Need advice on hydraulic hose sizing for loader YM2220D

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parabola
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Need advice on hydraulic hose sizing for loader YM2220D

Postby parabola » Sat Mar 23, 2019 8:28 am

Howdy all,
Long time lurker here, first time poster! Really appreciate the wealth of knowledge here; it has served me well during maintenance and some repairs. I have some fairly detailed questions below so any info shared would certainly be put to use. Please bear with me while i explain things.

I have an 83 YM2220D with 917 hours assuming the instrument cluster is original. It has a Koyker 150 loader and am currently rebuilding the cylinders to seal things up again. The hydraulic hoses have also seen better days so I have decided to piece together some replacements from Surplus Center in preparation for the season and could use some advice on hose sizing from any hydraulic gurus out there.

The loader currently has all 3/8" (-6) hoses with -8 fittings. That's 3/8" hose from the head to the valve, valve to hard lines, and to the lift and curl cylinders from the hard lines. Head, valve, and bungs on the cylinders are all -8 1/2" fittings. The cylinders are all 2" (1.25" rod). The loader has performed fine in the past five or so years i have owned the tractor, although i have no basis for comparison, nor do i know if things have been running hot because lines are actually too small. My initial thought was to step up the size of the hoses to 1/2" (-8) to match the fittings. However, the more I learn about hydraulic hose sizing, and the more I think about my particular system design, the more questions I have. Here is the manual for my loader to get a picture of the hose and hard line layouts... http://www.koykermfg.com/images/koyker-manuals/archived/150.pdf Again, I do have the 2" cylinders option.

I have looked at many nomographs for hydraulic hose sizing like this https://www.ryco.com.au/technical/general-information/hose-size-selection-nomograph/ and the data says my situation could benefit from 1/2" hoses, but there are some details i still need to work out.

My 276D shop manual (same as 2220D evidently) states that my hydraulic pump output is 8.24gpm at 2600 rpms. That sounds high to me when considering that most of the other Yanmar owners on forums i have seen have pumps that output in the 4-5 gpm range. If I take my 8.24gpm and draw a line to the sweet spot of 15 ft/s velocity on that sizing nomograph, i get a spot on recommendation for 1/2" hose (-8). Now if I draw a line between 8.24ish gpm and my existing 3/8" hose, the chart shows well over 20ft/s velocity which all the info sites says is inefficient and will create excessive heat, etc.

The more I look at my system, I don't think the answer is as straight forward as looking at that nomograph. Particularly with my pump in that I am putting a lot of faith in considering 8.24gpm a fact. Can anyone confirm that 8.24gpm is indeed the output of my pump?? Surely tolerances are less now some 36 years later of use. Plus, i really do not run this joker at 2600 rpms as it seems pretty wound out. These two things would decrease flow rating right off the bat i would think. With that in mind, let's estimate flow is around 6.5gpm at say 2000-2200ish rpms- at the same desired 15 ft/s velocity target on the nomograph, i get a hose size smack dab in between 3/8 and 1/2. The lower the estimated gpm, the closer to 3/8" recommendation I get. Similar results for other lower than 8.24 gpm what-if scenarios.

I still feel like there are other considerations still. I know that everyone says to opt for larger hose size for longer hose runs. Longest hoses in my system are from the head to the valve, and of course the metal hard lines on the loader itself, which measure out really close to 1/2" I.D. Another point of confusion for me is how to treat the hoses that tee into (or wye off of rather) the hard line for each function. Two hoses (one for each left cylinder, one for each right cylinder) feed off of each hard line on the loader. Seems keeping the hose size for each cylinder hose the same size as the hard line they feed off of would be excessive and might slow the operation down. Granted, i do not have much practical hydraulic knowledge, just basing any fluid dynamic assumptions on what i have seen hotrodding and wrenching on cars.

With all that info and analysis, here are some different options i have come up with:
1) quit got dang overthinking things and go with the same 3/8" size hoses that have been on there for however many years
2) step up to all 1/2" hoses with the goal that efficiency would increase
3 )hybrid approach: go 1/2" hoses to and from head and valve, and maybe even from valve to loader hard lines, but go with 3/8 hose to the cylinders from the hard lines since they in essence tee off of each hard line anyway, also with the goal that efficiency would increase and hope that performance would increase as well. Here, longer lengths would follow recommendations for a bigger size, and even if the sections of hose from hard line to the cylinders were undersized at 3/8", meaning higher end of velocity, but they are shorter which recommendations say is okay

Please let me know what you guys think or if you need any other information to continue the discussion.

A huge thank you for reading and any practical wisdom or book knowledge you can pass along! I hope finalize my parts list and put in an order as soon as possible, so much appreciated.
Thanks again,
Matt in NC with 1983 YM2220D

winston
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Re: Need advice on hydraulic hose sizing for loader YM2220D

Postby winston » Sun Mar 24, 2019 1:45 pm

I think your 3/8" are more than adequate. I had a 2002D yanmar with 1/4" hoses and now own a 2008 Bobcat CT235 which also has 1/4" hose. The Bobcat implement pump is rated at 7.94 gpm. Loader response is quick even at idle. My loader has 2-1/2" cylinders.

Aaron
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Location: Iowa Park, TX

Re: Need advice on hydraulic hose sizing for loader YM2220D

Postby Aaron » Sun Mar 24, 2019 6:56 pm

I agree. I don't think you would notice any difference increasing to 1/2". I will see if I can find the actual GPM tomorrow but Im pretty sure it is under 8gpm.

parabola
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Re: Need advice on hydraulic hose sizing for loader YM2220D

Postby parabola » Mon Mar 25, 2019 7:34 am

Many thanks, gentlemen. Appreciate your time and information. I have 2 of the cylinders rebuilt now. Man, those piston seals are a real B@#$^! Even after heating them up in pan of hydro fluid with heat gun and infrared thermo to 210*+. I found pushing the seals over a greased long funnel to limber them up a little right before wrangling into the piston recesses worked. Glands are a cakewalk in comparison. No leaks though after running.

I had hoped rebuilt cylinders would solve my leak down issue on the lift action in addition to stopping the fluid losses. Does not seem to be the case...still leaking down slowly about 6" or so before ultimately holding solid. The 3PH does not do this so i feel the issue is in the loader valve. Tilt is fine, looking like the culprit is lift circuit not seating. May just go with this brand spankin new valve with the new hoses https://www.surpluscenter.com/Hydraulics/Hydraulic-Valves/Directional-Control-Valves/2-Spool-Compact-10-GPM-Joystick-Control-Valve-9-7401.axd, bend the joystick shaft to bring knob up a little, and call it a day (still need to check mounting bolt hole centerlines). Regen would be nice. I'll save the original valve for surgery at a later date to have on standby for when I find a neat use for it.

Thanks again Winston and Aaron. If you happen to run across that GPM rating for the 2220D, please let me know.
Cheers,
Matt
YM2220D
Koyker model 150 loader
North Carolina :D

Aaron
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Posts: 2896
Joined: Thu Jul 26, 2007 12:39 pm
Location: Iowa Park, TX

Re: Need advice on hydraulic hose sizing for loader YM2220D

Postby Aaron » Mon Mar 25, 2019 2:25 pm

One of the US models that uses that same pump says 6.2gpm which is more in line with what I would have guessed.

parabola
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Re: Need advice on hydraulic hose sizing for loader YM2220D

Postby parabola » Tue Mar 26, 2019 8:23 am

Very nice, thanks Aaron! Much appreciated. 3/8" all the way :mrgreen:
YM2220D
Koyker model 150 loader
North Carolina :D


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