Hyd. quick connect problems?

[diggerjim]

I plan on building a 3 pt. hyd. winch attachment. /w3tcompact/icons/hmm.gif While reading thru an old Farm Journal I came across an article claiming the quick connect/disconnect couplers reduce flow by as much as 5-7 gpm. Has anyone experienced problems using quick connecters?

Thanks in advance
Jim

 

[Phred]

Jim,

Maybe I am missing something but the quick couplings are industry standard. Ones like
<A target="_blank" HREF=http://www.parker.com/quickcouplings/>http://www.parker.com/quickcouplings/</A>

The connector will not block the flow or reduce it per say. What it will do is drop the pressure a little due to the turbulence in the flow through the connector. But then again a pipe or any other connector will also drop the pressure some what.
If you glance at the 8200 series which is typical of many tractors the chart from parker shows that the pressure drop increases as the flow rate increases. But even at 10 GPM, which is a pretty big compact tractor the 1/2 coupling only drops 20 psi. Working presure is probably ~2700 psi. So thats 0.7% drop. You will never notice.

Fred

 

[rdbrumfield]

I mounted an 8000lb unit in my loader and am using the extra remote ports on my 5300 jd. no problems. Its's been on there for 5 yrs. Here's a pic.

 

[diggerjim]

Fred and Randall
I was just wondering the implications of using the quick disconnects with a hyd. motor to power the winch. I understand (somewhat) that Pasquels(?) law says pressure will remain nearly constant regardless of the shape of the vessel, but the QD connectors would restrict flow due to the smaller orfice that the fluid must flow thru. That flow would in turn then be used to run the hyd. motor...just concerned with if I should use a PTO stand alone system as I'm sure my Yanmar has a very limited hyd. capability. I like to thouroughly research design limitations and forseeable flaws before I build.

Thanks very much for the imput and I really like the pic of the winch on the FEL.../w3tcompact/icons/smile.gif /w3tcompact/icons/smile.gif /w3tcompact/icons/smile.gif

 

[rdbrumfield]

Hi Diggerjam;
My hyd system put out 16-18 gal a min.
The quick disconnects, I don't think hold the oil back much at all. They are the same ones that jd engineered for anything that you would hook to them. My loader hooks into the stock ports on the back and the remote I use for the winch is the same. If you were restricting much you should hear the relief howling. With mine putting 18 gpm, anything less would be not be a problem.
I haven't checked the line speed on it, but it is in tune with the tractor when I'm in 3 in creep gear. That is if I'm stuck and am pulling with the winch and helping with the tires, there is no noticable slippage from the tires.
The winch is a 36-1 ratio. I used 90 w that it came with but there was always seepage. I filled it with some good grease and I mean filled full. It just about doubled the pulling power, I couldn't believe the difference. It will pull the tractor on dry pavement in four wheel drive with the brakes locked up.
What you can't see, is a sturdy eye that I can attach a small pulley to on the backside of the bucket. I use that at times if I need a sideways pull, keeps the line going in the winch properly.
I have some rear winch pics from pto units that I built. The winch is the same, just a hyd unit instead. I need to get them scanned though.
have fun with it, Randall

 

[rdbrumfield]

I might add that a pto system is cheaper and will pull harder and faster.
the other thing is if you are using a high mount winch, one that sit on a deck rather than down between the frame, be sure the the line is spooled underneath when coming into the winch. Coming over the top puts unneccesarry strain on the attaching bolts and could possibly rip the winch off the mount.
When I build for a customer, I use 9-1 gears. Gives me about 200 fpm at 1000 pto rpm.
Randall

 

[HayDR]

The winch likely bypasses at 4-6 gal a min. A winch does not demand much flow. Anything that is in the lines like a valve or coupler restricts flow and creates heat. The big thing is dissipation of that heat. A good rule of thumb for systems without an oil cooler is for every one gal. of flow per min. you need 2 gal. of reserve of unused oil. Most implements do not demand more than 6-8 gal a min. so 1/2" couplers are acceptable. If you run a hammer mill that demands 12 GPM or above it is best to use 3/4" couplers so the couplers are not adding extra heat to the system. The problem is if you have a compact tractor that has 3/8" couplers the flow should not exceed 3-4 GPM or you will risk damage to the hyd. system on the tractor because the tractor can not dissipate the heat quick enough because of a small amount of hyd. oil in its reservoir. It an attachment just needs 3 GPM and your tractor is putting out 10 GPM then this will cause heat problems very quickly. Most utility size tractors have flow adjustments so an operator can slow the flow down so excess heat in not created by the bypass of extra oil flow not needed. If you hear the tractor valve squealing then you are forcing too much oil to the implement.

 

[hazmat]

CCI,

My TC has an oil Cooler, not sure about the yanmar

Pascal's law applies to static situations (non-flowing) <A target="_blank" HREF=http://www.svce.ac.in/~msubbu/FM-WebBook/Unit-I/PascalsLaw.htm>pascal's law</A>

Fluid Dynamics 101

Pressure (psi) and flow (gpm) are inter-related and depend on several factors.

#1: Pump performance curve, usually given as Pressure vs. flow. For a given pump The higher the pressure the lower the flow & the higher the flow, the lower the pressure

#2: Plumbing: Size of pipe, surface finish etc. Larger pipe will allow more flow for a given pressure. Or, to get the same flow out of a smaller pipe, you have to increase the pressure. All pipe has pressure loss associated with it, X psi per unit length.

#3: Restrictions: We often talk about "reducing the flow" or "restricting the flow" The missing part is for a given pressure. If you could bump up the system pressure, you can get back to the original flow rate. As a restriction reduces the flow, the pressure rises. What you "hear" is the pressure relief valve operating as you exceed the designed system pressure.

A flow reducer is an intentional restriciton. If it is calibrated it will indicate X GPM at Y Pressure. If it is adjustable, you will find that it closely follows the pump performance curve. A well designed flow reducer will divert the excess back to the reservior.

One thing to keep in mind, is that due to the conservation of mass, the flow is the same everywhere in the system. it doesn't start as 10GPM at the pump and come down to 3GPM at a restriction, it is 3GPM everywhere. (unless you have parallel circuits, but that's a lesson for a different day).

OK, lesson is over. Bottom line, the quick connectors are designed to be as unrestrictive as possible thus they should have no problem powering your winch. They should also have a rating; Ie 10GPM at 2000psi with 5psi pressure drop. Where does the pressure go? As other's have mentioned mostly heat.

Edit here:

A note regarding heat. The pump is what puts energy into the fluid. If you crank up the pump, but don't flow any fluid, you get alot of heat as it is stiring up the fluid that isn't going anywhere. Most (if not all tractors) return the fluid to the reservoir if no circuits are energized (Open Center). Keeping thngs cool.

CCI is correct regarding too much fluid towards an attachement, then you get excess heat buildup. Basically the attachment is a restriction that isn't returning the excess flow to the reservoir, it is increasing the pressure is the system. the relief valve blows, but doesn't flow enough fluid & the pump starts cooking the oil.

So size your pump to the winch or get a flow reducer that returns fluid to the reservoir.

 

[diggerjim]

hazmat
Thanks for the info. I'm quite aware of heat buildup. My trencher attachment has its own power unit. The heat is substantial if I encounter hard digging. The unit has a oil cooler with fan. It cycles on and off by temp. sensor. Its quite nice during the winter with enough heat to warm up to. In the summer its a bummer.

After considering all the info I've decided to go pto power to the winch unless I come up with a FEL with a stand alone hyd. system. I think my Yanmar's hyd. pump may be too weak to utilize for equipment requirements. Thanks for the lessons tho as I'm sure the information will be used later.

Jim