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How Do You Run Your Hydro?


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#16 HowardsMF155 ONLINE  

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Posted March 04, 2012 - 12:20 PM

The only time I don't run full out is when I am getting into a tight parking spot in the barn due to tractor overpopulation.


And I'm sure that doesn't happen very often :rofl2: :rofl2:

#17 TUDOR OFFLINE  

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Posted March 08, 2012 - 03:43 AM

Anything that is hydrostatic is designed for the engine to be run at full throttle when in use. I won't say I always follow this but that is how they are designed to be run as it at full RPM that the pump and motor of a hydro system have the appropriate operating pressure.


The key words, "appropriate operating pressure".

Hydros will develop full pressure at any rpm from idle to full throttle. What is missing at low throtttle settings is pump flow. Since hydraulic horsepower is a function of flow and pressure, low flow means low horsepower, even at maximum pressure. Operators try to compensate for this with a higher swash plate angle and the result most often is cavitation, felt at the drive control as a lessening of resistance of the control to movement by the operator and is often accompanied by a slight vibration. This situation is unhealthy for the pump and the cure is more revs to reduce the swash plate angle for a given ground speed.

Likewise, a low rpm may require maximum pressure to accomplish a task resulting in the relief valve actuating and dumping enough flow to relieve the overpressure. This can also be felt in the drive control as mentioned above and it carries an audio warning as well. The relief valve will emit a high pitched squeal as it pops and closes many times per second in the process of dumping pressure. Same cure, more revs.

Low rpm means low horsepower to do a task and low flow for the hydro. The hydro tries to compensate with higher pressure at the motor and the operator tries to get more fluid flow. The net result can be either of these situations or a stalled engine. Higher than normal heat generation is a given with high pressures, accompanied by insufficient fan speed for cooling. Keeping the pressure low and the fan speed up requires higher revs, but going to extremes only burns fuel unnecessarily.

I judge the hydro's horsepower required for the task at hand and set the throttle accordingly, usually 1/2 to 2/3 throttle unless travelling a distance, high tractive power is required, or the implement in use demands more. I apply the same procedures to both the K46 in my Husqvarna and the Sundstrand in my MF1655, although high tractive power is not the Husqvarna YT's strong suit.

Works for me.

Edited by TUDOR, March 08, 2012 - 04:07 AM.

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#18 bgkid2966 OFFLINE  

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Posted March 09, 2012 - 09:35 AM

I tend to use 1/2 to 3/4 throttle all the time except when the snow gets heavy to push. I am only trying to preserve a well worn K301 from an early rebuild. It already smokes and has a little rod rattle, so no pushing it for now. The CC129 seems to do well for me, and I have never had an issue with the hydro, except for leaks.

Geno
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#19 bhts OFFLINE  

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Posted March 09, 2012 - 09:47 AM

As the others have stated full throttle when i am doing anything other then putting it around.
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#20 tractorman604 OFFLINE  

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Posted March 09, 2012 - 01:14 PM

I wish i had a hydro so i get in the game.Do you have a massey hydro for sale Doug?

#21 GMGarski OFFLINE  

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Posted March 15, 2012 - 08:42 PM

Full throttle here !!!
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#22 tractorbeam OFFLINE  

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Posted March 15, 2012 - 09:52 PM

I run mine at full throttle almost all the time. I always run full when doing any type of work with the tractor. I rarely let it idle if I am off of the tractor either.

The only time I don't run full out is when I am getting into a tight parking spot in the barn due to tractor overpopulation. I have to laugh because this is me too. I have a pretty tight fit for my equipment in the shop and I refuse to leave my stuff outside.


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#23 DH1 ONLINE  

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Posted March 20, 2012 - 06:00 PM

I see that this thread is pinned.
Maybe a poll should be added so we can see a summary of what everybody does on 1 page.
-Light duty work
-Heavy duty work
-Driving around.
-???

#24 HowardsMF155 ONLINE  

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Posted March 20, 2012 - 07:48 PM

It appears that the results of that poll would be overwhelmingly for running wide open. Lots of helpful replies here, I've resolved to run my hydro wide open most of the time. Looks like it will just work out better that way.

#25 wrbourget OFFLINE  

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Posted March 23, 2012 - 07:40 AM

I found that it depends on the machine, I have many different hydro's and they all work differently. My JD L130 is strongest at 1/2 throttle and up, My 185 the hydro is just as strong at idle as it is at full throttle, my Cub cadet 123 is strong just off idle to full, and my 129 is strongest right around 3/4 throttle under load but free wheeling it works good just off idle, and that 990 with a load works good from 1/4 throttle to 1/2 throttle the governor always gives it the right amount of RPMs it needs no matter what. Personally I would never run any of my machines wide open for any extended periods of time, I always run my stuff at 3/4 throttle and if i need more power I will go full but i back off after.
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#26 William R OFFLINE  

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Posted March 24, 2012 - 07:13 PM

Just putting around I run 1/2 to 3/4 throttle. When working I run just under full throttle my JD 855 has pto speed on tach and its just under full throttle I forget rpm with out going out to look .Being interested at this point went and got my JD 140 manual it says note Always operatepower driven equipmentsuch as mower, snowthower. rotarytiller , ect, at full engine throttle unless other wise specified in the equipment operaters manual. Use the hydrostatic control lever to select a safe travel speed. Proper travel speedwill depend firston the type of equipment used on the tractor and second on field ,garden or yard conditions. Operators manual OM-M45023 Issue AO Just had to see what they recomended.
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#27 wrbourget OFFLINE  

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Posted March 24, 2012 - 09:35 PM

Just putting around I run 1/2 to 3/4 throttle. When working I run just under full throttle my JD 855 has pto speed on tach and its just under full throttle I forget rpm with out going out to look .Being interested at this point went and got my JD 140 manual it says note Always operatepower driven equipmentsuch as mower, snowthower. rotarytiller , ect, at full engine throttle unless other wise specified in the equipment operaters manual. Use the hydrostatic control lever to select a safe travel speed. Proper travel speedwill depend firston the type of equipment used on the tractor and second on field ,garden or yard conditions. Operators manual OM-M45023 Issue AO Just had to see what they recomended.

Most of us don't sit there with a tachometer and adjust throttle cable and the governor like were supposed to do, wide open throttle on the throttle lever is supposed to be what ever the engines peek RPM is by the governor with no load at all. All engines make whatever HP and torque at a certain rpm so if your hydro isn't performing like it should it's either to much throttle or not enough you dont make all the HP it can make if it's going over that RPM limit as well, it's going to start making less HP and torque.
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#28 TUDOR OFFLINE  

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Posted March 26, 2012 - 04:11 AM

All engines make whatever HP and torque at a certain rpm so if your hydro isn't performing like it should it's either to much throttle or not enough you dont make all the HP it can make if it's going over that RPM limit as well, it's going to start making less HP and torque.


Hydros in good condition perform like they should at any rpm within their rating. The only difference is that at low rpm they flow less oil and therefore deliver less power, even at relief pressure.

At an idle speed of 1200 rpm, a light hydro, such as is in a Craftsman LT can put out a little over 2 hp, whereas a Sundstrand 15 in a JD 400 will produce 4 hp at the same rpm. Since a LT/GT only requires 2 - 3 hp for movement for most normal tasks on level ground, slightly off idle is all that is required. But you're not going to move very fast (1/3 travel speed) and the pressure is going to be up there, at least to start it moving.

At 1/2 throttle (2400 rpm), the light hydro will throughput almost 5 hp. That's enough power to break traction with most LTs and more than a few GTs without traction aids (chains). At that rpm level, 2/3 of max travel speed is available and, due to the increased flow rate, less pressure is required.

At 2/3 throttle (2800 rpm), the light hydro can now produce over 5 hp and 3/4 travel speed, with a corresponding reduction in pressure.

And so it goes up to the 3600, or thereabouts, rpm that the governor is set for at full throttle. I don't know about other hydros, but the Sundstrand 15 is manufacturer rated for up to 4000 rpm.

Most of the light hydros are rated at about 7 hp with an input of 3600 rpm and are driven by engines as large as 25 hp. For such an engine to lose enough hp due to overspeed to negatively affect the hydro's performance sort of stretches the believeable. Even the big Sundstrand will only soak up 12.5 hp at 3600 rpm. At 4000 rpm, you may have a point. It will take up a whole 13.8 hp and it is conceiveable that the engine hp will drop off that fast. An older Chevy 350 might make 225 hp at 4400 rpm, but at 5100 rpm it's down to about 60 hp and the valves are floating.

Edited by TUDOR, March 26, 2012 - 04:38 AM.

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#29 wrbourget OFFLINE  

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Posted March 26, 2012 - 08:19 AM

I learned about how much a governor adjustment can effect the hydro's performance a long time ago when we had two JD 318s, they were bought at the same time one was new and the other was second hand with 30 hours on it. There was nothing different about the two except the new one would back up the trailer ramps at idle and the used one wouldn't, we really didn't think much about it till we took them out to the potato fields to do some plowing and that's when we figured out that the used one had a big problem. I drove off the trailer and went right to work and he farted around before he got to work, i had two passes done and was 1/2 way through the third when he jumped in ad he quickly caught up to me and had to slow down. We knew instantly that something was seriously wrong with it it had no power at all so we took it back and started tinkering with it to see what it was, we checked the compression, we changed the points, plugs, condenser, and all that but it just wouldn't pull like it should.

We ended up taking it back to the dealer and we said there is something wrong with the hydro in this thing fix it, well after two weeks they brought it back and said there is nothing wrong with this hydro, they checked all the pressures and all that and all was with in spec, they said we didn't set the points right and that's what the problem was. I tried it and i knew it wasn't fixed, but i did notice that the when you loaded the engine the guvnor didn't dip in like the other one did, it just lunged the engine down so that's where i stated looking. What i did was a side by side comparison and what i found was that the gov spring was in a lower hole on the arm its self so i put the spring in the same hole as it was on the new machine and took it out and tried it.

Right away i thought i had the problem solved because it backed on the trailer at idle, so i didn't even bother trying it i just figured it was fixed and used the tractor all summer long with no troubles, it wasn't till we went to go plow with it that it was obvious it still had a problem. If it wasn't for the other tractor we more than likely would have not noticed it had a problem but it was still much slower than the other one, so it was back to fooling around with it and all that. Out of frustration we took it to another JD mechanic who had it for a while and his assessment was, "it just has different characteristics than the other one" blah blah blah and so on.

I kept playing with it till one night about 11:30 or so all the planets must of alined just right, i had bought a little tool for checking the tension on the gov. spring and was pulling on it and i just happened to be looking down the carb at the same time and noticed the butter fly wasn't opening to full throttle. After further inspection it was going wide open the problem was that it was going past wide open and was closing, once that was adjusted properly the two tractors would run in tandem like two trains running down the track.

The whole point here is that little maladjustment on the governor, it was just a little tweak with a pair of needle nose pliers that cut the performance of the hydro in 1/2. In the first 30 hours in the life of that tractor something happened to the engine, the engine was taken apart for some reason we will never know, but when it was put back together the gov. setting were ignored and if it wasn't for comparing it to the other tractor we would not have known there was a lack of power and speed.

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Edited by wrbourget, March 27, 2012 - 06:45 AM.

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#30 TUDOR OFFLINE  

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Posted March 26, 2012 - 10:16 PM

That sounds like an engine problem which had nothing to do with the hydro. The difference in performance was purely engine rpm which would naturally affect whatever transmission, hydro or gear, that it was powering.

Engines create the power that transmissions apply to the rear end. If the power is not available, you can't affix the blame to the transmission.

You did an excellent job of finding out why the engine was not producing the power that it should have and then taking the necessary corrective action to remedy the situation.

Well done!!
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