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Some attachments have three hoses instead of the customary two. The third hose is the case drain line. Ingersoll makes a case drain kit to retrofit tractors that don't have one. However, if you are handy, you can make up your own case drain. All it consists of is a bracket mounted below the PTO valve that will allow another quick coupler to be installed. From there, a hydraulic hose connects the quick coupler to a Tee fitting that you have to install in the steel line that runs between the OUT port of the travel/lift valve and the oil cooler.
 

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At the risk of sounding stupid what purpose does it serve? Does it allow the fluid to flow back from the attachment to the pump so when and if you disconnenct the attachment you don't have to deal with the access fluid? Is having the drain somehow better than the customary two line system? I have a hydrabagger on my machine that I am planning to take off for the winter. I've seen recommendation to disconnect the supply and return lines and reconnect with a loop and to disconnect the drain but no mention of what to do at that connection point.

WM
 

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The case drain in a hydraulic motor is fundamentally a strategy for managing internal oil leakage and main seal robustness.

Basically, the inside of the motor working parts (gears, etc) operate at high pressures (say up to 2000psi). Internal sealing parts can be much more robust and cost effective, if allowed to weep just a bit of oil, rather than be 100% contained. The metal bits and castings have no problem with 2000psi, but the seals are more subject to failure.

The casting cavity in which those parts reside then has a 'case drain', so allowing those surrounding cavities to operate at return oil pressures (maybe 200 psi). Any internal leakage off the workign parts finds it way from the 2000 psi working sections, out in to the low pressure cavity and back to the reservoir.

Then, as you can surely imagine, it is much easier for the whole system to keep body seals, main shaft seals, etc. robust and intact at 200psi.

Don't confuse the 'case drain' with the Ingersoll series oil flow ... the primary oil goes from the pump, to the PTO, to the implement, back to the tractor and on in to the TCV where it does something useful like drive the tractor, and then to the reservoir. The case drain doesn't drain off 'what the implement uses', but more like 'what the implement leaks off'.

Now, this whole thing is especially motivated in a hydraulic motor supplier and equipment OEM when the implement has a lot of inertia.

If you think about the hydravac or chipper/shredder, which have a heavy high interia blower and flywheel, then that machine does not stop spinning when you shut off the PTO. It must coast down. While coasting, the motor has become an uncontrolled oil pump, with the PTO return oil circuit shut off hard. That's where the case drain is most crucial ... during coast down, that pressurized oil created by the flywheel driving the motor is simply dumped back to reservoir via the case drain circuit.

Hope that helps and isn't too redundant with posted FAQs.

Brian
 

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Willowmaster said:
At the risk of sounding stupid what purpose does it serve? WM
WM ... and certainly no sounding stupid here.

That question comes to the underlying engineering of these hydraulic systems and is a really common question as people wander in to this depth of understanding. It really is pretty simple, but neither intuitive nor necessarily common for everyone working with hydraulics.

Good to surface the learning opportunity for all, every now and again.

As for looping the PTO hose, that is common recommendation. This protects you against the PTO accidentally getting engaged and the oil flow being dead headed. If the PTO engages with nothing hooked up, the oil flow is blocked and there is no relief valve upstream. If the loop hose is in place, it is just like an implement that returns the oil flow to the tractor, but it is of course doing nothing ... just bypassing the oil safely.

The case drain fitting, when disconnected, is just like any other cap or test point on the whole system. It does nothing and needs nothing other than to keep the quick connect fitting clean so you don't introduce dirt in the system next time you hook up ...

Brian
 

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Having a case drain makes changing the hydraulic drive oil much easier. I remove the quick disconnect from the case drain hose and put the hose into a container to catch the oil and let the tractor idle until the oil flow gets airy, shut the tractor down and refill the reservoir, run to bleed out the air. You evacuate a little less oil than draining from the TCV, but a lot less messy. :lol:
Mad Mackie in CT
 

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wurkenman said:
This is what the do it yourself case drain looks like. Just tap into the return line.
Where's the smaller hose drain to? Is there a shut off valve near - I don't see one. Should there be one [shut off valve] below the tee?

Kenneth
 

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Install the case drain "Tee" in the return oil line going to the oil cooler. This way the case drain oil goes thru the oil cooler, get cooled, and then to the oil tank for reuse. Most have a quick disconnect on the other end of the hose where it connects to the implement case drain hose. Bear in mind that although these are oil return hoses, at times pressures in these hoses can get up to 200 PSI. 300 PSI working pressure hose is minimum recommended for these hoses, both oil cooler and case drain.
Mad Mackie in CT
 

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1973 Case 444, 1974 Case 644, 1976 Case 446, 1977 Case 646
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Last summer I picked up a chipper shredder that was hydraulic driven. It was not a Ingersoll brand, but maybe Bandit or something like that. I got it for $300 and it appeared to be brand new. I attached it to my 646 on the 3 pt. and ran it a few times. It seemed to shred up branches very well but chipping was another story. It was suppose to chip up to a 3" branch and did but it was a very slow process. I hauled them to the road and let the town chip them up with their much larger machine and then have them leave them for me. I use my loader to fill a oil tank trailer and put them in my nursery to rot and make topsoil. ANYWAY, it does not have a drain line, just the two lines, one in and one out. Would this make the chipper more efficient, or just a safeguard for the seals?
 

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The case drain is simply a motor construction technique to further safeguard the main shaft seal from high pressure.

Motors are made with and without case drains. Perhaps one set of machining and seal construction is more expensive, so that favors having a case drain if the equipment can tolerate it.

Ingersoll introduced case drains after several of the higher inertia machines (hydracutter, vacuum, etc) had been in the field for a while. One can only presume it was under guidance from the motor manufacturers in response to seal failures in the field.



If your implement has a case drain, you must use it.

If no case drain, then I highly recommend idling the machine to the lowest speed prior to disengaging the PTO. The lower the machine inertia at time of disengagement ... the lower the pressures the seal will see.


Brian
 

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Thank you Brian for your insight. Idling the engine down before disengagement makes perfect sense to me.

Harry
 

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It sounds to me to really protect the implement motor you could idle it down, then shut off the engine, and then shut off the pto valve.
Yes ... but to be clear it is not that simple if your motor is equipped with a case drain.

I reiterate ... DO NOT run a case drain motor without the proper circuit on your tractor and hooked up correctly. Case drain motors will not tolerate the static body pressure and WILL blow seals if they are not properly hooked up.

Brian
 

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Yes ... but to be clear it is not that simple if your motor is equipped with a case drain.

I reiterate ... DO NOT run a case drain motor without the proper circuit on your tractor and hooked up correctly. Case drain motors will not tolerate the static body pressure and WILL blow seals if they are not properly hooked up.

Brian
I should have been more clear.

I meant to safe guard the motors that do not have a case drain, do what I said. My thoughts were if it became a problem to the degree that a change was made, one should pay attention to it. So, being stuck with a design that does not have a case drain means you should be extra cautious to avoid damage.
 
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