How much reservoir capacity do I really need?

ptsg · Aug 22, 2021

Dstig, you'll be just fine with 12 gallons. Heck, you would be just fine with 10 or less too.

It's not that you'll be running the broom constantly under load like 8 to 12 hours a day like a construction company cleaning out old milled asphalt on a paving job... The broom will be underload going forward, then you lift it to go back or even just backing up with the broom on the ground and all the load is gone and you get minimal heat building up.

I run somewhere between 6 to 7 gallon tank on my homemade backhoe with a 9 GPM + 4GPM pumps. Yes it's way undersize but works just fine. Just using the arm, it never gets up above 100F. When using the homemade flail mower, that is most of the time under 2000 to 2600 PSI, the temps do increase to about 140F and that's still plenty fine. No harm at all.

dstig1 · Dec 11, 2021

Now that the broom is complete and I have used it a few times, I figured I would close the loop here. If you want to see that thread it is in Build it Yourself - Sweepster rebuild... (link in the first post of this thread too).

So I ended up with the tank holding ~22 gal, and I have 20 gal of fresh Dexron tranny fluid in it. Everything seems to run fine, but I am a bit disappointed about the float in the head. The springs are supposed to allow it to float, but I find it is very touchy and if the ground changes slightly and the broom digs in a bit more, it stalls the broom motor so you have to constantly adjust the joystick on the FEL to keep it in the zone. Far more than I expected.

So the hydraulics. I added a pressure gage in the line coming out of the relief valve that I can see from the cab. Relief valve is set for 2000 psi from the factory. At first I thought I would just do that to check things out, but I find it is helpful to keep track of what is going on, so i will probably leave it. When the broom motor stalls or the load is seriuosly heavy I see it go to 2000 psi but much of the time is spent in the 1200-1600ish range. At free spin unloaded I see about 500 psi. Now we just got buried in over a foot of snow and I went out once halfway yesterday evening and then this afternoon after it stopped. Brooms are not really made for this and it was moderately heavy snow too.

I have been checking temps of the tank surface with my IR gun from time to time right after I stop. Most times I am seeing 120-130F but after an earlier long stretch it got up as high as 145F. Today was brutal on it and when i finally stopped it was around 170F. That is still safe, but hotter than I would like to see. The 140ish range seems safer, but again this was a brutal test and pretty rare for up here. I thought the broom would be a good choice as most of the snows we get are much lighter (under 4"), but we do get a big dump maybe once or twice each winter.

So I am still contemplating the need for an additional radiator but not yet convinced it is necessary. Plus i have not been very excited with the performance given how poorly the float works. I'm not sure if there is a good fix for that or not, but I need to think about it some more. For the time being, it works, and is getting the job done, so I am going to keep using it this winter and see how it goes with more time under my belt.

Anyways, that is where it stands, for those who may be interested.

CJONE · Dec 12, 2021

Ok, I really did not want to comment but you are good at 170 degrees. You will not see any issues as long as your components are not worn. You want some temp in there to keep moisture at bay. I shoot for 150 to 170 degrees on the systems I build. Once you see a CONTINUOUS temp at 190+ only then would I look at cooling. As far as res size LD1 is right it means NOTHING unless you have all the info. I have systems with hydropacks (res and cooler together) running for hours at 3000psi and 35gpm. 4 gallons usable on the res. I can also take a 50 gallon res with 20 gpm of flow and bring it to 200 deg in less than 30 min by putting it over a relief at 2500 psi. So to say someone does not know what they are talking about has to be done very carefully. I will say oldnslow does and LD1 has good info. The only thing I will ask on you res is did you run your return BELOW the oil level? Cj

dstig1 · Dec 12, 2021

CJ - One of the big issues with designing this is that many things were unknown until it was built and run. I had no idea what pressures to really expect until I got it going other than they said to limit to 2000psi. Now I know more, but if I really needed to alter it, most changes at this point are major surgery of course. About the only easy thing i can do is add a radiator if I had to. This IS the prototype...

The unit is old and the motor is a question mark as to what internal condition it is in, but it does seem to work OK. One of the things that made me stop and check temps was that something seemed to be not working quite right like it wasn't throwing snow as well as it was earlier. I sensed that it had changed somewhat. So fluid at higher temps might be an issue with the degree of wear/hours the motor has on it. Perhaps. So while I get your point on keeping moisture at bay, it may not be the best for this motor to run in that 170 range. A bit of speculation in that statement, but it seems to match observations.

To answer your question, The return filter is actually located inside the tank and sticks down ~6" and should be well below the fluid level. The exit port is dead center on the bottom of the filter housing. I think fluid level is about 3-4" below the top of the tank right now with 20 gal (4x 5 gal buckets) but I should check again. I could add another gallon or two as each gallon adds about 7/8" to the fluid level but I also want to leave enough head space for expansion, etc.

Thanks for the feedback. That's why I posted it after all!
-Dave

LD1 · Dec 13, 2021

Glad it's working so far. Sounds like only some minor tweaks.

Glad you didn't go with a 10 gallon tank.

As far as the warmer fluid "maybe" making a difference....you can always try thicker fluid. Did you use iso 32, 46, or 68?

CJONE · Dec 13, 2021

dstig1 said:
CJ - One of the big issues with designing this is that many things were unknown until it was built and run. I had no idea what pressures to really expect until I got it going other than they said to limit to 2000psi. Now I know more, but if I really needed to alter it, most changes at this point are major surgery of course. About the only easy thing i can do is add a radiator if I had to. This IS the prototype...

The unit is old and the motor is a question mark as to what internal condition it is in, but it does seem to work OK. One of the things that made me stop and check temps was that something seemed to be not working quite right like it wasn't throwing snow as well as it was earlier. I sensed that it had changed somewhat. So fluid at higher temps might be an issue with the degree of wear/hours the motor has on it. Perhaps. So while I get your point on keeping moisture at bay, it may not be the best for this motor to run in that 170 range. A bit of speculation in that statement, but it seems to match observations.

To answer your question, The return filter is actually located inside the tank and sticks down ~6" and should be well below the fluid level. The exit port is dead center on the bottom of the filter housing. I think fluid level is about 3-4" below the top of the tank right now with 20 gal (4x 5 gal buckets) but I should check again. I could add another gallon or two as each gallon adds about 7/8" to the fluid level but I also want to leave enough head space for expansion, etc.

Thanks for the feedback. That's why I posted it after all!
-Dave

It will not hurt a thing to run that motor all day at 190 deg. Seals and oil are the only things in that motor effected by heat. (Within reason of course) if I remember you had trans fluid in it. That is only about a 7 weight and that is a trick I use for customers out in North Dakota for oilfield equipment when it gets cold is to cut their 15 wt with a barrel of dextron2 . Like LDI said if your suction lines are big enough to pull a 15wt fluid (aw46) then you could jump up to that BUT that is just a band aid for something slowing down as heat enters into the system, usually it is a weak pump but the motor will do the same. Under a load you can find the issue with a heat gun. If stuff is not worn it will work fine on 10 weight aw32. I normally don't get into the 20 weight aw68 unless there is piston units in the system. I understand the prototype thing but that is where you have to be able to modify easily as it is part of r and d. I rarely have a customer that can give me accurate information on torque to drive something and that is key to designing a long lasting system, most accept that a change or 2 will be needed and I just don't work for the ones that don't! Cj