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Ronald Hribar

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I just purchased a 616 on ebay. Does this tractor have enough hydraulic power to operate loader. Or is the pressure at 750 PSI also?
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From all the discussion I've seen about this issue, the problem is not hdraulic pressure, it's system capacity. There's not enough oil in the hydro to fill up the lift cylinders of a loader, if I recall correctly....
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The Flow and pressure from the charge pump of a hydro is not enough to run a loader satisfactorily. Thats why they put a pump on the loader external of the tractor.
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I thought it might be lower pressure. As for oil capacity , Had thought I could suppliment supply with loader frame tank. So all the attachments for the PowRMax are low pressure systems. When looking at cylinders, do not recall seeing 750 psi cylinders. Are the cylinders specific for Simplicity, or all garden tractors?
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Ron, Nearly all hydraulic cylinders are good to at least 1500 psi, some to 3500 psi. The hydrostatic systems are not designed for high pressure and high capacity. There is not enough fluid in the reservoir to cover more than a small cylinder with more than about a 4 inch stroke. Front end loaders will have as much a 20 inches of stroke with as many as four cylinders and also the cylinders are larger diameter than the small lift cylinder. The volume of fluid needed is the volume of the rod in the cylinder. This is what constitutes the difference in volume between when the cylinder is contracted and extended. You also need enough extra oil in reserve for it to cool and to allow the foam to settle out so the pump is always pumping fluid, not foam. A cylinder is a cylinder. If it bolts on, has correct stroke, is correct diameter, and will hold the required pressure. If you want more lifting power, then go to a larger diameter cylinder. Force is pressure (psi) x cylinder piston area. By-the-way, a 2500 psi cylinder will work fine on a 750 psi system. The pressure rating has to do with the burst pressure of the cylinder and the type of seals that it uses.
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So if I add an additional supply tank to system it would work? I was thinking of tank in loader frame. Or am I missing something in the return process. I have 2 one way cylinders and one two way on the loader. Would it help if they were all two way?
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quote:
Originally posted by Ronald Hribar
So if I add an additional supply tank to system it would work? I was thinking of tank in loader frame. Or am I missing something in the return process. I have 2 one way cylinders and one two way on the loader. Would it help if they were all two way?
Two way cylinders have fluid on both sides of the piston. As the piston moves, fluid on the low pressure side is displaced and forced back to the reservoir. A one way cylinder has fluid on only one side. As the piston moves, fluid from the reservoir is used with no fluid being replenished. Therefore, theoretically, a one way cylinder requires a larger reservoir. However, as Rod stated, a reservoir also permits fluid to cool and to allow the foam to settle out so the pump is always pumping fluid, not foam (which will cause cavitation). Some reservoirs may only be a plain tank, while others may require baffles. A reservoir is a very important component of a properly designed system. Position of inlet and outlet are important. (I have learned the hard way in fabricating reservoirs for my own system designs).
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Ron, I would also question the volume of the hydrostatic charge pump. These are designed to drive the tractor and also a small hydrolift cylinder. I can see the possibility that lifting the bucket of a front end loader could stop the tractor from moving if the pump is not large enough. I would not even consider trying to run a loader off the hydrostatic charge pump. Loaders should have a separate pump.
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Ron, I have a 9020 that I designed a loader for that uses the charge pump to operate it. It works pretty good for what I use it for, but a dedicated pump for the loader would work better. I modified the implement relief valve so I have about 960psi of presure, the lift cylinders are 1.5" bore, the bucket cylinder is 2" bore. I have picked up some 500# rocks with it!
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did you provide additional resvoir? are cylinders one way and two way? has it affected hydrostatic? I will not being doing heavy work, loading multch, some times top soil, biggest rock i have maybe 10 pounds, and do not have enough for bucketful.
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All the cylinders are double-acting. No I didnt ad any more oil capacity, the transmission hold six quarts. When I first purged the system I made sure the oil level stayed upto full so the pump didn't starve. It does affect the hydrostat a little, not enough to cause a problem. This loader is the best attachment, It sure beats a wheelbarrow!!
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