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Greetings everyone . A few months ago I asked a question about how the Case hydrive worked and what was the difference between hydrive and hydrostatic drive - someone did answered my question , however recently my computer crashed and I unfortunately lost a bunch of stuff I saved . If it's not asking too much & the person that responded to my question the last time I asked would be willing to educate me again -I would appreciate it . In fact if anyone can answer my question I am all ears . Thanks , Mike
 

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I saved this from a forum member awhile back...so I cannot take credit for the info. Much thanks to that person.

Re: Hydrive Vs. Hydrostatic
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The difference is the way the pumps are designed. A hydraulic pump in a Hy-Drive system is known as a positive displacement gear pump. What that means is this. Everytime the engine rotates that pump one full revolution, the pump forces a pre-determined amount of oil to exit the "OUT" port on the pump. Pumps like that are "rated" in gallons per minute of oil being pumped at a certain engine rpm and a certain pressure (PSI).

The oil that is put out by a fixed displacement pump is in constant motion. It circulates through the hydraulic system continuously and therefore, makes itself available to do no tasks, one task or several tasks at the same time. That's why it will move the tractor forward or backward while spinning a hydraulic motor that is powering a rototiller, a Hydra Bagger, finishing mower, Bush Hog and so forth.

A hydrostatic pump is a totally different type of pump. It is a "variable displacement pump" which means that when it is at rest, it has no displacement so it pumps no oil at all. It just sits there rotating, ready to pump oil. In order to get it to pump oil, the operator has to use a hand or foot control that is mechanically connected to a shaft on the side of the pump. When the shaft is rotated clockwise slightly, a small amount of oil is pumped out of one side of the pump housing. If the shaft is rotated slightly counter-clockwise, then a small amount of oil is pumped out of the other side of the pump housing.

In other words, the operator can control the direction that oil flows from the pump and in turn, control the direction that the tractor moves in. The speed of the tractor is controlled by how far the shaft is moved in one direction or the other. As the amount of rotation is increased, so is the displacement of the pump. The more the displacement is increased, the greater the volume of oil leaving the pump and going to the drive motor that propels the tractor.

The "problem" with a hydro pump is that they are normally only good for one task and that is to propel the tractor in either direction If the engine is running and the tractor is sitting still, then there is no oil circulating that can be used to spin another motor or to make a hydraulic cylinder go back and forth.

Now, there are special hydrostatic pumps that have positive displacement pumps bolted to the back of them or have an internal PD pump. But can you spell E X P E N S I V E ? Not many true hydro pumps are priced below the $1000.00 mark. The stamped steel tractors you see at the big box stores all use an integrated pump/motor/trans-axle unit that is often not servicable or repairable. When something fails inside, you buy the whole thing.

This is why the Case/Ingersoll system has such a loyal following. The tractors themselves are as tough as nails, easy to work on and parts are not expensive.
 

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The information about the hydrauluics not working while the tractor is not in montion is inaccurate as far as GT hydro units are concerned.I own a lot of different brands of garden tractors with hydros and all of them equiped with hydraulics the hydraulics work just fine whether the hydro is being used to propel the tractor or not.One of the big advantages a hydro has over the Hydraulic pump and hydraulic motor system is the hydro will keep a consistant accurate flow and can be set and speed will remain constant,on my Case tractors I have to keep my hand on the speed control lever and the tractor will free wheel down a hill without holding back .Each system has its advantages and disadvantages I guess.
 

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If you read what was said, you will realize that the wording is correct. A true hydrostatic pump does not move any oil whatsoever when the tractor is standing still. If it did move oil, then the tractor would move.

All hydrostatic pumps have a secondary pump in them that is totally separate from the actual hydro pump, although it is contained in the same housing. The secondary pump is called a "charge pump" and its purpose is to circulate oil from the reservoir, into the hydro pump and back to the reservoir for cooling. It also ensures that there is a constant supply of oil available to the hydro pump for it to send to the drive motor.

On cheap hydro units, you cannot tap into the charge pump circuit but on the better ones, you can. The tractors you are referring to have the better hydro in them and that's the hydraulic power that you are referring to that is constantly available for things such as a tilt or lift cylinder for a blade or for power steering.

As for you having to keep your hand on the travel lever.....well that's due to some wear and tear items that you have not got around to replacing as of yet and not the fault of the tractor. When your Case was brand new, it was possible to set the travel speed and then go back to hanging onto that can of beer to keep it from spilling.

If you want to put an end to the runaway problem on grades, open up your wallet and buy a holding valve kit off of e-bay or buy the newer travel/lift valve with the holding feature built into it and install that one on your tractor. Once you have either of those and you repair your travel linkage, you will totally change your mind about the Hy driv system.
 

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I'm going by how different 20-40 year old GT with comparable amount of use still run and operate.I'm buying these tractors for $100-$500 so I'm not really interested in having to spending a pile of $$$$ on one for it to operate correctly.Just throwing out my experiences with them for the original poster.
 

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I'm going by how different 20-40 year old GT with comparable amount of use still run and operate.I'm buying these tractors for $100-$500 so I'm not really interested in having to spending a pile of $$$$ on one for it to operate correctly.Just throwing out my experiences with them for the original poster.
Worn linkage is worn linkage whether the tractor has hydraulic drive or hydrostatic drive. Either type of drive will fail to maintain ground speed if there is a lot of slop in the linkage or the items designed to hold the control lever/pedal in one position are incapable of doing that any longer.

In addition, the travel/lift valve with the holding feature became standard on Ingersoll tractors in 1986 which puts all models built in that year and up to 1990 in your 20 year old category. And prior to that, many tractors left the factory with the holding valve kit installed as far back as 1978 which puts those models into your 30 plus category.

The point is this. I don't think that it's very fair to make a judgment about a particular drive system in a tractor if it is not in good repair. If a particular Ferrari is in dire need of a valve job, that doesn't make all Ferrari's of the same model and year to be inferior. And if you have only experienced a Ferrari that is well-worn, then how are you in a position to judge how good a Ferrari actually is?

But that's just me throwing out my own personal experiences. Everyone else's mileage may vary.
 

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I'm not basing it on just one I now have 3 Case GT runnning and operating a 220,
444,446 and they are all pretty much the same.I use about 20 different GT on a regular basis on my farming and gardening operation including Case,Simplicity,Hines,Craftsman FF,AC,Bolens,Wheel Horse,Massey Ferguson,New Holland,Ariens,Pasquali,Ford,Bush Hog,
MTD 990 so I proably get about as good of a comparsion of the good and bad of all the brands as anyone.
 

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May I respectfully remind you what you said?

"One of the big advantages a hydro has over the Hydraulic pump and hydraulic motor system is the hydro will keep a consistant accurate flow and can be set and speed will remain constant"

That's the statement I disagree with because the same thing can be done with hydraulic drive. Whether you own one Case GT or five Case GT's, it does not matter. Parts wear out no matter the brand or the drive system. If owners refuse to replace worn out parts in a timely manner, then they can't expect the tractor to perform the way it was designed to. If I don't replace the disc brake pads on my vehicle, does that mean drum brakes are superior to discs?

Sorry but I fail to see how a badly maintained tractor has any bearing on the actual difference between hydraulic drive and hydrostatic drive. The true issue is in how the two pumps are constructed internally and not about the condition of the linkages used to control the flow of oil.
 

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I'm not basing it on just one I now have 3 Case GT runnning and operating a 220,
444,446 and they are all pretty much the same.I use about 20 different GT on a regular basis on my farming and gardening operation including Case,Simplicity,Hines,Craftsman FF,AC,Bolens,Wheel Horse,Massey Ferguson,New Holland,Ariens,Pasquali,Ford,Bush Hog,
MTD 990 so I proably get about as good of a comparsion of the good and bad of all the brands as anyone.
Just curious.... why do you have 15 different brands? Seems to me it would be a nightmare to stock filters, belts, bearings and other maintenance items, not to mention having the general knowledge to keep them all maintained and repaired.
 

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Toro I enjoy collecting a variety of useful machinery I can use here on my farm and I don't have to stock much as most are pretty trouble free and I live within 20 miles of several good parts stores and dealers.Plus there is no one garden tractor brand that does everything the best each brand has its strong and weak points and of course I buy not by brand but by availability and cost.I've ditched a couple brands because they didn't live up to their reputations at least not for me.
Castoff I understand what you're saying but I can't see spending too much money on my Case to make it usable by making the drive stay constant at a certain setting and not take off rolling down every hill.How much do you think the parts will cost me to get my 40 year old Case to operate as smoothly as my 40 year New Holland S 14 if you've ever driven an Ariens or NH S model.I like the Case in some respects but that taking off downhill free wheeling isn't going to work here it'll get me killed.It'd be really dangerous with a good size load behind it.
 

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Castoff I understand what you're saying but I can't see spending too much money on my Case to make it usable by making the drive stay constant at a certain setting and not take off rolling down every hill.How much do you think the parts will cost me to get my 40 year old Case to operate as smoothly as my 40 year New Holland S 14 if you've ever driven an Ariens or NH S model.I like the Case in some respects but that taking off downhill free wheeling isn't going to work here it'll get me killed.It'd be really dangerous with a good size load behind it.
While it might pain you greatly to release $20.00 and the moths from your wallet to buy an Operator's Manual from bhildret, by reading that book you would learn how to control those three Case GT's you own while descending grades. :sidelaugh

Aside from that, a new neutral safety switch cost about $35.00 and is a key component in keeping the travel lever in one spot. If the tension spring is weak, I'm sure that it's only a few bucks.

Holding valve kits sell on e-Bay for $175.00 to $225.00 plus shipping and provide absolute control over these tractors. One of the premier makers of helmets for motorcycling and racing is Bell. Back in the sixties they had a slogan that went like this. "If you consider your head to be worth only $10.00, then go buy a $10.00 helmet."

You obviously see this "runaway" problem as a threat to your personal safety so let me ask you this. How much is your safety worth to you?
 

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As for me, I just use the travel control lever when going down hill. A little reverse pressure goes a long way. The ratcheting-type sound might bother your ears, but not nearly as much as these trees will bother your head,arms,legs etc,etc!! Just as an aside: does the holding device only work in low range? Thanks and regards as always: Jack-(not really a baptist but I've fallen:thThumbsU into the nearby river occasionally).
 

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If you're Baptist Jack I must be Psychic as I see a couple Case parts tractors in my future(LOL)
LOL! I have 2 case 446's that will probably hit the parts bin here shortly. The Onan's that came off them are now in parts. Sold my 444 as a non running parts tractor.
For the 446's the Onan's just arent worth rebuilding. A Briggs repower from smallenginewarehouse I think is a better option but I dont plan to keep the 446's so why waste the money. Parts anyone? :trink39:
 
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