

  20. #20
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    Re: Any hydraulics experts know the answer to this question.

    Never restrict the suction. The pressure side can be restricted a bit though.

  21. #21
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    Re: Any hydraulics experts know the answer to this question.

    I gonna guess that at least half of the machines I have with hydraulics have ball valves at the tank on the pump feed.... And so far none of them have ever been closed while the pump is in operation.

  22. #22
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    Re: Any hydraulics experts know the answer to this question.

    Ya, but you don't have a dog LIKE MY DOG. Lil' bstd will close a valve just to shut ya down at noon, when it's time for his noon treat. He's very time sensitive. I carry doggy biskitz in my pockets for such emergencies.

  23. #23
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    Re: Any hydraulics experts know the answer to this question.

    After a quick glance thru this thread I have not seen any mention of whether or not you are using a full port valve ? I'm guessing , but a full port 1/2" ball valve will out flow a reduced port 3/4" valve . Just food for thought as all valves are not the same .

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